Sample records for bacterial production measurements

  1. Measurement of the incorporation rates of four amino acids into proteins for estimating bacterial production.

    PubMed

    Servais, P

    1995-03-01

    In aquatic ecosystems, [(3)H]thymidine incorporation into bacterial DNA and [(3)H]leucine incorporation into proteins are usually used to estimate bacterial production. The incorporation rates of four amino acids (leucine, tyrosine, lysine, alanine) into proteins of bacteria were measured in parallel on natural freshwater samples from the basin of the river Meuse (Belgium). Comparison of the incorporation into proteins and into the total macromolecular fraction showed that these different amino acids were incorporated at more than 90% into proteins. From incorporation measurements at four subsaturated concentrations (range, 2-77 nm), the maximum incorporation rates were determined. Strong correlations (r > 0.91 for all the calculated correlations) were found between the maximum incorporation rates of the different tested amino acids over a range of two orders of magnitude of bacterial activity. Bacterial production estimates were calculated using theoretical and experimental conversion factors. The productions calculated from the incorporation rates of the four amino acids were in good concordance, especially when the experimental conversion factors were used (slope range, 0.91-1.11, and r > 0.91). This study suggests that the incorporation of various amino acids into proteins can be used to estimate bacterial production.

  2. The effects of light, primary production, and temperature on bacterial production at Station ALOHA

    NASA Astrophysics Data System (ADS)

    Viviani, D. A.; Church, M. J.

    2016-02-01

    In the open oceans, bacterial metabolism is responsible for a large fraction of the movement of reduced carbon through these ecosystems. While broad meta-analyses suggest that factors such as temperature or primary production control rates of bacterial production over large geographic scales, to date little is known about how these factors influence variability in bacterial production in the open sea. Here we present two years of measurements of 3H-leucine incorporation, a proxy for bacterial production, at the open ocean field site of the Hawaii Ocean Time-series, Station ALOHA (22° 45'N, 158° 00'W). By examining 3H-leucine incorporation over monthly, daily, and hourly scales, this work provides insight into processes controlling bacterial growth in this persistently oligotrophic habitat. Rates of 3H-leucine incorporation were consistently 60% greater when measured in the light than in the dark, highlighting the importance of sunlight in fueling bacterial metabolism in this ecosystem. Over diel time scales, rates of 3H-leucine incorporation were quasi-sinusoidal, with rates in the light higher near midday, while rates in the dark were greatest after sunset. Depth-integrated (0 -125 m) rates of 3H-leucine incorporation in both light and dark were more variable ( 5- and 4-fold, respectively) than coincident measurements of primary production ( 2-fold). On average, rates of bacterial production averaged 2 and 4% of primary production (in the dark and light, respectively). At near-monthly time scales, rates of 3H-leucine incorporation in both light and dark were significantly related to temperature. Our results suggest that in the subtropical oligotrophic Pacific, bacterial production appears decoupled from primary production as a result of seasonal-scale variations in temperature and light.

  3. Use of the [(14)C]leucine incorporation technique to measure bacterial production in river sediments and the epiphyton.

    PubMed

    Fischer, H; Pusch, M

    1999-10-01

    Bacterial production is a key parameter for the understanding of carbon cycling in aquatic ecosystems, yet it remains difficult to measure in many aquatic habitats. We therefore tested the applicability of the [(14)C]leucine incorporation technique for the measurement of bulk bacterial production in various habitats of a lowland river ecosystem. To evaluate the method, we determined (i) extraction efficiencies of bacterial protein from the sediments, (ii) substrate saturation of leucine in sediments, the biofilms on aquatic plants (epiphyton), and the pelagic zone, (iii) bacterial activities at different leucine concentrations, (iv) specificity of leucine uptake by bacteria, and (v) the effect of the incubation technique (perfused-core incubation versus slurry incubation) on leucine incorporation into protein. Bacterial protein was best extracted from sediments and precipitated by hot trichloroacetic acid treatment following ultrasonication. For epiphyton, an alkaline-extraction procedure was most efficient. Leucine incorporation saturation occurred at 1 microM in epiphyton and 100 nM in the pelagic zone. Saturation curves in sediments were difficult to model but showed the first level of leucine saturation at 50 microM. Increased uptake at higher leucine concentrations could be partly attributed to eukaryotes. Addition of micromolar concentrations of leucine did not enhance bacterial electron transport activity or DNA replication activity. Similar rates of leucine incorporation into protein calculated for whole sediment cores were observed after slurry and perfused-core incubations, but the rates exhibited strong vertical gradients after the core incubation. We conclude that the leucine incorporation method can measure bacterial production in a wide range of aquatic habitats, including fluvial sediments, if substrate saturation and isotope dilution are determined.

  4. Use of the [14C]Leucine Incorporation Technique To Measure Bacterial Production in River Sediments and the Epiphyton

    PubMed Central

    Fischer, Helmut; Pusch, Martin

    1999-01-01

    Bacterial production is a key parameter for the understanding of carbon cycling in aquatic ecosystems, yet it remains difficult to measure in many aquatic habitats. We therefore tested the applicability of the [14C]leucine incorporation technique for the measurement of bulk bacterial production in various habitats of a lowland river ecosystem. To evaluate the method, we determined (i) extraction efficiencies of bacterial protein from the sediments, (ii) substrate saturation of leucine in sediments, the biofilms on aquatic plants (epiphyton), and the pelagic zone, (iii) bacterial activities at different leucine concentrations, (iv) specificity of leucine uptake by bacteria, and (v) the effect of the incubation technique (perfused-core incubation versus slurry incubation) on leucine incorporation into protein. Bacterial protein was best extracted from sediments and precipitated by hot trichloroacetic acid treatment following ultrasonication. For epiphyton, an alkaline-extraction procedure was most efficient. Leucine incorporation saturation occurred at 1 μM in epiphyton and 100 nM in the pelagic zone. Saturation curves in sediments were difficult to model but showed the first level of leucine saturation at 50 μM. Increased uptake at higher leucine concentrations could be partly attributed to eukaryotes. Addition of micromolar concentrations of leucine did not enhance bacterial electron transport activity or DNA replication activity. Similar rates of leucine incorporation into protein calculated for whole sediment cores were observed after slurry and perfused-core incubations, but the rates exhibited strong vertical gradients after the core incubation. We conclude that the leucine incorporation method can measure bacterial production in a wide range of aquatic habitats, including fluvial sediments, if substrate saturation and isotope dilution are determined. PMID:10508068

  5. Seasonal Bacterial Production in a Dimictic Lake as Measured by Increases in Cell Numbers and Thymidine Incorporation

    PubMed Central

    Lovell, Charles R.; Konopka, Allan

    1985-01-01

    Rates of primary and bacterial production in Little Crooked Lake were calculated from the rates of incorporation of H14CO3− and [methyl-3H]thymidine, respectively. Growth rates of bacteria in diluted natural samples were determined for epilimnetic and metalimnetic bacterial populations during the summers of 1982 and 1983. Exponential growth was observed in these diluted samples, with increases in cell numbers of 30 to 250%. No lag was observed in bacterial growth in 14 of 16 experiments. Correlation of bacterial growth rates to corresponding rates of thymidine incorporation by natural samples produced a conversion factor of 2.2 × 1018 cells produced per mole of thymidine incorporated. The mass of the average bacterial cell in the lake was 1.40 × 10−14 ± 0.05 × 10−14 g of C cell−1. Doubling times of natural bacteria calculated from thymidine incorporation rates and in situ cell numbers ranged from 0.35 to 12.00 days (median, 1.50 days). Bacterial production amounted to 66.7 g of C m−2 from April through September, accounting for 29.4% of total (primary plus bacterial) production during this period. The vertical and seasonal distribution of bacterial production in Little Crooked Lake was strongly influenced by the distribution of primary production. From April through September 1983, the depth of maximum bacterial production rates in the water column was related to the depth of high rates of primary production. On a seasonal basis, primary production increased steadily from May through September, and bacterial production increased from May through August and then decreased in September. PMID:16346743

  6. Bacterial secondary production on vascular plant detritus: relationships to detritus composition and degradation rate.

    PubMed Central

    Moran, M A; Hodson, R E

    1989-01-01

    Bacterial production at the expense of vascular plant detritus was measured for three emergent plant species (Juncus effusus, Panicum hemitomon, and Typha latifolia) degrading in the littoral zone of a thermally impacted lake. Bacterial secondary production, measured as tritiated thymidine incorporation into DNA, ranged from 0.01 to 0.81 microgram of bacterial C mg of detritus-1 day-1. The three plant species differed with respect to the amount of bacterial productivity they supported per milligram of detritus, in accordance with the predicted biodegradability of the plant material based on initial nitrogen content, lignin content, and C/N ratio. Bacterial production also varied throughout the 22 weeks of in situ decomposition and was positively related to the nitrogen content and lignin content of the remaining detritus, as well as to the temperature of the lake water. Over time, production was negatively related to the C/N ratio and cellulose content of the degrading plant material. Bacterial production on degrading plant material was also calculated on the basis of plant surface area and ranged from 0.17 to 1.98 micrograms of bacterial C cm-2 day-1. Surface area-based calculations did not correlate well with either initial plant composition or changing composition of the remaining detritus during decomposition. The rate of bacterial detritus degradation, calculated from measured production of surface-attached bacteria, was much lower than the actual rate of weight loss of plant material. This discrepancy may be attributable to the importance of nonbacterial organisms in the degradation and loss of plant material from litterbags or to the microbially mediated solubilization of particulate material prior to bacterial utilization, or both. PMID:2802603

  7. Bacterial symbionts and natural products

    PubMed Central

    Crawford, Jason M.; Clardy, Jon

    2011-01-01

    The study of bacterial symbionts of eukaryotic hosts has become a powerful discovery engine for chemistry. This highlight looks at four case studies that exemplify the range of chemistry and biology involved in these symbioses: a bacterial symbiont of a fungus and a marine invertebrate that produce compounds with significant anticancer activity, and bacterial symbionts of insects and nematodes that produce compounds that regulate multilateral symbioses. In the last ten years, a series of shocking revelations – the molecular equivalents of a reality TV show’s uncovering the true parents of a well known individual or a deeply hidden family secret – altered the study of genetically encoded small molecules, natural products for short. These revelations all involved natural products produced by bacterial symbionts, and while details differed, two main plot lines emerged: parentage, in which the real producers of well known natural products with medical potential were not the organisms from which they were originally discovered, and hidden relationships, in which bacterially produced small molecules turned out to be the unsuspected regulators of complex interactions. For chemists, these studies led to new molecules, new biosynthetic pathways, and an understanding of the biological functions these molecules fulfill. PMID:21594283

  8. Bacterial and primary production in the Greenland Sea

    NASA Astrophysics Data System (ADS)

    Børsheim, Knut Yngve

    2017-12-01

    Bacterial production rates were measured in water profiles collected in the Greenland Sea and adjacent areas. Hydrography and nutrients throughout the water column were measured along 75°N from 12°W to 10°E at 20 km distance intervals. Net primary production rates from satellite sensed data were compared with literature values from 14C incubations and used for regional and seasonal comparisons. Maximum bacterial production rates were associated with the region close to the edge of the East Greenland current, and the rates decreased gradually towards the center of the Greenland Sea central gyre. Integrated over the upper 20 m the maximum bacterial production rate was 17.9 mmol C m- 2 day- 1, and east of the center of the gyre the average integrated rate was 4.6 mmol C m- 2 day- 1. It is hypothesized that high bacterial production rates in the western Greenland Sea were sustained by organic material carried from the Arctic Ocean by the East Greenland Current. The depth profiles of nitrate and phosphate were very similar both sides of the Arctic front, with 2% higher values between 500 m and 2000 m in the Arctic domain, and a N/P ratio of 13.6. The N/Si ratio varied by depth and region, with increasing silicate depletion from 1500 m depth to the surface. The rate of depletion from 1500 m depth to surface in the Atlantic domain was twice as high as in the Arctic domain. Net primary production rates in the area between the edge of the East Greenland current and the center of the Greenland Sea gyre was 96 mmol C m- 2 day- 1 at the time of the expedition in 2006, and 78 mmol C m- 2 day- 1 east of the center including the Atlantic domain. Annual net primary production estimated from satellite data in the Greenland Sea increased substantially in the period between 2003 and 2016, and the rate of increase was lowest close to the East Greenland Current.

  9. Bacterial Cellulose Production from Industrial Waste and by-Product Streams.

    PubMed

    Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

    2015-07-01

    The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102-138 g · water/g · dry bacterial cellulose, viscosities of 4.7-9.3 dL/g, degree of polymerization of 1889.1-2672.8, stress at break of 72.3-139.5 MPa and Young's modulus of 0.97-1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

  10. Bacterial Cellulose Production from Industrial Waste and by-Product Streams

    PubMed Central

    Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

    2015-01-01

    The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients. PMID:26140376

  11. Bacterial cellulose as an example product for sustainable production and consumption.

    PubMed

    Jang, Woo Dae; Hwang, Ji Hyeon; Kim, Hyun Uk; Ryu, Jae Yong; Lee, Sang Yup

    2017-09-01

    Life cycle of bacterial cellulose. Sustainable production and consumption of bio-based products are showcased using bacterial cellulose as an example. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  12. Seasonal and spatial patterns of heterotrophic bacterial production, respiration, and biomass in the subarctic NE Pacific

    NASA Astrophysics Data System (ADS)

    Sherry, Nelson D.; Boyd, Philip W.; Sugimoto, Kugako; Harrison, Paul J.

    1999-11-01

    Heterotrophic bacterial biomass, production, and respiration rates were measured during winter, spring, and summer in the subarctic NE Pacific from September 1995 to June 1997. Sampling took place on six cruises at five hydrographic stations along the east/west line-P transect from slope waters at P4 (1200 m depth) to the open-ocean waters at Ocean Station Papa (OSP) (4250 m depth). Interannual variability was small relative to seasonal and spatial variability. Biomass, derived from cell counts (assuming 20 fg C cell -1), was ca. 12 μg C l -1 in the winter and increased to 20-35 μg C l -1 in the spring and summer all along line-P. Bacterial production from [ 3H]-thymidine and [ 14C]-leucine incorporation rates was lowest in the winter (ca. 0.5 μg C l -1 d -1) with little spatial variability. Production increased 10-fold in spring at P4 (to ca. 4.5 μg C l -1 d -1). In contrast, only a 2-fold increase in bacterial production was observed over this period at the more oceanic stations. Rates of production in late summer were highest over the annual cycle at all stations ranging from ca. 6 at P4 to ca. 2 μg C l -1 d -1 at OSP. Bacterial (<1 μm size fraction) respiration, measured from dark-bottle O 2 consumption over 24 or 48 h, was <10 μg C l -1 d -1 during the winter and spring. Respiration rates increased >10-fold to ca. 100 μg C l -1 d -1 at P4 in the summer, but, interestingly, did not increase from spring to summer at the more oceanic stations. Thus bacterial growth efficiency, defined as production/(production+respiration), decreased in the spring westwards from the slope waters (P4) to the open-ocean (OSP), but increased westwards in the summer. Bacterial production was highly correlated with temperature at OSP ( r2=0.88) and less so at P4 ( r2=0.50). The observed temporal and spatial trends presented in this study suggest that seasonal changes in bacterial biomass were greatly affected by changes in loss processes, that bacterial biomass is regulated by

  13. Production of bacterial cellulose from alternate feedstocks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    D. N. Thompson; M. A. Hamilton

    2000-05-07

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS and HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  14. Production of Bacterial Cellulose from Alternate Feedstocks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thompson, David Neil; Hamilton, Melinda Ann

    2000-05-01

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS & HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  15. Method for Bacterial Growth and Ammonia Production and Effect of Inhibitory Substances in Disposable Absorbent Hygiene Products.

    PubMed

    Forsgren-Brusk, Ulla; Yhlen, Birgitta; Blomqvist, Marie; Larsson, Peter

    The purpose of this study was to evaluate a pragmatic laboratory method to provide a technique for developing incontinence products better able to reduce malodor when used in the clinical setting. Bacterial growth and bacterially formed ammonia in disposable absorbent incontinence products was measured by adding synthetic urine inoculated with bacteria to test samples cut from the crotch area of the product. The inhibitory effect's of low pH (4.5 and 4.9) and 3 antimicrobial substances-chlorhexidine, polyhexamethylene biguanide (PHMB), and thymol-at 2 concentrations each, were studied. From the initial inocula of 3.3 log colony-forming units per milliliter (cfu/mL) at baseline, the bacterial growth of the references increased to 5.0 to 6.0 log cfu/mL at 6 hours for Escherichia coli, Proteus mirabilis, and Enterococcus faecalis. At 12 hours there was a further increase to 7.0 to 8.9 log cfu/mL. Adjusting the pH of the superabsorbent in the incontinence product from 6.0 to pH 4.5 and pH 4.9 significantly (P < .05) inhibited the bacterial growth rates, in most cases, both at 6 and 12 hours. The effect was most pronounced at pH 4.5. Chlorhexidine had significant (P < .05) inhibitory effect on E. coli and E. faecalis, and at 12 hours also on P. mirabilis. For PHMB and thymol the results varied. At 6 hours, the ammonia concentration in the references (pH 6.0) was 200 to 300 ppm and it was 1500 to 1600 ppm at 8 hours. At pH 4.5, no or little ammonia production was measured at 6 and 8 hours. At pH 4.9, there was a significant reduction (P < .01). Chlorhexidine and PHMB exerted a significant (P < .01 or P < .001) inhibitory effect on ammonia production at both concentrations and at 6 and 8 hours. Thymol 0.003% and 0.03% showed inhibitory effect at both 6 hours (P < .01 or P < .001) and at 8 hours (P < .05 or P < .001). The method described in this study can be used to compare the ability of various disposable absorbent products to inhibit bacterial growth and ammonia

  16. Temperature controls on aquatic bacterial production and community dynamics in arctic lakes and streams.

    PubMed

    Adams, Heather E; Crump, Byron C; Kling, George W

    2010-05-01

    The impact of temperature on bacterial activity and community composition was investigated in arctic lakes and streams in northern Alaska. Aquatic bacterial communities incubated at different temperatures had different rates of production, as measured by (14)C-leucine uptake, indicating that populations within the communities had different temperature optima. Samples from Toolik Lake inlet and outlet were collected at water temperatures of 14.2 degrees C and 15.9 degrees C, respectively, and subsamples incubated at temperatures ranging from 6 degrees C to 20 degrees C. After 5 days, productivity rates varied from 0.5 to approximately 13.7 microg C l(-1) day(-1) and two distinct activity optima appeared at 12 degrees C and 20 degrees C. At these optima, activity was 2- to 11-fold higher than at other incubation temperatures. The presence of two temperature optima indicates psychrophilic and psychrotolerant bacteria dominate under different conditions. Community fingerprinting via denaturant gradient gel electrophoresis (DGGE) of 16S rRNA genes showed strong shifts in the composition of communities driven more by temperature than by differences in dissolved organic matter source; e.g. four and seven unique operational taxonomic units (OTUs) were found only at 2 degrees C and 25 degrees C, respectively, and not found at other incubation temperatures after 5 days. The impact of temperature on bacteria is complex, influencing both bacterial productivity and community composition. Path analysis of measurements of 24 streams and lakes sampled across a catchment 12 times in 4 years indicates variable timing and strength of correlation between temperature and bacterial production, possibly due to bacterial community differences between sites. As indicated by both field and laboratory experiments, shifts in dominant community members can occur on ecologically relevant time scales (days), and have important implications for understanding the relationship of bacterial

  17. Light Conditions Affect the Measurement of Oceanic Bacterial Production via Leucine Uptake

    PubMed Central

    Morán, Xosé Anxelu G.; Massana, Ramon; Gasol, Josep M.

    2001-01-01

    The effect of irradiance in the range of 400 to 700 nm or photosynthetically active radiation (PAR) on bacterial heterotrophic production estimated by the incorporation of 3H-leucine (referred to herein as Leu) was investigated in the northwestern Mediterranean Sea and in a coastal North Atlantic site, with Leu uptake rates ranging over 3 orders of magnitude. We performed in situ incubations under natural irradiance levels of Mediterranean samples taken from five depths around solar noon and compared them to incubations in the dark. In two of the three stations large differences were found between light and dark uptake rates for the surfacemost samples, with dark values being on average 133 and 109% higher than in situ ones. Data obtained in coastal North Atlantic waters confirmed that dark enclosure may increase Leu uptake rates more than threefold. To explain these differences, on-board experiments of Leu uptake versus irradiance were performed with Mediterranean samples from depths of 5 and 40 m. Incubations under a gradient of 12 to 1,731 μmol of photons m−2 s−1 evidenced a significant increase in incorporation rates with increasing PAR in most of the experiments, with dark-incubated samples departing from this pattern. These results were not attributed to inhibition of Leu uptake in the light but to enhanced bacterial response when transferred to dark conditions. The ratio of dark to light uptake rates increased as dissolved inorganic nitrogen concentrations decreased, suggesting that bacterial nutrient deficiency was overcome by some process occurring only in the dark bottles. PMID:11525969

  18. Effects of Fe nanoparticles on bacterial growth and biosurfactant production

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Vipulanandan, Cumaraswamy; Cooper, Tim F.; Vipulanandan, Geethanjali

    2013-01-01

    Environmental conditions can have a major impact on bacterial growth and production of secondary products. In this study, the effect of different concentrations of Fe nanoparticles on the growth of Serratia sp. and on its production of a specific biosurfactant was investigated. The Fe nanoparticles were produced using the foam method, and the needle-shaped nanoparticles were about 30 nm in diameter. It was found that Fe nanoparticles can have either a positive or a negative impact on the bacterial growth and biosurfactant production, depending on their concentration. At 1 mg/L of Fe nanoparticle concentration the bacterial growth increased by 57 % and biosurfactant production increased by 63 %. When the Fe nanoparticle concentration was increased to 1 g/L, the bacterial growth decreased by 77 % and biosurfactant activity was undetectable. The biosurfactant itself was not directly affected by Fe nanoparticles over the range of concentrations studied, indicating that the observed changes in biosurfactant activity resulted indirectly from the effect of nanoparticles on the bacteria. These negative effects with nanoparticle exposures were temporary, demonstrated by the restoration of biosurfactant activity when the bacteria initially exposed to Fe nanoparticles were allowed to regrow in the absence of nanoparticles. Finally, the kinetics of bacterial growth and biosurfactant production were modeled. The model's predictions agreed with the experimental results.

  19. Coupling Bacterial Activity Measurements with Cell Sorting by Flow Cytometry.

    PubMed

    Servais; Courties; Lebaron; Troussellier

    1999-08-01

    > Abstract A new procedure to investigate the relationship between bacterial cell size and activity at the cellular level has been developed; it is based on the coupling of radioactive labeling of bacterial cells and cell sorting by flow cytometry after SYTO 13 staining. Before sorting, bacterial cells were incubated in the presence of tritiated leucine using a procedure similar to that used for measuring bacterial production by leucine incorporation and then stained with SYTO 13. Subpopulations of bacterial cells were sorted according to their average right-angle light scatter (RALS) and fluorescence. Average RALS was shown to be significantly related to the average biovolume. Experiments were performed on samples collected at different times in a Mediterranean seawater mesocosm enriched with nitrogen and phosphorus. At four sampling times, bacteria were sorted in two subpopulations (cells smaller and larger than 0.25 µm(3)). The results indicate that, at each sampling time, the growth rate of larger cells was higher than that of smaller cells. In order to confirm this tendency, cell sorting was performed on six subpopulations differing in average biovolume during the mesocosm follow-up. A clear increase of the bacterial growth rates was observed with increasing cell size for the conditions met in this enriched mesocosm.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p180.html

  20. A comprehensive review of glycosylated bacterial natural products

    PubMed Central

    Elshahawi, Sherif I.; Shaaban, Khaled A.; Kharel, Madan K.

    2015-01-01

    A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts. PMID:25735878

  1. The in situ bacterial production of fluorescent organic matter; an investigation at a species level.

    PubMed

    Fox, B G; Thorn, R M S; Anesio, A M; Reynolds, D M

    2017-11-15

    Aquatic dissolved organic matter (DOM) plays an essential role in biogeochemical cycling and transport of organic matter throughout the hydrological continuum. To characterise microbially-derived organic matter (OM) from common environmental microorganisms (Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa), excitation-emission matrix (EEM) fluorescence spectroscopy was employed. This work shows that bacterial organisms can produce fluorescent organic matter (FOM) in situ and, furthermore, that the production of FOM differs at a bacterial species level. This production can be attributed to structural biological compounds, specific functional proteins (e.g. pyoverdine production by P. aeruginosa), and/or metabolic by-products. Bacterial growth curve data demonstrates that the production of FOM is fundamentally related to microbial metabolism. For example, the majority of Peak T fluorescence (> 75%) is shown to be intracellular in origin, as a result of the building of proteins for growth and metabolism. This underpins the use of Peak T as a measure of microbial activity, as opposed to bacterial enumeration as has been previously suggested. This study shows that different bacterial species produce a range of FOM that has historically been attributed to high molecular weight allochthonous material or the degradation of terrestrial FOM. We provide definitive evidence that, in fact, it can be produced by microbes within a model system (autochthonous), providing new insights into the possible origin of allochthonous and autochthonous organic material present in aquatic systems. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Bacterial and primary production in the pelagic zone of the Kara Sea

    NASA Astrophysics Data System (ADS)

    Sazhin, A. F.; Romanova, N. D.; Mosharov, S. A.

    2010-10-01

    Data on the bacterial and primary production, which were obtained simultaneously for the same water samples, are presented for three regions of the Kara Sea. The samples were collected for the transect westwards of the Yamal Peninsula, along the St. Anna Trough, and the transect in Ob Bay. Direct counts of the DAPI-stained bacterial cells were performed. The bacterial production and grazing rates were determined using a direct method when metabolic inhibitors vancomycin and penicillin were added. The primary production rates were estimated using the 14C method. The average primary production was 112.6, 58.5, and 28.7 mg C m-2 day-1, and the bacterial production was 12.8, 48.9, and 81.6 mg C m-2 day-1 along the Yamal Peninsula, the St. Anna Trough, and Ob Bay, respectively. The average bacterial carbon demand was 34.6, 134.5, and 220.4 mg C m-2 day-1 for these regions, respectively. The data obtained lead us to conclude that the phytoplankton-synthesized organic matter is generally insufficient to satisfy the bacterial carbon demand and may be completely assimilated via the heterotrophic processes in the marine ecosystems. Therefore, the bacterial activity and, consequently, the amount of the synthesized biomass (i.e., the production) both depend directly on the phytoplankton’s condition and activity. We consider these relationships to be characteristics of the Kara Sea’s biota.

  3. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  4. Engineering microbial hosts for production of bacterial natural products.

    PubMed

    Zhang, Mingzi M; Wang, Yajie; Ang, Ee Lui; Zhao, Huimin

    2016-08-27

    Covering up to end 2015Microbial fermentation provides an attractive alternative to chemical synthesis for the production of structurally complex natural products. In most cases, however, production titers are low and need to be improved for compound characterization and/or commercial production. Owing to advances in functional genomics and genetic engineering technologies, microbial hosts can be engineered to overproduce a desired natural product, greatly accelerating the traditionally time-consuming strain improvement process. This review covers recent developments and challenges in the engineering of native and heterologous microbial hosts for the production of bacterial natural products, focusing on the genetic tools and strategies for strain improvement. Special emphasis is placed on bioactive secondary metabolites from actinomycetes. The considerations for the choice of host systems will also be discussed in this review.

  5. Contrasting ability to take up leucine and thymidine among freshwater bacterial groups: implications for bacterial production measurements

    PubMed Central

    Pérez, María Teresa; Hörtnagl, Paul; Sommaruga, Ruben

    2010-01-01

    We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiography. Our results showed that leucine was taken up by 70–80% of Bacteria-positive cells, whereas only 15–43% of Bacteria-positive cells were able to take up thymidine. When a saturating substrate concentration in combination with a short incubation was used, 80–90% of Betaproteobacteria and 67–79% of Actinobacteria were positive for leucine uptake, whereas thymidine was taken up by < 10% of Betaproteobacteria and by < 1% of the R-BT subgroup that dominated this bacterial group. Bacterial abundance was a good predictor of the relative contribution of bacterial groups to leucine uptake, whereas when thymidine was used Actinobacteria represented the large majority (> 80%) of the cells taking up this substrate. Increasing the substrate concentration to 100 nM did not affect the percentage of R-BT cells taking up leucine (> 90% even at low concentrations), but moderately increased the fraction of thymidine-positive R-BT cells to a maximum of 35% of the hybridized cells. Our results show that even at very high concentrations, thymidine is not taken up by all, otherwise active, bacterial cells. PMID:19725866

  6. A panorama of bacterial inulinases: Production, purification, characterization and industrial applications.

    PubMed

    Singh, Ram Sarup; Chauhan, Kanika; Kennedy, John F

    2017-03-01

    Inulinases are important hydrolysing enzymes which specifically act on β-2, 1 linkages of inulin to produce fructose or fructooligosaccharides. Fungi, yeasts and bacteria are the potent microbial sources of inulinases. The data on bacterial inulinases is scarce as compared to other microbial sources. Inulinases yield from bacteria is very less as compared to fungal and yeast sources of inulinases. Submerged fermentation (SmF) is the method of choice for the production of inulinases from bacterial sources. Moreover, inulin is a potent substrate for the production of inulinases in SmF. Many bacterial inulinases have been reported to display magnificent environment abiding features and variability in their biophysical and biochemical properties. These properties have attracted intention of many researchers towards exploring adverse ecological niches for more distinctive inulinase producing bacterial strains. Inulinases are substantially important in current biotechnological era due to their numerous industrial applications. High fructose syrup and fructooligosaccharides are two major industrial applications of inulinases. Additionally, there are many reports on the production of various metabolites like citric acid, lactic acid, ethanol, biofuels, butanediol etc. using mixed cultures of inulinase producing organisms with other microorganisms. The present review mainly envisages inulinase producing bacterial sources, inulinase production, purification, characterization and their applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

    PubMed Central

    Busalmen, J. P.; de Sánchez, S. R.; Schiffrin, D. J.

    1998-01-01

    Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf) of 1.38 and a thickness (df) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated. PMID:9758786

  8. Production and Status of Bacterial Cellulose in Biomedical Engineering

    PubMed Central

    Moniri, Mona; Boroumand Moghaddam, Amin; Abdul Rahim, Raha; Bin Ariff, Arbakariya; Zuhainis Saad, Wan; Navaderi, Mohammad; Mohamad, Rosfarizan

    2017-01-01

    Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.

  9. Bacterial production and their role in the removal of dissolved organic matter from tributaries of drinking water reservoirs.

    PubMed

    Kamjunke, Norbert; Oosterwoud, Marieke R; Herzsprung, Peter; Tittel, Jörg

    2016-04-01

    Enhanced concentrations of dissolved organic matter (DOM) in freshwaters are an increasing problem in drinking water reservoirs. In this study we investigated bacterial DOM degradation rates in the tributaries of the reservoirs and tested the hypotheses that (1) DOM degradation is high enough to decrease DOM loads to reservoirs considerably, (2) DOM degradation is affected by stream hydrology, and (3) phosphorus addition may stimulate bacterial DOM degradation. Bacterial biomass production, which was used as a measure of DOM degradation, was highest in summer, and was usually lower at upstream than at downstream sites. An important proportion of bacterial production was realized in epilithic biofilms. Production of planktonic and biofilm bacteria was related to water temperature. Planktonic production weakly correlated to DOM quality and to total phosphorus concentration. Addition of soluble reactive phosphorus did not stimulate bacterial DOM degradation. Overall, DOM was considerably degraded in summer at low discharge levels, whereas degradation was negligible during flood events (when DOM load in reservoirs was high). The ratio of DOM degradation to total DOM release was negatively related to discharge. On annual average, only 0.6-12% of total DOM released by the catchments was degraded within the tributaries. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Anti-Biofilm Performance of Three Natural Products against Initial Bacterial Attachment

    PubMed Central

    Salta, Maria; Wharton, Julian A.; Dennington, Simon P.; Stoodley, Paul; Stokes, Keith R.

    2013-01-01

    Marine bacteria contribute significantly towards the fouling consortium, both directly (modern foul release coatings fail to prevent “slime” attachment) and indirectly (biofilms often excrete chemical cues that attract macrofouling settlement). This study assessed the natural product anti-biofilm performance of an extract of the seaweed, Chondrus crispus, and two isolated compounds from terrestrial sources, (+)-usnic acid and juglone, against two marine biofilm forming bacteria, Cobetia marina and Marinobacter hydrocarbonoclasticus. Bioassays were developed using quantitative imaging and fluorescent labelling to test the natural products over a range of concentrations against initial bacterial attachment. All natural products affected bacterial attachment; however, juglone demonstrated the best anti-biofilm performance against both bacterial species at a concentration range between 5–20 ppm. In addition, for the first time, a dose-dependent inhibition (hormetic) response was observed for natural products against marine biofilm forming bacteria. PMID:24192819

  11. Biogenic amine formation and bacterial contribution in Natto products.

    PubMed

    Kim, Bitna; Byun, Bo Young; Mah, Jae-Hyung

    2012-12-01

    Twenty-one Natto products currently distributed in Korea were analysed for biogenic amine contents and tested to determine physicochemical and bacterial contributions to biogenic amine formation. Among them, nine products (about 43%) had β-phenylethylamine or tyramine contents greater than the toxic dose (30mg/kg and 100mg/kg, respectively) of each amine, although no products showed total amounts of biogenic amines above the harmful level (1000mg/kg), which indicates that the amounts of biogenic amines in some Natto products are not within the safe level for human health. From four different Natto products, that contained noticeable levels of β-phenylethylamine and tyramine, 80 bacterial strains were isolated. All the strains were identified to be Bacillus subtilis and highly capable of producing β-phenylethylamine and tyramine. Therefore, it seems likely that the remarkable contents of β-phenylethylamine and tyramine in Natto predominantly resulted from the strains highly capable of producing those amines present in the food. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Method for construction of bacterial strains with increased succinic acid production

    DOEpatents

    Donnelly, Mark I.; Sanville-Millard, Cynthia; Chatterjee, Ranjini

    2000-01-01

    A fermentation process for producing succinic acid is provided comprising selecting a bacterial strain that does not produce succinic acid in high yield, disrupting the normal regulation of sugar metabolism of said bacterial strain, and combining the mutant bacterial strain and selected sugar in anaerobic conditions to facilitate production of succinic acid. Also provided is a method for changing low yield succinic acid producing bacteria to high yield succinic acid producing bacteria comprising selecting a bacterial strain having a phosphotransferase system and altering the phosphotransferase system so as to allow the bacterial strain to simultaneously metabolize different sugars.

  13. Anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues for methane production.

    PubMed

    Li, Guixia; Zhong, Weizhang; Wang, Rui; Chen, Jiaqi; Li, Zaixing

    2017-08-01

    Optimum anaerobic conditions of cephalosporin bacterial residues after thermal-alkaline pretreatment were determined by orthogonal experiments. And through biochemical methane potential tests (BMPs) for cephalosporin bacterial residues, the ability for bacterial degradation of cephalosporin was also evaluated. The thermal-alkaline pretreatment with the optimum values of 6% NaOH at 105 °C for 15 min significantly improved digestion performance. With the thermal-alkaline pretreatment, the specific methane yield of the pretreated cephalosporin bacterial residue increased by 254.79% compared with that of the un-pretreated cephalosporin bacterial residue. The results showed that anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues could be one of the options for efficient methane production and waste treatment. This work investigates the thermal-alkaline pretreatment of cephalosporin bacterial residues, which can increase their methane yield by 254.79% compared with no pretreatment. The digestion performance is significantly improved under the condition of 6% NaOH at 105 °C for 15 min. The results show that anaerobic digestion of thermal-alkaline-pretreated cephalosporin bacterial residues could be one of the options for efficient methane production and waste treatment.

  14. Glycerol Monolaurate Inhibits Lipase Production by Clinical Ocular Isolates Without Affecting Bacterial Cell Viability.

    PubMed

    Flanagan, Judith Louise; Khandekar, Neeta; Zhu, Hua; Watanabe, Keizo; Markoulli, Maria; Flanagan, John Terence; Papas, Eric

    2016-02-01

    We sought to determine the relative lipase production of a range of ocular bacterial isolates and to assess the efficacy of glycerol monolaurate (GML) in inhibiting this lipase production in high lipase-producing bacteria without affecting bacterial cell growth. Staphylococcus aureus,Staphylococcus epidermidis,Propionibacterium acnes, and Corynebacterium spp. were inoculated at a density of 10(6)/mL in varying concentrations of GML up to 25 μg/mL for 24 hours at 37 °C with constant shaking. Bacterial suspensions were centrifuged, bacterial cell density was determined, and production of bacterial lipase was quantified using a commercial lipase assay kit. Staphylococcus spp. produced high levels of lipase activity compared with P. acnes and Corynebacterium spp. GML inhibited lipase production by Staphylococcal spp. in a dose-dependent manner, with S. epidermidis lipase production consistently more sensitive to GML than S. aureus. Glycerol monolaurate showed significant (P < 0.05) lipase inhibition above concentrations of 15 μg/mL in S. aureus and was not cytotoxic up to 25 μg/mL. For S. epidermidis, GML showed significant (P < 0.05) lipase inhibition above 7.5 μg/mL. Lipase activity varied between species and between strains. Staphylococcal spp. produced higher lipase activity compared with P. acnes and Corynebacterium spp. Glycerol monolaurate inhibited lipase production by S. aureus and S. epidermidis at concentrations that did not adversely affect bacterial cell growth. GML can be used to inhibit ocular bacterial lipase production without proving detrimental to commensal bacteria viability.

  15. Bacterial cellulose production by Gluconacetobacter sp. PKY5 in a rotary biofilm contactor.

    PubMed

    Kim, Yong-Jun; Kim, Jin-Nam; Wee, Young-Jung; Park, Don-Hee; Ryu, Hwa-Won

    2007-04-01

    A rotary biofilm contactor (RBC) inoculated with Gluconacetobacter sp. RKY5 was used as a bioreactor for improved bacterial cellulose production. The optimal number of disk for bacterial cellulose production was found to be eight, at which bacterial cellulose and cell concentrations were 5.52 and 4.98 g/L. When the aeration rate was maintained at 1.25 vvm, bacterial cellulose and cell concentrations were maximized (5.67 and 5.25 g/L, respectively). The optimal rotation speed of impeller in RBC was 15 rpm. When the culture pH in RBC was not controlled during fermentation, the maximal amount of bacterial cellulose (5.53 g/L) and cells (4.91 g/L) was obtained. Under the optimized culture conditions, bacterial cellulose and cell concentrations in RBC reached to 6.17 and 5.58 g/L, respectively.

  16. Bacterial Cellulose Production by Gluconacetobacter sp. RKY5 in a Rotary Biofilm Contactor

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jun; Kim, Jin-Nam; Wee, Young-Jung; Park, Don-Hee; Ryu, Hwa-Won

    A rotary biofilm contactor (RBC) inoculated with Gluconacetobacter sp. RKY5 was used as a bioreactor for improved bacterial cellulose production. The optimal number of disk for bacterial cellulose production was found to be eight, at which bacterial cellulose and cell concentrations were 5.52 and 4.98 g/L. When the aeration rate was maintained at 1.25 vvm, bacterial cellulose and cell concentrations were maximized (5.67 and 5.25 g/L, respectively). The optimal rotation speed of impeller in RBC was 15 rpm. When the culture pH in RBC was not controlled during fermentation, the maximal amount of bacterial cellulose (5.53 g/L) and cells (4.91 g/L) was obtained. Under the optimized culture conditions, bacterial cellulose and cell concentrations in RBC reached to 6.17 and 5.58 g/L, respectively.

  17. Use of metabolic inhibitors to estimate protozooplankton grazing and bacterial production in a monomictic eutrophic lake with an anaerobic hypolimnion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sanders, R.W.; Porter, K.G.

    Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenical) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with (/sup 3/H)thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence ofmore » the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. The authors recommended that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors.« less

  18. RAPA: a novel in vitro method to evaluate anti-bacterial skin cleansing products.

    PubMed

    Ansari, S A; Gafur, R B; Jones, K; Espada, L A; Polefka, T G

    2010-04-01

    Development of efficacious anti-bacterial skin cleansing products has been limited by the availability of a pre-clinical (in vitro) method to predict clinical efficacy adequately. We report a simple and rapid method, designated as rapid agar plate assay (RAPA), that uses the bacteriological agar surface as a surrogate substrate for skin and combines elements of two widely used in vivo (clinical) methods (Agar Patch and Cup Scrub). To simulate the washing of the human hand or forearm skin with the test product, trypticase soy agar plates were directly washed with the test product and rinsed under running tap water. After air-drying the washed plates, test bacteria (Staphylococcus aureus or Escherichia coli) were applied and the plates were incubated at 37 degrees C for 18-24 h. Using S. aureus as the test organism, anti-bacterial bar soap containing triclocarbanilide showed a strong linear relationship (R(2) = 0.97) between bacterial dose and their per cent reduction. A similar dose-response relationship (R(2) = 0.96) was observed for anti-bacterial liquid hand soap against E. coli. RAPA was able to distinguish between anti-bacterial products based on the nature and level of actives in them. In limited comparative tests, results obtained by RAPA were comparable with the results obtained by clinical agar patch and clinical cup scrub methods. In conclusion, RAPA provides a simple, rugged and reproducible in vitro method for testing the relative efficacy of anti-bacterial skin cleansing products with a likelihood of comparable clinical efficacy. Further testing is warranted to improve the clinical predictability of this method.

  19. Bacterial Populations Associated with Smokeless Tobacco Products

    PubMed Central

    Han, Jing; Sanad, Yasser M.; Deck, Joanna; Sutherland, John B.; Li, Zhong; Walters, Matthew J.; Duran, Norma; Holman, Matthew R.

    2016-01-01

    ABSTRACT There are an estimated 8 million users of smokeless tobacco products (STPs) in the United States, and yet limited data on microbial populations within these products exist. To better understand the potential microbiological risks associated with STP use, a study was conducted to provide a baseline microbiological profile of STPs. A total of 90 samples, representing 15 common STPs, were purchased in metropolitan areas in Little Rock, AR, and Washington, DC, in November 2012, March 2013, and July 2013. Bacterial populations were evaluated using culture, pyrosequencing, and denaturing gradient gel electrophoresis (DGGE). Moist-snuff products exhibited higher levels of bacteria (average of 1.05 × 106 CFU/g STP) and diversity of bacterial populations than snus (average of 8.33 × 101 CFU/g STP) and some chewing tobacco products (average of 2.54 × 105 CFU/g STP). The most common species identified by culturing were Bacillus pumilus, B. licheniformis, B. safensis, and B. subtilis, followed by members of the genera Oceanobacillus, Staphylococcus, and Tetragenococcus. Pyrosequencing analyses of the 16S rRNA genes identified the genera Tetragenococcus, Carnobacterium, Lactobacillus, Geobacillus, Bacillus, and Staphylococcus as the predominant taxa. Several species identified are of possible concern due to their potential to cause opportunistic infections and reported abilities to reduce nitrates to nitrites, which may be an important step in the formation of carcinogenic tobacco-specific N′-nitrosamines. This report provides a microbiological baseline to help fill knowledge gaps associated with microbiological risks of STPs and to inform potential regulations regarding manufacture and testing of STPs. IMPORTANCE It is estimated that there 8 million users of smokeless tobacco products (STPs) in the United States; however, there are limited data on microbial populations that exist within these products. The current study was undertaken to better understand the

  20. Cost-effective production of bacterial cellulose using acidic food industry by-products.

    PubMed

    Revin, Victor; Liyaskina, Elena; Nazarkina, Maria; Bogatyreva, Alena; Shchankin, Mikhail

    2018-03-13

    To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  1. Bacterial production of the biodegradable plastics polyhydroxyalkanoates.

    PubMed

    Urtuvia, Viviana; Villegas, Pamela; González, Myriam; Seeger, Michael

    2014-09-01

    Petroleum-based plastics constitute a major environmental problem due to their low biodegradability and accumulation in various environments. Therefore, searching for novel biodegradable plastics is of increasing interest. Microbial polyesters known as polyhydroxyalkanoates (PHAs) are biodegradable plastics. Life cycle assessment indicates that PHB is more beneficial than petroleum-based plastics. In this report, bacterial production of PHAs and their industrial applications are reviewed and the synthesis of PHAs in Burkholderia xenovorans LB400 is described. PHAs are synthesized by a large number of microorganisms during unbalanced nutritional conditions. These polymers are accumulated as carbon and energy reserve in discrete granules in the bacterial cytoplasm. 3-hydroxybutyrate and 3-hydroxyvalerate are two main PHA units among 150 monomers that have been reported. B. xenovorans LB400 is a model bacterium for the degradation of polychlorobiphenyls and a wide range of aromatic compounds. A bioinformatic analysis of LB400 genome indicated the presence of pha genes encoding enzymes of pathways for PHA synthesis. This study showed that B. xenovorans LB400 synthesize PHAs under nutrient limitation. Staining with Sudan Black B indicated the production of PHAs by B. xenovorans LB400 colonies. The PHAs produced were characterized by GC-MS. Diverse substrates for the production of PHAs in strain LB400 were analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Bacterial community changes in an industrial algae production system.

    PubMed

    Fulbright, Scott P; Robbins-Pianka, Adam; Berg-Lyons, Donna; Knight, Rob; Reardon, Kenneth F; Chisholm, Stephen T

    2018-04-01

    While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms. Even with closed systems, bacteria are known to enter and cohabitate, but little is known about these communities. Therefore, the richness, structure, and composition of bacterial communities were characterized in closed photobioreactor cultivations of Nannochloropsis salina in F/2 medium at different scales, across nine months spanning late summer-early spring, and during a sequence of serially inoculated cultivations. Using 16S rRNA sequence data from 275 samples, bacterial communities in small, medium, and large cultures were shown to be significantly different. Larger systems contained richer bacterial communities compared to smaller systems. Relationships between bacterial communities and algae growth were complex. On one hand, blooms of a specific bacterial type were observed in three abnormal, poorly performing replicate cultivations, while on the other, notable changes in the bacterial community structures were observed in a series of serial large-scale batch cultivations that had similar growth rates. Bacteria common to the majority of samples were identified, including a single OTU within the class Saprospirae that was found in all samples. This study contributes important information for crop protection in algae systems, and demonstrates the complex ecosystems that need to be understood for consistent, successful industrial algae cultivation. This is the first study to profile bacterial communities during the scale-up process of industrial algae systems.

  3. Particulate organic matter predicts bacterial productivity in a river dominated estuary

    NASA Astrophysics Data System (ADS)

    Crump, B. C.

    2015-12-01

    Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

  4. Mass production of bacterial communities adapted to the degradation of volatile organic compounds (TEX).

    PubMed

    Lapertot, Miléna; Seignez, Chantal; Ebrahimi, Sirous; Delorme, Sandrine; Peringer, Paul

    2007-06-01

    This study focuses on the mass cultivation of bacteria adapted to the degradation of a mixture composed of toluene, ethylbenzene, o-, m- and p-xylenes (TEX). For the cultivation process Substrate Pulse Batch (SPB) technique was adapted under well-automated conditions. The key parameters to be monitored were handled by LabVIEW software including, temperature, pH, dissolved oxygen and turbidity. Other parameters, such as biomass, ammonium or residual substrate concentrations needed offline measurements. SPB technique has been successfully tested experimentally on TEX. The overall behavior of the mixed bacterial population was observed and discussed along the cultivation process. Carbon and nitrogen limitations were shown to affect the integrity of the bacterial cells as well as their production of exopolymeric substances (EPS). Average productivity and yield values successfully reached the industrial specifications, which were 0.45 kg(DW)m(-3) d(-1) and 0.59 g(DW)g (C) (-1) , respectively. Accuracy and reproducibility of the obtained results present the controlled SPB process as a feasible technique.

  5. Contribution of heterotrophic bacterial production to the carbon budget of the river Seine (France).

    PubMed

    Servais, P; Garnier, J

    1993-01-01

    Bacterial activity was measured in the river Seine by two methods, (3)H-thymidine incorporation into DNA and (3)H-leucine incorporation into proteins. Both incorporation rates are characterized by low values upstream of Paris, a large increase just downstream of the outfall of the Achères treatment plant effluents, and then decreasing values further downstream. The covariation of both activities is demonstrated by the constancy of the molar ratio (leucine to thymidine incorporation rate) in the range of 6 to 8 for all the samples, except in the perturbed area where it is higher (15 to 35). These high values of molar ratio are linked to the introduction into the river of large sized bacteria ([Symbol: see text]1 µm) with higher incorporation rates per cell or biomass unit than the small autochthonous bacteria (< 1 µm). Growth rates of large bacteria were on average 3.7 times higher than those of small bacteria. Bacterial production was calculated with experimentally determined conversion factors (0.5 × 10(18) cells per mole of thymidine incorporated and 900 gC per mole of leucine incorporated) and by taking into account the activity of both size classes of bacteria measured through fractionation experiments (post-incubation filtration). Production estimated in the perturbed area downstream of Ach6res was very high, up to 60 µgC liter(-1)h(-1) in the summer. Carbon consumption by bacteria in the area perturbed by the Ach6res effluents was calculated assuming a growth yield of 0.2 and compared to the load of biodegradable organic matter discharged by the treatment plant. In summer, an additional supply of organic matter is required to account for the intense bacterial activity, suggesting the importance of phytoplankton production in the carbon budget.

  6. In vitro effects of anthocyanidins on sinonasal epithelial nitric oxide production and bacterial physiology

    PubMed Central

    Hariri, Benjamin M.; Payne, Sakeena J.; Chen, Bei; Mansfield, Corrine; Doghramji, Laurel J.; Adappa, Nithin D.; Palmer, James N.; Kennedy, David W.; Niv, Masha Y.

    2016-01-01

    Background: T2R bitter taste receptors play a crucial role in sinonasal innate immunity by upregulating mucociliary clearance and nitric oxide (NO) production in response to bitter gram-negative quorum-sensing molecules in the airway surface liquid. Previous studies showed that phytochemical flavonoid metabolites, known as anthocyanidins, taste bitter and have antibacterial effects. Our objectives were to examine the effects of anthocyanidins on NO production by human sinonasal epithelial cells and ciliary beat frequency, and their impact on common sinonasal pathogens Pseudomonas aeruginosa and Staphylococcus aureus. Methods: Ciliary beat frequency and NO production were measured by using digital imaging of differentiated air-liquid interface cultures prepared from primary human cells isolated from residual surgical material. Plate-based assays were used to determine the effects of anthocyanidins on bacterial swimming and swarming motility. Biofilm formation and planktonic growth were also assessed. Results: Anthocyanidin compounds triggered epithelial cells to produce NO but not through T2R receptors. However, anthocyanidins did not impact ciliary beat frequency. Furthermore, they did not reduce biofilm formation or planktonic growth of P. aeruginosa. In S. aureus, they did not reduce planktonic growth, and only one compound had minimal antibiofilm effects. The anthocyanidin delphinidin and anthocyanin keracyanin were found to promote bacterial swimming, whereas anthocyanidin cyanidin and flavonoid myricetin did not. No compounds that were tested inhibited bacterial swarming. Conclusion: Results of this study indicated that, although anthocyanidins may elicited an innate immune NO response from human cells, they do not cause an increase in ciliary beating and they may also cause a pathogenicity-enhancing effect in P. aeruginosa. Additional studies are necessary to understand how this would affect the use of anthocyanidins as therapeutics. This study emphasized the

  7. Estimating bacterial production in marine waters from the simultaneous incorporation of thymidine and leucine.

    PubMed

    Chin-Leo, G; Kirchman, D L

    1988-08-01

    We examined the simultaneous incorporation of [H]thymidine and [C]leucine to obtain two independent indices of bacterial production (DNA and protein syntheses) in a single incubation. Incorporation rates of leucine estimated by the dual-label method were generally higher than those obtained by the single-label method, but the differences were small (dual/single = 1.1 +/- 0.2 [mean +/- standard deviation]) and were probably due to the presence of labeled leucyl-tRNA in the cold trichloroacetic acid-insoluble fraction. There were no significant differences in thymidine incorporation between dual- and single-label incubations (dual/ single = 1.03 +/- 0.13). Addition of the two substrates in relatively large amounts (25 nM) did not apparently increase bacterial activity during short incubations (<5 h). With the dual-label method we found that thymidine and leucine incorporation rates covaried over depth profiles of the Chesapeake Bay. Estimates of bacterial production based on thymidine and leucine differed by less than 25%. Although the need for appropriate conversion factors has not been eliminated, the dual-label approach can be used to examine the variation in bacterial production while ensuring that the observed variation in incorporation rates is due to real changes in bacterial production rather than changes in conversion factors or introduction of other artifacts.

  8. The Effect of Various Oral Hygiene Products on Bacterial Growth

    NASA Astrophysics Data System (ADS)

    Viswanath, S.; Aggrawal, A.; Vazirani, S.

    2017-12-01

    In this experiment, we tested the antimicrobial effectiveness of six different oral hygiene products. We used three natural cleansing products (coconut oil, sea salt, and baking soda), as well as three synthetic products, which were the Colgate toothpaste varieties of sensitivity, cavity protection, and whitening. We mixed water with each of the products to create a paste that could be uniformly applied to the surface of a disc. We then dipped the discs into the solutions and placed them in petri dishes that were pre-treated with bacterial cells. After 72 hours, we measured the area around the disc that was bacteria-free, which is known as the zone of inhibition. This experiment was repeated twice, with one petri dish per product for each trial, and two different types of agar. We were surprised to discover that almost all the products had no zone of inhibition, with bacteria growing throughout the petri dish, and to the disc. The only cleaning product that showed a significant antibacterial result was the Colgate sensitivity toothpaste. During the two trials, the sensitivity toothpaste had a zone of inhibition of 14.8 cm2 and 8.7 cm2, respectively. Coconut oil was the only other product to have a measurable zone of inhibition with an area of 0.3 cm2. We concluded that only the sensitivity toothpaste was effective in killing bacteria, perhaps due to its different hygienic goal of protecting the tooth's nerves. This toothpaste contains ingredients called potassium nitrate and strontium chloride, which blocks tubules in the dentin, the hard, bony tissue beneath the enamel. Sensitivity toothpaste strengthens the tooth, by blocking decaying substances such as oral bacteria (Knights, 2014).

  9. Bacterial symbionts and natural products.

    PubMed

    Crawford, Jason M; Clardy, Jon

    2011-07-21

    The study of bacterial symbionts of eukaryotic hosts has become a powerful discovery engine for chemistry. This highlight looks at four case studies that exemplify the range of chemistry and biology involved in these symbioses: a bacterial symbiont of a fungus and a marine invertebrate that produce compounds with significant anticancer activity, and bacterial symbionts of insects and nematodes that produce compounds that regulate multilateral symbioses.

  10. Bacterial and fungal composition profiling of microbial based cleaning products.

    PubMed

    Subasinghe, R M; Samarajeewa, A D; Meier, M; Coleman, G; Clouthier, H; Crosthwait, J; Tayabali, A F; Scroggins, R; Shwed, P S; Beaudette, L A

    2018-06-01

    Microbial based cleaning products (MBCPs) are a new generation of cleaning products that are gaining greater use in household, institutional, and industrial settings. Little is known about the exact microbial composition of these products because they are not identified in detail on product labels and formulations are often proprietary. To gain a better understanding of their microbial and fungal composition towards risk assessment, the cultivable microorganisms and rDNA was surveyed for microbial content in five different MBCPs manufactured and sold in North America. Individual bacterial and fungal colonies were identified by ribosequencing and fatty acid methyl ester (FAME) gas chromatography. Metagenomic DNA (mDNA) corresponding to each of the products was subjected to amplification and short read sequencing of seven of the variable regions of the bacterial 16S ribosomal DNA. Taken together, the cultivable microorganism and rDNA survey analyses showed that three of the products were simple mixtures of Bacillus species. The two other products featured a mixture of cultivable fungi with Bacilli, and by rDNA survey analysis, they featured greater microbial complexity. This study improves our understanding of the microbial composition of several MBCPs towards a more comprehensive risk assessment. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  11. Community respiration/production and bacterial activity in the upper water column of the central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Sherr, Barry F.; Sherr, Evelyn B.

    2003-04-01

    Community metabolism (respiration and production) and bacterial activity were assessed in the upper water column of the central Arctic Ocean during the SHEBA/JOIS ice camp experiment, October 1997-September 1998. In the upper 50 m, decrease in integrated dissolved oxygen (DO) stocks over a period of 124 d in mid-winter suggested a respiration rate of ˜3.3 nM O 2 h -1 and a carbon demand of ˜4.5 gC m -2. Increase in 0-50 m integrated stocks of DO during summer implied a net community production of ˜20 gC m -2. Community respiration rates were directly measured via rate of decrease in DO in whole seawater during 72-h dark incubation experiments. Incubation-based respiration rates were on average 3-fold lower during winter (11.0±10.6 nM O 2 h -1) compared to summer (35.3±24.8 nM O 2 h -1). Bacterial heterotrophic activity responded strongly, without noticeable lag, to phytoplankton growth. Rate of leucine incorporation by bacteria (a proxy for protein synthesis and cell growth) increased ˜10-fold, and the cell-specific rate of leucine incorporation ˜5-fold, from winter to summer. Rates of production of bacterial biomass in the upper 50 m were, however, low compared to other oceanic regions, averaging 0.52±0.47 ngC l -1 h -1 during winter and 5.1±3.1 ngC l -1 h -1 during summer. Total carbon demand based on respiration experiments averaged 2.4±2.3 mgC m -3 d -1 in winter and 7.8±5.5 mgC m -3 d -1 in summer. Estimated bacterial carbon demand based on bacterial productivity and an assumed 10% gross growth efficiency was much lower, averaging about 0.12±0.12 mgC m -3 d -1 in winter and 1.3±0.7 mgC m -3 d -1 in summer. Our estimates of bacterial activity during summer were an order of magnitude less than rates reported from a summer 1994 study in the central Arctic Ocean, implying significant inter-annual variability of microbial processes in this region.

  12. Estimating Bacterial Production in Marine Waters from the Simultaneous Incorporation of Thymidine and Leucine

    PubMed Central

    Chin-Leo, Gerardo; Kirchman, David L.

    1988-01-01

    We examined the simultaneous incorporation of [3H]thymidine and [14C]leucine to obtain two independent indices of bacterial production (DNA and protein syntheses) in a single incubation. Incorporation rates of leucine estimated by the dual-label method were generally higher than those obtained by the single-label method, but the differences were small (dual/single = 1.1 ± 0.2 [mean ± standard deviation]) and were probably due to the presence of labeled leucyl-tRNA in the cold trichloroacetic acid-insoluble fraction. There were no significant differences in thymidine incorporation between dual- and single-label incubations (dual/ single = 1.03 ± 0.13). Addition of the two substrates in relatively large amounts (25 nM) did not apparently increase bacterial activity during short incubations (<5 h). With the dual-label method we found that thymidine and leucine incorporation rates covaried over depth profiles of the Chesapeake Bay. Estimates of bacterial production based on thymidine and leucine differed by less than 25%. Although the need for appropriate conversion factors has not been eliminated, the dual-label approach can be used to examine the variation in bacterial production while ensuring that the observed variation in incorporation rates is due to real changes in bacterial production rather than changes in conversion factors or introduction of other artifacts. PMID:16347706

  13. Bacterial community dynamics and product distribution during pH-adjusted fermentation of vegetable wastes.

    PubMed

    Ye, N-F; Lü, F; Shao, L-M; Godon, J-J; He, P-J

    2007-10-01

    To estimate the effect of pH on the structures of bacterial community during fermentation of vegetable wastes and to investigate the relationship between bacterial community dynamics and product distribution. The bacterial communities in five batch tests controlled at different pH values [uncontrolled (about pH 4), 5, 6, 7 and 8] were monitored by denaturing gradient gel electrophoresis (DGGE) and single-strand conformation polymorphism (SSCP). The two fingerprinting methods provided consistent results and principal component analysis indicated a close similarity of bacterial community at pH 7 and 8 in addition to those at pH 4-6. This clustering also corresponded to dominant metabolic pathway. Thus, pH 7-8 shifted from alcohol-forming to acid-forming, especially butyric acid, whereas both alcohol-forming and acid-forming dominated at pH 5-6, and at pH 4, fermentation was inhibited. Shannon-weaver index was calculated to analyse the DGGE profiles, which revealed that the bacterial diversities at pH 7 and 8 were the highest while those at pH 5 and 4 (uncontrolled) were the lowest. According to sequencing results of the bands excised from DGGE gels, lactic acid bacteria and Clostridium sp. were predominant at all pH values, but varieties in species were observed as pH changed and time prolonged. The bacterial community during fermentation was materially influenced by pH and the diverse product distribution was related to the shift of different bacterial population. The study reveals that the impact of pH on fermentation product distribution is implemented primarily by changes of bacterial community. It also provides information about the comparison of two fingerprinting methods, DGGE and SSCP.

  14. Viral lysis, flagellate grazing potential, and bacterial production in Lake Pavin.

    PubMed

    Bettarel, Y; Amblard, C; Sime-Ngando, T; Carrias, J-F; Sargos, D; Garabétian, F; Lavandier, P

    2003-02-01

    Abundances of different compartments of the microbial loop (i.e., viruses, heterotrophic bacteria, nonpigmented nanoflagellates, and pigmented nanoflagellates), bacterial heterotrophic production (BHP), viral lysis, and potential flagellate grazing impacts on the bacterial assemblages were estimated during a short-term study (24 h) conducted in June 1998 in the epilimnion (5 m) and metalimnion (10 m) of a moderate-altitude oligomesotrophic lake (Lake Pavin, France). Viral and bacterial abundances were higher in the metalimnion than in the epilimnion, whereas pigmented and nonpigmented nanoflagellates were more numerous in the epilimnion. The control of the BHP due to viral lysis (determined by examination of viral-containing bacteria using a transmission electron microscope) was significantly higher in the meta- (range = 6.0-33.7%, mean = 15.6%) than in the epilimnion (3.5-10.3%, 6.4%). The same was for the losses of BHP from the potential predation by nanoflagellates which ranged from 0.5 to 115.4% (mean = 38.7%) in the epilimnion, and from 0.7 to 97.5% (mean = 66.7%) in the metalimnion. Finally, estimated viral mediated mortality rates from the percentage of visibly infected cells and potential nanoflagellate grazing rates based on assumed clearance rates suggest that flagellates consumed a larger proportion of bacterial production than was lost to viral lysis.

  15. Light-Stimulated Bacterial Production and Amino Acid Assimilation by Cyanobacteria and Other Microbes in the North Atlantic Ocean▿

    PubMed Central

    Michelou, Vanessa K.; Cottrell, Matthew T.; Kirchman, David L.

    2007-01-01

    We examined the contribution of photoheterotrophic microbes—those capable of light-mediated assimilation of organic compounds—to bacterial production and amino acid assimilation along a transect from Florida to Iceland from 28 May to 9 July 2005. Bacterial production (leucine incorporation at a 20 nM final concentration) was on average 30% higher in light than in dark-incubated samples, but the effect varied greatly (3% to 60%). To further characterize this light effect, we examined the abundance of potential photoheterotrophs and measured their contribution to bacterial production and amino acid assimilation (0.5 nM addition) using flow cytometry. Prochlorococcus and Synechococcus were abundant in surface waters where light-dependent leucine incorporation was observed, whereas aerobic anoxygenic phototrophic bacteria were abundant but did not correlate with the light effect. The per-cell assimilation rates of Prochlorococcus and Synechococcus were comparable to or higher than those of other prokaryotes, especially in the light. Picoeukaryotes also took up leucine (20 nM) and other amino acids (0.5 nM), but rates normalized to biovolume were much lower than those of prokaryotes. Prochlorococcus was responsible for 80% of light-stimulated bacterial production and amino acid assimilation in surface waters south of the Azores, while Synechococcus accounted for on average 12% of total assimilation. However, nearly 40% of the light-stimulated leucine assimilation was not accounted for by these groups, suggesting that assimilation by other microbes is also affected by light. Our results clarify the contribution of cyanobacteria to photoheterotrophy and highlight the potential role of other photoheterotrophs in biomass production and dissolved-organic-matter assimilation. PMID:17630296

  16. Ecosystem productivity is associated with bacterial phylogenetic distance in surface marine waters.

    PubMed

    Galand, Pierre E; Salter, Ian; Kalenitchenko, Dimitri

    2015-12-01

    Understanding the link between community diversity and ecosystem function is a fundamental aspect of ecology. Systematic losses in biodiversity are widely acknowledged but the impact this may exert on ecosystem functioning remains ambiguous. There is growing evidence of a positive relationship between species richness and ecosystem productivity for terrestrial macro-organisms, but similar links for marine micro-organisms, which help drive global climate, are unclear. Community manipulation experiments show both positive and negative relationships for microbes. These previous studies rely, however, on artificial communities and any links between the full diversity of active bacterial communities in the environment, their phylogenetic relatedness and ecosystem function remain hitherto unexplored. Here, we test the hypothesis that productivity is associated with diversity in the metabolically active fraction of microbial communities. We show in natural assemblages of active bacteria that communities containing more distantly related members were associated with higher bacterial production. The positive phylogenetic diversity-productivity relationship was independent of community diversity calculated as the Shannon index. From our long-term (7-year) survey of surface marine bacterial communities, we also found that similarly, productive communities had greater phylogenetic similarity to each other, further suggesting that the traits of active bacteria are an important predictor of ecosystem productivity. Our findings demonstrate that the evolutionary history of the active fraction of a microbial community is critical for understanding their role in ecosystem functioning. © 2015 John Wiley & Sons Ltd.

  17. Production of Phloroglucinol, a Platform Chemical, in Arabidopsis using a Bacterial Gene.

    PubMed

    Abdel-Ghany, Salah E; Day, Irene; Heuberger, Adam L; Broeckling, Corey D; Reddy, Anireddy S N

    2016-12-07

    Phloroglucinol (1,3,5-trihydroxybenzene; PG) and its derivatives are phenolic compounds that are used for various industrial applications. Current methods to synthesize PG are not sustainable due to the requirement for carbon-based precursors and co-production of toxic byproducts. Here, we describe a more sustainable production of PG using plants expressing a native bacterial or a codon-optimized synthetic PhlD targeted to either the cytosol or chloroplasts. Transgenic lines were analyzed for the production of PG using gas and liquid chromatography coupled to mass spectroscopy. Phloroglucinol was produced in all transgenic lines and the line with the highest PhlD transcript level showed the most accumulation of PG. Over 80% of the produced PG was glycosylated to phlorin. Arabidopsis leaves have the machinery to glycosylate PG to form phlorin, which can be hydrolyzed enzymatically to produce PG. Furthermore, the metabolic profile of plants with PhlD in either the cytosol or chloroplasts was altered. Our results provide evidence that plants can be engineered to produce PG using a bacterial gene. Phytoproduction of PG using a bacterial gene paves the way for further genetic manipulations to enhance the level of PG with implications for the commercial production of this important platform chemical in plants.

  18. Fluoro-luminometric real-time measurement of bacterial viability and killing.

    PubMed

    Lehtinen, Janne; Virta, Marko; Lilius, Esa Matti

    2003-10-01

    The viability and killing of Escherichia coli was measured on a real-time basis using a fluoro-luminometric device, which allows successive measurements of fluorescence and bioluminescence without user intervention. Bacteria were made fluorescent and bioluminescent by expression of gfp and insect luciferase (lucFF) genes. The green fluorescent protein (GFP) is a highly fluorescent, extremely stable protein, which accumulates in cells during growth, and therefore the measured fluorescence signal was proportional to the total number of cells. The luciferase reaction is dependent of ATP produced by living cells, so that the bioluminescence level was a direct measure of the viable cells. In contrast to the bacterial luciferase, the insect luciferase uses a water-soluble and nonvolatile substrate, which makes automated multi-well microplate assay possible. For the validation of the assay, the proportion of living and dead cell populations was experimentally modified by incubating E. coli cells in the presence of various ethanol concentrations. Bacterial viability and killing measured by a fluoro-luminometric assay correlated fairly well with the reference methods: conventional plate counting, optical density measurement and various flow cytometric analyses. The real-time assay described here allows following the changes in bacterial cultures and assessing the bactericidal and other effects of various chemical, immunological and physical agents simultaneously in large numbers of samples.

  19. Bacterial carbon utilization in vertical subsurface flow constructed wetlands.

    PubMed

    Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T

    2008-03-01

    Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

  20. Suitability of Optical, Physical and Chemical Measurements for Detection of Changes in Bacterial Drinking Water Quality

    PubMed Central

    Ikonen, Jenni; Pitkänen, Tarja; Miettinen, Ilkka T.

    2013-01-01

    In this study, different optical, physical and chemical measurements were tested for their capacity to detect changes in water quality. The tests included UV-absorbance at 254 nm, absorbance at 420 nm, turbidity, particle counting, temperature, pH, electric conductivity (EC), free chlorine concentration and ATP concentration measurements. Special emphasis was given to investigating the potential for measurement tools to detect changes in bacterial concentrations in drinking water. Bacterial colony counts (CFU) and total bacterial cell counts (TBC) were used as reference methods for assessing the bacterial water quality. The study consists of a series of laboratory scale experiments: monitoring of regrowth of Pseudomonas fluorescens, estimation of the detection limits for optical measurements using Escherichia coli dilutions, verification of the relationships by analysing grab water samples from various distribution systems and utilisation of the measurements in the case of an accidentally contaminated distribution network. We found significant correlations between the tested measurements and the bacterial water quality. As the bacterial contamination of water often co-occurs with the intrusion of matrixes containing mainly non-bacterial components, the tested measurement tools can be considered to have the potential to rapidly detect any major changes in drinking water quality. PMID:24284353

  1. Suitability of optical, physical and chemical measurements for detection of changes in bacterial drinking water quality.

    PubMed

    Ikonen, Jenni; Pitkänen, Tarja; Miettinen, Ilkka T

    2013-10-25

    In this study, different optical, physical and chemical measurements were tested for their capacity to detect changes in water quality. The tests included UV-absorbance at 254 nm, absorbance at 420 nm, turbidity, particle counting, temperature, pH, electric conductivity (EC), free chlorine concentration and ATP concentration measurements. Special emphasis was given to investigating the potential for measurement tools to detect changes in bacterial concentrations in drinking water. Bacterial colony counts (CFU) and total bacterial cell counts (TBC) were used as reference methods for assessing the bacterial water quality. The study consists of a series of laboratory scale experiments: monitoring of regrowth of Pseudomonas fluorescens, estimation of the detection limits for optical measurements using Escherichia coli dilutions, verification of the relationships by analysing grab water samples from various distribution systems and utilisation of the measurements in the case of an accidentally contaminated distribution network. We found significant correlations between the tested measurements and the bacterial water quality. As the bacterial contamination of water often co-occurs with the intrusion of matrixes containing mainly non-bacterial components, the tested measurement tools can be considered to have the potential to rapidly detect any major changes in drinking water quality.

  2. Isotopomers as a method for differentiating between bacterial and fungal production of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Sutka, R. L.; Adams, G.; Ostrom, N.; Ostrom, P.

    2007-12-01

    In order to study the importance of fungi to nitrous oxide (N2O) production in the environment it is critical to have a non-intrusive method for differentiating between fungal and bacterial N2O production. Site preference (SP), the difference in d15N between the central and outer N atoms in N2O, has been used to differentiate between bacterial nitrification and denitrification. In this study we compare the SP, d15N and d18O of N2O produced by the two best-studied fungal denitrifiers, Fusarium oxysporum and Cylindrocarpon tonkinense, to data from our previous bacterial studies. Both d18O and SP values remained fairly constant during the course of nitrite reduction which likely reflects isotopic exchange with water in the case of d18O and conservative behavior in SP that has been observed previously (Sutka et al., 2006). We observed a wide range of fractionation factors for fungal denitrification, -74.7 to -6.6 ‰, and non-linear behavior indicating that fractionation was controlled by more than one step. We interpret the small degree of fractionation as reflecting fractionation during diffusion and the more negative values as being controlled by enzymatic fractionation. Data from this and our previous study of bacterial production (Sutka et al., 2006) reveals that N2O produced via nitrification by fungi can be differentiated from N2O produced by bacterial denitrification primarily on the basis of d18O. The site preference of N2O produced by F. oxysporum and C. tonkinense was 37.1 ± 2.5 ‰ and 36.9 ± 2.8 ‰, respectively. These results indicate that isotopomers can be used as a basis for differentiating bacterial and fungal denitrification. Our work further reveals the role that fungal and bacterial nitric oxide reductases have in determining site preference during N2O production.

  3. Th2 Allergic Immune Response to Inhaled Fungal Antigens is Modulated By TLR-4-Independent Bacterial Products

    PubMed Central

    Allard, Jenna B.; Rinaldi, Lisa; Wargo, Matt; Allen, Gilman; Akira, Shizuo; Uematsu, Satoshi; Poynter, Matthew E.; Hogan, Deborah A.; Rincon, Mercedes; Whittaker, Laurie A.

    2009-01-01

    SUMMARY Allergic airway disease is characterized by eosinophilic inflammation, mucus hypersecretion and increased airway resistance. Fungal antigens are ubiquitous within the environment and are well know triggers of allergic disease. Bacterial products are also frequently encountered within the environment and may alter the immune response to certain antigens. The consequence of simultaneous exposure to bacterial and fungal products on the lung adaptive immune response has not been explored. Here we show that oropharyngeal aspiration of fungal lysates (Candida albicans, Aspergillus fumigatus) promotes airway eosinophilia, secretion of Th2 cytokines and mucus cell metaplasia. In contrast, oropharyngeal exposure to bacterial lysates (Pseudomonas aeruginosa) promotes airway inflammation characterized by neutrophils, Th1 cytokine secretion and no mucus production. More importantly, administration of bacterial lysates together with fungal lysates deviates the adaptive immune response to a Th1 type associated with neutrophilia and diminished mucus production. The immunomodulatory effect that bacterial lysates have on the response to fungi is TLR4-independent but MyD88 dependent. Thus, different types of microbial products within the airway can alter the host's adaptive immune response, and potentially impact the development of allergic airway disease to environmental fungal antigens. PMID:19224641

  4. Measurement of Bacterial Bioluminescence Intensity and Spectrum: Current Physical Techniques and Principles.

    PubMed

    Jia, Kun; Ionescu, Rodica Elena

    2016-01-01

    : Bioluminescence is light production by living organisms, which can be observed in numerous marine creatures and some terrestrial invertebrates. More specifically, bacterial bioluminescence is the "cold light" produced and emitted by bacterial cells, including both wild-type luminescent and genetically engineered bacteria. Because of the lively interplay of synthetic biology, microbiology, toxicology, and biophysics, different configurations of whole-cell biosensors based on bacterial bioluminescence have been designed and are widely used in different fields, such as ecotoxicology, food toxicity, and environmental pollution. This chapter first discusses the background of the bioluminescence phenomenon in terms of optical spectrum. Platforms for bacterial bioluminescence detection using various techniques are then introduced, such as a photomultiplier tube, charge-coupled device (CCD) camera, micro-electro-mechanical systems (MEMS), and complementary metal-oxide-semiconductor (CMOS) based integrated circuit. Furthermore, some typical biochemical methods to optimize the analytical performances of bacterial bioluminescent biosensors/assays are reviewed, followed by a presentation of author's recent work concerning the improved sensitivity of a bioluminescent assay for pesticides. Finally, bacterial bioluminescence as implemented in eukaryotic cells, bioluminescent imaging, and cancer cell therapies is discussed.

  5. Enhancement of a culture-based bacterial detection system (eBDS) for platelet products based on measurement of oxygen consumption.

    PubMed

    Holme, Stein; McAlister, Morven B; Ortolano, Girolamo A; Chong, Chiyong; Cortus, Mary Anne; Jacobs, Michael R; Yomtovian, Roslyn; Freundlich, Lawrence F; Wenz, Barry

    2005-06-01

    An enhanced bacterial detection system (Pall eBDS) was developed that distinguishes itself from its predecessor (Pall BDS) by removal of the platelet (PLT)-retaining filter allowing for optimal bacterial transfer, modification of the culture tablet to reduce the confounding effects of respiring PLTs while enhancing bacterial growth, and facilitation of nutrients and gas exchange by agitating the sample pouch during incubation at 35 degrees C. The objective was to evaluate the performance of the new eBDS. Leukoreduced whole blood-derived PLT concentrates (LR-PCs) and LR single-donor PLTs (LR-SDPs) were inoculated with 1 to 15 colony-forming units (CFUs) of bacteria per mL in studies of each of 10 bacterial species associated with fatal transfusion-transmitted bacterial infection. Immediately after inoculation and after 24 hours of storage at 22 degrees C, samples of inoculated LR-PCs were aseptically transferred into the eBDS pouches. Pouches were then incubated for 24 hours at 35 degrees C with agitation and oxygen concentration was then measured. Median inoculation levels ranged from 5 to 13 CFUs per mL for each species studied. No significant differences in oxygen concentration were found when comparing LR-PCs with LR-SDPs. When sampling occurred from the PLTs 24 hours after inoculation, all 280 cases (24-33 replicates of each species) were detected as contaminated by the device (100% sensitivity). No false-positives were obtained with 713 uninoculated PLT units. The eBDS demonstrated improved detection sensitivity in the range of 1 to 15 CFUs per mL with no observed false-positives compared to the original BDS (detection range 100 to 500 CFUs/mL) with no false-positives.

  6. Bacteriophages and Bacterial Plant Diseases

    PubMed Central

    Buttimer, Colin; McAuliffe, Olivia; Ross, R. P.; Hill, Colin; O’Mahony, Jim; Coffey, Aidan

    2017-01-01

    Losses in crop yields due to disease need to be reduced in order to meet increasing global food demands associated with growth in the human population. There is a well-recognized need to develop new environmentally friendly control strategies to combat bacterial crop disease. Current control measures involving the use of traditional chemicals or antibiotics are losing their efficacy due to the natural development of bacterial resistance to these agents. In addition, there is an increasing awareness that their use is environmentally unfriendly. Bacteriophages, the viruses of bacteria, have received increased research interest in recent years as a realistic environmentally friendly means of controlling bacterial diseases. Their use presents a viable control measure for a number of destructive bacterial crop diseases, with some phage-based products already becoming available on the market. Phage biocontrol possesses advantages over chemical controls in that tailor-made phage cocktails can be adapted to target specific disease-causing bacteria. Unlike chemical control measures, phage mixtures can be easily adapted for bacterial resistance which may develop over time. In this review, we will examine the progress and challenges for phage-based disease biocontrol in food crops. PMID:28163700

  7. Bacterial dynamics during yearlong spontaneous fermentation for production of ngari, a dry fermented fish product of Northeast India.

    PubMed

    Devi, Khunjamayum Romapati; Deka, Manab; Jeyaram, Kumaraswamy

    2015-04-16

    Ngari is the most popular traditionally processed non-salted fish product, prepared from sun-dried small cyprinid fish Puntius sophore (Ham.) in Manipur state of Northeast India. The microbial involvement in ngari production remained uncertain due to its low moisture content and yearlong incubation in anaerobically sealed earthen pots without any significant change in total microbial count. The culture-independent PCR-DGGE analysis used during this study confirmed a drastic bacterial community structural change in comparison to its raw material. To understand the bacterial dynamics during this dry fermentation, time series samples collected over a period of nine months through destructive sampling from two indigenous ngari production centres were analysed by using both culture-dependent and culture-independent molecular methods. A total of 210 bacteria isolated from the samples were identified by amplified ribosomal DNA restriction analysis (ARDRA) based grouping and 16S rRNA gene sequence similarity analysis. The dominant bacteria were Staphylococcus cohnii subsp. cohnii (38.0%), Tetragenococcus halophilus subsp. flandriensis (16.8%), a novel phylotype related to Lactobacillus pobuzihii (7.2%), Enterococcus faecium (7.2%), Bacillus indicus (6.3%) and Staphylococcus carnosus (3.8%). Distinct bacterial dynamics with the emergence of T. halophilus at third month (10(6)CFU/g), L. pobuzihii at sixth month (10(6)CFU/g), S. carnosus at three to six months (10(4)CFU/g) and B. indicus at six to nine months (10(5)CFU/g) in both the production centres was observed during ngari fermentation. However, the other two dominant bacteria S. cohnii and E. faecium were isolated throughout the fermentation with the population of 10(6)CFU/g and 10(4)CFU/g respectively. Culture-independent PCR-DGGE analysis further showed the presence of additional species, in which Kocuria halotolerans and Macrococcus caseolyticus disappeared during fermentation while Clostridium irregulare and

  8. Dynamic bacterial and fungal microbiomes during sweet sorghum ensiling impact bioethanol production.

    PubMed

    Gallagher, Daniella; Parker, David; Allen, Damian J; Tsesmetzis, Nicolas

    2018-05-23

    Significant low-cost biofuel production volumes could be achieved from commercial-scale silage by redirecting lactic acid fermentation to ethanol production. A temporal metagenomic analysis on ensiled sweet sorghum inoculated with an ethanologenic yeast has been conducted to understand the underlying microbial processes during bioethanol production. Individual silage buckets approximating silage piles were prepared with freshly harvested material and supplemented with ethanologenic yeast, sulfuric acid or both. The ensiling progress was assessed using high performance liquid chromatography, microbial taxonomic identification and abundance. The combined treatment with Saccharomyces and acid led to a steady reduction of bacterial abundance and microbial diversity with Lactobacillus becoming the dominant genus during the late timepoints. Furthermore, the addition of acid to inhibit bacterial growth hindered Saccharomyces ability to compete with native yeasts like Candida. Knowledge of the response of the in-situ microbial community to the various treatments during ensiling will help improve current methodologies for bioethanol production. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  9. Proteomics as a Quality Control Tool of Pharmaceutical Probiotic Bacterial Lysate Products

    PubMed Central

    Klein, Günter; Schanstra, Joost P.; Hoffmann, Janosch; Mischak, Harald; Siwy, Justyna; Zimmermann, Kurt

    2013-01-01

    Probiotic bacteria have a wide range of applications in veterinary and human therapeutics. Inactivated probiotics are complex samples and quality control (QC) should measure as many molecular features as possible. Capillary electrophoresis coupled to mass spectrometry (CE/MS) has been used as a multidimensional and high throughput method for the identification and validation of biomarkers of disease in complex biological samples such as biofluids. In this study we evaluate the suitability of CE/MS to measure the consistency of different lots of the probiotic formulation Pro-Symbioflor which is a bacterial lysate of heat-inactivated Escherichia coli and Enterococcus faecalis. Over 5000 peptides were detected by CE/MS in 5 different lots of the bacterial lysate and in a sample of culture medium. 71 to 75% of the total peptide content was identical in all lots. This percentage increased to 87–89% when allowing the absence of a peptide in one of the 5 samples. These results, based on over 2000 peptides, suggest high similarity of the 5 different lots. Sequence analysis identified peptides of both E. coli and E. faecalis and peptides originating from the culture medium, thus confirming the presence of the strains in the formulation. Ontology analysis suggested that the majority of the peptides identified for E. coli originated from the cell membrane or the fimbrium, while peptides identified for E. faecalis were enriched for peptides originating from the cytoplasm. The bacterial lysate peptides as a whole are recognised as highly conserved molecular patterns by the innate immune system as microbe associated molecular pattern (MAMP). Sequence analysis also identified the presence of soybean, yeast and casein protein fragments that are part of the formulation of the culture medium. In conclusion CE/MS seems an appropriate QC tool to analyze complex biological products such as inactivated probiotic formulations and allows determining the similarity between lots. PMID

  10. Production and Reutilization of Fluorescent Dissolved Organic Matter by a Marine Bacterial Strain, Alteromonas macleodii

    PubMed Central

    Goto, Shuji; Tada, Yuya; Suzuki, Koji; Yamashita, Youhei

    2017-01-01

    The recalcitrant fraction of marine dissolved organic matter (DOM) plays an important role in carbon storage on the earth’s surface. Bacterial production of recalcitrant DOM (RDOM) has been proposed as a carbon sequestration process. It is still unclear whether bacterial physiology can affect RDOM production. In this study, we conducted a batch culture using the marine bacterial isolate Alteromonas macleodii, a ubiquitous gammaproteobacterium, to evaluate the linkage between bacterial growth and DOM production. Glucose (1 mmol C L-1) was used as the sole carbon source, and the bacterial number, the DOM concentration in terms of carbon, and the excitation–emission matrices (EEMs) of DOM were monitored during the 168-h incubation. The incubation period was partitioned into the exponential growth (0–24 h) and stationary phases (24–168 h) based on the growth curve. Although the DOM concentration decreased during the exponential growth phase due to glucose consumption, it remained stable during the stationary phase, corresponding to approximately 4% of the initial glucose in terms of carbon. Distinct fluorophores were not evident in the EEMs at the beginning of the incubation, but DOM produced by the strain exhibited five fluorescent peaks during exponential growth. Two fluorescent peaks were similar to protein-like fluorophores, while the others could be categorized as humic-like fluorophores. All fluorophores increased during the exponential growth phase. The tryptophan-like fluorophore decreased during the stationary phase, suggesting that the strain reused the large exopolymer. The tyrosine-like fluorophore seemed to be stable during the stationary phase, implying that the production of tyrosine-containing small peptides through the degradation of exopolymers was correlated with the reutilization of the tyrosine-like fluorophore. Two humic-like fluorophores that showed emission maxima at the longer wavelength (525 nm) increased during the stationary phase

  11. Characterization of Bacterial Communities in Selected Smokeless Tobacco Products Using 16S rDNA Analysis

    PubMed Central

    Tyx, Robert E.; Stanfill, Stephen B.; Keong, Lisa M.; Rivera, Angel J.; Satten, Glen A.; Watson, Clifford H.

    2016-01-01

    The bacterial communities present in smokeless tobacco (ST) products have not previously reported. In this study, we used Next Generation Sequencing to study the bacteria present in U.S.-made dry snuff, moist snuff and Sudanese toombak. Sample diversity and taxonomic abundances were investigated in these products. A total of 33 bacterial families from four phyla, Actinobacteria, Firmicutes, Proteobacteria and Bacteroidetes, were identified. U.S.-produced dry snuff products contained a diverse distribution of all four phyla. Moist snuff products were dominated by Firmicutes. Toombak samples contained mainly Actinobacteria and Firmicutes (Aerococcaceae, Enterococcaceae, and Staphylococcaceae). The program PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) was used to impute the prevalence of genes encoding selected bacterial toxins, antibiotic resistance genes and other pro-inflammatory molecules. PICRUSt also predicted the presence of specific nitrate reductase genes, whose products can contribute to the formation of carcinogenic nitrosamines. Characterization of microbial community abundances and their associated genomes gives us an indication of the presence or absence of pathways of interest and can be used as a foundation for further investigation into the unique microbiological and chemical environments of smokeless tobacco products. PMID:26784944

  12. Production of bacterial cellulose and enzyme from waste fiber sludge

    PubMed Central

    2013-01-01

    Background Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated. Results Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar. Conclusions It was shown that waste fiber sludge is a suitable raw material for production of

  13. A Novel Platform for Evaluating the Environmental Impacts on Bacterial Cellulose Production.

    PubMed

    Basu, Anindya; Vadanan, Sundaravadanam Vishnu; Lim, Sierin

    2018-04-10

    Bacterial cellulose (BC) is a biocompatible material with versatile applications. However, its large-scale production is challenged by the limited biological knowledge of the bacteria. The advent of synthetic biology has lead the way to the development of BC producing microbes as a novel chassis. Hence, investigation on optimal growth conditions for BC production and understanding of the fundamental biological processes are imperative. In this study, we report a novel analytical platform that can be used for studying the biology and optimizing growth conditions of cellulose producing bacteria. The platform is based on surface growth pattern of the organism and allows us to confirm that cellulose fibrils produced by the bacteria play a pivotal role towards their chemotaxis. The platform efficiently determines the impacts of different growth conditions on cellulose production and is translatable to static culture conditions. The analytical platform provides a means for fundamental biological studies of bacteria chemotaxis as well as systematic approach towards rational design and development of scalable bioprocessing strategies for industrial production of bacterial cellulose.

  14. Use of Natural Antimicrobial Peptides and Bacterial Biopolymers for Cultured Pearl Production

    PubMed Central

    Simon-Colin, Christelle; Gueguen, Yannick; Bachere, Evelyne; Kouzayha, Achraf; Saulnier, Denis; Gayet, Nicolas; Guezennec, Jean

    2015-01-01

    Cultured pearls are the product of grafting and rearing of Pinctada margaritifera pearl oysters in their natural environment. Nucleus rejections and oyster mortality appear to result from bacterial infections or from an inappropriate grafting practice. To reduce the impact of bacterial infections, synthetic antibiotics have been applied during the grafting practice. However, the use of such antibiotics presents a number of problems associated with their incomplete biodegradability, limited efficacy in some cases, and an increased risk of selecting for antimicrobial resistant bacteria. We investigated the application of a marine antimicrobial peptide, tachyplesin, which is present in the Japanese horseshoe crab Tachypleus tridentatus, in combination with two marine bacterial exopolymers as alternative treatment agents. In field studies, the combination treatment resulted in a significant reduction in graft failures vs. untreated controls. The combination of tachyplesin (73 mg/L) with two bacterial exopolysaccharides (0.5% w/w) acting as filming agents, reduces graft-associated bacterial contamination. The survival data were similar to that reported for antibiotic treatments. These data suggest that non-antibiotic treatments of pearl oysters may provide an effective means of improving oyster survival following grafting procedures. PMID:26110895

  15. D-lactic acid measurements in the diagnosis of bacterial infections.

    PubMed Central

    Smith, S M; Eng, R H; Campos, J M; Chmel, H

    1989-01-01

    Body fluids suspected of bacterial infection were cultured and examined for the presence of D-lactic acid, a specific bacterial metabolite. We examined 206 patients and 264 specimens. D-Lactic acid was found in concentrations of greater than or equal to 0.15 mM in 11 of 11 infected and 6 of 40 noninfected ascitic fluids, 6 of 6 infected and 4 of 33 noninfected pleural fluids, 4 of 4 infected and 0 of 13 noninfected synovial fluids, and 26 of 27 infected and 2 of 130 noninfected cerebrospinal fluids. The overall sensitivity was 79.7%, and the specificity was 99.5% when the D-lactic acid concentration was at least 0.15 mM. The most important clinical utility of the D-lactic acid measurement appears to be for patients with bacterial infection in various body compartments and in patients who have already received antimicrobial therapy. An elevation in D-lactic acid may indicate the presence of bacterial infection even when cultures are negative. PMID:2715313

  16. Phage bacteriolysis, protistan bacterivory potential, and bacterial production in a freshwater reservoir: coupling with temperature.

    PubMed

    Pradeep Ram, A S; Boucher, D; Sime-Ngando, T; Debroas, D; Romagoux, J C

    2005-07-01

    Phage abundance and infection of bacterioplankton were studied from March to November 2003 in the Sep Reservoir (Massif Central, France), together with temperature, chlorophyll, bacteria (abundance and production), and heterotrophic nanoflagellates (abundance and potential bacterivory). Virus abundance (VA) ranged from 0.6 to 13 x 10(10) viruses l(-1), exceeding bacterial abundance (BA) approximately sixfold on average. In terms of carbon, viruses corresponded to up to 25% of bacterial biomass. A multiple regression model indicated that BA was the best predictor for VA (R(2) = 0.75). The frequency of infected bacteria (estimated from the percentage of visibly infected cells) varied from 1% to 32% and was best explained by a combination of temperature (R(2) = 0.20) and bacterial production (R(2) = 0.25). Viruses and flagellates contributed about equally to bacterial mortality. Both factors destroyed 55% of bacterial production, with a shift from phage bacteriolysis in early spring to protistan bacterivory in late summer. The vertical differences in most of the biological variables were not significant, contrasting with the seasonal differences (i.e., spring vs. summer-autumn). All biological variables under study were indeed significantly coupled to temperature. We regarded this to be the consequence of the enhanced discharge of the reservoir in 2003 (compared to previous years). This substantially weakened the stability and the thermal inertia of the water column, thereby establishing temperature as a stronger forcing factor in setting the conditions for optimal metabolic activity of microbial communities.

  17. Application of the [3H]Leucine Incorporation Technique for Quantification of Bacterial Secondary Production Associated with Decaying Wetland Plant Litter

    PubMed Central

    Gillies, Jane E.; Kuehn, Kevin A.; Francoeur, Steven N.; Neely, Robert K.

    2006-01-01

    The radiolabeled leucine incorporation technique for quantifying rates of bacterial production has increased in popularity since its original description for bacterioplankton communities. Prior studies addressing incorporation conditions (e.g., substrate saturation) for bacterial communities in other habitats, such as decaying plant litter, have reported a wide range of final leucine concentrations (400 nM to 50 μM) required to achieve saturation-level uptake. We assessed the application of the [3H]leucine incorporation procedure for measuring bacterial production on decaying wetland plant litter. Substrate saturation experiments (nine concentrations, 10 nM to 50 μM final leucine concentration) were conducted on three dates for microbial communities colonizing the submerged litter of three emergent plant species (Typha angustifolia, Schoenoplectus validus, and Phragmites australis). A modified [3H]leucine protocol was developed by coupling previously described incubation and alkaline extraction protocols with microdialysis (500 molecular weight cutoff membrane) of the final radiolabeled protein extract. The incorporation of [3H]leucine into protein exhibited a biphasic saturation curve, with lower apparent Km values ranging from 400 nM to 4.2 μM depending on the plant species studied. Upper apparent Km values ranged from 1.3 to 59 μM. These results suggest differential uptake by litter-associated microbial assemblages, with the lower apparent Km values possibly representing bacterial uptake and higher apparent Km values representing a combination of both bacterial and nonbacterial (e.g., eukaryotic) uptake. PMID:16957215

  18. Estimating Bacterioplankton Production by Measuring [3H]thymidine Incorporation in a Eutrophic Swedish Lake

    PubMed Central

    Bell, Russell T.; Ahlgren, Gunnel M.; Ahlgren, Ingemar

    1983-01-01

    Bacterioplankton abundance, [3H]thymidine incorporation, 14CO2 uptake in the dark, and fractionated primary production were measured on several occasions between June and August 1982 in eutrophic Lake Norrviken, Sweden. Bacterioplankton abundance and carbon biomass ranged from 0.5 × 109 to 2.4 × 109 cells liter−1 and 7 to 47 μg of C liter−1, respectively. The average bacterial cell volume was 0.185 μm3. [3H]thymidine incorporation into cold-trichloroacetic acid-insoluble material ranged from 12 × 10−12 to 200 × 10−12 mol liter−1 h−1. Bacterial carbon production rates were estimated to be 0.2 to 7.1 μg of C liter−1 h−1. Bacterial production estimates from [3H]thymidine incorporation and 14CO2 uptake in the dark agreed when activity was high but diverged when activity was low and when blue-green algae (cyanobacteria) dominated the phytoplankton. Size fractionation indicated negligible uptake of [3H]thymidine in the >3-μm fraction during a chrysophycean bloom in early June. We found that >50% of the 3H activity was in the >3-μm fraction in late August; this phenomenon was most likely due to Microcystis spp., their associated bacteria, or both. Over 60% of the 14CO2 uptake in the dark was attributed to algae on each sampling occasion. Algal exudate was an important carbon source for planktonic bacteria. Bacterial production was roughly 50% of primary production. PMID:16346304

  19. Measuring masses of single bacterial whole cells with a quadrupole ion trap.

    PubMed

    Peng, Wen-Ping; Yang, Yi-Chang; Kang, Ming-Wei; Lee, Yuan T; Chang, Huan-Cheng

    2004-09-29

    A novel method has been developed to precisely measure the masses of single bacterial whole cells using a quadrupole ion trap as an electrodynamic balance. The bacterial cells were introduced into the ion trap by matrix-assisted laser desorption/ionization, confined in space by audio frequency ac fields, and detected by elastic light scattering. Mass measurement accuracy approaching 0.1% was achieved for Escherichia coli K-12 with a mass distribution of +/-3% from 60 repetitive measurements of the particles and their clusters. This is the first high-precision mass measurement reported for any intact microorganisms with masses greater than 1 x 1010 Da. The method opens new avenues for high-precision mass measurement of single microbial particles and offers an alternative approach for rapid identification of microorganisms by mass spectrometry.

  20. Pyrosequencing analysis for characterization of bacterial diversity in a soil as affected by integrated livestock-cotton production systems

    USDA-ARS?s Scientific Manuscript database

    Impacts of integrated livestock-crop production systems compared to specialized systems on soil bacterial diversity have not been well documented. We used a bacterial tag encoded FLX amplicon pyrosequencing (bTEFAP) method to evaluate bacterial diversity of a clay loam soil (Fine, mixed, thermic To...

  1. Diversity of the dominant bacterial species on sliced cooked pork products at expiration date in the Belgian retail.

    PubMed

    Geeraerts, Wim; Pothakos, Vasileios; De Vuyst, Luc; Leroy, Frédéric

    2017-08-01

    Pork-based cooked products, such as cooked hams, are economically valuable foods that are vulnerable to bacterial spoilage, even when applying cooling and modified atmosphere packaging (MAP). Besides a common presence of Brochothrix thermosphacta, their microbiota are usually dominated by lactic acid bacteria (LAB). Yet, the exact LAB species diversity can differ considerably among products. In this study, 42 sliced cooked pork samples were acquired from three different Belgian supermarkets to map their bacterial heterogeneity. The community compositions of the dominant bacterial species were established by analysing a total of 702 isolates from selective agar media by (GTG) 5 -PCR fingerprinting followed by gene sequencing. Most of the isolates belonged to the genera Carnobacterium, Lactobacillus, and Leuconostoc, with Leuconostoc carnosum and Leuconostoc gelidum subsp. gelidum being the most dominant members. The diversity of the dominant bacterial species varied when comparing samples from different production facilities and, in some cases, even within the same product types. Although LAB consistently dominated the microbiota of sliced cooked pork products in the Belgian market, results indicated that bacterial diversity needs to be addressed on the level of product composition and batch variation. Dedicated studies will be needed to substantiate potential links between such variability and microbial composition. For instance, the fact that higher levels of lactobacilli were associated with the presence of potassium lactate (E326) may be suggestive of selective pressure but needs to be validated, as this finding referred to a single product only. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Performance of improved bacterial cellulose application in the production of functional paper.

    PubMed

    Basta, A H; El-Saied, H

    2009-12-01

    The purpose of this work was to study the feasibility of producing economic flame retardant bacterial cellulose (BC) and evaluating its behaviour in paper production. This type of BC was prepared by Gluconacetobacter subsp. xylinus and substituting the glucose in the cultivation medium by glucose phosphate as a carbon source; as well as using corn steep liquor as a nitrogen source. The investigated processing technique did not dispose any toxic chemicals that pollute the surroundings or cause unacceptable effluents, making the process environmentally safe. The fire retardant behaviour of the investigated BC has been studied by non-isothermal thermogravimetric analysis (TGA & DTGA). The activation energy of each degradation stage and the order of degradation were estimated using the Coats-Redfern equation and the least square method. Strength, optical properties, and thermogravimetric analysis of BC-phosphate added paper sheets were also tested. The study confirmed that the use of glucose phosphate along with glucose was significant in the high yield production of phosphate containing bacterial cellulose (PCBC1); more so than the use of glucose phosphate alone (PCBC2). Incorporating 5% of the PCBC with wood pulp during paper sheet formation was found to significantly improve kaolin retention, strength, and fire resistance properties as compared to paper sheets produced from incorporating bacterial cellulose (BC). This modified BC is a valuable product for the preparation of specialized paper, in addition to its function as a fillers aid.

  3. Bacterial avirulence genes.

    PubMed

    Leach, J E; White, F F

    1996-01-01

    Although more than 30 bacterial avirulence genes have been cloned and characterized, the function of the gene products in the elictitation of resistance is unknown in all cases but one. The product of avrD from Pseudomonas syringae pv. glycinea likely functions indirectly to elicit resistance in soybean, that is, evidence suggests the gene product is an enzyme involved in elicitor production. In most if not all cases, bacterial avirulence gene function is dependent on interactions with the hypersensitive response and pathogenicity (hrp) genes. Many hrp genes are similar to genes involved in delivery of pathogenicity factors in mammalian bacterial pathogens. Thus, analogies between mammalian and plant pathogens may provide needed clues to elucidate how virulence gene products control induction of resistance.

  4. Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica.

    PubMed

    Grossmann, S; Dieckmann, G S

    1994-08-01

    Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 x 10 to 3 x 10 liter, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low concentrations of phytoplankton in the water column during freezing, incorporation of bacteria into newly formed ice via attachment to algal cells or aggregates was not recorded in this study. As soon as the ice had formed, the general metabolic activity of bacterial populations was strongly suppressed. Furthermore, the ratio of [H]leucine incorporation into proteins to [H]thymidine incorporation into DNA changed during ice growth. In thick pack ice, bacterial activity recovered and growth rates up to 0.6 day indicated actively dividing populations. However, biomass-specific utilization of organic compounds remained lower than in open water. Bacterial concentrations of up to 2.8 x 10 cells liter along with considerably enlarged cell volumes accumulated within thick pack ice, suggesting reduced mortality rates of bacteria within the small brine pores. In the course of ice development, bacterial carbon production increased from about 0.01 to 0.4 mug of C liter h. In thick ice, bacterial secondary production exceeded primary production of microalgae.

  5. Factors affecting the bacterial community composition and heterotrophic production of Columbia River estuarine turbidity maxima.

    PubMed

    Herfort, Lydie; Crump, Byron C; Fortunato, Caroline S; McCue, Lee Ann; Campbell, Victoria; Simon, Holly M; Baptista, António M; Zuber, Peter

    2017-12-01

    Estuarine turbidity maxima (ETM) function as hotspots of microbial activity and diversity in estuaries, yet, little is known about the temporal and spatial variability in ETM bacterial community composition. To determine which environmental factors affect ETM bacterial populations in the Columbia River estuary, we analyzed ETM bacterial community composition (Sanger sequencing and amplicon pyrosequencing of 16S rRNA gene) and bulk heterotrophic production ( 3 H-leucine incorporation rates). We collected water 20 times to cover five ETM events and obtained 42 samples characterized by different salinities, turbidities, seasons, coastal regimes (upwelling vs. downwelling), locations, and particle size. Spring and summer populations were distinct. All May samples had similar bacterial community composition despite having different salinities (1-24 PSU), but summer non-ETM bacteria separated into marine, freshwater, and brackish assemblages. Summer ETM bacterial communities varied depending on coastal upwelling or downwelling conditions and on the sampling site location with respect to tidal intrusion during the previous neap tide. In contrast to ETM, whole (>0.2 μm) and free-living (0.2-3 μm) assemblages of non-ETM waters were similar to each other, indicating that particle-attached (>3 μm) non-ETM bacteria do not develop a distinct community. Brackish water type (ETM or non-ETM) is thus a major factor affecting particle-attached bacterial communities. Heterotrophic production was higher in particle-attached than free-living fractions in all brackish waters collected throughout the water column during the rise to decline of turbidity through an ETM event (i.e., ETM-impacted waters). However, free-living communities showed higher productivity prior to or after an ETM event (i.e., non-ETM-impacted waters). This study has thus found that Columbia River ETM bacterial communities vary based on seasons, salinity, sampling location, and particle size, with the

  6. Luffa sponge offsets the negative effects of aeration on bacterial cellulose production.

    PubMed

    Krusong, W; Kerdpiboon, S; Pornpukdeewattana, S; Jindaprasert, A

    2016-12-01

    To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9 l min -1 ). However, with 0·5% LSM-CM and an aeration rate of 3 l min -1 , a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24 g l -1 ). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8 ± 0·4 to 6·6 ± 0·4 g l -1 ) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration. © 2016 The Society for Applied Microbiology.

  7. Intermittency measurement in two-dimensional bacterial turbulence

    NASA Astrophysics Data System (ADS)

    Qiu, Xiang; Ding, Long; Huang, Yongxiang; Chen, Ming; Lu, Zhiming; Liu, Yulu; Zhou, Quan

    2016-06-01

    In this paper, an experimental velocity database of a bacterial collective motion, e.g., Bacillus subtilis, in turbulent phase with volume filling fraction 84 % provided by Professor Goldstein at Cambridge University (UK), was analyzed to emphasize the scaling behavior of this active turbulence system. This was accomplished by performing a Hilbert-based methodology analysis to retrieve the scaling property without the β -limitation. A dual-power-law behavior separated by the viscosity scale ℓν was observed for the q th -order Hilbert moment Lq(k ) . This dual-power-law belongs to an inverse-cascade since the scaling range is above the injection scale R , e.g., the bacterial body length. The measured scaling exponents ζ (q ) of both the small-scale (k >kν ) and large-scale (k measured intermittency parameters are μS=0.26 and μL=0.17 , respectively, for the small- and large-scale motions. It implies that the former cascade is more intermittent than the latter one, which is also confirmed by the corresponding singularity spectrum f (α ) versus α . Comparison with the conventional two-dimensional Ekman-Navier-Stokes equation, a continuum model indicates that the origin of the multifractality could be a result of some additional nonlinear interaction terms, which deservers a more careful investigation.

  8. Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon

    NASA Astrophysics Data System (ADS)

    Van Wambeke, F.; Pfreundt, U.; Barani, A.; Berthelot, H.; Moutin, T.; Rodier, M.; Hess, W. R.; Bonnet, S.

    2015-12-01

    N2 fixation fuels ~ 50 % of new primary production in the oligotrophic South Pacific Ocean. The VAHINE mesocosm experiment designed to track the fate of diazotroph derived nitrogen (DDN) in the New Caledonia lagoon. Here, we examined the temporal dynamics of heterotrophic bacterial production during this experiment. Three replicate large-volume (~ 50 m3) mesocosms were deployed and were intentionally fertilized with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. We specifically examined relationships between N2 fixation rates and primary production, determined bacterial growth efficiency and established carbon budgets of the system from the DIP fertilization to the end of the experiment (days 5-23). Heterotrophic bacterioplankton production (BP) and alkaline phosphatase activity (APA) were statistically higher during the second phase of the experiment (P2: days 15-23), when chlorophyll biomass started to increase compared to the first phase (P1: days 5-14). Among autotrophs, Synechococcus abundances increased during P2, possibly related to its capacity to assimilate leucine and to produce alkaline phosphatase. Bacterial growth efficiency based on the carbon budget was notably higher than generally cited for oligotrophic environments (27-43 %), possibly due to a high representation of proteorhodopsin-containing organisms within the picoplanctonic community. The carbon budget showed that the main fate of gross primary production (particulate + dissolved) was respiration (67 %), and export through sedimentation (17 %). BP was highly correlated with particulate primary production and chlorophyll biomass during both phases of the experiment but slightly correlated, and only during P2 phase, with N2 fixation rates. Our results suggest that most of the DDN reached the heterotrophic bacterial community through indirect processes, like mortality, lysis and grazing.

  9. Metagenetic analysis of the bacterial communities of edible insects from diverse production cycles at industrial rearing companies.

    PubMed

    Vandeweyer, D; Crauwels, S; Lievens, B; Van Campenhout, L

    2017-11-16

    Despite the continuing development of new insect-derived food products, microbial research on edible insects and insect-based foods is still very limited. The goal of this study was to increase the knowledge on the microbial quality of edible insects by comparing the bacterial community composition of mealworms (Tenebrio molitor) and crickets (Acheta domesticus and Gryllodes sigillatus) from several production cycles and rearing companies. Remarkable differences in the bacterial community composition were found between different mealworm rearing companies and mealworm production cycles from the same company. In comparison with mealworms, the bacterial community composition of the investigated crickets was more similar among different companies, and was highly similar between both cricket species investigated. Mealworm communities were dominated by Spiroplasma and Erwinia species, while crickets were abundantly colonised by (Para)bacteroides species. With respect to food safety, only a few operational taxonomic units could be associated with potential human pathogens such as Cronobacter or spoilage bacteria such as Pseudomonas. In summary, our results implicate that at least for cricket rearing, production cycles of constant and good quality in terms of bacterial composition can be obtained by different rearing companies. For mealworms however, more variation in terms of microbial quality occurs between companies. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Identification of bacterial contaminants from calcium carbonate filler production lines and an evaluation of biocide based decontamination procedures.

    PubMed

    Odić, Duško; Prah, Jana; Avguštin, Gorazd

    2017-04-01

    The aim of this study was to analyze the bacterial community in the production line of a calcium carbonate filler production company and to investigate possible causes for bacterial presence. Throughout 2012, 24 carbonate slurry and six groundwater samples were analyzed. Pseudomonas and Microbacterium were the most frequent contaminants in the slurry, whereas Pseudomonas and Brevundimonas dominated the groundwater samples. Of the 43 different bacterial strains isolated, only five were found both in the slurry and the groundwater, indicating that the latter was not a major source of contamination. The efficacy of 54 commercial biocidal formulations was tested against an artificial bacterial consortium composed of selected slurry isolates. A formulation containing 7.5-15% (v v -1 ) bronopol and 1.0-2.5% (v v -1 ) [chloroisothiazolinone (CIT) + methylisothiazolinone (MIT)] exhibited the highest efficacy. Of the possible causes for bacterial presence, sporogenesis and biocide adsorption to carbonate particles were found to be less probable compared to bacterial adsorption to particles, and the acquisition of resistance to biocides.

  11. Contribution of dinitrogen fixation to bacterial and primary productivity in the Gulf of Aqaba (Red Sea)

    NASA Astrophysics Data System (ADS)

    Rahav, E.; Herut, B.; Mulholland, M. R.; Voß, B.; Stazic, D.; Steglich, C.; Hess, W. R.; Berman-Frank, I.

    2013-06-01

    We evaluated the seasonal contribution of heterotrophic and autotrophic diazotrophy to the total dinitrogen (N2) fixation in a representative pelagic station in the northern Gulf of Aqaba in early spring when the water column was mixed and during summer under full thermal stratification. N2 fixation rates were low during the mixed period (˜ 0.1 nmol N L-1 d-1) and were significantly coupled with both primary and bacterial productivity. During the stratified period N2 fixation rates were four-fold higher (˜ 0.4 nmol N L-1 d-1) and were significantly correlated solely with bacterial productivity. Furthermore, while experimental enrichment of seawater by phosphorus (P) enhanced bacterial productivity and N2 fixation rates during both seasons primary productivity was stimulated by P only in the early spring. Metatranscriptomic analyses from the stratified period identified the major diazotrophic contributors as related to heterotrophic prokaryotes from the Euryarchaeota and Desulfobacterales (Deltaproteobacteria) or Chlorobiales (Chlorobia). Moreover, during this season, experimental amendments to seawater applying a combination of the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and a mixture of amino acids increased both bacterial productivity and N2 fixation rates. Our findings from the northern Gulf of Aqaba indicate a~shift in the diazotrophic community from phototrophic and heterotrophic populations, including small blooms of the cyanobacterium Trichodesmium, in winter/early spring, to predominantly heterotrophic diazotrophs in summer that may be both P and carbon limited as the additions of P and amino acids illustrated.

  12. Effects of carbon dioxide on metabolite production and bacterial communities during kimchi fermentation.

    PubMed

    Park, Doo Hyun

    2018-04-24

    Bacterial communities and metabolites in kimchi fermented under conventional conditions (CC) compared to CO 2 -rich environments (CO 2 ) were analyzed. After a 20-day fermentation, lactic and acetic acid productions were 54 and 69 mM under CC, and 19 and 12 mM under CO 2 , respectively. The final pH of kimchi fermented under CC (CC-fermenting) and CO 2 (CO 2 -fermenting) were 4.1 and 4.7, respectively. For bacterial communities, OTU and Chao1 indices were both 35 in fresh kimchi, 10 and 15 in CC-fermenting kimchi, and 8 and 24 in CO 2 -fermenting kimchi, respectively. Shannon and Simpson indices were 3.47 and 0.93 in fresh kimchi, 1.87-0.06 and 0.46-0.01 in CC-fermenting kimchi, and 1.65-0.44 and 0.63-0.12 in CO 2 -fermenting kimchi, respectively. Non-lactic acid bacteria were eliminated in fermenting kimchi after 12 days under CC and 6 days under CO 2 . I conclude that carbon dioxide can alter bacterial communities, reduce metabolite production, and improve fermented kimchi quality.

  13. A Consistent and Predictable Commercial Broiler Chicken Bacterial Microbiota in Antibiotic-Free Production Displays Strong Correlations with Performance.

    PubMed

    Johnson, Timothy J; Youmans, Bonnie P; Noll, Sally; Cardona, Carol; Evans, Nicholas P; Karnezos, T Peter; Ngunjiri, John M; Abundo, Michael C; Lee, Chang-Won

    2018-06-15

    Defining the baseline bacterial microbiome is critical to understanding its relationship with health and disease. In broiler chickens, the core microbiome and its possible relationships with health and disease have been difficult to define, due to high variability between birds and flocks. Presented here are data from a large, comprehensive microbiota-based study in commercial broilers. The primary goals of this study included understanding what constitutes the core bacterial microbiota in the broiler gastrointestinal, respiratory, and barn environments; how these core players change across age, geography, and time; and which bacterial taxa correlate with enhanced bird performance in antibiotic-free flocks. Using 2,309 samples from 37 different commercial flocks within a vertically integrated broiler system and metadata from these and an additional 512 flocks within that system, the baseline bacterial microbiota was defined using 16S rRNA gene sequencing. The effects of age, sample type, flock, and successive flock cycles were compared, and results indicate a consistent, predictable, age-dependent bacterial microbiota, irrespective of flock. The tracheal bacterial microbiota of broilers was comprehensively defined, and Lactobacillus was the dominant bacterial taxon in the trachea. Numerous bacterial taxa were identified, which were strongly correlated with broiler chicken performance across multiple tissues. While many positively correlated taxa were identified, negatively associated potential pathogens were also identified in the absence of clinical disease, indicating that subclinical dynamics occur that impact performance. Overall, this work provides necessary baseline data for the development of effective antibiotic alternatives, such as probiotics, for sustainable poultry production. IMPORTANCE Multidrug-resistant bacterial pathogens are perhaps the greatest medical challenge we will face in the 21st century and beyond. Antibiotics are necessary in animal

  14. Methane production and small intestinal bacterial overgrowth in children living in a slum.

    PubMed

    Mello, Carolina Santos; Tahan, Soraia; Melli, Lígia Cristina F L; Rodrigues, Mirian Silva do Carmo; de Mello, Ricardo Martin Pereira; Scaletsky, Isabel Cristina Affonso; de Morais, Mauro Batista

    2012-11-07

    To analyze small intestinal bacterial overgrowth in school-aged children and the relationship between hydrogen and methane production in breath tests. This transversal study included 85 children residing in a slum and 43 children from a private school, all aged between 6 and 10 years, in Osasco, Brazil. For characterization of the groups, data regarding the socioeconomic status and basic housing sanitary conditions were collected. Anthropometric data was obtained in children from both groups. All children completed the hydrogen (H(2)) and methane (CH(4)) breath test in order to assess small intestinal bacterial overgrowth (SIBO). SIBO was diagnosed when there was an increase in H(2) ≥ 20 ppm or CH(4) ≥ 10 ppm with regard to the fasting value until 60 min after lactulose ingestion. Children from the slum group had worse living conditions and lower nutritional indices than children from the private school. SIBO was found in 30.9% (26/84) of the children from the slum group and in 2.4% (1/41) from the private school group (P = 0.0007). Greater hydrogen production in the small intestine was observed in children from the slum group when compared to children from the private school (P = 0.007). A higher concentration of hydrogen in the small intestine (P < 0.001) and in the colon (P < 0.001) was observed among the children from the slum group with SIBO when compared to children from the slum group without SIBO. Methane production was observed in 63.1% (53/84) of the children from the slum group and in 19.5% (8/41) of the children from the private school group (P < 0.0001). Methane production was observed in 38/58 (65.5%) of the children without SIBO and in 15/26 (57.7%) of the children with SIBO from the slum. Colonic production of hydrogen was lower in methane-producing children (P = 0.017). Children who live in inadequate environmental conditions are at risk of bacterial overgrowth and methane production. Hydrogen is a substrate for methane production in the colon.

  15. Role of water-soluble polysaccharides in bacterial cellulose production.

    PubMed

    Ishida, Takehiko; Mitarai, Makoto; Sugano, Yasushi; Shoda, Makoto

    2003-08-20

    Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 474-478, 2003.

  16. Impact of bacterial DMS production on [DMS/P] under ocean acidification (KOSMOS_2.0): insights from the subtropics.

    NASA Astrophysics Data System (ADS)

    Suffrian, K.; Posman, K.; Matrai, P.; Countway, P. D.; Archer, S. D.

    2016-02-01

    Marine dimethyl sulfide (DMS), a ubiquitous atmospheric trace gas, comprises the largest source of sulphur to the atmosphere. So far, temperate and high-latitude ocean acidification (OA) mesocosm experiments point to a decrease of this precursor for cloud condensation nuclei, leading to fewer clouds, and resulting in an increased radiative force. To our knowledge no experiments have yet been carried out which address multiple forcings (temperature and pCO2) in the subtropics. We thus joined the 55-day KOSMOS large mesocosm experiment on Gran Canaria to investigate if the observed decrease could be global. As subtropical and tropical oceans comprise a large proportion of the world's oceans, we were i.a. interested if 1) increasing ocean acidification in a subtropical environment would also decrease [DMS], and if 2) bacterial DMS production could explain a large part of potential decreases. Here we focus on the first phase (day 1-23), showing the impact of OA on [DMS] and [DMSP] (dimethylsulfoniopropionate). Bacteria are thought to be the main DMS producers, so we used 35S-DMSP as a tracer to investigate the impact of bacterial DMS production on observed [DMS] decreases correlated with increasing OA. [DMS] showed a strong inverse correlation with [H+] (-50% vs. ambient control). [DMSPp] (-37%) and [DMSPd] (-20%) also decreased with increasing [H+]. Our results support findings from higher latitude mesocosm experiments, thus suggesting the effect might be global. Bacterial DMS production rates, their rate constants, and yields during the peak in [DMS] were negatively correlated with [H+] on single days, while gross DMS-production was high enough to support observed [DMS] increases. Bacterial DMSP uptake rates and DMS production rates were not correlated with [H+] on any other day. Bacterial effects alone are thus not enough to explain observed changes in standing stocks. We will further explore the results by normalizing to bacterial protein production, cell abundance

  17. Studies on Batch Production of Bacterial Concentrates from Mixed Species Lactic Starters

    PubMed Central

    Pettersson, H. E.

    1975-01-01

    Optimum growth conditions for mixed species starter FDs 0172 at constant pH in skim milk, whey, and tryptone medium were investigated. Growth rate and maximum population were optimal at 30 C. pH values between 5.5 and 7.0 did not influence the growth rate and maximum population obtainable. Lactic acid-producing activity declined rapidly after reaching the end of the exponential growth phase. The bacterial balance was found to be influenced by the growth parameters: media, pH, temperature, and neutralizer. Skim milk or whey medium at 25 C, pH 6.5, and neutralized with 20% (vol/vol) NH4OH kept the bacterial balance almost constant throughout the cultivation. Grown in tryptone medium at constant pH, the changes in bacterial balance and other metabolic activities were striking compared to the other two media tested. The effect of lactate as an inhibitor was found to be complex, changing with the growth conditions. Concentrates made from mixed species starters FDs 0172, FD 0570, CH 0170, CHs 0170, and T 27 were comparable to controls when cultivated at the optimum conditions found and thereafter centrifuged. Aroma production, proteolytic activity, and CO2 production did not change significantly compared to controls when cultivated at optimum conditions in skim milk or whey medium. PMID:16350009

  18. Bacterial antisense RNAs are mainly the product of transcriptional noise.

    PubMed

    Lloréns-Rico, Verónica; Cano, Jaime; Kamminga, Tjerko; Gil, Rosario; Latorre, Amparo; Chen, Wei-Hua; Bork, Peer; Glass, John I; Serrano, Luis; Lluch-Senar, Maria

    2016-03-01

    cis-Encoded antisense RNAs (asRNAs) are widespread along bacterial transcriptomes. However, the role of most of these RNAs remains unknown, and there is an ongoing discussion as to what extent these transcripts are the result of transcriptional noise. We show, by comparative transcriptomics of 20 bacterial species and one chloroplast, that the number of asRNAs is exponentially dependent on the genomic AT content and that expression of asRNA at low levels exerts little impact in terms of energy consumption. A transcription model simulating mRNA and asRNA production indicates that the asRNA regulatory effect is only observed above certain expression thresholds, substantially higher than physiological transcript levels. These predictions were verified experimentally by overexpressing nine different asRNAs in Mycoplasma pneumoniae. Our results suggest that most of the antisense transcripts found in bacteria are the consequence of transcriptional noise, arising at spurious promoters throughout the genome.

  19. Bioaugmentation of Hydrogenispora ethanolica LX-B affects hydrogen production through altering indigenous bacterial community structure.

    PubMed

    Yang, Zhiman; Guo, Rongbo; Shi, Xiaoshuang; He, Shuai; Wang, Lin; Dai, Meng; Qiu, Yanling; Dang, Xiaoxiao

    2016-07-01

    Bioaugmentation can facilitate hydrogen production from complex organic substrates, but it still is unknown how indigenous microbial communities respond to the added bacteria. Here, using a Hydrogenispora ethanolica LX-B (named as LX-B) bioaugmentation experiments, the distribution of metabolites and the responses of indigenous bacterial communities were investigated via batch cultivation (BC) and repeated batch cultivation (RBC). In BC the LX-B/sludge ratio of 0.12 achieved substantial high hydrogen yield, which was over twice that of control. In RBC one-time bioaugmentation and repeated batch bioaugmentation of LX-B resulted in the hydrogen yield that was average 1.2-fold and 0.8-fold higher than that in control, respectively. This improved hydrogen production performance mainly benefited from a shift in composition of the indigenous bacterial community caused by LX-B bioaugmentation. The findings represented an important step in understanding the relationship between bioaugmentation, a shift in bacterial communities, and altered bioreactor performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Bacterial overgrowth and methane production in children with encopresis.

    PubMed

    Leiby, Alycia; Mehta, Devendra; Gopalareddy, Vani; Jackson-Walker, Susan; Horvath, Karoly

    2010-05-01

    To assess the prevalence of small intestinal bacterial overgrowth (SIBO) and methane production in children with encopresis. Radiographic fecal impaction (FI) scores were assessed in children with secondary, retentive encopresis and compared with the breath test results. Breath tests with hypoosmotic lactulose solution were performed in both the study patients (n = 50) and gastrointestinal control subjects (n = 39) groups. The FI scores were significantly higher in the patients with encopresis who were methane producers (P < .01). SIBO was diagnosed in 21 of 50 (42%) patients with encopresis and 9 of 39 (23%) of control subjects (P = .06). Methane was produced in 56% of the patients with encopresis versus 23.1% of the control subjects in the gastrointestinal group (P < .01). Fasting methane level was elevated in 48% versus 10.3 %, respectively (P < .01). Children with FI and encopresis had a higher prevalence of SIBO, elevated basal methane levels, and higher methane production. Methane production was associated with more severe colonic impaction. Further study is needed to determine whether methane production is a primary or secondary factor in the pathogenesis of SIBO and encopresis.

  1. Isotope Effects Associated with N2O Production By Fungal and Bacterial Nitric Oxide Reductases: Implications for Tracing Microbial Production Pathways

    NASA Astrophysics Data System (ADS)

    Ostrom, N. E.; Yang, H.; Gandhi, H.; Hegg, E. L.

    2014-12-01

    Site preference (SP), the difference in δ15N between the central (α) and outer (β) N atoms in N2O, has emerged as a conservative tracer of microbial N2O production. The key advantages of SP relative to bulk isotopes are (1) that it is independent of the isotope composition of the substrates of nitrification and denitrification and (2) has not been shown to exhibit fractionation during production. In pure microbial culture distinct SP values for N2O production from bacterial denitrification, including nitrifier-denitrification (-10 to 0 ‰), relative to hydroxylamine oxidation and fungal denitrification (33-37 ‰) provide a promising basis to resolve production pathways. In this study, we determined the δ15N, δ18O, δ15Nα, and δ15Nβ of N2O generated by purified fungal (P450nor) and bacterial nitric oxide reductases. The isotope values were used to calculate SP values, enrichment factors (e), and kinetic isotope effects (KIEs). Both O and Nα displayed normal isotope effects during enzymatic NO reduction by the P450nor with e values of -25.7‰ (KIE = 1.0264) and -12.6‰ (KIE = 1.0127), respectively. However, bulk nitrogen (average δ15N of Nα and Nβ) and Nβ exhibited inverse isotope effects with e values of 14.0‰ (KIE = 0.9862) and 36.1‰ (KIE = 0.9651), respectively. The observed inverse isotope effect in δ15Nβ is consistent with reversible binding of the first NO in the P450nor reaction mechanism. Experiments with bacterial nitric oxide reductase are ongoing, however, preliminary data indicates a inverse isotope effect in the α and β positions and a normal isotope effect in δ18O. In contrast to the constant SP observed during N2O production observed in microbial cultures, the SP measured for purified P450nor was not constant, increasing from ~15‰ to ~29‰ during the course of the reaction. Our results clearly indicate that fractionation of SP during N2O production by P450nor is not zero, and that SP values higher and lower than the

  2. Thin stillage supplementation greatly enhances bacterial cellulose production by Gluconacetobacter xylinus.

    PubMed

    Wu, Jyh-Ming; Liu, Ren-Han

    2012-09-01

    Thin stillage (TS), a wastewater from rice wine distillery can well sustain the growth of Gluconacetobacter xylinus for production of bacterial cellulose (BC). When used as a supplement to the traditional BC production medium (Hestrin and Schramm medium), the enhancement of BC production increased with the amount of TS supplemented in a static culture of G. xylinus. When TS was employed to replace distilled water for preparing HS medium (100%TS-HS medium), the BC production in this 100%TS-HS medium was enhanced 2.5-fold to a concentration of 10.38 g/l with sugar to BC conversion yield of 57% after 7 days cultivation. The cost-free TS as a supplement in BC production medium not only can greatly enhance the BC production, but also can effectively dispose the nuisance wastewater of rice wine distillery. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Bacterial antisense RNAs are mainly the product of transcriptional noise

    PubMed Central

    Lloréns-Rico, Verónica; Cano, Jaime; Kamminga, Tjerko; Gil, Rosario; Latorre, Amparo; Chen, Wei-Hua; Bork, Peer; Glass, John I.; Serrano, Luis; Lluch-Senar, Maria

    2016-01-01

    cis-Encoded antisense RNAs (asRNAs) are widespread along bacterial transcriptomes. However, the role of most of these RNAs remains unknown, and there is an ongoing discussion as to what extent these transcripts are the result of transcriptional noise. We show, by comparative transcriptomics of 20 bacterial species and one chloroplast, that the number of asRNAs is exponentially dependent on the genomic AT content and that expression of asRNA at low levels exerts little impact in terms of energy consumption. A transcription model simulating mRNA and asRNA production indicates that the asRNA regulatory effect is only observed above certain expression thresholds, substantially higher than physiological transcript levels. These predictions were verified experimentally by overexpressing nine different asRNAs in Mycoplasma pneumoniae. Our results suggest that most of the antisense transcripts found in bacteria are the consequence of transcriptional noise, arising at spurious promoters throughout the genome. PMID:26973873

  4. Bacterial cellulose biosynthesis: diversity of operons, subunits, products, and functions.

    PubMed

    Römling, Ute; Galperin, Michael Y

    2015-09-01

    Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits - which differ among various taxa - affect the enzymatic activity and product yield in vivo by modulating (i) the expression of the biosynthesis apparatus, (ii) the export of the nascent β-D-glucan polymer to the cell surface, and (iii) the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of resulting biofilms, which is particularly important for the interactions of bacteria with higher organisms - leading to rhizosphere colonization and modulating the virulence of cellulose-producing bacterial pathogens inside and outside of host cells. We review the organization of four principal types of cellulose synthase operon found in various bacterial genomes, identify additional bcs genes that encode components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms and in the choice between acute infection and persistence in the host. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

    PubMed Central

    Römling, Ute; Galperin, Michael Y.

    2015-01-01

    Summary Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host. PMID:26077867

  6. Strategies for cost-effective and enhanced production of bacterial cellulose.

    PubMed

    Islam, Mazhar Ul; Ullah, Muhammad Wajid; Khan, Shaukat; Shah, Nasrullah; Park, Joong Kon

    2017-09-01

    Bacterial cellulose (BC) has received substantial attention because of its high purity, mechanical strength, crystallinity, liquid-absorbing capabilities, biocompatibility, and biodegradability etc. These properties allow BC to be used in various fields, especially in industries producing medical, electronic, and food products etc. A major discrepancy associated with BC is its high production cost, usually much higher than the plant cellulose. To address this limitations, researchers have developed several strategies for enhanced production of BC including the designing of advanced reactors and utilization of various carbon sources. Another promising approach is the production of BC from waste materials such as food, industrial, agricultural, and brewery wastes etc. which not only reduces the overall BC production cost but is also environment-friendly. Besides, exploration of novel and efficient BC producing microbial strains provides impressive boost to the BC production processes. To this end, development of genetically engineered microbial strains has proven useful for enhanced BC production. In this review, we have summarized major efforts to enhance BC production in order to make it a cost-effective biopolymer. This review can be of interest to researchers investigating strategies for enhanced BC production, as well as companies exploring pilot projects to scale up BC production for industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Bacterial production in the water column of small streams highly depends on terrestrial dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Graeber, Daniel; Poulsen, Jane R.; Rasmussen, Jes J.; Kronvang, Brian; Zak, Dominik; Kamjunke, Norbert

    2016-04-01

    In the recent years it has become clear that the largest part of the terrestrial dissolved organic carbon (DOC) pool is removed on the way from the land to the ocean. Yet it is still unclear, where in the freshwater systems terrestrial DOC is actually taken up, and for streams DOC uptake was assumed to happen mostly at the stream bottom (benthic zone). However, a recent monitoring study implies that water column but not benthic bacteria are strongly affected by the amount and composition of DOM entering streams from the terrestrial zone. We conducted an experiment to compare the reaction of the bacterial production and heterotrophic uptake in the water column and the benthic zone to a standardized source of terrestrial DOC (leaf leachate from Beech litter). In detail, we sampled gravel and water from eight streams with a gradient in stream size and land use. For each stream four different treatments were incubated at 16°C for three days and each stream: filtered stream water with gravel stones (representing benthic zone bacteria) or unfiltered stream water (representing water column bacteria), both either with (n = 5) or, without (n = 3) leaf leachate. We found that the bacterial uptake of leaf litter DOC was higher for the benthic zone likely due to the higher bacterial production compared to the water column. In contrast, the bacterial production per amount of leaf leachate DOC taken up was significantly higher for the bacteria in the water column than for those in the benthic zone. This clearly indicates a higher growth efficiency with the leaf leachate DOC for the bacteria in the water column than in the benthic zone. We found a high variability for the growth efficiency in the water column, which was best explained by a negative correlation of the DOC demand with stream width (R² = 0.86, linear correlation of log-transformed data). This was not the case for the benthic zone bacteria (R² = 0.02). This implies that water column bacteria in very small streams

  8. Methane production and small intestinal bacterial overgrowth in children living in a slum

    PubMed Central

    Mello, Carolina Santos; Tahan, Soraia; Melli, Lígia Cristina FL; Rodrigues, Mirian Silva do Carmo; de Mello, Ricardo Martin Pereira; Scaletsky, Isabel Cristina Affonso; de Morais, Mauro Batista

    2012-01-01

    AIM: To analyze small intestinal bacterial overgrowth in school-aged children and the relationship between hydrogen and methane production in breath tests. METHODS: This transversal study included 85 children residing in a slum and 43 children from a private school, all aged between 6 and 10 years, in Osasco, Brazil. For characterization of the groups, data regarding the socioeconomic status and basic housing sanitary conditions were collected. Anthropometric data was obtained in children from both groups. All children completed the hydrogen (H2) and methane (CH4) breath test in order to assess small intestinal bacterial overgrowth (SIBO). SIBO was diagnosed when there was an increase in H2 ≥ 20 ppm or CH4 ≥ 10 ppm with regard to the fasting value until 60 min after lactulose ingestion. RESULTS: Children from the slum group had worse living conditions and lower nutritional indices than children from the private school. SIBO was found in 30.9% (26/84) of the children from the slum group and in 2.4% (1/41) from the private school group (P = 0.0007). Greater hydrogen production in the small intestine was observed in children from the slum group when compared to children from the private school (P = 0.007). A higher concentration of hydrogen in the small intestine (P < 0.001) and in the colon (P < 0.001) was observed among the children from the slum group with SIBO when compared to children from the slum group without SIBO. Methane production was observed in 63.1% (53/84) of the children from the slum group and in 19.5% (8/41) of the children from the private school group (P < 0.0001). Methane production was observed in 38/58 (65.5%) of the children without SIBO and in 15/26 (57.7%) of the children with SIBO from the slum. Colonic production of hydrogen was lower in methane-producing children (P = 0.017). CONCLUSION: Children who live in inadequate environmental conditions are at risk of bacterial overgrowth and methane production. Hydrogen is a substrate for

  9. Investigating alternative strategies for managing bacterial angular leaf spot in strawberry nursery production

    USDA-ARS?s Scientific Manuscript database

    The focus of this article is to discuss some of the approaches we have tested for managing the bacterial pathogen Xanthomonas fragariae in infected strawberry nursery stock. X. fragariae causes angular leaf spot (ALS) in strawberry. The pathogen is transmitted to production fields almost exclusively...

  10. Microbial biomass and productivity in seagrass beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moriarty, P.J.W.; Boon, P.I.; Hansen, J.A.

    1985-01-01

    Different methods for measuring the rates of processes mediated by bacteria in sediments and the rates of bacterial cell production have been compared. In addition, net production of the seagrass Zostera capricorni and bacterial production have been compared and some interrelationships with the nitrogen cycle discussed. Seagrass productivity was estimated by measuring the plastochrone interval using a leaf stapling technique. The average productivity over four seasons was 1.28 +- 0.28 g C/m/sup 2/ day (meand +- standard deviation, n = 4). Bacterial productivity was measured five times throughout a year using the rate of tritiated thymidine incorporated into DNA. Averagemore » values were 33 +- 12 mg C/m/sup 2/ day for sediment and 23 +- 4 for water column (n = 5). Spatial variability between samples was greater than seasonal variation for both seagrass productivity and bacterial productivity. On one occasion, bacterial productivity was measured using the rate of /sup 32/P incorporated into phospholipid. The values were comparable to those obtained with tritiated thymidine. The rate of sulfate reduction was 10 mmol SO/sub 4//m/sup 2/ day. The rate of methanogenesis was low, being 5.6 mg CH/sub 4/ produced/m/sup 2/ day. A comparison of C flux measured using rates of sulfate reduction and DNA synthesis indicated that anaerobic processes were predominant in these sediments. An analysis of microbial biomass and community structure, using techniques of phospholipid analysis, showed that bacteria were predominant members of the microbial biomass and that of these strictly anaerobic bacteria were the main components. Ammonia concentration in interstitial water varied from 23 to 71 ..mu..M. Estimates of the amount of ammonia required by seagrass showed that the ammonia would turn over about once per day. Rapid recycling of nitrogen by bacteria and bacterial grazers is probably important.« less

  11. Microbial biomass and productivity in seagrass beds

    NASA Technical Reports Server (NTRS)

    Moriarty, D. J.; Boon, P. I.; Hansen, J. A.; Hunt, W. G.; Poiner, I. R.; Pollard, P. C.; Skyring, G. W.; White, D. C.

    1985-01-01

    Different methods for measuring the rates of processes mediated by bacteria in sediments and the rates of bacterial cell production have been compared. In addition, net production of the seagrass Zostera capricorni and bacterial production have been compared and some interrelationships with the nitrogen cycle discussed. Seagrass productivity was estimated by measuring the plastochrone interval using a leaf stapling technique. The average productivity over four seasons was 1.28 +/- 0.28 g C m-2 day-1 (mean +/- standard deviation, n = 4). Bacterial productivity was measured five times throughout a year using the rate of tritiated thymidine incorporated into DNA. Average values were 33 +/- 12 mg C m-2 day-1 for sediment and 23 +/- 4 for water column (n = 5). Spatial variability between samples was greater than seasonal variation for both seagrass productivity and bacterial productivity. On one occasion, bacterial productivity was measured using the rate of 32P incorporated into phospholipid. The values were comparable to those obtained with tritiated thymidine. The rate of sulfate reduction was 10 mmol SO4(-2) m-2 day-1. The rate of methanogenesis was low, being 5.6 mg CH4 produced m-2 day-1. A comparison of C flux measured using rates of sulfate reduction and DNA synthesis indicated that anaerobic processes were predominant in these sediments. An analysis of microbial biomass and community structure, using techniques of phospholipid analysis, showed that bacteria were predominant members of the microbial biomass and that of these, strictly anaerobic bacteria were the main components. Ammonia concentration in interstitial water varied from 23 to 71 micromoles. Estimates of the amount of ammonia required by seagrass showed that the ammonia would turn over about once per day. Rapid recycling of nitrogen by bacteria and bacterial grazers is probably important.

  12. Cellulosic hydrogen production with a sequencing bacterial hydrolysis and dark fermentation strategy.

    PubMed

    Lo, Yung-Chung; Bai, Ming-Der; Chen, Wen-Ming; Chang, Jo-Shu

    2008-11-01

    In this study, cellulose hydrolysis activity of two mixed bacterial consortia (NS and QS) was investigated. Combination of NS culture and BHM medium exhibited better hydrolytic activity under the optimal condition of 35 degrees C, initial pH 7.0, and 100rpm agitation. The NS culture could hydrolyze carboxymethyl cellulose (CMC), rice husk, bagasse and filter paper, among which CMC gave the best hydrolysis performance. The CMC hydrolysis efficiency increased with increasing CMC concentration from 5 to 50g/l. With a CMC concentration of 10g/l, the total reducing sugar (RS) production and the RS producing rate reached 5531.0mg/l and 92.9mg/l/h, respectively. Furthermore, seven H2-producing bacterial isolates (mainly Clostridium species) were used to convert the cellulose hydrolysate into H2 energy. With an initial RS concentration of 0.8g/l, the H2 production and yield was approximately 23.8ml/l and 1.21mmol H2/g RS (0.097mmol H2/g cellulose), respectively.

  13. Reduction of bacterial volatile sulfur compound production by licoricidin and licorisoflavan A from licorice.

    PubMed

    Tanabe, Shin-ichi; Desjardins, Jacynthe; Bergeron, Chantal; Gafner, Stefan; Villinski, Jacquelyn R; Grenier, Daniel

    2012-03-01

    Halitosis affects a large proportion of the population and is, in most cases, caused by the production of volatile sulfur compounds (VSCs), particularly methyl mercaptan and hydrogen sulfide, by specific bacterial species colonizing the oral cavity. In this study, a supercritical extract of Chinese licorice (Glycyrrhiza uralensis), and its major isoflavans, licoricidin and licorisoflavan A, were investigated for their effect on growth, VSC production and protease activity of Porphyromonas gingivalis, Prevotella intermedia and Solobacterium moorei, which have been associated with halitosis. The effects of licorice extract, licoricidin, and licorisoflavan A on VSC production in a saliva model were also tested. We first showed that licoricidin and licorisoflavan A, and to a lesser extent the licorice extract, were effective in inhibiting the growth of all three bacterial species, with minimal inhibitory concentrations in the range of 2-80 µg ml(-1). The licorice extract and the two isolates licoricidin and licorisoflavan A, were able to dose-dependently reduce VSC production by P. gingivalis, Prev. intermedia, and S. moorei as well as by a human saliva model. Although the extract and isolates did not inhibit the proteolytic activity of bacteria, they blocked the conversion of cysteine into hydrogen sulfide by Prev. intermedia. Lastly, the deodorizing effects of the licorice extract, licoricidin, and licorisoflavan A were demonstrated, as they can neutralize P. gingivalis-derived VSCs. Licorisoflavan A (10 µg ml(-1)) was found to be the most effective by reducing VSC levels by 50%. Within the limitations of this study, it can be concluded that a licorice supercritical extract and its major isoflavans (licoricidin and licorisoflavan A) represent natural ingredients with a potential for reducing bacterial VSC production and therefore for controlling halitosis.

  14. Measuring bacterial activity and community composition at high hydrostatic pressure using a novel experimental approach: a pilot study.

    PubMed

    Wannicke, Nicola; Frindte, Katharina; Gust, Giselher; Liskow, Iris; Wacker, Alexander; Meyer, Andreas; Grossart, Hans-Peter

    2015-05-01

    In this pilot study, we describe a high-pressure incubation system allowing multiple subsampling of a pressurized culture without decompression. The system was tested using one piezophilic (Photobacterium profundum), one piezotolerant (Colwellia maris) bacterial strain and a decompressed sample from the Mediterranean deep sea (3044 m) determining bacterial community composition, protein production (BPP) and cell multiplication rates (BCM) up to 27 MPa. The results showed elevation of BPP at high pressure was by a factor of 1.5 ± 1.4 and 3.9 ± 2.3 for P. profundum and C. maris, respectively, compared to ambient-pressure treatments and by a factor of 6.9 ± 3.8 fold in the field samples. In P. profundum and C. maris, BCM at high pressure was elevated (3.1 ± 1.5 and 2.9 ± 1.7 fold, respectively) compared to the ambient-pressure treatments. After 3 days of incubation at 27 MPa, the natural bacterial deep-sea community was dominated by one phylum of the genus Exiguobacterium, indicating the rapid selection of piezotolerant bacteria. In future studies, our novel incubation system could be part of an isopiestic pressure chain, allowing more accurate measurement of bacterial activity rates which is important both for modeling and for predicting the efficiency of the oceanic carbon pump. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Empirical Leucine-to-Carbon Conversion Factors for Estimating Heterotrophic Bacterial Production: Seasonality and Predictability in a Temperate Coastal Ecosystem▿

    PubMed Central

    Calvo-Díaz, Alejandra; Morán, Xosé Anxelu G.

    2009-01-01

    Leucine-to-carbon conversion factors (CFs) are needed for converting substrate incorporation into biomass production of heterotrophic bacteria. During 2006 we performed 20 dilution experiments for determining the spatiotemporal variability of empirical CFs in temperate Atlantic coastal waters. Values (0.49 to 1.92 kg C mol Leu−1) showed maxima in autumn to early winter and minima in summer. Spatially averaged CFs were significantly negatively correlated with in situ leucine incorporation rates (r = −0.91) and positively correlated with phosphate concentrations (r = 0.76). These relationships, together with a strong positive covariation between cell-specific leucine incorporation rates and carbon contents (r = 0.85), were interpreted as a strategy to maximize survival through protein synthesis and low growth rates under nutrient limitation (low CFs) until favorable conditions stimulate cell division relative to protein synthesis (high CFs). A multiple regression with in situ leucine incorporation rates and cellular carbon contents explained 96% of CF variance in our ecosystem, suggesting their potential prediction from more easily measurable routine variables. The use of the theoretical CF of 1.55 kg C mol Leu−1 would have resulted in a serious overestimation (73%) of annual bacterial production rates. Our results emphasize the need for considering the temporal scale in CFs for bacterial production studies. PMID:19304821

  16. Production of nano bacterial cellulose from waste water of candied jujube-processing industry using Acetobacter xylinum.

    PubMed

    Li, Zheng; Wang, Lifen; Hua, Jiachuan; Jia, Shiru; Zhang, Jianfei; Liu, Hao

    2015-04-20

    The work is aimed to investigate the suitability of waste water of candied jujube-processing industry for the production of bacterial cellulose (BC) by Gluconacetobacter xylinum CGMCC No.2955 and to study the structure properties of bacterial cellulose membranes. After acid pretreatment, the glucose of hydrolysate was higher than that of waste water of candied jujube. The volumetric yield of bacterial cellulose in hydrolysate was 2.25 g/L, which was 1.5-folds of that in waste water of candied jujube. The structures indicated that the fiber size distribution was 3-14 nm in those media with an average diameter being around 5.9 nm. The crystallinity index of BC from pretreatment medium was lower than that of without pretreatment medium and BCs from various media had similar chemical binding. Ammonium citrate was a key factor for improving production yield and the crystallinity index of BC. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Control of biofouling by xanthine oxidase on seawater reverse osmosis membranes from a desalination plant: enzyme production and screening of bacterial isolates from the full-scale plant.

    PubMed

    Nagaraj, V; Skillman, L; Li, D; Xie, Z; Ho, G

    2017-07-01

    Control of biofouling on seawater reverse osmosis (SWRO) membranes is a major challenge as treatments can be expensive, damage the membrane material and often biocides do not remove the polymers in which bacteria are embedded. Biological control has been largely ignored for biofouling control. The objective of this study was to demonstrate the effectiveness of xanthine oxidase enzyme against complex fouling communities and then identify naturally occurring bacterial strains that produce the free radical generating enzyme. Initially, 64 bacterial strains were isolated from different locations of the Perth Seawater Desalination Plant. In our preceding study, 25/64 isolates were selected from the culture collection as models for biofouling studies, based on their prevalence in comparison to the genomic bacterial community. In this study, screening of these model strains was performed using a nitroblue tetrazolium assay in the presence of hypoxanthine as substrate. Enzyme activity was measured by absorbance. Nine of 25 strains tested positive for xanthine oxidase production, of which Exiguobacterium from sand filters and Microbacterium from RO membranes exhibited significant levels of enzyme production. Other genera that produced xanthine oxidase were Marinomonas, Pseudomonas, Bacillus, Pseudoalteromonas and Staphylococcus. Strain variations were observed between members of the genera Microbacterium and Bacillus. Xanthine oxidase, an oxidoreductase enzyme that generates reactive oxygen species, is endogenously produced by many bacterial species. In this study, production of the enzyme by bacterial isolates from a full-scale desalination plant was investigated for potential use as biological control of membrane fouling in seawater desalination. We have previously demonstrated that free radicals generated by a commercially available xanthine oxidase in the presence of a hypoxanthine substrate, effectively dispersed biofilm polysaccharides on industrially fouled membranes

  18. Bacterial and Fungal Proteolytic Enzymes: Production, Catalysis and Potential Applications.

    PubMed

    da Silva, Ronivaldo Rodrigues

    2017-09-01

    Submerged and solid-state bioprocesses have been extensively explored worldwide and employed in a number of important studies dealing with microbial cultivation for the production of enzymes. The development of these production technologies has facilitated the generation of new enzyme-based products with applications in pharmaceuticals, food, bioactive peptides, and basic research studies, among others. The applicability of microorganisms in biotechnology is potentiated because of their various advantages, including large-scale production, short time of cultivation, and ease of handling. Currently, several studies are being conducted to search for new microbial peptidases with peculiar biochemical properties for industrial applications. Bioprospecting, being an important prerequisite for research and biotechnological development, is based on exploring the microbial diversity for enzyme production. Limited information is available on the production of specific proteolytic enzymes from bacterial and fungal species, especially on the subgroups threonine and glutamic peptidases, and the seventh catalytic type, nonhydrolytic asparagine peptide lyase. This gap in information motivated the present study about these unique biocatalysts. In this study, the biochemical and biotechnological aspects of the seven catalytic types of proteolytic enzymes, namely aspartyl, cysteine, serine, metallo, glutamic, and threonine peptidase, and asparagine peptide lyase, are summarized, with an emphasis on new studies, production, catalysis, and application of these enzymes.

  19. Indigenous bacteria and bacterial metabolic products in the gastrointestinal tract of broiler chickens.

    PubMed

    Rehman, Habib Ur; Vahjen, Wilfried; Awad, Wageha A; Zentek, Jürgen

    2007-10-01

    The gastrointestinal tract is a dynamic ecosystem containing a complex microbial community. In this paper, the indigenous intestinal bacteria and the microbial fermentation profile particularly short chain fatty acids (SCFA), lactate, and ammonia concentrations are reviewed. The intestinal bacterial composition changes with age. The bacterial density of the small intestine increases with age and comprises of lactobacilli, streptococci, enterobacteria, fusobacteria and eubacteria. Strict anaerobes (anaerobic gram-positive cocci, Eubacterium spp., Clostridium spp., Lactobacillus spp., Fusobacterium spp. and Bacteroides) are predominating caecal bacteria in young broilers. Data from culture-based studies showed that bifidobacteria could not be isolated from young birds, but were recovered from four-week-old broilers. Caecal lactobacilli accounted for 1.5-24% of the caecal bacteria. Gene sequencing of caecal DNA extracts showed that the majority of bacteria belonged to Clostridiaceae. Intestinal bacterial community is influenced by the dietary ingredients, nutrient levels and physical structure of feed. SCFA and other metabolic products are affected by diet formulation and age. Additional studies are required to know the bacterial metabolic activities together with the community analysis of the intestinal bacteria. Feed composition and processing have great potential to influence the activities of intestinal bacteria towards a desired direction in order to support animal health, well-being and microbial safety of broiler meat.

  20. Bacterial Production and Enzymatic Activities in Deep-Sea Sediments of the Pacific Ocean: Biogeochemical Implications of Different Temperature Constraints

    NASA Astrophysics Data System (ADS)

    Danovaro, R.; Corinaldesi, C.; dell'Anno, A.

    2002-12-01

    The deep-sea bed, acting as the ultimate sink for organic material derived from the upper oceans primary production, is now assumed to play a key role in biogeochemical cycling of organic matter on global scale. Early diagenesis of organic matter in marine sediments is dependent upon biological processes (largely mediated by bacterial activity) and by molecular diffusion. Organic matter reaching the sea floor by sedimentation is subjected to complex biogeochemical transformations that make organic matter largely unsuitable for direct utilization by benthic heterotrophs. Extracellular enzymatic activities in the sediment is generally recognized as the key step in the degradation and utilization of organic polymers by bacteria and a key role in biopolymeric carbon mobilization is played by aminopeptidase, alkaline phosphatase and glucosidase activities. In the present study we investigated bacterial density, bacterial C production and exo-enzymatic activities (aminopeptidase, glucosidase and phosphatase activity) in deep-sea sediments of the Pacific Ocean in relation with the biochemical composition of sediment organic matter (proteins, carbohydrates and lipids), in order to gather information on organic matter cycling and diagenesis. Benthic viral abundance was also measured to investigate the potential role of viruses on microbial loop functioning. Sediment samples were collected at eight stations (depth ranging from 2070-3100 m) along two transects located at the opposite side (north and south) of ocean seismic ridge Juan Fernandez (along latitudes 33° 20' - 33° 40'), constituted by the submerged vulcanoes, which connects the Chilean coasts to Rapa Nui Island. Since the northern and southern sides of this ridge apparently displayed small but significant differences in deep-sea temperature (related to the general ocean circulation), this sampling strategy allowed also investigating the role of different temperature constraints on bacterial activity and

  1. Novel approach for the use of dairy industry wastes for bacterial growth media production.

    PubMed

    Kasmi, Mariam; Elleuch, Lobna; Dahmeni, Ameni; Hamdi, Moktar; Trabelsi, Ismail; Snoussi, Mejdi

    2018-04-15

    This work proposes a novel approach for the reuse and the recovery of dairy wastes valuable components. Thermal coagulation was performed for dairy effluents and the main responsible fraction for the organic matter content (protein and fat) was separated. Dairy curds were prepared for the formulation of bacterial growth media. Protein, sugar, fat and fatty acids contents have been assessed. Samples treated at 100 °C exhibited marked improvement in terms of protein (25-50%) recovery compared to those treated at 80 °C. Fatty acid analysis revealed the presence of unsaturated fatty acids (mainly oleic acid) that are essential to promote Lactobacillus growth. Previously isolated and identified bacterial strains from dairy wastes (Lactobacillus paracasei, Lactobacillus plantarum, Lactococcus lactis and Lactobacillus brevis) were investigated for their ability to grow on the formulated media. All the tested lactic acid bacteria exhibited greater bacterial growth on the formulated media supplemented with glucose only or with both glucose and yeast extract compared to the control media. By reference to the commercial growth medium, the productivity ratio of the supplemented bactofugate (B) and decreaming (D) formulated media exceeded 0.6 for L. paracasei culture. Whereas, the productivity ratio of the supplemented B medium was greater than 1 compared to the control medium for all the tested strains. As for the supplemented D medium, its productivity ratio was greater than 1 compared to the control medium for both L. paracasei and L. plantarum strains. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lemmer, Kimberly C.; Zhang, Weiping; Langer, Samantha J.

    ABSTRACT Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation inRhodobacter sphaeroides. By screening anR. sphaeroidesTn5mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their totalmore » lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCEThis paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these

  3. Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production.

    PubMed

    Lemmer, Kimberly C; Zhang, Weiping; Langer, Samantha J; Dohnalkova, Alice C; Hu, Dehong; Lemke, Rachelle A; Piotrowski, Jeff S; Orr, Galya; Noguera, Daniel R; Donohue, Timothy J

    2017-05-23

    Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides By screening an R. sphaeroides Tn 5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCE This paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these alterations can be

  4. Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

    DOE PAGES

    Lemmer, Kimberly C.; Zhang, Weiping; Langer, Samantha J.; ...

    2017-05-23

    ABSTRACT Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation inRhodobacter sphaeroides. By screening anR. sphaeroidesTn5mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their totalmore » lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCEThis paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these

  5. Expert Opinion on Three Phage Therapy Related Topics: Bacterial Phage Resistance, Phage Training and Prophages in Bacterial Production Strains.

    PubMed

    Rohde, Christine; Resch, Grégory; Pirnay, Jean-Paul; Blasdel, Bob G; Debarbieux, Laurent; Gelman, Daniel; Górski, Andrzej; Hazan, Ronen; Huys, Isabelle; Kakabadze, Elene; Łobocka, Małgorzata; Maestri, Alice; Almeida, Gabriel Magno de Freitas; Makalatia, Khatuna; Malik, Danish J; Mašlaňová, Ivana; Merabishvili, Maia; Pantucek, Roman; Rose, Thomas; Štveráková, Dana; Van Raemdonck, Hilde; Verbeken, Gilbert; Chanishvili, Nina

    2018-04-05

    Phage therapy is increasingly put forward as a "new" potential tool in the fight against antibiotic resistant infections. During the "Centennial Celebration of Bacteriophage Research" conference in Tbilisi, Georgia on 26-29 June 2017, an international group of phage researchers committed to elaborate an expert opinion on three contentious phage therapy related issues that are hampering clinical progress in the field of phage therapy. This paper explores and discusses bacterial phage resistance, phage training and the presence of prophages in bacterial production strains while reviewing relevant research findings and experiences. Our purpose is to inform phage therapy stakeholders such as policy makers, officials of the competent authorities for medicines, phage researchers and phage producers, and members of the pharmaceutical industry. This brief also points out potential avenues for future phage therapy research and development as it specifically addresses those overarching questions that currently call for attention whenever phages go into purification processes for application.

  6. Expert Opinion on Three Phage Therapy Related Topics: Bacterial Phage Resistance, Phage Training and Prophages in Bacterial Production Strains

    PubMed Central

    Rohde, Christine; Resch, Grégory; Blasdel, Bob G.; Gelman, Daniel; Górski, Andrzej; Hazan, Ronen; Huys, Isabelle; Kakabadze, Elene; Łobocka, Małgorzata; Maestri, Alice; Makalatia, Khatuna; Malik, Danish J.; Mašlaňová, Ivana; Merabishvili, Maia; Rose, Thomas; Štveráková, Dana; Van Raemdonck, Hilde; Verbeken, Gilbert; Chanishvili, Nina

    2018-01-01

    Phage therapy is increasingly put forward as a “new” potential tool in the fight against antibiotic resistant infections. During the “Centennial Celebration of Bacteriophage Research” conference in Tbilisi, Georgia on 26–29 June 2017, an international group of phage researchers committed to elaborate an expert opinion on three contentious phage therapy related issues that are hampering clinical progress in the field of phage therapy. This paper explores and discusses bacterial phage resistance, phage training and the presence of prophages in bacterial production strains while reviewing relevant research findings and experiences. Our purpose is to inform phage therapy stakeholders such as policy makers, officials of the competent authorities for medicines, phage researchers and phage producers, and members of the pharmaceutical industry. This brief also points out potential avenues for future phage therapy research and development as it specifically addresses those overarching questions that currently call for attention whenever phages go into purification processes for application. PMID:29621199

  7. Legacy effects of anaerobic soil disinfestation on soil bacterial community composition and production of pathogen-suppressing volatiles

    PubMed Central

    van Agtmaal, Maaike; van Os, Gera J.; Hol, W.H. Gera; Hundscheid, Maria P.J.; Runia, Willemien T.; Hordijk, Cornelis A.; de Boer, Wietse

    2015-01-01

    There is increasing evidence that microbial volatiles (VOCs) play an important role in natural suppression of soil-borne diseases, but little is known on the factors that influence production of suppressing VOCs. In the current study we examined whether a stress-induced change in soil microbial community composition would affect the production by soils of VOCs suppressing the plant-pathogenic oomycete Pythium. Using pyrosequencing of 16S ribosomal gene fragments we compared the composition of bacterial communities in sandy soils that had been exposed to anaerobic disinfestation (AD), a treatment used to kill harmful soil organisms, with the composition in untreated soils. Three months after the AD treatment had been finished, there was still a clear legacy effect of the former anaerobic stress on bacterial community composition with a strong increase in relative abundance of the phylum Bacteroidetes and a significant decrease of the phyla Acidobacteria, Planctomycetes, Nitrospirae, Chloroflexi, and Chlorobi. This change in bacterial community composition coincided with loss of production of Pythium suppressing soil volatiles (VOCs) and of suppression of Pythium impacts on Hyacinth root development. One year later, the composition of the bacterial community in the AD soils was reflecting that of the untreated soils. In addition, both production of Pythium-suppressing VOCs and suppression of Pythium in Hyacinth bioassays had returned to the levels of the untreated soil. GC/MS analysis identified several VOCs, among which compounds known to be antifungal, that were produced in the untreated soils but not in the AD soils. These compounds were again produced 15 months after the AD treatment. Our data indicate that soils exposed to a drastic stress can temporarily lose pathogen suppressive characteristics and that both loss and return of these suppressive characteristics coincides with shifts in the soil bacterial community composition. Our data are supporting the

  8. Application of Recombinant Factor C Reagent for the Detection of Bacterial Endotoxins in Pharmaceutical Products.

    PubMed

    Bolden, Jay; Smith, Kelly

    2017-01-01

    Recombinant Factor C (rFC) is non-animal-derived reagent used to detect bacterial endotoxins in pharmaceutical products. Despite the fact that the reagent was first commercially available nearly 15 years ago, the broad use of rFC in pharmaceutical industry has long been lagging, presumably due to historical single-source supplier concerns and the lack of inclusion in worldwide pharmacopeias. Commercial rFC reagents are now available from multiple manufacturers, thus single sourcing is no longer an issue. We report here the successful validation of several pharmaceutical products by an end-point florescence-based endotoxin method using the rFC reagent. The method is equivalent or superior to the compendia bacterial endotoxins test method. Based on the comparability data and extenuating circumstances, the incorporation of the end point fluorescence technique and rFC reagent in global compendia bacterial endotoxins test chapters is desired and warranted. LAY ABSTRACT: Public health has been protected for over 30 years with the use of a purified blood product of the horseshoe crab, limulus amebocyte lysate. More recently, this blood product can be produced in biotech manufacturing processes, which reduces potential impacts to the horseshoe crab and related species dependent upon the crab, for example, migrating shorebirds. The pharmaceutical industry has been slow to adopt the use of this reagent, Recombinant Factor C (rFC), for various reasons. We evaluated the use of rFC across many pharmaceutical products, and in other feasibility demonstration experiments, and found rFC to be a suitable alternative to the animal-derived limulus amebocyte lysate. Incorporation of rFC and its analytical method into national testing standards would provide an equivalent or better test while continuing to maintain patient safety for those who depend on medicines and while securing pharmaceutical supply chains. In addition, widespread use of this method would benefit existing animal

  9. Measurement of Interleukin-6 in Cerebrospinal Fluid for the Diagnosis of Bacterial Meningitis.

    PubMed

    Dano, Ibrahim Dan; Sadou, Hassimi; Issaka, Bassira; Oukem-Boyer, Odile Ouwe Missi

    It is assessed whether the measurement of interleukin-6 in the cerebrospinal fluid can serve as a biomarker for the diagnosis of bacterial meningitis. Cerebrospinal fluid was obtained from 152 patients aged 0-15 years suspected of having meningitis. These patients were classified into the following groups: Bacterial meningitis (n = 85), aseptic meningitis (n = 35) and non-meningitis/control (n = 32) based on leukocyte count and bacterial identification by culture and molecular biology. Interleukin-6 concentrations in cerebrospinal fluid were measured by enzyme-linked immunosorbent assay. This study found a significant difference of the mean cerebrospinal fluid interleukin-6 level (p≤0.01) between patients with bacterial meningitis (3,538.69±2,560.78 pg mL -1) and patients with aseptic meningitis (332.51±470.69 pg mL -1) or those of the control group (205.83±79.39 pg mL -1). There was also a significant difference of the mean cerebrospinal fluid interleukin-6 level between patients with aseptic meningitis and those of the control group. Interleukin-6 had the highest area under the ROC curve: 0.94 (95% confidence interval: 0.901-0.979) compared to that of cerebrospinal fluid glucose and total protein. At a cut-off value of 1,065.96 pg mL -1, interleukin-6 had a sensitivity of 76.2% and specificity of 100%. Interleukin-6 is a potential biomarker for the differential diagnosis of meningitis.

  10. Exposure to bacterial products lipopolysaccharide and flagellin and hepatocellular carcinoma: a nested case-control study.

    PubMed

    Fedirko, Veronika; Tran, Hao Quang; Gewirtz, Andrew T; Stepien, Magdalena; Trichopoulou, Antonia; Aleksandrova, Krasimira; Olsen, Anja; Tjønneland, Anne; Overvad, Kim; Carbonnel, Franck; Boutron-Ruault, Marie-Christine; Severi, Gianluca; Kühn, Tilman; Kaaks, Rudolf; Boeing, Heiner; Bamia, Christina; Lagiou, Pagona; Grioni, Sara; Panico, Salvatore; Palli, Domenico; Tumino, Rosario; Naccarati, Alessio; Peeters, Petra H; Bueno-de-Mesquita, H B; Weiderpass, Elisabete; Castaño, José María Huerta; Barricarte, Aurelio; Sánchez, María-José; Dorronsoro, Miren; Quirós, J Ramón; Agudo, Antonio; Sjöberg, Klas; Ohlsson, Bodil; Hemmingsson, Oskar; Werner, Mårten; Bradbury, Kathryn E; Khaw, Kay-Tee; Wareham, Nick; Tsilidis, Konstantinos K; Aune, Dagfinn; Scalbert, Augustin; Romieu, Isabelle; Riboli, Elio; Jenab, Mazda

    2017-04-04

    Leakage of bacterial products across the gut barrier may play a role in liver diseases which often precede the development of liver cancer. However, human studies, particularly from prospective settings, are lacking. We used a case-control study design nested within a large prospective cohort to assess the association between circulating levels of anti-lipopolysaccharide (LPS) and anti-flagellin immunoglobulin A (IgA) and G (IgG) (reflecting long-term exposures to LPS and flagellin, respectively) and risk of hepatocellular carcinoma. A total of 139 men and women diagnosed with hepatocellular carcinoma between 1992 and 2010 were matched to 139 control subjects. Multivariable rate ratios (RRs), including adjustment for potential confounders, hepatitis B/C positivity, and degree of liver dysfunction, were calculated with conditional logistic regression. Antibody response to LPS and flagellin was associated with a statistically significant increase in the risk of hepatocellular carcinoma (highest vs. lowest quartile: RR = 11.76, 95% confidence interval = 1.70-81.40; P trend  = 0.021). This finding did not vary substantially by time from enrollment to diagnosis, and did not change after adjustment for chronic infection with hepatitis B and C viruses. These novel findings, based on exposures up to several years prior to diagnosis, support a role for gut-derived bacterial products in hepatocellular carcinoma development. Further study into the role of gut barrier failure and exposure to bacterial products in liver diseases is warranted.

  11. Magnesium aminoclay enhances lipid production of mixotrophic Chlorella sp. KR-1 while reducing bacterial populations.

    PubMed

    Kim, Bohwa; Praveenkumar, Ramasamy; Lee, Jiye; Nam, Bora; Kim, Dong-Myung; Lee, Kyubock; Lee, Young-Chul; Oh, You-Kwan

    2016-11-01

    Improving lipid productivity and preventing overgrowth of contaminating bacteria are critical issues relevant to the commercialization of the mixotrophic microalgae cultivation process. In this paper, we report the use of magnesium aminoclay (MgAC) nanoparticles for enhanced lipid production from oleaginous Chlorella sp. KR-1 with simultaneous control of KR-1-associated bacterial growth in mixotrophic cultures with glucose as the model substrate. Addition of 0.01-0.1g/L MgAC promoted microalgal biomass production better than the MgAC-less control, via differential biocidal effects on microalgal and bacterial cells (the latter being more sensitive to MgAC's bio-toxicity than the former). The inhibition effect of MgAC on co-existing bacteria was, as based on density-gradient-gel-electrophoresis (DGGE) analysis, largely dosage-dependent and species-specific. MgAC also, by inducing an oxidative stress environment, increased both the cell size and lipid content of KR-1, resulting in a considerable, ∼25% improvement of mixotrophic algal lipid productivity (to ∼410mgFAME/L/d) compared with the untreated control. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Using Natural Products to Treat Resistant and Persistent Bacterial Infections

    NASA Astrophysics Data System (ADS)

    Deering, Robert W.

    Antimicrobial resistance is a growing threat to human health both worldwide and in the United States. Most concerning is the emergence of multi-drug resistant (MDR) bacterial pathogens, especially the 'ESKAPE' pathogens for which treatment options are dwindling. To complicate the problem, approvals of antibiotic drugs are extremely low and many research and development efforts in the pharmaceutical industry have ceased, leaving little certainty that critical new antibiotics are nearing the clinic. New antibiotics are needed to continue treating these evolving infections. In addition to antibiotics, approaches that aim to inhibit or prevent antimicrobial resistance could be useful. Also, studies that improve our understanding of bacterial pathophysiology could lead to new therapies for infectious disease. Natural products, especially those from the microbial world, have been invaluable as resources for new antibacterial compounds and as insights into bacterial physiology. The goal of this dissertation is to find new ways to treat resistant bacterial infections and learn more about the pathophysiology of these bacteria. Investigations of natural products to find molecules able to be used as new antibiotics or to modulate resistance and other parts of bacterial physiology are crucial aspects of the included studies. The first included study, which is reported in chapter two, details a chemical investigation of a marine Pseudoalteromonas sp. Purification efforts of the microbial metabolites were guided by testing against a resistance nodulation of cell division model of efflux pumps expressed in E. coli. These pumps play an important role in the resistance of MDR Gram negative pathogens such as Pseudomonas aeruginosa and Enterobacteriaceae. Through this process, 3,4-dibromopyrrole-2,5-dione was identified as a potent inhibitor of the RND efflux pumps and showed synergistic effects against the E. coli strain with common antibiotics including fluoroquinolones, beta

  13. Evidence against a bacterial endotoxin masking effect in biologic drug products by limulus amebocyte lysate detection.

    PubMed

    Bolden, Jay S; Claerbout, Mark E; Miner, Matthew K; Murphy, Marie A; Smith, Kelly R; Warburton, Rob E

    2014-01-01

    The inability to detect endotoxin using compendia methods is a potential safety concern for patients due to the lack of endotoxin removal capabilities at the fill-finish stage in typical aseptic biologic drug product manufacturing. We have successfully demonstrated endotoxin challenge study recovery methodology using mammalian cell-produced biologic drug products and drug substances in citrate, histidine, phosphate, and sodium acetate buffer formulations containing polysorbate, challenged with an endotoxin analyte, for up to 6 months of storage. Successful recovery was similarly demonstrated for a preserved, peptide-containing drug product formulation. To isolate a potential masking-or low-endotoxin recovery-source, additional studies were performed to evaluate factors including product manufacturing contact surfaces, drug product matrix with and without polysorbate, individual matrix components, protein concentration, reagent suppliers, an orthogonal test method, and storage conditions. In all cases, acceptable recoveries were observed. Bacterial endotoxin is known to be chemically stable at physiological conditions. Purified endotoxin in aqueous conditions is likely to self-aggregate or bind to surfaces. Neither the nature of, nor the storage conditions of, the studied formulation matrices were shown experimentally to render the challenge endotoxin biologically inactive. The results highlight the importance of appropriate study design in assessing the recovery of endotoxins. Bacterial endotoxin is a Gram-negative bacterial cell wall component that is harmful to humans at threshold concentrations, and it is not expected to be in aseptically-produced pharmaceutical medicines. It has been suggested that endotoxin cannot be detected over time in certain biopharmaceutical drug product formulations containing citrate, phosphate, and polysorbate components via an unknown masking mechanism. We have generated and present data here that indicate that endotoxin can be

  14. Large-Scale Bioinformatics Analysis of Bacillus Genomes Uncovers Conserved Roles of Natural Products in Bacterial Physiology.

    PubMed

    Grubbs, Kirk J; Bleich, Rachel M; Santa Maria, Kevin C; Allen, Scott E; Farag, Sherif; Shank, Elizabeth A; Bowers, Albert A

    2017-01-01

    Bacteria possess an amazing capacity to synthesize a diverse range of structurally complex, bioactive natural products known as specialized (or secondary) metabolites. Many of these specialized metabolites are used as clinical therapeutics, while others have important ecological roles in microbial communities. The biosynthetic gene clusters (BGCs) that generate these metabolites can be identified in bacterial genome sequences using their highly conserved genetic features. We analyzed an unprecedented 1,566 bacterial genomes from Bacillus species and identified nearly 20,000 BGCs. By comparing these BGCs to one another as well as a curated set of known specialized metabolite BGCs, we discovered that the majority of Bacillus natural products are comprised of a small set of highly conserved, well-distributed, known natural product compounds. Most of these metabolites have important roles influencing the physiology and development of Bacillus species. We identified, in addition to these characterized compounds, many unique, weakly conserved BGCs scattered across the genus that are predicted to encode unknown natural products. Many of these "singleton" BGCs appear to have been acquired via horizontal gene transfer. Based on this large-scale characterization of metabolite production in the Bacilli , we go on to connect the alkylpyrones, natural products that are highly conserved but previously biologically uncharacterized, to a role in Bacillus physiology: inhibiting spore development. IMPORTANCE Bacilli are capable of producing a diverse array of specialized metabolites, many of which have gained attention for their roles as signals that affect bacterial physiology and development. Up to this point, however, the Bacillus genus's metabolic capacity has been underexplored. We undertook a deep genomic analysis of 1,566 Bacillus genomes to understand the full spectrum of metabolites that this bacterial group can make. We discovered that the majority of the specialized

  15. Agricultural and Management Practices and Bacterial Contamination in Greenhouse versus Open Field Lettuce Production

    PubMed Central

    Holvoet, Kevin; Sampers, Imca; Seynnaeve, Marleen; Jacxsens, Liesbeth; Uyttendaele, Mieke

    2014-01-01

    The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards. PMID:25546272

  16. Agricultural and management practices and bacterial contamination in greenhouse versus open field lettuce production.

    PubMed

    Holvoet, Kevin; Sampers, Imca; Seynnaeve, Marleen; Jacxsens, Liesbeth; Uyttendaele, Mieke

    2014-12-23

    The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards.

  17. Volatiles in Inter-Specific Bacterial Interactions

    PubMed Central

    Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities. PMID:26733959

  18. Factors influencing production of lipase under metal supplementation by bacterial strain, Bacillus subtilis BDG-8.

    PubMed

    Dhevahi, B; Gurusamy, R

    2014-11-01

    Lipases are biocatalyst having wide applications in industries due to their versatile properties. In the present study, a lipolytic bacterial strain, Bacillus subtilis BDG-8 was isolated from an oil based industrial soil. The effect of selenium and nickel as a media supplement on enhancement of lipase production, was studied individually with the isolated strain by varying the concentration of selected metal. 60 μg l(-1) selenium enhanced lipase production to an enzyme activity measuring 7.8 U ml(-1) while 40 μgI(-1) nickel gave the maximum enzyme activity equivalent to 7.5 U ml(-1). However, nickel and selenium together at a range of concentration with an equal w/v ratio, at 60 μg l(-1) each, showed the maximum lipase activity of 8.5 U ml(-1). The effect of pH and temperature on lipase production showed maximum enzyme activity in the presence of each of the metals at pH 7 and 35°C among the other tested ranges. After optimisation of the parameters such as metal concentration, pH and temperature lipase production by Bacillus subtilis BDG-8 had increased several folds. This preliminary investigation may consequently lead as to various industrial applications such as treatment of wastewater contaminated with metal or oil with simultaneous lipase production.

  19. Root bacterial endophytes alter plant phenotype, but not physiology

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Henning, Jeremiah A.; Weston, David J.; Pelletier, Dale A.

    Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from the Populus root microbiome, influenced plant phenotype. Here, we chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype of Populus trichocarpa and measured the response of plant growth related traits (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, netmore » photosynthesis, net photosynthesis at saturating light–A sat, and saturating CO 2–A max). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf growth rate up to 137% relative to non-inoculated control plants, evidence that plants respond to bacteria by modifying morphology. However, endophyte inoculation had no influence on total plant biomass and photosynthetic traits (net photosynthesis, chlorophyll content). In sum, bacterial inoculation did not significantly increase plant carbon fixation and biomass, but their presence altered where and how carbon was being allocated in the plant host.« less

  20. Root bacterial endophytes alter plant phenotype, but not physiology

    DOE PAGES

    Henning, Jeremiah A.; Weston, David J.; Pelletier, Dale A.; ...

    2016-11-01

    Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from the Populus root microbiome, influenced plant phenotype. Here, we chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype of Populus trichocarpa and measured the response of plant growth related traits (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, netmore » photosynthesis, net photosynthesis at saturating light–A sat, and saturating CO 2–A max). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf growth rate up to 137% relative to non-inoculated control plants, evidence that plants respond to bacteria by modifying morphology. However, endophyte inoculation had no influence on total plant biomass and photosynthetic traits (net photosynthesis, chlorophyll content). In sum, bacterial inoculation did not significantly increase plant carbon fixation and biomass, but their presence altered where and how carbon was being allocated in the plant host.« less

  1. Recombinant Plants Provide a New Approach to the Production of Bacterial Polysaccharide for Vaccines

    PubMed Central

    Smith, Claire M.; Fry, Stephen C.; Gough, Kevin C.; Patel, Alexandra J. F.; Glenn, Sarah; Goldrick, Marie; Roberts, Ian S.; Andrew, Peter W.

    2014-01-01

    Bacterial polysaccharides have numerous clinical or industrial uses. Recombinant plants could offer the possibility of producing bacterial polysaccharides on a large scale and free of contaminating bacterial toxins and antigens. We investigated the feasibility of this proposal by cloning and expressing the gene for the type 3 synthase (cps3S) of Streptococcus pneumoniae in Nicotinia tabacum, using the pCambia2301 vector and Agrobacterium tumefaciens-mediated gene transfer. In planta the recombinant synthase polymerised plant-derived UDP-glucose and UDP-glucuronic acid to form type 3 polysaccharide. Expression of the cps3S gene was detected by RT-PCR and production of the pneumococcal polysaccharide was detected in tobacco leaf extracts by double immunodiffusion, Western blotting and high-voltage paper electrophoresis. Because it is used a component of anti-pneumococcal vaccines, the immunogenicity of the plant-derived type 3 polysaccharide was tested. Mice immunised with extracts from recombinant plants were protected from challenge with a lethal dose of pneumococci in a model of pneumonia and the immunised mice had significantly elevated levels of serum anti-pneumococcal polysaccharide antibodies. This study provides the proof of the principle that bacterial polysaccharide can be successfully synthesised in plants and that these recombinant polysaccharides could be used as vaccines to protect against life-threatening infections. PMID:24498433

  2. Copper effects on bacterial activity of estuarine silty sediments

    NASA Astrophysics Data System (ADS)

    Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

    2007-07-01

    Bacteria of silty estuarine sediments were spiked with copper to 200 μg Cu g -1 dry weight sediment in order to assess the impact of copper on bacterial degradation of organic matter and on bacterial biomass production. Bacterial density was determined by direct counting under epifluorescence microscopy and bacterial production by the incorporation of 3H-Leucine. Leucine turnover rate was evaluated by 14C-leucine incorporation and ectoenzymatic activities were estimated as the hydrolysis rate of model substrates for β-glucosidase and leucine-aminopeptidase. The presence of added copper in the microcosms elicited, after 21 days of incubation, generalised anoxia and a decrease in organic matter content. The non-eroded surface of the copper-spiked sediment showed, when compared to the control, a decrease in bacterial abundance and significant lower levels of bacterial production and of leucine turnover rate. Bacterial production and leucine turnover rate decreased to 1.4% and 13% of the control values, respectively. Ectoenzymatic activities were also negatively affected but by smaller factors. After erosion by the water current in laboratory flume conditions, the eroded surface of the control sediment showed a generalised decline in all bacterial activities. The erosion of the copper-spiked sediment showed, however, two types of responses with respect to bacterial activities at the exposed surface: positive responses of bacterial production and leucine turnover rate contrasting with slight negative responses of ectoenzymatic activities. The effects of experimental erosion in the suspended cells were also different in the control and in the copper-spiked sediment. Bacterial cells in the control microcosm exhibited, when compared to the non-eroded sediment cells, decreases in all activities after the 6-h suspension. The response of the average suspended copper-spiked sediment cell differed from the control by a less sharp decrease in ectoenzymatic activities and

  3. The molecular bacterial load assay replaces solid culture for measuring early bactericidal response to antituberculosis treatment.

    PubMed

    Honeyborne, Isobella; Mtafya, Bariki; Phillips, Patrick P J; Hoelscher, Michael; Ntinginya, Elias N; Kohlenberg, Anke; Rachow, Andrea; Rojas-Ponce, Gabriel; McHugh, Timothy D; Heinrich, Norbert

    2014-08-01

    We evaluated the use of the molecular bacterial load (MBL) assay, for measuring viable Mycobacterium tuberculosis in sputum, in comparison with solid agar and liquid culture. The MBL assay provides early information on the rate of decline in bacterial load and has technical advantages over culture in either form. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  4. Bacterial communities associated with production facilities of two newly drilled thermogenic natural gas wells in the Barnett Shale (Texas, USA).

    PubMed

    Davis, James P; Struchtemeyer, Christopher G; Elshahed, Mostafa S

    2012-11-01

    We monitored the bacterial communities in the gas-water separator and water storage tank of two newly drilled natural gas wells in the Barnett Shale in north central Texas, using a 16S rRNA gene pyrosequencing approach over a period of 6 months. Overall, the communities were composed mainly of moderately halophilic and halotolerant members of the phyla Firmicutes and Proteobacteria (classes Βeta-, Gamma-, and Epsilonproteobacteria) in both wells at all sampling times and locations. Many of the observed lineages were encountered in prior investigations of microbial communities from various fossil fluid formations and production facilities. In all of the samples, multiple H(2)S-producing lineages were encountered; belonging to the sulfate- and sulfur-reducing class Deltaproteobacteria, order Clostridiales, and phylum Synergistetes, as well as the thiosulfate-reducing order Halanaerobiales. The bacterial communities from the separator and tank samples bore little resemblance to the bacterial communities in the drilling mud and hydraulic-fracture waters that were used to drill these wells, suggesting the in situ development of the unique bacterial communities in such well components was in response to the prevalent geochemical conditions present. Conversely, comparison of the bacterial communities on temporal and spatial scales suggested the establishment of a core microbial community in each sampled location. The results provide the first overview of bacterial dynamics and colonization patterns in newly drilled, thermogenic natural gas wells and highlights patterns of spatial and temporal variability observed in bacterial communities in natural gas production facilities.

  5. Bacterial Identification Using Light Scattering Measurements: a Preliminary Report

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1971-01-01

    The light scattering properties of single bacterial cells were examined as a possible means of identification. Three species were studied with streptococcus faecalis exhibiting a unique pattern; the light-scattering traces for staphylococcus aureus and escherichia coli were quite similar although differences existed. Based on preliminary investigations, the light scattering approach appeared promising with additional research needed to include a wide variety of bacterial species, computer capability to handle and analyze data, and expansion of light scattering theory to include bacterial cells.

  6. Measuring bacterial cells size with AFM

    PubMed Central

    Osiro, Denise; Filho, Rubens Bernardes; Assis, Odilio Benedito Garrido; Jorge, Lúcio André de Castro; Colnago, Luiz Alberto

    2012-01-01

    Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described. PMID:24031837

  7. Experimental sulfate amendment alters peatland bacterial community structure.

    PubMed

    Strickman, R J S; Fulthorpe, R R; Coleman Wasik, J K; Engstrom, D R; Mitchell, C P J

    2016-10-01

    As part of a long-term, peatland-scale sulfate addition experiment, the impact of varying sulfate deposition on bacterial community responses was assessed using 16S tag encoded pyrosequencing. In three separate areas of the peatland, sulfate manipulations included an eight year quadrupling of atmospheric sulfate deposition (experimental), a 3-year recovery to background deposition following 5years of elevated deposition (recovery), and a control area. Peat concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, were measured, the production of which is attributable to a growing list of microorganisms, including many sulfate-reducing Deltaproteobacteria. The total bacterial and Deltaproteobacterial community structures in the experimental treatment differed significantly from those in the control and recovery treatments that were either indistinguishable or very similar to one another. Notably, the relatively rapid return (within three years) of bacterial community structure in the recovery treatment to a state similar to the control, demonstrates significant resilience of the peatland bacterial community to changes in atmospheric sulfate deposition. Changes in MeHg accumulation between sulfate treatments correlated with changes in the Deltaproteobacterial community, suggesting that sulfate may affect MeHg production through changes in the community structure of this group. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Messing with Bacterial Quorum Sensing

    PubMed Central

    González, Juan E.; Keshavan, Neela D.

    2006-01-01

    Quorum sensing is widely recognized as an efficient mechanism to regulate expression of specific genes responsible for communal behavior in bacteria. Several bacterial phenotypes essential for the successful establishment of symbiotic, pathogenic, or commensal relationships with eukaryotic hosts, including motility, exopolysaccharide production, biofilm formation, and toxin production, are often regulated by quorum sensing. Interestingly, eukaryotes produce quorum-sensing-interfering (QSI) compounds that have a positive or negative influence on the bacterial signaling network. This eukaryotic interference could result in further fine-tuning of bacterial quorum sensing. Furthermore, recent work involving the synthesis of structural homologs to the various quorum-sensing signal molecules has resulted in the development of additional QSI compounds that could be used to control pathogenic bacteria. The creation of transgenic plants that express bacterial quorum-sensing genes is yet another strategy to interfere with bacterial behavior. Further investigation on the manipulation of quorum-sensing systems could provide us with powerful tools against harmful bacteria. PMID:17158701

  9. Temperature-driven adaptation of the bacterial community in peat measured by using thymidine and leucine incorporation.

    PubMed

    Ranneklev, S B; Bååth, E

    2001-03-01

    The temperature-driven adaptation of the bacterial community in peat was studied, by altering temperature to simulate self-heating and a subsequent return to mesophilic conditions. The technique used consisted of extracting the bacterial community from peat using homogenization-centrifugation and measuring the rates of thymidine (TdR) or leucine (Leu) incorporation by the extracted bacterial community at different temperatures. Increasing the peat incubation temperature from 25 degrees C to 35, 45, or 55 degrees C resulted in a selection of bacterial communities whose optimum temperatures for activity correlated to the peat incubation temperatures. Although TdR and Leu incorporations were significantly correlated, the Leu/TdR incorporation ratios were affected by temperature. Higher Leu/TdR incorporation ratios were found at higher temperatures of incubation of the extracted bacterial community. Higher Leu/TdR incorporation ratios were also found for bacteria in peat samples incubated at higher temperatures. The reappearance of the mesophilic community and disappearance of the thermophilic community when the incubation temperature of the peat was shifted down were monitored by measuring TdR incorporation at 55 degrees C (thermophilic activity) and 25 degrees C (mesophilic activity). Shifting the peat incubation temperature from 55 to 25 degrees C resulted in a recovery of the mesophilic activity, with a subsequent disappearance of the thermophilic activity. The availability of substrate for bacterial growth varied over time and among different peat samples. To avoid confounding effects of substrate availability, a temperature adaptation index was calculated. This index consisted of the log(10) ratio of TdR incorporation at 55 and 25 degrees C. The temperature index decreased linearly with time, indicating that no thermophilic activity would be detected by the TdR technique 1 month after the temperature downshift. There were no differences between the slopes of the

  10. Temperature-Driven Adaptation of the Bacterial Community in Peat Measured by Using Thymidine and Leucine Incorporation

    PubMed Central

    Ranneklev, Sissel Brit; Bååth, Erland

    2001-01-01

    The temperature-driven adaptation of the bacterial community in peat was studied, by altering temperature to simulate self-heating and a subsequent return to mesophilic conditions. The technique used consisted of extracting the bacterial community from peat using homogenization-centrifugation and measuring the rates of thymidine (TdR) or leucine (Leu) incorporation by the extracted bacterial community at different temperatures. Increasing the peat incubation temperature from 25°C to 35, 45, or 55°C resulted in a selection of bacterial communities whose optimum temperatures for activity correlated to the peat incubation temperatures. Although TdR and Leu incorporations were significantly correlated, the Leu/TdR incorporation ratios were affected by temperature. Higher Leu/TdR incorporation ratios were found at higher temperatures of incubation of the extracted bacterial community. Higher Leu/TdR incorporation ratios were also found for bacteria in peat samples incubated at higher temperatures. The reappearance of the mesophilic community and disappearance of the thermophilic community when the incubation temperature of the peat was shifted down were monitored by measuring TdR incorporation at 55°C (thermophilic activity) and 25°C (mesophilic activity). Shifting the peat incubation temperature from 55 to 25°C resulted in a recovery of the mesophilic activity, with a subsequent disappearance of the thermophilic activity. The availability of substrate for bacterial growth varied over time and among different peat samples. To avoid confounding effects of substrate availability, a temperature adaptation index was calculated. This index consisted of the log10 ratio of TdR incorporation at 55 and 25°C. The temperature index decreased linearly with time, indicating that no thermophilic activity would be detected by the TdR technique 1 month after the temperature downshift. There were no differences between the slopes of the temperature adaptation indices over time for

  11. Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds.

    PubMed

    Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Al-Hosni, Khadija; Kang, Sang-Mo; Seo, Chang-Woo; Lee, In-Jung

    2017-06-01

    Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml -1 to 38.80 ± 1.35 μg ml -1 . We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.

  12. Methane Production in Dairy Cows Correlates with Rumen Methanogenic and Bacterial Community Structure.

    PubMed

    Danielsson, Rebecca; Dicksved, Johan; Sun, Li; Gonda, Horacio; Müller, Bettina; Schnürer, Anna; Bertilsson, Jan

    2017-01-01

    Methane (CH 4 ) is produced as an end product from feed fermentation in the rumen. Yield of CH 4 varies between individuals despite identical feeding conditions. To get a better understanding of factors behind the individual variation, 73 dairy cows given the same feed but differing in CH 4 emissions were investigated with focus on fiber digestion, fermentation end products and bacterial and archaeal composition. In total 21 cows (12 Holstein, 9 Swedish Red) identified as persistent low, medium or high CH 4 emitters over a 3 month period were furthermore chosen for analysis of microbial community structure in rumen fluid. This was assessed by sequencing the V4 region of 16S rRNA gene and by quantitative qPCR of targeted Methanobrevibacter groups. The results showed a positive correlation between low CH 4 emitters and higher abundance of Methanobrevibacter ruminantium clade. Principal coordinate analysis (PCoA) on operational taxonomic unit (OTU) level of bacteria showed two distinct clusters ( P < 0.01) that were related to CH 4 production. One cluster was associated with low CH 4 production (referred to as cluster L) whereas the other cluster was associated with high CH 4 production (cluster H) and the medium emitters occurred in both clusters. The differences between clusters were primarily linked to differential abundances of certain OTUs belonging to Prevotella . Moreover, several OTUs belonging to the family Succinivibrionaceae were dominant in samples belonging to cluster L. Fermentation pattern of volatile fatty acids showed that proportion of propionate was higher in cluster L, while proportion of butyrate was higher in cluster H. No difference was found in milk production or organic matter digestibility between cows. Cows in cluster L had lower CH 4 /kg energy corrected milk (ECM) compared to cows in cluster H, 8.3 compared to 9.7 g CH 4 /kg ECM, showing that low CH 4 cows utilized the feed more efficient for milk production which might indicate a more

  13. Methane Production in Dairy Cows Correlates with Rumen Methanogenic and Bacterial Community Structure

    PubMed Central

    Danielsson, Rebecca; Dicksved, Johan; Sun, Li; Gonda, Horacio; Müller, Bettina; Schnürer, Anna; Bertilsson, Jan

    2017-01-01

    Methane (CH4) is produced as an end product from feed fermentation in the rumen. Yield of CH4 varies between individuals despite identical feeding conditions. To get a better understanding of factors behind the individual variation, 73 dairy cows given the same feed but differing in CH4 emissions were investigated with focus on fiber digestion, fermentation end products and bacterial and archaeal composition. In total 21 cows (12 Holstein, 9 Swedish Red) identified as persistent low, medium or high CH4 emitters over a 3 month period were furthermore chosen for analysis of microbial community structure in rumen fluid. This was assessed by sequencing the V4 region of 16S rRNA gene and by quantitative qPCR of targeted Methanobrevibacter groups. The results showed a positive correlation between low CH4 emitters and higher abundance of Methanobrevibacter ruminantium clade. Principal coordinate analysis (PCoA) on operational taxonomic unit (OTU) level of bacteria showed two distinct clusters (P < 0.01) that were related to CH4 production. One cluster was associated with low CH4 production (referred to as cluster L) whereas the other cluster was associated with high CH4 production (cluster H) and the medium emitters occurred in both clusters. The differences between clusters were primarily linked to differential abundances of certain OTUs belonging to Prevotella. Moreover, several OTUs belonging to the family Succinivibrionaceae were dominant in samples belonging to cluster L. Fermentation pattern of volatile fatty acids showed that proportion of propionate was higher in cluster L, while proportion of butyrate was higher in cluster H. No difference was found in milk production or organic matter digestibility between cows. Cows in cluster L had lower CH4/kg energy corrected milk (ECM) compared to cows in cluster H, 8.3 compared to 9.7 g CH4/kg ECM, showing that low CH4 cows utilized the feed more efficient for milk production which might indicate a more efficient microbial

  14. Reliability of Haemophilus influenzae biofilm measurement via static method, and determinants of in vitro biofilm production.

    PubMed

    Obaid, Najla A; Tristram, Stephen; Narkowicz, Christian K; Jacobson, Glenn A

    2016-12-01

    Information is lacking regarding the precision of microtitre plate (MTP) assays used to measure biofilm. This study investigated the precision of an MTP assay to measure biofilm production by nontypeable Haemophilus influenzae (NTHi) and the effects of frozen storage and inoculation technique on biofilm production. The density of bacterial final growth was determined by absorbance after 18-20 h incubation, and biofilm production was then measured by absorbance after crystal violet staining. Biofilm formation was categorised as high and low for each strain. For the high biofilm producing strains of NTHi, interday reproducibility of NTHi biofilm formation measured using the MTP assay was excellent and met the acceptance criteria, but higher variability was observed in low biofilm producers. Method of inoculum preparation was a determinant of biofilm formation with inoculum prepared directly from solid media showing increased biofilm production for at least one of the high producing strains. In general, storage of NTHi cultures at -80 °C for up to 48 weeks did not have any major effect on their ability to produce biofilm.

  15. Quality of dissolved organic matter affects planktonic but not biofilm bacterial production in streams.

    PubMed

    Kamjunke, Norbert; Herzsprung, Peter; Neu, Thomas R

    2015-02-15

    Streams and rivers are important sites of organic carbon mineralization which is dependent on the land use within river catchments. Here we tested whether planktonic and epilithic biofilm bacteria differ in their response to the quality of dissolved organic carbon (DOC). Thus, planktonic and biofilm bacterial production was compared with patterns of DOC along a land-use gradient in the Bode catchment area (Germany). The freshness index of DOC was positively related to the proportion of agricultural area in the catchment. The humification index correlated with the proportion of forest area. Abundance and production of planktonic bacteria were lower in headwaters than at downstream sites. Planktonic production was weakly correlated to the total concentration of DOC but more strongly to quality-measures as revealed by spectra indexes, i.e. positively to the freshness index and negatively to the humification index. In contrast to planktonic bacteria, abundance and production of biofilm bacteria were independent of DOC quality. This finding may be explained by the association of biofilm bacteria with benthic algae and an extracellular matrix which represent additional substrate sources. The data show that planktonic bacteria seem to be regulated at a landscape scale controlled by land use, whereas biofilm bacteria are regulated at a biofilm matrix scale controlled by autochthonous production. Thus, the effects of catchment-scale land use changes on ecosystem processes are likely lower in small streams dominated by biofilm bacteria than in larger streams dominated by planktonic bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Evaluating clinical periodontal measures as surrogates for bacterial exposure: The Oral Infections and Vascular Disease Epidemiology Study (INVEST)

    PubMed Central

    2010-01-01

    Background Epidemiologic studies of periodontal infection as a risk factor for cardiovascular disease often use clinical periodontal measures as a surrogate for the underlying bacterial exposure of interest. There are currently no methodological studies evaluating which clinical periodontal measures best reflect the levels of subgingival bacterial colonization in population-based settings. We investigated the characteristics of clinical periodontal definitions that were most representative of exposure to bacterial species that are believed to be either markers, or themselves etiologic, of periodontal disease. Methods 706 men and women aged ≥ 55 years, residing in northern Manhattan were enrolled. Using DNA-DNA checkerboard hybridization in subgingival biofilms, standardized values for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia were averaged within mouth and summed to define "bacterial burden". Correlations of bacterial burden with clinical periodontal constructs defined by the severity and extent of attachment loss (AL), pocket depth (PD) and bleeding on probing (BOP) were assessed. Results Clinical periodontal constructs demonstrating the highest correlations with bacterial burden were: i) percent of sites with BOP (r = 0.62); ii) percent of sites with PD ≥ 3 mm (r = 0.61); and iii) number of sites with BOP (r = 0.59). Increasing PD or AL severity thresholds consistently attenuated correlations, i.e., the correlation of bacterial burden with the percent of sites with PD ≥ 8 mm was only r = 0.16. Conclusions Clinical exposure definitions of periodontal disease should incorporate relatively shallow pockets to best reflect whole mouth exposure to bacterial burden. PMID:20056008

  17. Effect of partially replacing a barley-based concentrate with flaxseed-based products on the rumen bacterial population of lactating Holstein dairy cows.

    PubMed

    Castillo-Lopez, E; Moats, J; Aluthge, N D; Ramirez Ramirez, H A; Christensen, D A; Mutsvangwa, T; Penner, G B; Fernando, S C

    2018-01-01

    The effects of partial replacement of a barley-based concentrate with flaxseed-based products on the rumen bacterial population of lactating Holstein dairy cows were evaluated. Treatments fed were CONT, a normal diet that included barley silage, alfalfa hay and a barley-based concentrate that contained no flaxseed or faba beans; FLAX, inclusion of a nonextruded flaxseed-based product containing 55·0% flaxseed, 37·8% field peas and 6·9% alfalfa; EXT, similar to FLAX, but the product was extruded and EXTT, similar to FLAX, but product was extruded and field peas were replaced by high-tannin faba beans. The rumen bacterial population was evaluated by utilizing 16S rRNA gene sequencing. Most abundant phyla, families and genera were unaffected. However, some taxa were affected; for example, unsaturated fatty acid content was negatively correlated with Clostridiaceae, and tannin content was negatively correlated with BS11 and Paraprevotellaceae. Predominant rumen bacterial taxa were not affected, but the abundance of some taxa found in lower proportions shifted, possibly due to sensitivity to unsaturated fatty acids or tannins. Flaxseed-based products were effective for partially replacing barley-based concentrate in rations of lactating dairy cows. No negative effects of these products were observed on the abundance of predominant rumen bacterial taxa, with only minor shifts in less abundant bacteria. © 2017 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.

  18. Bacterial surface adaptation

    NASA Astrophysics Data System (ADS)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  19. Bacterial cellulose production by Gluconacetobacter xylinus by employing alternative culture media.

    PubMed

    Jozala, Angela Faustino; Pértile, Renata Aparecida Nedel; dos Santos, Carolina Alves; de Carvalho Santos-Ebinuma, Valéria; Seckler, Marcelo Martins; Gama, Francisco Miguel; Pessoa, Adalberto

    2015-02-01

    Bacterial cellulose (BC) is used in different fields as a biological material due to its unique properties. Despite there being many BC applications, there still remain many problems associated with bioprocess technology, such as increasing productivity and decreasing production cost. New technologies that use waste from the food industry as raw materials for culture media promote economic advantages because they reduce environmental pollution and stimulate new research for science sustainability. For this reason, BC production requires optimized conditions to increase its application. The main objective of this study was to evaluate BC production by Gluconacetobacter xylinus using industry waste, namely, rotten fruits and milk whey, as culture media. Furthermore, the structure of BC produced at different conditions was also determined. The culture media employed in this study were composed of rotten fruit collected from the disposal of free markets, milk whey from a local industrial disposal, and their combination, and Hestrin and Schramm media was used as standard culture media. Although all culture media studied produced BC, the highest BC yield-60 mg/mL-was achieved with the rotten fruit culture. Thus, the results showed that rotten fruit can be used for BC production. This culture media can be considered as a profitable alternative to generate high-value products. In addition, it combines environmental concern with sustainable processes that can promote also the reduction of production cost.

  20. Prospecting for new bacterial metabolites: a glossary of approaches for inducing, activating and upregulating the biosynthesis of bacterial cryptic or silent natural products.

    PubMed

    Zarins-Tutt, Joseph Scott; Barberi, Tania Triscari; Gao, Hong; Mearns-Spragg, Andrew; Zhang, Lixin; Newman, David J; Goss, Rebecca Jane Miriam

    2016-01-01

    Covering: up to 2015. Over the centuries, microbial secondary metabolites have played a central role in the treatment of human diseases and have revolutionised the pharmaceutical industry. With the increasing number of sequenced microbial genomes revealing a plethora of novel biosynthetic genes, natural product drug discovery is entering an exciting second golden age. Here, we provide a concise overview as an introductory guide to the main methods employed to unlock or up-regulate these so called 'cryptic', 'silent' and 'orphan' gene clusters, and increase the production of the encoded natural product. With a predominant focus on bacterial natural products we will discuss the importance of the bioinformatics approach for genome mining, the use of first different and simple culturing techniques and then the application of genetic engineering to unlock the microbial treasure trove.

  1. The Effect of Light on Bacterial Activity in a Seaweed Holobiont.

    PubMed

    Coelho-Souza, Sergio A; Jenkins, Stuart R; Casarin, Antonio; Baeta-Neves, Maria Helena; Salgado, Leonardo T; Guimaraes, Jean R D; Coutinho, Ricardo

    2017-11-01

    Holobionts are characterized by the relationship between host and their associated organisms such as the biofilm associated with macroalgae. Considering that light is essential to macroalgae survival, the aim of this study was to verify the effect of light on the heterotrophic activity in biofilms of the brown macroalgae Sargassum furcatum during its growth cycle. Measurements of heterotrophic activity were done under natural light levels at different times during a daily cycle and under an artificial extinction of natural light during the afternoon. We also measured Sargassum primary production under these light levels in the afternoon. Both measurements were done with and without photosynthesis inhibitor and antibiotics. Biofilm composition was mainly represented by bacteria but diatoms, cyanobacteria, and other organisms were also common. When a peak of diatom genera was recorded, the heterotrophic activity of the biofilm was higher. Heterotrophic activity was usually highest during the afternoon and the presence of a photosynthesis inhibitor caused an average reduction of 17% but there was no relationship with Sargassum primary production. These results indicate that autotrophic production in the biofilm was reduced by the inhibitor with consequences on bacterial activity. Heterotrophic activity was mainly bacterial and the antibiotics chloramphenicol and penicillin were more effective than streptomycin. We suggest primary producers in the biofilm are more important to increase bacterial activity than the macroalgae itself because of coherence of the peaks of heterotrophic and autotrophic activity in biofilm during the afternoon and the effects of autotrophic inhibitors on heterotrophic activity.

  2. Size of bacterial ice-nucleation sites measured in situ by radiation inactivation analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Govindarajan, A.G.; Lindow, S.E.

    1988-03-01

    Four bacterial species are known to catalyze ice formation at temperatures just below 0/sup 0/C. To better understand the relationship between the molecular structure of bacterial ice-nucleation site(s) and the quantitative and qualitative features of the ice-nucleation-active phenotype, the authors determined by ..gamma..-radiation analysis the in situ size of ice-nucleation sites in strains of Pseudomonas syringae and Erwinia herbicola and in Escherichia coli HB101 carrying the plasmid pICE1.1. Lyophilized cells of each bacterial strain were irradiated with a flux of ..gamma.. radiation from 0 to 10.2 Mrad. Differential concentrations of active ice nuclei decreased as a first-order function of radiationmore » dose in all strains as temperature was decreased from -2/sup 0/C to -14/sup 0/C in 1/sup 0/C intervals. Sizes of ice nuclei were calculated from the /sup +/-radiation flux at which 37% of initial ice nuclei active within each 1/sup 0/C temperature interval remained. The minimum mass of a functional ice nucleus was about 150 kDa for all strains. The size of ice nuclei increased logarithmically with increasing temperature from -12/sup 0/CC to -2/sup 0/C, where the estimated nucleant mass was 19,000 kDa. The ice nucleant in these three bacterial species may represent an oligomeric structure, composed at least in part of an ice gene product that can self-associate to assume many possible sizes.« less

  3. Long-term organic-inorganic fertilization ensures great soil productivity and bacterial diversity after natural-to-agricultural ecosystem conversion.

    PubMed

    Xun, Weibing; Xu, Zhihui; Li, Wei; Ren, Yi; Huang, Ting; Ran, Wei; Wang, Boren; Shen, Qirong; Zhang, Ruifu

    2016-09-01

    Natural ecosystems comprise the planet's wild plant and animal resources, but large tracts of land have been converted to agroecosystems to support the demand for agricultural products. This conversion limits the number of plant species and decreases the soil biological diversity. Here we used high-throughput 16S rRNA gene sequencing to evaluate the responses of soil bacterial communities in long-term converted and fertilized red soils (a type of Ferralic Cambisol). We observed that soil bacterial diversity was strongly affected by different types of fertilization management. Oligotrophic bacterial taxa demonstrated large relative abundances in chemically fertilized soil, whereas copiotrophic bacterial taxa were found in large relative abundances in organically fertilized and fallow management soils. Only organic-inorganic fertilization exhibited the same local taxonomic and phylogenetic diversity as that of a natural ecosystem. However, the independent use of organic or inorganic fertilizer reduced local taxonomic and phylogenetic diversity and caused biotic homogenization. This study demonstrated that the homogenization of bacterial communities caused by natural-to-agricultural ecosystem conversion can be mitigated by employing rational organic-inorganic fertilization management.

  4. Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system

    NASA Astrophysics Data System (ADS)

    Sempels, Wouter; de Dier, Raf; Mizuno, Hideaki; Hofkens, Johan; Vermant, Jan

    2013-04-01

    The deposition of material at the edge of evaporating droplets, known as the ‘coffee ring effect’, is caused by a radially outward capillary flow. This phenomenon is common to a wide array of systems including colloidal and bacterial systems. The role of surfactants in counteracting these coffee ring depositions is related to the occurrence of local vortices known as Marangoni eddies. Here we show that these swirling flows are universal, and not only lead to a uniform deposition of colloids but also occur in living bacterial systems. Experiments on Pseudomonas aeruginosa suggest that the auto-production of biosurfactants has an essential role in creating a homogeneous deposition of the bacteria upon drying. Moreover, at biologically relevant conditions, intricate time-dependent flows are observed in addition to the vortex regime, which are also effective in reversing the coffee ring effect at even lower surfactant concentrations.

  5. Inhibition of bacterial quorum sensing by vanilla extract.

    PubMed

    Choo, J H; Rukayadi, Y; Hwang, J-K

    2006-06-01

    The purpose of this study was to search for a novel quorum sensing inhibitor and analyse its inhibitory activity. Quorum sensing inhibition was monitored using the Tn-5 mutant, Chromobacterium violaceum CV026. Vanilla beans (Vanilla planifolia Andrews) were extracted using 75% (v/v) aqueous methanol and added to C. violaceum CV026 cultures. Inhibitory activity was measured by quantifying violacein production using a spectrophotometer. The results have revealed that vanilla extract significantly reduced violacein production in a concentration-dependent manner, indicating inhibition of quorum sensing. Vanilla, a widely used spice and flavour, can inhibit bacterial quorum sensing. The results suggest that the intake of vanilla-containing food materials might promote human health by inhibiting quorum sensing and preventing bacterial pathogenesis. Further studies are required to isolate specific substances from vanilla extract acting as quorum sensing inhibitors.

  6. Archaeal and Bacterial Community Structure in an Anaerobic Digestion Reactor (Lagoon Type) Used for Biogas Production at a Pig Farm.

    PubMed

    Pampillón-González, Liliana; Ortiz-Cornejo, Nadia L; Luna-Guido, Marco; Dendooven, Luc; Navarro-Noya, Yendi E

    2017-01-01

    Biogas production from animal waste is an economically viable way to reduce environmental pollution and produce valuable products, i.e., methane and a nutrient-rich organic waste product. An anaerobic digestion reactor for biogas production from pig waste was sampled at the entrance, middle (digestion chamber), and exit of a digester, while the bacterial and archaeal community structure was studied by 16S rRNA gene metagenomics. The number of bacterial operational taxonomic units (OTU)-97% was 3-7 times larger than that of archaeal ones. Bacteria and Archaea found in feces of animals (e.g., Clostridiaceae, Lachnospiraceae, Ruminococcaceae, Methanosarcina, Methanolobus, Methanosaeta, and Methanospirillum) dominated the entrance of the digester. The digestion chamber was dominated by anaerobic sugar-fermenting OP9 bacteria and the syntrophic bacteria Candidatus Cloacamonas (Waste Water of Evry 1; WWE1). The methanogens dominant in the digestion chamber were the acetoclastic Methanosaeta and the hydrogenothrophic Methanoculleus and Methanospirillum. Similar bacterial and archaeal groups that dominated in the middle of the digestion chamber were found in the waste that left the digester. Predicted functions associated with degradation of xenobiotic compounds were significantly different between the sampling locations. The microbial community found in an anaerobic digestion reactor loaded with pig manure contained microorganisms with biochemical capacities related to the 4 phases of methane production. © 2017 S. Karger AG, Basel.

  7. Production of peptone from boso fish (Oxyeleotris marmorata) for bacterial growth medium

    NASA Astrophysics Data System (ADS)

    Priatni, S.; Kosasih, W.; Budiwati, T. A.; Ratnaningrum, D.

    2017-03-01

    Underutilized Oxyeleotris marmorata fish is abundant and widespread in Indonesia. The study aimed to use O. marmorata fish for peptone production using papain from dried latex of papaya fruit. The peptone was applied as nitrogen sources for bacterial growth. The resulted peptone was optimized at 50-65°C for 5-8 hr, using 0.1% of papain at pH 6.0. Characterization of peptone was based on the soluble protein content, N-amino content, % degree hydrolysis (DH), SDS PAGE profile and growth of bacteria Escherichia coli and Staphylococcus aureus. The results indicated that the optimum condition for hydrolysis was at 50°C for 7 hr (p < 0.05). Fish peptone soluble protein content was of 8.6 mg/mL, α-amino was 0.59%, and AN/TN 5.47%. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS PAGE) profile of peptone showed a major band with molecular weight between 17-28 kDa. Fish peptone effectiveness for E. coli and S. aureus growth was similar with commercial bacterial peptone.

  8. Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos.

    PubMed

    Marui, Junichiro; Boulom, Sayvisene; Panthavee, Wanchai; Momma, Mari; Kusumoto, Ken-Ichi; Nakahara, Kazuhiko; Saito, Masayoshi

    2015-01-01

    A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacteria seemed to vary in the 10 products collected from Thailand and Laos. Tetragenococci were common in products from central Thailand and Vientiane in Laos which had salinities of not less than 11% and pH values ranging from 5.6 to 6.1. However, lactobacilli were common in products from northern Thailand which had the lowest salinities (8.3-8.6%) and pH values (4.5-4.8) of all the samples examined. Two Lactobacillus and one Tetragenococcus species were detected in one product from northeastern Thailand containing 10% salt. These results suggest that salinity in pla-ra/pa-daek is an important determinant of the representative genus of lactic acid bacteria such as, Tetragenococcus or Lactobacillus. Additionally, differences in the acidity between these two groups seemed to be related to the production of d-/l-lactic acid in the lactic acid bacteria in each product. This is the first study to report a correlation between bacterial community structure and taste components in pla-ra/pa-daek products from various regions. This scientific work on a traditional fermented food will be useful in helping local producers meet differing consumer preferences in various regions.

  9. Illumina sequencing-based analyses of bacterial communities during short-chain fatty-acid production from food waste and sewage sludge fermentation at different pH values.

    PubMed

    Cheng, Weixiao; Chen, Hong; Yan, ShuHai; Su, Jianqiang

    2014-09-01

    Short-chain fatty acids (SCFAs) can be produced by primary and waste activated sludge anaerobic fermentation. The yield and product spectrum distribution of SCFAs can be significantly affected by different initial pH values. However, most studies have focused on the physical and chemical aspects of SCFA production by waste activated sludge fermentation at different pH values. Information on the bacterial community structures during acidogenic fermentation is limited. In this study, comparisons of the bacterial communities during the co-substrate fermentation of food wastes and sewage sludge at different pH values were performed using the barcoded Illumina paired-end sequencing method. The results showed that different pH environments harbored a characteristic bacterial community, including sequences related to Lactobacillus, Prevotella, Mitsuokella, Treponema, Clostridium, and Ureibacillus. The most abundant bacterial operational taxonomic units in the different pH environments were those related to carbohydrate-degrading bacteria, which are associated with constituents of co-substrate fermentation. Further analyses showed that during organic matter fermentation, a core microbiota composed of Firmicutes, Proteobacteria, and Bacteroidetes existed. Comparison analyses revealed that the bacterial community during fermentation was significantly affected by the pH, and that the diverse product distribution was related to the shift in bacterial communities.

  10. Engineering Escherichia coli for Biodiesel Production Utilizing a Bacterial Fatty Acid Methyltransferase▿†

    PubMed Central

    Nawabi, Parwez; Bauer, Stefan; Kyrpides, Nikos; Lykidis, Athanasios

    2011-01-01

    The production of low-cost biofuels in engineered microorganisms is of great interest due to the continual increase in the world's energy demands. Biodiesel is a renewable fuel that can potentially be produced in microbes cost-effectively. Fatty acid methyl esters (FAMEs) are a common component of biodiesel and can be synthesized from either triacylglycerol or free fatty acids (FFAs). Here we report the identification of a novel bacterial fatty acid methyltransferase (FAMT) that catalyzes the formation of FAMEs and 3-hydroxyl fatty acid methyl esters (3-OH-FAMEs) from the respective free acids and S-adenosylmethionine (AdoMet). FAMT exhibits a higher specificity toward 3-hydroxy free fatty acids (3-OH-FFAs) than FFAs, synthesizing 3-hydroxy fatty acid methyl esters (3-OH-FAMEs) in vivo. We have also identified bacterial members of the fatty acyl-acyl carrier protein (ACP) thioesterase (FAT) enzyme family with distinct acyl chain specificities. These bacterial FATs exhibit increased specificity toward 3-hydroxyacyl-ACP, generating 3-OH-FFAs, which can subsequently be utilized by FAMTs to produce 3-OH-FAMEs. PhaG (3-hydroxyacyl ACP:coenzyme A [CoA] transacylase) constitutes an alternative route to 3-OH-FFA synthesis; the coexpression of PhaG with FAMT led to the highest level of accumulation of 3-OH-FAMEs and FAMEs. The availability of AdoMet, the second substrate for FAMT, is an important factor regulating the amount of methyl esters produced by bacterial cells. Our results indicate that the deletion of the global methionine regulator metJ and the overexpression of methionine adenosyltransferase result in increased methyl ester synthesis. PMID:21926202

  11. In situ real-time measurement of physical characteristics of airborne bacterial particles

    NASA Astrophysics Data System (ADS)

    Jung, Jae Hee; Lee, Jung Eun

    2013-12-01

    Bioaerosols, including aerosolized bacteria, viruses, and fungi, are associated with public health and environmental problems. One promising control method to reduce the harmful effects of bioaerosols is thermal inactivation via a continuous-flow high-temperature short-time (HTST) system. However, variations in bioaerosol physical characteristics - for example, the particle size and shape - during the continuous-flow inactivation process can change the transport properties in the air, which can affect particle deposition in the human respiratory system or the filtration efficiency of ventilation systems. Real-time particle monitoring techniques are a desirable alternative to the time-consuming process of microscopic analysis that is conventionally used in sampling and particle characterization. Here, we report in situ real-time optical scattering measurements of the physical characteristics of airborne bacteria particles following an HTST process in a continuous-flow system. Our results demonstrate that the aerodynamic diameter of bacterial aerosols decreases when exposed to a high-temperature environment, and that the shape of the bacterial cells is significantly altered. These variations in physical characteristics using optical scattering measurements were found to be in agreement with the results of scanning electron microscopy analysis.

  12. A low cost color-based bacterial biosensor for measuring arsenic in groundwater.

    PubMed

    Huang, Chi-Wei; Wei, Chia-Cheng; Liao, Vivian Hsiu-Chuan

    2015-12-01

    Using arsenic (As) contaminated groundwater for drinking or irrigation has caused major health problems for humans around the world, raising a need to monitor As level efficiently and economically. This study developed a color-based bacterial biosensor which is easy-to-use and inexpensive for measuring As and could be complementary to current As detecting techniques. The arsR-lacZ recombinant gene cassette in nonpathogenic strain Escherichia coli DH5α was used in the color-based biosensor which could be observed by eyes or measured by spectrometer. The developed bacterial biosensor demonstrates a quantitative range from 10 to 500μgL(-1) of As in 3-h reaction time. Furthermore, the biosensor was able to successfully detect and estimate As concentration in groundwater sample by measuring optical density at 595nm (OD595). Among different storage methods used in this study, biosensor in liquid at 4°C showed the longest shelf life about 9d, and liquid storage at RT and cell pellet could also be stored for about 3-5d. In conclusion, this study showed that the As biosensor with reliable color signal and economical preservation methods is useful for rapid screening of As pollutant, providing the potential for large scale screening and better management strategies for environmental quality control. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Using the overlay assay to qualitatively measure bacterial production of and sensitivity to pneumococcal bacteriocins.

    PubMed

    Maricic, Natalie; Dawid, Suzanne

    2014-09-30

    Streptococcus pneumoniae colonizes the highly diverse polymicrobial community of the nasopharynx where it must compete with resident organisms. We have shown that bacterially produced antimicrobial peptides (bacteriocins) dictate the outcome of these competitive interactions. All fully-sequenced pneumococcal strains harbor a bacteriocin-like peptide (blp) locus. The blp locus encodes for a range of diverse bacteriocins and all of the highly conserved components needed for their regulation, processing, and secretion. The diversity of the bacteriocins found in the bacteriocin immunity region (BIR) of the locus is a major contributor of pneumococcal competition. Along with the bacteriocins, immunity genes are found in the BIR and are needed to protect the producer cell from the effects of its own bacteriocin. The overlay assay is a quick method for examining a large number of strains for competitive interactions mediated by bacteriocins. The overlay assay also allows for the characterization of bacteriocin-specific immunity, and detection of secreted quorum sensing peptides. The assay is performed by pre-inoculating an agar plate with a strain to be tested for bacteriocin production followed by application of a soft agar overlay containing a strain to be tested for bacteriocin sensitivity. A zone of clearance surrounding the stab indicates that the overlay strain is sensitive to the bacteriocins produced by the pre-inoculated strain. If no zone of clearance is observed, either the overlay strain is immune to the bacteriocins being produced or the pre-inoculated strain does not produce bacteriocins. To determine if the blp locus is functional in a given strain, the overlay assay can be adapted to evaluate for peptide pheromone secretion by the pre-inoculated strain. In this case, a series of four lacZ-reporter strains with different pheromone specificity are used in the overlay.

  14. Bacterial community structure and variation in a full-scale seawater desalination plant for drinking water production.

    PubMed

    Belila, A; El-Chakhtoura, J; Otaibi, N; Muyzer, G; Gonzalez-Gil, G; Saikaly, P E; van Loosdrecht, M C M; Vrouwenvelder, J S

    2016-05-01

    Microbial processes inevitably play a role in membrane-based desalination plants, mainly recognized as membrane biofouling. We assessed the bacterial community structure and diversity during different treatment steps in a full-scale seawater desalination plant producing 40,000 m(3)/d of drinking water. Water samples were taken over the full treatment train consisting of chlorination, spruce media and cartridge filters, de-chlorination, first and second pass reverse osmosis (RO) membranes and final chlorine dosage for drinking water distribution. The water samples were analyzed for water quality parameters (total bacterial cell number, total organic carbon, conductivity, pH, etc.) and microbial community composition by 16S rRNA gene pyrosequencing. The planktonic microbial community was dominated by Proteobacteria (48.6%) followed by Bacteroidetes (15%), Firmicutes (9.3%) and Cyanobacteria (4.9%). During the pretreatment step, the spruce media filter did not impact the bacterial community composition dominated by Proteobacteria. In contrast, the RO and final chlorination treatment steps reduced the Proteobacterial relative abundance in the produced water where Firmicutes constituted the most dominant bacterial group. Shannon and Chao1 diversity indices showed that bacterial species richness and diversity decreased during the seawater desalination process. The two-stage RO filtration strongly reduced the water conductivity (>99%), TOC concentration (98.5%) and total bacterial cell number (>99%), albeit some bacterial DNA was found in the water after RO filtration. About 0.25% of the total bacterial operational taxonomic units (OTUs) were present in all stages of the desalination plant: the seawater, the RO permeates and the chlorinated drinking water, suggesting that these bacterial strains can survive in different environments such as high/low salt concentration and with/without residual disinfectant. These bacterial strains were not caused by contamination during

  15. Investigation of bacterial biofilm in the human middle ear using optical coherence tomography and acoustic measurements

    PubMed Central

    Nguyen, Cac T.; Robinson, Sarah R.; Jung, Woonggyu; Novak, Michael A.; Boppart, Stephen A.; Allen, Jont B.

    2013-01-01

    Children with chronic otitis media (OM) often have conductive hearing loss which results in communication difficulties and requires surgical treatment. Recent studies have provided clinical evidence that there is a one-to-one correspondence between chronic OM and the presence of a bacterial biofilm behind the tympanic membrane (TM). Here we investigate the acoustic effects of bacterial biofilms, confirmed using optical coherence tomography (OCT), in adult ears. Non-invasive OCT images are collected to visualize the cross-sectional structure of the middle ear, verifying the presence of a biofilm behind the TM. Wideband measurements of acoustic reflectance and impedance (0.2 to 6 [kHz]) are used to study the acoustic properties of ears with confirmed bacterial biofilms. Compared to known acoustic properties of normal middle ears, each of the ears with a bacterial biofilm has an elevated power reflectance in the 1 to 3 [kHz] range, corresponding to an abnormally small resistance (real part of the impedance). These results provide assistance for the clinical diagnosis of a bacterial biofilm, which could lead to improved treatment of chronic middle ear infection and further understanding of the impact of chronic OM on conductive hearing loss. PMID:23588039

  16. Bacterial Biotransformation of Pentachlorophenol and Micropollutants Formed during Its Production Process

    PubMed Central

    Lopez-Echartea, Eglantina; Macek, Tomas; Demnerova, Katerina; Uhlik, Ondrej

    2016-01-01

    Pentachlorophenol (PCP) is a toxic and persistent wood and cellulose preservative extensively used in the past decades. The production process of PCP generates polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) as micropollutants. PCDD/Fs are also known to be very persistent and dangerous for human health and ecosystem functioning. Several physico-chemical and biological technologies have been used to remove PCP and PCDD/Fs from the environment. Bacterial degradation appears to be a cost-effective way of removing these contaminants from soil while causing little impact on the environment. Several bacteria that cometabolize or use these pollutants as their sole source of carbon have been isolated and characterized. This review summarizes current knowledge on the metabolic pathways of bacterial degradation of PCP and PCDD/Fs. PCP can be successfully degraded aerobically or anaerobically by bacteria. Highly chlorinated PCDD/Fs are more likely to be reductively dechlorinated, while less chlorinated PCDD/Fs are more prone to aerobic degradation. The biochemical and genetic basis of these pollutants’ degradation is also described. There are several documented studies of effective applications of bioremediation techniques for the removal of PCP and PCDD/Fs from soil and sediments. These findings suggest that biodegradation can occur and be applied to treat these contaminants. PMID:27869691

  17. Controls on bacterial and archaeal community structure and greenhouse gas production in natural, mined, and restored Canadian peatlands

    PubMed Central

    Basiliko, Nathan; Henry, Kevin; Gupta, Varun; Moore, Tim R.; Driscoll, Brian T.; Dunfield, Peter F.

    2013-01-01

    Northern peatlands are important global C reservoirs, largely because of their slow rates of microbial C mineralization. Particularly in sites that are heavily influenced by anthropogenic disturbances, there is scant information about microbial ecology and whether or not microbial community structure influences greenhouse gas production. This work characterized communities of bacteria and archaea using terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of 16S rRNA and functional genes across eight natural, mined, or restored peatlands in two locations in eastern Canada. Correlations were explored among chemical properties of peat, bacterial and archaeal community structure, and carbon dioxide (CO2) and methane (CH4) production rates under oxic and anoxic conditions. Bacteria and archaea similar to those found in other peat soil environments were detected. In contrast to other reports, methanogen diversity was low in our study, with only 2 groups of known or suspected methanogens. Although mining and restoration affected substrate availability and microbial activity, these land-uses did not consistently affect bacterial or archaeal community composition. In fact, larger differences were observed between the two locations and between oxic and anoxic peat samples than between natural, mined, and restored sites, with anoxic samples characterized by less detectable bacterial diversity and stronger dominance by members of the phylum Acidobacteria. There were also no apparent strong linkages between prokaryote community structure and CH4 or CO2 production, suggesting that different organisms exhibit functional redundancy and/or that the same taxa function at very different rates when exposed to different peat substrates. In contrast to other earlier work focusing on fungal communities across similar mined and restored peatlands, bacterial and archaeal communities appeared to be more resistant or resilient to peat substrate changes brought

  18. Bacterial interactions in dental biofilm development.

    PubMed

    Hojo, K; Nagaoka, S; Ohshima, T; Maeda, N

    2009-11-01

    Recent analyses with ribosomal RNA-based technologies have revealed the diversity of bacterial populations within dental biofilms, and have highlighted their important contributions to oral health and disease. Dental biofilms are exceedingly complex and multispecies ecosystems, where oral bacteria interact cooperatively or competitively with other members. Bacterial interactions that influence dental biofilm communities include various different mechanisms. During the early stage of biofilm formation, it is known that planktonic bacterial cells directly attach to surfaces of the oral cavity or indirectly bind to other bacterial cells that have already colonized. Adherence through co-aggregation may be critical for the temporary retention of bacteria on dental surfaces, and may facilitate eventual bacterial colonization. It is likely that metabolic communication, genetic exchange, production of inhibitory factors (e.g., bacteriocins, hydrogen peroxide, etc.), and quorum-sensing are pivotal regulatory factors that determine the bacterial composition and/or metabolism. Since each bacterium can easily access a neighboring bacterial cell and its metabolites, genetic exchanges and metabolic communication may occur frequently in dental biofilms. Quorum-sensing is defined as gene regulation in response to cell density, which influences various functions, e.g., virulence and bacteriocin production. In this review, we discuss these important interactions among oral bacteria within the dental biofilm communities.

  19. Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos

    PubMed Central

    MARUI, Junichiro; BOULOM, Sayvisene; PANTHAVEE, Wanchai; MOMMA, Mari; KUSUMOTO, Ken-Ichi; NAKAHARA, Kazuhiko; SAITO, Masayoshi

    2015-01-01

    A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacteria seemed to vary in the 10 products collected from Thailand and Laos. Tetragenococci were common in products from central Thailand and Vientiane in Laos which had salinities of not less than 11% and pH values ranging from 5.6 to 6.1. However, lactobacilli were common in products from northern Thailand which had the lowest salinities (8.3–8.6%) and pH values (4.5–4.8) of all the samples examined. Two Lactobacillus and one Tetragenococcus species were detected in one product from northeastern Thailand containing 10% salt. These results suggest that salinity in pla-ra/pa-daek is an important determinant of the representative genus of lactic acid bacteria such as, Tetragenococcus or Lactobacillus. Additionally, differences in the acidity between these two groups seemed to be related to the production of d-/l-lactic acid in the lactic acid bacteria in each product. This is the first study to report a correlation between bacterial community structure and taste components in pla-ra/pa-daek products from various regions. This scientific work on a traditional fermented food will be useful in helping local producers meet differing consumer preferences in various regions. PMID:25918672

  20. Production of migration inhibitory factor in response to bacterial and fungal antigens in patients with untreated Graves' disease

    PubMed Central

    Wall, Jack R.; Ryan, E. Ann

    1980-01-01

    Tests for the production of migration inhibitory factor by peripheral blood leukocytes in response to ubiquitous bacterial and fungal antigens were carried out in patients with untreated Graves' disease and in healthy control subjects. Dose-response studies, tests for the production of this factor after 72 hours' stimulation with phytohemagglutinin as a test for reserve, and tests before and after 24 hours' preculture to deplete suppressor cells were also performed in some patients. The antigens used were Candida, Trichophyton-Oidiomyces-Epidermophyton, mumps live attenuated virus and purified protein derivative of tuberculin. The production of migration inhibitory factor was measured by the agarose microdroplet method. The production of migration inhibitory factor in response to all the antigens except mumps virus was slightly greater in the patients than in the control subjects, although the differences were not significant. The dose-response characteristics and the production of migration inhibitory factor after stimulation with phytohemagglutinin were similar in the two groups. The production of migration inhibitory factor in response to suboptimal concentrations of Candida, Trichophyton-Oidiomyces-Epidermophyton and mumps virus was not enhanced in either group after 24 hours' preculture apart from a slight increase in response to mumps virus in the patients. These results fail to support the suggestion that patients with Graves' disease have a deficiency of suppressor cells. PMID:6446374

  1. In Situ Hydrocarbon Degradation by Indigenous Nearshore Bacterial Populations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cherrier, J.

    ). Results from these time series experiments demonstrated that short-term exposure of petroleum to UV light enhanced hydrocarbon degradation by 48% over that observed for non-photo-oxidized petroleum. Despite the greater bio-availability of the photo-oxidized over the non-photo-oxidized petroleum, an initial lag in CO{sub 2} production was observed indicating potential phototoxicity of the photo- by-products. {delta}{sup 13}C analysis and mass balance calculations reveal that co-metabolism with pinfish resulted in increased hydrocarbon degradation for both photo-oxidized and non-photo-oxidized petroleum each by over 100%. These results demonstrate the cumulative effect of photo-oxidation and co-metabolism on petroleum hydrocarbon degradation by natural bacterial populations indigenous to systems chronically impacted by hydrocarbon input. To address the second objective of this proposal bacterial concentrates were collected from Bayboro Harbor in April 2001 for nucleic acid extraction and subsequent natural radiocarbon abundance analyses. Unfortunately, however, all of these samples were lost due to a faulty compressor in our -70 freezer. The freezer was subsequently repaired and samples were again collected from Bayboro Harbor in June 2002 and again December 2002. Several attempts were made to extract the nucleic acid samples--however, the student was not able to successfully extract and an adequate amount of uncontaminated nucleic acid samples for subsequent natural radiocarbon abundance measurements of the bacterial carbon by accelerator mass spectrometry (i.e. require at least 50 {micro}g carbon for AMS measurement). Consequently, we were not able to address the second objective of this proposed work.« less

  2. Soil bacterial diversity in degraded and restored lands of Northeast Brazil.

    PubMed

    Araújo, Ademir Sérgio Ferreira; Borges, Clovis Daniel; Tsai, Siu Mui; Cesarz, Simone; Eisenhauer, Nico

    2014-11-01

    Land degradation deteriorates biological productivity and affects environmental, social, and economic sustainability, particularly so in the semi-arid region of Northeast Brazil. Although some studies exist reporting gross measures of soil microbial parameters and processes, limited information is available on how land degradation and restoration strategies influence the diversity and composition of soil microbial communities. In this study we compare the structure and diversity of bacterial communities in degraded and restored lands in Northeast Brazil and determine the soil biological and chemical properties influencing bacterial communities. We found that land degradation decreased the diversity of soil bacteria as indicated by both reduced operational taxonomic unit (OTU) richness and Shannon index. Soils under native vegetation and restoration had significantly higher bacterial richness and diversity than degraded soils. Redundancy analysis revealed that low soil bacterial diversity correlated with a high respiratory quotient, indicating stressed microbial communities. By contrast, soil bacterial communities in restored land positively correlated with high soil P levels. Importantly, however, we found significant differences in the soil bacterial community composition under native vegetation and in restored land, which may indicate differences in their functioning despite equal levels of bacterial diversity.

  3. Effect of organic acids production and bacterial community on the possible mechanism of phosphorus solubilization during composting with enriched phosphate-solubilizing bacteria inoculation.

    PubMed

    Wei, Yuquan; Zhao, Yue; Shi, Mingzi; Cao, Zhenyu; Lu, Qian; Yang, Tianxue; Fan, Yuying; Wei, Zimin

    2018-01-01

    Enriched phosphate-solubilizing bacteria (PSB) agent were acquired by domesticated cultivation, and inoculated into kitchen waste composting in different stages. The effect of different treatments on organic acids production, tricalcium phosphate (TCP) solubilization and their relationship with bacterial community were investigated during composting. Our results pointed out that inoculation affected pH, total acidity and the production of oxalic, lactic, citric, succinic, acetic and formic acids. We also found a strong advantage in the solubilization of TCP and phosphorus (P) availability for PSB inoculation especially in the cooling stage. Redundancy analysis and structural equation models demonstrated inoculation by different methods changed the correlation of the bacterial community composition with P fractions as well as organic acids, and strengthened the cooperative function related to P transformation among species during composting. Finally, we proposed a possible mechanism of P solubilization with enriched PSB inoculation, which was induced by bacterial community and organic acids production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Measuring bacterial growth by refractive index tapered fiber optic biosensor.

    PubMed

    Zibaii, Mohammad Ismail; Kazemi, Alireza; Latifi, Hamid; Azar, Mahmoud Karimi; Hosseini, Seyed Masoud; Ghezelaiagh, Mohammad Hossein

    2010-12-02

    A single-mode tapered fiber optic biosensor was utilized for real-time monitoring of the Escherichia coli (E. coli K-12) growth in an aqueous medium. The applied fiber tapers were fabricated using heat-pulling method with waist diameter and length of 6-7μm and 3mm, respectively. The bacteria were immobilized on the tapered surface using Poly-l-Lysine. By providing the proper condition, bacterial population growth on the tapered surface increases the average surface density of the cells and consequently the refractive index (RI) of the tapered region would increase. The adsorption of the cells on the tapered fiber leads to changes in the optical characteristics of the taper. This affects the evanescent field leading to changes in optical throughput. The bacterial growth rate was monitored at room temperature by transmission of a 1558.17nm distributed feedback (DFB) laser through the tapered fiber. At the same condition, after determining the growth rate of E. coli by means of colony counting method, we compared the results with that obtained from the fiber sensor measurements. This novel sensing method, promises new application such as rapid analysis of the presence of bacteria. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. Bacterial community dynamics and activity in relation to dissolved organic matter availability during sea-ice formation in a mesocosm experiment.

    PubMed

    Eronen-Rasimus, Eeva; Kaartokallio, Hermanni; Lyra, Christina; Autio, Riitta; Kuosa, Harri; Dieckmann, Gerhard S; Thomas, David N

    2014-02-01

    The structure of sea-ice bacterial communities is frequently different from that in seawater. Bacterial entrainment in sea ice has been studied with traditional microbiological, bacterial abundance, and bacterial production methods. However, the dynamics of the changes in bacterial communities during the transition from open water to frozen sea ice is largely unknown. Given previous evidence that the nutritional status of the parent water may affect bacterial communities during ice formation, bacterial succession was studied in under ice water and sea ice in two series of mesocosms: the first containing seawater from the North Sea and the second containing seawater enriched with algal-derived dissolved organic matter (DOM). The composition and dynamics of bacterial communities were investigated with terminal restriction fragment length polymorphism (T-RFLP), and cloning alongside bacterial production (thymidine and leucine uptake) and abundance measurements (measured by flow cytometry). Enriched and active sea-ice bacterial communities developed in ice formed in both unenriched and DOM-enriched seawater (0-6 days). γ-Proteobacteria dominated in the DOM-enriched samples, indicative of their capability for opportunistic growth in sea ice. The bacterial communities in the unenriched waters and ice consisted of the classes Flavobacteria, α- and γ-Proteobacteria, which are frequently found in natural sea ice in polar regions. Furthermore, the results indicate that seawater bacterial communities are able to adapt rapidly to sudden environmental changes when facing considerable physicochemical stress such as the changes in temperature, salinity, nutrient status, and organic matter supply during ice formation. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  6. Impact of metal stress on the production of secondary metabolites in Pteris vittata L. and associated rhizosphere bacterial communities.

    PubMed

    Pham, Hoang Nam; Michalet, Serge; Bodillis, Josselin; Nguyen, Tien Dat; Nguyen, Thi Kieu Oanh; Le, Thi Phuong Quynh; Haddad, Mohamed; Nazaret, Sylvie; Dijoux-Franca, Marie-Geneviève

    2017-07-01

    Plants adapt to metal stress by modifying their metabolism including the production of secondary metabolites in plant tissues. Such changes may impact the diversity and functions of plant associated microbial communities. Our study aimed to evaluate the influence of metals on the secondary metabolism of plants and the indirect impact on rhizosphere bacterial communities. We then compared the secondary metabolites of the hyperaccumulator Pteris vittata L. collected from a contaminated mining site to a non-contaminated site in Vietnam and identified the discriminant metabolites. Our data showed a significant increase in chlorogenic acid derivatives and A-type procyanidin in plant roots at the contaminated site. We hypothesized that the intensive production of these compounds could be part of the antioxidant defense mechanism in response to metals. In parallel, the structure and diversity of bulk soil and rhizosphere communities was studied using high-throughput sequencing. The results showed strong differences in bacterial composition, characterized by the dominance of Proteobacteria and Nitrospira in the contaminated bulk soil, and the enrichment of some potential human pathogens, i.e., Acinetobacter, Mycobacterium, and Cupriavidus in P. vittata's rhizosphere at the mining site. Overall, metal pollution modified the production of P. vittata secondary metabolites and altered the diversity and structure of bacterial communities. Further investigations are needed to understand whether the plant recruits specific bacteria to adapt to metal stress.

  7. Impact of ZnO and Ag Nanoparticles on Bacterial Growth and Viability

    NASA Astrophysics Data System (ADS)

    Olson, M. S.; Digiovanni, K. A.

    2007-12-01

    Hundreds of consumer products containing nanomaterials are currently available in the U.S., including computers, clothing, cosmetics, sports equipment, medical devices and product packaging. Metallic nanoparticles can be embedded in or coated on product surfaces to provide antimicrobial, deodorizing, and stain- resistant properties. Although these products have the potential to provide significant benefit to the user, the impact of these products on the environment remains largely unknown. The purpose of this project is to study the effect of metallic nanoparticles released to the environment on bacterial growth and viability. Inhibition of bacterial growth was tested by adding doses of suspended ZnO and Ag nanoparticles into luria broth prior to inoculation of Escherichia coli cells. ZnO particles (approximately 40 nm) were obtained commercially and Ag particles (12-14 nm) were fabricated by reduction of silver nitrate with sodium borohydride. Toxicity assays were performed to test the viability of E. coli cells exposed to both ZnO and Ag nanoparticles using the LIVE/DEAD BacLight bacterial viability kit (Invitrogen). Live cells stain green whereas cells with compromised membranes that are considered dead or dying stain red. Cells were first grown, stained, and exposed to varying doses of metallic nanoparticles, and then bacterial viability was measured hourly using fluorescence microscopy. Results indicate that both ZnO and Ag nanoparticles inhibit the growth of E. coli in liquid media. Preliminary results from toxicity assays confirm the toxic effect of ZnO and Ag nanoparticles on active cell cultures. Calculated death rates resulting from analyses of toxicity studies will be presented.

  8. Radiolabel ratio method for measuring pulmonary clearance of intratracheal bacterial challenges

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    LaForce, F.M.; Boose, D.S.

    Calculation of bacterial clearance is a fundamental step in any study of in situ lung antibacterial defenses. A method is described whereby about 85% of a radiolabeled bacterial inoculum was consistently introduced into the bronchopulmonary tree of a mouse by the intratracheal route. Mice were then killed 1 and 4 hours later; their lungs were removed aseptically and homogenized, and viable bacteria and radiolabel counts were determined. Radiolabel counts fell slowly, and more than 80% of the original radiolabel was still present in homogenized lung samples from animals sacrificed 4 hours after challenge. Bacteria/isotope ratios for the bacterial inoculum andmore » homogenized lung samples from animals sacrificed immediately after challenge were very similar. Bacterial clearance values were the same whether computed from bacterial counts alone or according to a radiolabel ratio method whereby the change in the bacteria/isotope ratio in ground lung aliquots was divided by a similar ratio from bacteria used to inoculate animals. Some contamination resulted from oral streptococci being swept into the bronchopulmonary free during the aspiration process. This contamination was not a problem when penicillin was incorporated into the agar and penicillin-resistant strains were used for the bacterial challenges.« less

  9. Effect of inorganic salts on bacterial omega-3 PUFA production.

    PubMed

    Abd Elrazak, Ahmed; Ward, Alan C; Glassey, Jarka

    2017-03-16

    The increasing demand of omega-3 in the market and the challenges facing its conventional supplies led to an increasing interest to microbial omega-3 sources. This research concentrates on the statistical role of some metal ions on the biosynthesis and productivity of eicosapentaenoic acid (essential omega-3 element) in bacterial isolate, Shewanella 717. A Plackett-Burman design was applied to screen the main effect of all metal salts entrenched in the artificial sea water medium components. Four salts, in particular, in addition to the interaction among them were highlighted as having a statistically significant effect upon the growth and/or eicosapentaenoic acid production. A subsequent central composite design was performed to determine the exact optimum concentration of each of the chosen variables which was found to be 2.5, 1.8, 1.2, and 23 g/l, for Na 2 HPO 4 , MgSO 4 , KCl, and NaCl, respectively. All the experiments were performed with the minimal amount of carbon and nitrogen to eliminate any potential masking effect. A bioreactor batch run was operated and the ion uptake was monitored, using EDAX® electron microscopy, concluding that the process of microbial omega-3 production could be a phosphate-limited process. Optimizing the concentration of the tested metal ions led to a remarkable increase in the omega-3 productivity resulted in a 30, 9, and 10 times increase in yield, concentration, and percentage to the total fatty acids, respectively, even though the carbon and nitrogen were kept constant all over the research work.

  10. Corticosteroid suppression of antiviral immunity increases bacterial loads and mucus production in COPD exacerbations.

    PubMed

    Singanayagam, Aran; Glanville, Nicholas; Girkin, Jason L; Ching, Yee Man; Marcellini, Andrea; Porter, James D; Toussaint, Marie; Walton, Ross P; Finney, Lydia J; Aniscenko, Julia; Zhu, Jie; Trujillo-Torralbo, Maria-Belen; Calderazzo, Maria Adelaide; Grainge, Chris; Loo, Su-Ling; Veerati, Punnam Chander; Pathinayake, Prabuddha S; Nichol, Kristy S; Reid, Andrew T; James, Phillip L; Solari, Roberto; Wark, Peter A B; Knight, Darryl A; Moffatt, Miriam F; Cookson, William O; Edwards, Michael R; Mallia, Patrick; Bartlett, Nathan W; Johnston, Sebastian L

    2018-06-08

    Inhaled corticosteroids (ICS) have limited efficacy in reducing chronic obstructive pulmonary disease (COPD) exacerbations and increase pneumonia risk, through unknown mechanisms. Rhinoviruses precipitate most exacerbations and increase susceptibility to secondary bacterial infections. Here, we show that the ICS fluticasone propionate (FP) impairs innate and acquired antiviral immune responses leading to delayed virus clearance and previously unrecognised adverse effects of enhanced mucus, impaired antimicrobial peptide secretion and increased pulmonary bacterial load during virus-induced exacerbations. Exogenous interferon-β reverses these effects. FP suppression of interferon may occur through inhibition of TLR3- and RIG-I virus-sensing pathways. Mice deficient in the type I interferon-α/β receptor (IFNAR1 -/- ) have suppressed antimicrobial peptide and enhanced mucin responses to rhinovirus infection. This study identifies type I interferon as a central regulator of antibacterial immunity and mucus production. Suppression of interferon by ICS during virus-induced COPD exacerbations likely mediates pneumonia risk and raises suggestion that inhaled interferon-β therapy may protect.

  11. Evaluation of gastrointestinal bacterial population for the production of holocellulose enzymes for biomass deconstruction

    PubMed Central

    Asem, Dhaneshwaree; Leo, Vincent Vineeth; Passari, Ajit Kumar; Tonsing, Mary Vanlalhruaii; Joshi, J. Beslin; Uthandi, Sivakumar; Hashem, Abeer; Abd_Allah, Elsayed Fathi

    2017-01-01

    The gastrointestinal (GI) habitat of ruminant and non-ruminant animals sustains a vast ensemble of microbes that are capable of utilizing lignocellulosic plant biomass. In this study, an indigenous swine (Zovawk) and a domesticated goat (Black Bengal) were investigated to isolate bacteria having plant biomass degrading enzymes. After screening and enzymatic quantification of eighty-one obtained bacterial isolates, Serratia rubidaea strain DBT4 and Aneurinibacillus aneurinilyticus strain DBT87 were revealed as the most potent strains, showing both cellulase and xylanase production. A biomass utilization study showed that submerged fermentation (SmF) of D2 (alkaline pretreated pulpy biomass) using strain DBT4 resulted in the most efficient biomass deconstruction with maximum xylanase (11.98 U/mL) and FPase (0.5 U/mL) activities (55°C, pH 8). The present study demonstrated that bacterial strains residing in the gastrointestinal region of non-ruminant swine are a promising source for lignocellulose degrading microorganisms that could be used for biomass conversion. PMID:29023528

  12. Evaluation of gastrointestinal bacterial population for the production of holocellulose enzymes for biomass deconstruction.

    PubMed

    Asem, Dhaneshwaree; Leo, Vincent Vineeth; Passari, Ajit Kumar; Tonsing, Mary Vanlalhruaii; Joshi, J Beslin; Uthandi, Sivakumar; Hashem, Abeer; Abd Allah, Elsayed Fathi; Singh, Bhim Pratap

    2017-01-01

    The gastrointestinal (GI) habitat of ruminant and non-ruminant animals sustains a vast ensemble of microbes that are capable of utilizing lignocellulosic plant biomass. In this study, an indigenous swine (Zovawk) and a domesticated goat (Black Bengal) were investigated to isolate bacteria having plant biomass degrading enzymes. After screening and enzymatic quantification of eighty-one obtained bacterial isolates, Serratia rubidaea strain DBT4 and Aneurinibacillus aneurinilyticus strain DBT87 were revealed as the most potent strains, showing both cellulase and xylanase production. A biomass utilization study showed that submerged fermentation (SmF) of D2 (alkaline pretreated pulpy biomass) using strain DBT4 resulted in the most efficient biomass deconstruction with maximum xylanase (11.98 U/mL) and FPase (0.5 U/mL) activities (55°C, pH 8). The present study demonstrated that bacterial strains residing in the gastrointestinal region of non-ruminant swine are a promising source for lignocellulose degrading microorganisms that could be used for biomass conversion.

  13. Rapid measurement and prediction of bacterial contamination in milk using an oxygen electrode.

    PubMed

    Numthuam, Sonthaya; Suzuki, Hiroaki; Fukuda, Junji; Phunsiri, Suthiluk; Rungchang, Saowaluk; Satake, Takaaki

    2009-03-01

    An oxygen electrode was used to measure oxygen consumption to determine bacterial contamination in milk. Dissolved oxygen (DO) measured at 10-35 degrees C for 2 hours provided a reasonable prediction efficiency (r > or = 0.90) of the amount of bacteria between 1.9 and 7.3 log (CFU/mL). A temperature-dependent predictive model was developed that has the same prediction accuracy like the normal predictive model. The analysis performed with and without stirring provided the same prediction efficiency, with correlation coefficient of 0.90. The measurement of DO is a simple and rapid method for the determination of bacteria in milk.

  14. Hijacking bacterial glycosylation for the production of glycoconjugates, from vaccines to humanised glycoproteins.

    PubMed

    Cuccui, Jon; Wren, Brendan

    2015-03-01

    Glycosylation or the modification of a cellular component with a carbohydrate moiety has been demonstrated in all three domains of life as a basic post-translational process important in a range of biological processes. This review will focus on the latest studies attempting to exploit bacterial N-linked protein glycosylation for glycobiotechnological applications including glycoconjugate vaccine and humanised glycoprotein production. The challenges that remain for these approaches to reach full biotechnological maturity will be discussed. Oligosaccharyltransferase-dependent N-linked glycosylation can be exploited to make glycoconjugate vaccines against bacterial pathogens. Few technical limitations remain, but it is likely that the technologies developed will soon be considered a cost-effective and flexible alternative to current chemical-based methods of vaccine production. Some highlights from current glycoconjugate vaccines developed using this in-vivo production system include a vaccine against Shigella dysenteriae O1 that has passed phase 1 clinical trials, a vaccine against the tier 1 pathogen Francisella tularensis that has shown efficacy in mice and a vaccine against Staphylococcus aureus serotypes 5 and 8. Generation of humanised glycoproteins within bacteria was considered impossible due to the distinct nature of glycan modification in eukaryotes and prokaryotes. We describe the method used to overcome this conundrum to allow engineering of a eukaryotic pentasaccharide core sugar modification within Escherichia coli. This core was assembled by combining the function of the initiating transferase WecA, several Alg genes from Saccharomyces cerevisiae and the oligosaccharyltransferase function of the Campylobacter jejuni PglB. Further exploitation of a cytoplasmic N-linked glycosylation system found in Actinobacillus pleuropneumoniae where the central enzyme is known as N-linking glycosyltransferase has overcome some of the limitations demonstrated by the

  15. 7 CFR 58.135 - Bacterial estimate.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., GENERAL SPECIFICATIONS FOR APPROVED PLANTS AND STANDARDS FOR GRADES OF DAIRY PRODUCTS 1 General Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Quality Specifications for Raw Milk § 58.135 Bacterial estimate. (a) Methods of Testing. Milk shall be tested for bacterial estimate...

  16. Reduction of pasteurization temperature leads to lower bacterial outgrowth in pasteurized fluid milk during refrigerated storage: a case study.

    PubMed

    Martin, N H; Ranieri, M L; Wiedmann, M; Boor, K J

    2012-01-01

    Bacterial numbers over refrigerated shelf-life were enumerated in high-temperature, short-time (HTST) commercially pasteurized fluid milk for 15 mo before and 15 mo after reducing pasteurization temperature from 79.4°C (175°F) [corrected] to 76.1°C (169°F). Total bacterial counts were measured in whole fat, 2% fat, and fat-free milk products on the day of processing as well as throughout refrigerated storage (6°C) at 7, 14, and 21 d postprocessing. Mean total bacterial counts were significantly lower immediately after processing as well as at 21 d postprocessing in samples pasteurized at 76.1°C versus samples pasteurized at 79.4°C. In addition to mean total bacterial counts, changes in bacterial numbers over time (i.e., bacterial growth) were analyzed and were lower during refrigerated storage of products pasteurized at the lower temperature. Lowering the pasteurization temperature for unflavored fluid milk processed in a commercial processing facility significantly reduced bacterial growth during refrigerated storage. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

    PubMed

    Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

    2016-12-01

    Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

  18. The Heterotrophic Bacterial Response During the Meso-scale Southern Ocean Iron Experiment (SOFeX)

    NASA Astrophysics Data System (ADS)

    Oliver, J. L.; Barber, R. T.; Ducklow, H. W.

    2002-12-01

    Previous meso-scale iron enrichments have demonstrated the stimulatory effect of iron on primary productivity and the accelerated flow of carbon into the surface ocean foodweb. In stratified waters, heterotrophic activity can work against carbon export by remineralizing POC and/or DOC back to CO2, effectively slowing the biological pump. To assess the response of heterotrophic activity to iron enrichment, we measured heterotrophic bacterial production and abundance during the Southern Ocean Iron Experiment (SOFeX). Heterotrophic bacterial processes primarily affect the latter of the two carbon export mechanisms, removal of DOC to the deep ocean. Heterotrophic bacterial production (BP), measured via tritiated thymidine (3H-TdR) and leucine (3H-Leu) incorporation, increased ~40% over the 18-d observation period in iron fertilized waters south of the Polar Front (South Patch). Also, South Patch BP was 61% higher than in the surrounding unfertilized waters. Abundance, measured by flow cytometry (FCM) and acridine orange direct counts (AODC), also increased in the South Patch from 3 to 5 x 108 cells liter-1, a 70% increase. Bacterial biomass increased from ~3.6 to 6.3 μg C liter-1, a clear indication that production rates exceeded removal rates (bactivory, viral lysis) over the course of 18 days. Biomass within the fertilized patch was 11% higher than in surrounding unfertilized waters reflecting a similar trend. This pattern is in contrast to SOIREE where no accumulation of biomass was observed. High DNA-containing (HDNA) cells detected by FCM also increased over time in iron fertilized waters from 20% to 46% relative to the total population suggesting an active subpopulation of cells that were growing faster than the removal rates. In iron fertilized waters north of the Polar Front (North Patch), BP and abundance were ~90% and 80% higher, respectively, than in unfertilized waters. Our results suggest an active bacterial population that responded to iron fertilization

  19. Elevations of novel cytokines in bacterial meningitis in infants.

    PubMed

    Srinivasan, Lakshmi; Kilpatrick, Laurie; Shah, Samir S; Abbasi, Soraya; Harris, Mary C

    2018-01-01

    Bacterial meningitis is challenging to diagnose in infants, especially in the common setting of antibiotic pre-treatment, which diminishes yield of cerebrospinal fluid (CSF) cultures. Prior studies of diagnostic markers have not demonstrated sufficient accuracy. Interleukin-23 (IL-23), interleukin-18 (IL-18) and soluble receptor for advanced glycation end products (sRAGE) possess biologic plausibility, and may be useful as diagnostic markers in bacterial meningitis. In a prospective cohort study, we measured IL-23, IL-18 and sRAGE levels in CSF. We compared differences between infected and non-infected infants, and conducted receiver operating characteristic (ROC) analyses to identify individual markers and combinations of markers with the best diagnostic accuracy. 189 infants <6 months, including 8 with bacterial meningitis, 30 without meningitis, and 151 with indeterminate diagnosis (due to antibiotic pretreatment) were included. CSF IL-23, IL-18 and sRAGE levels were significantly elevated in infants with culture proven meningitis. Among individual markers, IL-23 possessed the greatest accuracy for diagnosis of bacterial meningitis (area under the curve (AUC) 0.9698). The combination of all three markers had an AUC of 1. IL-23, alone and in combination with IL-18 and sRAGE, identified bacterial meningitis with excellent accuracy. Following validation, these markers could aid clinicians in diagnosis of bacterial meningitis and decision-making regarding prolongation of antibiotic therapy.

  20. Increasing antibiotic resistance in preservative-tolerant bacterial strains isolated from cosmetic products.

    PubMed

    Orús, Pilar; Gomez-Perez, Laura; Leranoz, Sonia; Berlanga, Mercedes

    2015-03-01

    To ensure the microbiological quality, consumer safety and organoleptic properties of cosmetic products, manufacturers need to comply with defined standards using several preservatives and disinfectants. A drawback regarding the use of these preservatives is the possibility of generating cross-insusceptibility to other disinfectants or preservatives, as well as cross resistance to antibiotics. Therefore, the objective of this study was to understand the adaptive mechanisms of Enterobacter gergoviae, Pseudomonas putida and Burkholderia cepacia that are involved in recurrent contamination in cosmetic products containing preservatives. Diminished susceptibility to formaldehyde-donors was detected in isolates but not to other preservatives commonly used in the cosmetics industry, although increasing resistance to different antibiotics (β-lactams, quinolones, rifampicin, and tetracycline) was demonstrated in these strains when compared with the wild-type strain. The outer membrane protein modifications and efflux mechanism activities responsible for the resistance trait were evaluated. The development of antibiotic-resistant microorganisms due to the selective pressure from preservatives included in cosmetic products could be a risk for the emergence and spread of bacterial resistance in the environment. Nevertheless, the large contribution of disinfection and preservation cannot be denied in cosmetic products. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

  1. Evaluation of bacterial flora during the ripening of Kedong sufu, a typical Chinese traditional bacteria-fermented soybean product.

    PubMed

    Feng, Zhen; Gao, Wei; Ren, Dan; Chen, Xi; Li, Juan-juan

    2013-04-01

    Kedong sufu is a typical bacteria-fermented sufu in China. Isolation and identification of the autochthonous bacteria involved would allow the design of specific starters for this speciality. The purpose of the present study was to evaluate the bacterial flora during the ripening of Kedong sufu using polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and culturing. In terms of bacterial diversity, 22 strains were isolated and identified and 27 strains were detected by DGGE. Regarding bacterial dynamics, the results of culturing and PCR-DGGE exhibited a similar trend towards dominant strains. Throughout the fermentation of sufu, Enterococcus avium, Enterococcus faecalis and Staphylococcus carnosus were the dominant microflora, while the secondary microflora comprised Leuconostoc mesenteroides, Staphylococcus saprophyticus, Streptococcus lutetiensis, Kocuria rosea, Kocuria kristinae, Bacillus pumilus, Bacillus cereus and Bacillus subtilis. This study is the first to reveal the bacterial flora during the ripening of Kedong sufu using both culture-dependent and culture-independent methods. This information will help in the design of autochthonous starter cultures for the production of Kedong sufu with desirable characteristic sensory profiles and shorter ripening times. © 2012 Society of Chemical Industry.

  2. Bacterial contamination of ex vivo processed PBPC products under clean room conditions.

    PubMed

    Ritter, Markus; Schwedler, Joachim; Beyer, Jörg; Movassaghi, Kamran; Mutters, Reinier; Neubauer, Andreas; Schwella, Nimrod

    2003-11-01

    Patients undergoing high-dose radio- and/or chemotherapy and autologous or allogeneic PBPC transplantation are at high risk for infections owing to profound immunosuppression. In this study, the rate of microbial contamination of ex vivo processed PBPC products was analyzed, comparing preparation under clean room conditions to standard laboratory conditions. After implementation of good manufacturing practice conditions in the two participating institutions, the microbial contamination rate of 366 PBPC harvests from 198 patients was determined under certified clean room conditions (Group A) from 2000 until 2002. To investigate influence of improved environmental conditions along with other parameters, this set of samples was compared with a historical control set of 1413 PBPC products, which have been processed ex vivo under a clean bench in a regular laboratory room and were harvested from 626 patients (Group B) from 1989 until 2000. In Group B microbial contamination was found in 74 PBPC products (5.2%) from 57 patients. In Group A microbial growth was detected in 3 leukapheresis products (0.8%) from 3 patients. After exclusion of PBPC products, which were probably contaminated before manipulation, statistical analysis showed a significant difference (chi2= 10.339; p < 0.001). These data suggest an impact of clean room conditions on the bacterial contamination rate of PBPC products. To identify confounding variables, variables like technique of leukapheresis, culture methodology, and microbial colonization of central venous catheters were taken into account. Further variables might be identified in following studies.

  3. Condensed tannins affect bacterial and fungal microbiomes and mycotoxin production during ensiling and upon aerobic exposure.

    PubMed

    Peng, Kai; Jin, Long; Niu, Yan D; Huang, Qianqian; McAllister, Tim A; Yang, Hee Eun; Denise, Hubert; Xu, Zhongjun; Acharya, Surya; Wang, Shunxi; Wang, Yuxi

    2017-12-15

    Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g/kg DM of condensed tannin (CT) was ensiled without (Control) or with polyethylene glycol (PEG) for 76 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics were determined and bacterial and fungal communities were assessed using metagenomic sequencing. Addition of PEG that deactivated CT at ensiling increased ( P < 0.05∼0.001) soluble N, non-protein N, lactic acid, total volatile fatty acids, ammonia N, deoxynivalenol (DON) and ochratoxin A (OTA), but decreased ( P < 0.001) pH and water soluble carbohydrates. Concentration of DON and OTA increased ( P < 0.001) for both silages with the extent of increase being greater for Control than for PEG treated silage during aerobic exposure. The PEG treated silage exhibited higher ( P < 0.01∼0.001) copy numbers of total bacteria, Lactobacillus , yeasts and fungi than Control. Addition of PEG decreased ( P < 0.01) bacterial diversity during both ensiling and aerobic exposure, whereas it increased ( P < 0.05) fungal diversity during aerobic exposure. Addition of PEG at ensiling increased ( P < 0.05) abundances of Lactobacillus and Pediococcus , but decreased ( P < 0.01) abundances of Lactococcus and Leuconostoc Filamentous fungi were found in the microbiome at ensiling and after aerobic exposure, whereas the Bacillus were the dominate bacteria after aerobic exposure. In conclusion, CT decreased protein degradation and improved aerobic stability of silage. These desirable outcomes likely reflect the ability of PPC CT to inhibit those microorganisms involved in lowering silage quality and in the production of mycotoxins. IMPORTANCE The present study reports the effects of condensed tannins on the complex microbial communities involved in ensiling and aerobic exposure of purple prairie clover. This study documents the ability of condensed tannins to lower mycotoxin production and associated microbiome. Taxonomic bacterial

  4. Thermal design and turbidity sensor for autonomous bacterial growth measurements in spaceflight.

    PubMed

    van Benthem, Roel; Krooneman, Janneke; de Grave, Wubbo; Hammenga-Dorenbos, Hilma

    2009-04-01

    For application of biological air filters in manned spacecraft, research on bacterial growth is carried out under microgravity conditions. For the BIOFILTER experiment, flown in 2005 on FOTON M2, eight turbidity sensors to measure the growth rate of the bacterium Xanthobacter autotrophicus GJ10 were used. Also thermal management provisions were implemented to control the internal temperature. The design and performance of the BIOFILTER equipment as well as results of the biological ground reference experiments performed in 2006 are discussed. High-performance thermal (vacuum) insulation (lambda= 0.7 mW/mK) and phase change material were implemented, keeping the BIOFILTER internal temperature below 16 degrees C during the 4-day integration period between transport and launch. After launch, in microgravity, the growth of X. autotrophicus GJ10 was successfully triggered by a temperature increase by using an internal heater to 26 degrees C. Although the operation of the sensor electronics was not fully satisfying, the bacterial growth was measured with the sensors, revealing growth rates between 0.046 and 0.077 h(-1) in microgravity, that is, approximately 1.5-2.5 times slower than routinely measured on Earth under optimal laboratory conditions. For the ground-reference experiments the equipment box, containing the eight sensors, was placed on a random positioning machine performing random rotations at 0.5 degrees /min (settling compensation) and 90 degrees /min (microgravity simulation) while the environment was controlled, accurately repeating the BIOFILTER internal temperature profile. Despite the rotation speed differences, growth rates of 0.115 h(-1) were confirmed by both the ground reference experiments. Biological interpretation of the measurements is, however, compromised owing to poor mixing and other unknown physical and biological phenomena that need to be addressed for further space experiments using these kinds of systems.

  5. Detergent-compatible bacterial amylases.

    PubMed

    Niyonzima, Francois N; More, Sunil S

    2014-10-01

    Proteases, lipases, amylases, and cellulases are enzymes used in detergent formulation to improve the detergency. The amylases are specifically supplemented to the detergent to digest starchy stains. Most of the solid and liquid detergents that are currently manufactured contain alkaline enzymes. The advantages of using alkaline enzymes in the detergent formulation are that they aid in removing tough stains and the process is environmentally friendly since they reduce the use of toxic detergent ingredients. Amylases active at low temperature are preferred as the energy consumption gets reduced, and the whole process becomes cost-effective. Most microbial alkaline amylases are used as detergent ingredients. Various reviews report on the production, purification, characterization, and application of amylases in different industry sectors, but there is no specific review on bacterial or fungal alkaline amylases or detergent-compatible amylases. In this mini-review, an overview on the production and property studies of the detergent bacterial amylases is given, and the stability and compatibility of the alkaline bacterial amylases in the presence of the detergents and the detergent components are highlighted.

  6. Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

    PubMed Central

    Cheng, Kuan-Chen; Catchmark, Jeff M; Demirci, Ali

    2009-01-01

    Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The

  7. 9 CFR 113.64 - General requirements for live bacterial vaccines.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

  8. 9 CFR 113.64 - General requirements for live bacterial vaccines.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

  9. 9 CFR 113.64 - General requirements for live bacterial vaccines.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

  10. The Microbial Food Web in the Recently Flooded Sep Reservoir: Diel Fluctuations in Bacterial Biomass and Metabolic Activity in Relation to Phytoplankton and Flagellate Grazers.

    PubMed

    Jugnia, L.-B.; Tadonléké, R.D.; Sime-Ngando, T.; Devaux, J.

    2000-12-01

    The spatial distribution of the bacterial biomass and production and of potential heterotrophic activity (PHA) were measured every 4 h between 23 July (10:00 h) and 25 July (10:00 h) 1997 in a recently flooded oligo-mesotrophic reservoir (the Sep Reservoir, Puy-de-Dôme, France), in relation to temperature, the phytoplankton biomass and production, and the abundance of heterotrophic flagellates. The temperature varied slightly with time during the study, but the well-established thermal stratification agreed well with vertical distribution of the biological variables that were measured. Only the bacterial production and the PHA showed significant diel changes (t-test, p <0.05), with maxima at 18:00 h and minima at 02:00 h. A significant positive relation was found between bacterial abundance and that of heterotrophic flagellates, which, rather than being an association related to the thermal stratification of the water column, was considered to reflect a trophic relation between these two communities. A carbon balance analysis suggested that at least 30% of the C from primary production measured during the sampling period was used by bacteria, and that 42% of this secondary production, or 6% of the primary production, would be used for the development of the heterotrophic flagellates present. We conclude that the bacterioplankton forms, at least occasionally, an important source of carbon for higher trophic levels, and reject the hypothesis that bacterial production in the Sep Reservoir depends exclusively on organic matter of allochthonous origin.

  11. Bacterial diversity patterns of the intertidal biofilm in urban beaches of Río de la Plata.

    PubMed

    Piccini, C; García-Alonso, J

    2015-02-28

    Intertidal benthic ecosystems in estuaries are productive sites where microbial processes play critical roles in nutrients mineralization, primary production and trophic web. In this groundwork study we analyzed the bacterial community of intertidal biofilms from Río de la Plata beaches with different anthropogenic impacts. Several environmental parameters were measured and bacterial assemblages were analyzed by 16S-rDNA pyrosequencing. The average OTU found per sample was 527.3±122.5, showing similar richness and diversity among them. However, sites having the highest and lowest salinity displayed higher bacterial diversity. Assemblages from a site nearby an oil refinery, showing the lowest salinity and oxygen concentration, were clearly distinct from the rest. The weight of this splitting relied on OTUs belonging to Thauera, known by its ability to metabolize aromatic compounds. Our results suggest that intertidal bacterial assemblages would be structured by major estuarine variables such as salinity, and that anthropogenic-induced environmental parameters might also be relevant. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Zoonotic bacterial meningitis in human adults.

    PubMed

    van Samkar, Anusha; Brouwer, Matthijs C; van der Ende, Arie; van de Beek, Diederik

    2016-09-13

    To describe the epidemiology, etiology, clinical characteristics, treatment, outcome, and prevention of zoonotic bacterial meningitis in human adults. We identified 16 zoonotic bacteria causing meningitis in adults. Zoonotic bacterial meningitis is uncommon compared to bacterial meningitis caused by human pathogens, and the incidence has a strong regional distribution. Zoonotic bacterial meningitis is mainly associated with animal contact, consumption of animal products, and an immunocompromised state of the patient. In a high proportion of zoonotic bacterial meningitis cases, CSF analysis showed only a mildly elevated leukocyte count. The recommended antibiotic therapy differs per pathogen, and the overall mortality is low. Zoonotic bacterial meningitis is uncommon but is associated with specific complications. The suspicion should be raised in patients with bacterial meningitis who have recreational or professional contact with animals and in patients living in regions endemic for specific zoonotic pathogens. An immunocompromised state is associated with a worse prognosis. Identification of risk factors and underlying disease is necessary to improve treatment. © 2016 American Academy of Neurology.

  13. Feasibility of using a microalgal-bacterial consortium for treatment of toxic coke wastewater with concomitant production of microbial lipids.

    PubMed

    Ryu, Byung-Gon; Kim, Jungmin; Han, Jong-In; Yang, Ji-Won

    2017-02-01

    This study examined the feasibility of using an algal-bacterial process for removal of phenol and NH 4 + -N from differently diluted coke wastewater with simultaneous production of biomass. Under illumination, microalgal-bacterial (MSB) cultures performed complete phenol degradation at all dilutions of coke wastewater while sole microalgal culture (MSA) degraded a maximum of 27.3% of phenol (initial concentration: 24.0mgL -1 ) from 5-fold diluted wastewater. Furthermore, the MSB culture had the highest rate of NH 4 + -N removal (8.3mgL -1 d -1 ) and fatty acid production (20mgL -1 d -1 ) which were 2.3- and 1.5-fold higher than those observed in the MSA cultures, probably due to decreases in toxic organic pollutants. Multivariate analyses indicated that co-cultivation of activated sludge was directly correlated with the elevated removals of phenol and NH 4 + -N. In the presence of sludge, adequate dilution of the coke wastewater can maximize the effect of bacteria on NH 4 + -N removal and biomass production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Bacterial detection of platelets: current problems and possible resolutions.

    PubMed

    Blajchman, Morris A; Beckers, Erik A M; Dickmeiss, Ebbe; Lin, Lilly; Moore, Gillian; Muylle, Ludo

    2005-10-01

    The greatest transfusion-transmitted disease risk facing a transfusion recipient is that of bacterial sepsis. The prevalence of bacterial contamination in platelets and red blood cells is approximately 1 in 3,000 units transfused. The available data indicate that transfusion-associated sepsis develops after 1 in 25,000 platelet transfusions and 1 in 250,000 red blood cell transfusions. One of the most widely used strategies for decreasing bacterial sepsis risk is bacterial detection. A roundtable meeting of experts was convened during the XXVIII Annual Congress of the International Society of Blood Transfusion (Edinburgh, UK, July 2004) to provide a forum for experts to share their experiences in the routine bacterial detection of platelet products. This article summarizes the presentations, discussions, and recommendations of the panel. The data presented indicate that some of the current bacterial screening technology is useful for blocking the issuance of platelet units that contain relatively high levels of contaminating bacteria. Platelet units are usually released based on a test-negative status, which often become test-positive only upon longer storage. These data thus suggest that bacterial screening may not prevent all transfusion-transmitted bacterial infections. Two transfusion-transmitted case reports further highlighted the limitation of the routine bacterial screening of platelet products. It was felt that newer technologies, such as pathogen inactivation, may represent a more reliable process, with a higher level of safety. The panel thus recommended that the Transfusion Medicine community may need to change its thinking (paradigm) about bacterial detection, toward the possibility of the pathogen inactivation of blood products, to deal with the bacterial contamination issue. It was suggested, where permitted by regulatory agencies, that blood centers should consider adopting first-generation pathogen inactivation systems as a more effective approach

  15. Growth of Bacterial Colonies

    NASA Astrophysics Data System (ADS)

    Warren, Mya; Hwa, Terence

    2013-03-01

    On hard agar gel, there is insufficient surface hydration for bacteria to swim or swarm. Instead, growth occurs in colonies of close-packed cells, which expand purely due to repulsive interactions: individual bacteria push each other out of the way through the force of their growth. In this way, bacterial colonies represent a new type of ``active'' granular matter. In this study, we investigate the physical, biochemical, and genetic elements that determine the static and dynamic aspects of this mode of bacterial growth for E. coli. We characterize the process of colony expansion empirically, and use discrete and continuum models to examine the extent to which our observations can be explained by the growth characteristics of non-communicating cells, coupled together by physical forces, nutrients, and waste products. Our results challenge the commonly accepted modes of bacterial colony growth and provide insight into sources of growth limitation in crowded bacterial communities.

  16. Impact of bacterial biocontrol agents on aflatoxin biosynthetic genes, aflD and aflR expression, and phenotypic aflatoxin B₁ production by Aspergillus flavus under different environmental and nutritional regimes.

    PubMed

    Al-Saad, Labeed A; Al-Badran, Adnan I; Al-Jumayli, Sami A; Magan, Naresh; Rodríguez, Alicia

    2016-01-18

    The objectives of this study were to examine the efficacy of four bacterial antagonists against Aspergillus flavus using 50:50 ratio of bacterial cells/conidia for the control of aflatoxin B1 (AFB1) production on two different nutritional matrices, nutrient and maize-based media at different water availabilities (0.98, 0.94 water activity (aw) on nutrient medium; 0.995, 0.98 aw on maize meal agar medium) at 35°C. The indicators of efficacy used were the relative expression of one structural and regulatory gene in the biosynthetic pathway (aflD and aflR respectively) and the production of AFB1. These studies showed that some of the bacterial species could significantly inhibit the relative expression of the aflD and aflR genes at both 0.98 and 0.94 aw on nutrient agar. On maize-based media some of the bacterial antagonists reduced the activity of both genes at 0.94 aw and some at 0.995 aw. However, the results for AFB1 production were not consistent with the effects on gene expression. Some bacterial species stimulated AFB1 production on both nutrient and maize-based media regardless of aw. However, some bacterial treatments did inhibit AFB1 production significantly when compared to the control. Overall, this study suggests that temporal studies are required on the biosynthetic genes under different environmental and nutritional conditions to evaluate the potential of antagonists to control AFB1. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Bacterial Diversity and Mycotoxin Reduction During Maize Fermentation (Steeping) for Ogi Production

    PubMed Central

    Okeke, Chiamaka A.; Ezekiel, Chibundu N.; Nwangburuka, Cyril C.; Sulyok, Michael; Ezeamagu, Cajethan O.; Adeleke, Rasheed A.; Dike, Stanley K.; Krska, Rudolf

    2015-01-01

    Bacterial diversity and community structure of two maize varieties (white and yellow) during fermentation/steeping for ogi production, and the influence of spontaneous fermentation on mycotoxin reduction in the gruel were studied. A total of 142 bacterial isolates obtained at 24–96 h intervals were preliminarily identified by conventional microbiological methods while 60 selected isolates were clustered into 39 OTUs consisting of 15 species, 10 genera, and 3 phyla by 16S rRNA sequence analysis. Lactic acid bacteria constituted about 63% of all isolated bacteria and the genus Pediococcus dominated (white maize = 84.8%; yellow maize = 74.4%). Pediococcus acidilactici and Lactobacillus paraplantarum were found at all steeping intervals of white and yellow maize, respectively, while P. claussenii was present only at the climax stage of steeping white maize. In both maize varieties, P. pentosaceus was found at 24–72 h. Mycotoxin concentrations (μg/kg) in the unsteeped grains were: white maize (aflatoxin B1 = 0.60; citrinin = 85.8; cyclopiazonic acid = 23.5; fumonisins (B1/B2/B3) = 68.4–483; zearalenone = 3.3) and yellow maize (aflatoxins (B1/B2/M1) = 22.7–513; citrinin = 16,800; cyclopiazonic acid = 247; fumonisins (B1/B2/B3) = 252–1,586; zearalenone = 205). Mycotoxins in both maize varieties were significantly (p < 0.05) reduced across steeping periods. This study reports for the first time: (a) the association of L. paraplantarum, P. acidilactici, and P. claussenii with ogi production from maize, (b) citrinin occurrence in Nigerian maize and ogi, and (c) aflatoxin M1, citrinin and cyclopiazonic acid degradation/loss due to fermentation in traditional cereal-based fermented food. PMID:26697001

  18. Bacterial natural product biosynthetic domain composition in soil correlates with changes in latitude on a continent-wide scale.

    PubMed

    Lemetre, Christophe; Maniko, Jeffrey; Charlop-Powers, Zachary; Sparrow, Ben; Lowe, Andrew J; Brady, Sean F

    2017-10-31

    Although bacterial bioactive metabolites have been one of the most prolific sources of lead structures for the development of small-molecule therapeutics, very little is known about the environmental factors associated with changes in secondary metabolism across natural environments. Large-scale sequencing of environmental microbiomes has the potential to shed light on the richness of bacterial biosynthetic diversity hidden in the environment, how it varies from one environment to the next, and what environmental factors correlate with changes in biosynthetic diversity. In this study, the sequencing of PCR amplicons generated using primers targeting either ketosynthase domains from polyketide biosynthesis or adenylation domains from nonribosomal peptide biosynthesis was used to assess biosynthetic domain composition and richness in soils collected across the Australian continent. Using environmental variables collected at each soil site, we looked for environmental factors that correlated with either high overall domain richness or changes in the domain composition. Among the environmental variables we measured, changes in biosynthetic domain composition correlate most closely with changes in latitude and to a lesser extent changes in pH. Although it is unclear at this time the exact mix of factors that may drive the relationship between biosynthetic domain composition and latitude, from a practical perspective the identification of a latitudinal basis for differences in soil metagenome biosynthetic domain compositions should help guide future natural product discovery efforts. Published under the PNAS license.

  19. Novel keratin modified bacterial cellulose nanocomposite production and characterization for skin tissue engineering.

    PubMed

    Keskin, Zalike; Sendemir Urkmez, Aylin; Hames, E Esin

    2017-06-01

    As it is known that bacterial cellulose (BC) is a biocompatible and natural biopolymer due to which it has a large set of biomedical applications. But still it lacks some desired properties, which limits its uses in many other applications. Therefore, the properties of BC need to be boosted up to an acceptable level. Here in this study for the first time, a new natural nanocomposite was produced by the incorporating keratin (isolated from human hair) to the BC (produced by Acetobacter xylinum) to enhance dermal fibroblast cells' attachment. Two different approaches were used in BC based nanocomposite production: in situ and post modifications. BC/keratin nanocomposites were characterized using SEM, FTIR, EDX, XRD, DSC and XPS analyses. Both production methods have yielded successful results for production of BC based nanocomposite-containing keratin. In vitro cell culture experiments performed with human skin keratinocytes and human skin fibroblast cells indicate the potential of the novel BC/keratin nanocomposites for use in skin tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Production of bacterial cellulose using different carbon sources and culture media.

    PubMed

    Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

    2015-03-06

    In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Characterizing bacterial communities in paper production-troublemakers revealed.

    PubMed

    Zumsteg, Anita; Urwyler, Simon K; Glaubitz, Joachim

    2017-08-01

    Biofilm formation is a major cause of reduced paper quality and increased down time during paper manufacturing. This study uses Illumina next-generation sequencing to identify the microbial populations causing quality issues due to their presence in biofilms and slimes. The paper defects investigated contained traces of the films and/or slime of mainly two genera, Tepidimonas and Chryseobacterium. The Tepidimonas spp. found contributed on average 68% to the total bacterial population. Both genera have been described previously to be associated with biofilms in paper mills. There was indication that Tepidimonas spp. were present as compact biofilm in the head box of one paper machine and was filtered out by the paper web during production. On the other hand Tepidimonas spp. were also present to a large extent in the press and white waters of two nonproblematic paper machines. Therefore, the mere presence of a known biofilm producer alone is not sufficient to cause slimes and therefore paper defects and other critical factors are additionally at play. For instance, we identified Acidovorax sp., which is an early colonizer of paper machines, exhibiting the ability to form extracellular DNA matrices for attachment and biofilm formation. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  2. Quantifying school officials' exposure to bacterial pathogens at graduation ceremonies using repeated observational measures.

    PubMed

    Bishai, David; Liu, Liang; Shiau, Stephanie; Wang, Harrison; Tsai, Cindy; Liao, Margaret; Prakash, Shivaani; Howard, Tracy

    2011-06-01

    The purpose of this study was to estimate the risk of acquiring pathogenic bacteria as a result of shaking hands at graduation ceremonies. School officials participating in graduation ceremonies at elementary, secondary, and postsecondary schools were recruited. Specimens were collected before and immediately following graduation. Cultures identified any pathogenic bacteria in each specimen. Subjects shook a total of 5,209 hands. Staphylococcus aureus was separately detected on one pregraduation right hand, one postgraduation right hand, and one postgraduation left hand. Nonpathogenic bacteria were collected in 93% of specimens. Pregraduation and postgraduation specimens were of different strains. We measured a risk of one new bacterial acquisition in a sample exposed to 5,209 handshakes yielding an overall estimate of 0.019 pathogens acquired per handshake. We conclude that a single handshake at a graduation offers only a small risk of bacterial pathogen acquisition.

  3. Measuring Clinical Productivity.

    PubMed

    Hudson, Mark E; Lebovitz, Evan E

    2018-06-01

    Productivity measurements have been used to evaluate and compare physicians and physician practices. Anesthesiology is unique in that factors outside anesthesiologist control impact opportunity for revenue generation and make comparisons between providers and facilities challenging. This article uses data from the multicenter University of Pittsburgh Physicians Department of Anesthesiology to demonstrate factors influencing productivity opportunity by surgical facility, between department divisions and subspecialties within multispecialty divisions, and by individuals within divisions. The complexities of benchmarking anesthesiology productivity are demonstrated, and the potential value of creating a productivity profile for facilities and groups is illustrated. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Nitrous oxide production and mRNA expression analysis of nitrifying and denitrifying bacterial genes under floodwater disappearance and fertilizer application.

    PubMed

    Riya, Shohei; Takeuchi, Yuki; Zhou, Sheng; Terada, Akihiko; Hosomi, Masaaki

    2017-06-01

    A pulse of nitrous oxide (N 2 O) emission has been observed following the disappearance of floodwater by drainage. However, its mechanism is not well understood. We conducted a column study to clarify the mechanism for N 2 O production during floodwater disappearance by using a microsensor and determining the bacterial gene expression. An increase in N 2 O flux was observed following floodwater disappearance after the addition of NH 4 + , with a corresponding increase in the concentrations of NO 3 - and dissolved N 2 O in the oxic and anoxic soil layers, respectively. The transcription level of the bacterial amoA mRNA did not change, while that of nirK mRNA increased sharply after an hour of floodwater disappearance. An additional anoxic soil slurry experiment demonstrated that the addition of NO 3 - induced the expression of nirK gene and caused a concomitant increase in N 2 O production. These findings suggest that NO 3 - production in the oxic layers is important as it provides a substrate and induces the synthesis of denitrification enzymes in the anoxic layer during N 2 O production.

  5. Isolation of cell-free bacterial inclusion bodies.

    PubMed

    Rodríguez-Carmona, Escarlata; Cano-Garrido, Olivia; Seras-Franzoso, Joaquin; Villaverde, Antonio; García-Fruitós, Elena

    2010-09-17

    Bacterial inclusion bodies are submicron protein clusters usually found in recombinant bacteria that have been traditionally considered as undesirable products from protein production processes. However, being fully biocompatible, they have been recently characterized as nanoparticulate inert materials useful as scaffolds for tissue engineering, with potentially wider applicability in biomedicine and material sciences. Current protocols for inclusion body isolation from Escherichia coli usually offer between 95 to 99% of protein recovery, what in practical terms, might imply extensive bacterial cell contamination, not compatible with the use of inclusion bodies in biological interfaces. Using an appropriate combination of chemical and mechanical cell disruption methods we have established a convenient procedure for the recovery of bacterial inclusion bodies with undetectable levels of viable cell contamination, below 10⁻¹ cfu/ml, keeping the particulate organization of these aggregates regarding size and protein folding features. The application of the developed protocol allows obtaining bacterial free inclusion bodies suitable for use in mammalian cell cultures and other biological interfaces.

  6. A novel production process for optically pure L-lactic acid from kitchen refuse using a bacterial consortium at high temperatures.

    PubMed

    Tashiro, Yukihiro; Matsumoto, Hiroko; Miyamoto, Hirokuni; Okugawa, Yuki; Pramod, Poudel; Miyamoto, Hisashi; Sakai, Kenji

    2013-10-01

    We investigated L-lactic acid production in static batch fermentation of kitchen refuse using a bacterial consortium from marine-animal-resource (MAR) composts at temperatures ranging from 30 to 65 °C. At relatively low temperatures butyric acid accumulated, whereas at higher temperatures L-lactic acid was produced. In particular, fermentation at 50 °C produced 34.5 g L(-1) L-lactic acid with 90% lactic acid selectivity and 100% optical purity. Denaturing gradient gel electrophoresis indicated that dominant bacteria present in the original MAR composts diminished rapidly and Bacillus coagulans strains became the dominant contributors to L-lactic acid production at 45, 50 and 55 °C. This is the first report of the achievement of 100% optical purity of L-lactic acid using a bacterial consortium. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Carbon nanomaterials alter plant physiology and soil bacterial community composition in a rice-soil-bacterial ecosystem.

    PubMed

    Hao, Yi; Ma, Chuanxin; Zhang, Zetian; Song, Youhong; Cao, Weidong; Guo, Jing; Zhou, Guopeng; Rui, Yukui; Liu, Liming; Xing, Baoshan

    2018-01-01

    The aim of this study was to compare the toxicity effects of carbon nanomaterials (CNMs), namely fullerene (C 60 ), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), on a mini-ecosystem of rice grown in a loamy potted soil. We measured plant physiological and biochemical parameters and examined bacterial community composition in the CNMs-treated plant-soil system. After 30 days of exposure, all the three CNMs negatively affected the shoot height and root length of rice, significantly decreased root cortical cells diameter and resulted in shrinkage and deformation of cells, regardless of exposure doses (50 or 500 mg/kg). Additionally, at the high exposure dose of CNM, the concentrations of four phytohormones, including auxin, indoleacetic acid, brassinosteroid and gibberellin acid 4 in rice roots significantly increased as compared to the control. At the high exposure dose of MWCNTs and C 60 , activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) in roots increased significantly. High-throughput sequencing showed that three typical CNMs had little effect on shifting the predominant soil bacterial species, but the presence of CNMs significantly altered the composition of the bacterial community. Our results indicate that different CNMs indeed resulted in environmental toxicity to rice and soil bacterial community in the rhizosphere and suggest that CNMs themselves and their incorporated products should be reasonably used to control their release/discharge into the environment to prevent their toxic effects on living organisms and the potential risks to food safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A Straightforward Approach for 3D Bacterial Printing

    PubMed Central

    2017-01-01

    Sustainable and personally tailored materials production is an emerging challenge to society. Living organisms can produce and pattern an extraordinarily wide range of different molecules in a sustainable way. These natural systems offer an abundant source of inspiration for the development of new environmentally friendly materials production techniques. In this paper, we describe the first steps toward the 3-dimensional printing of bacterial cultures for materials production and patterning. This methodology combines the capability of bacteria to form new materials with the reproducibility and tailored approach of 3D printing systems. For this purpose, a commercial 3D printer was modified for bacterial systems, and new alginate-based bioink chemistry was developed. Printing temperature, printhead speed, and bioink extrusion rate were all adapted and customized to maximize bacterial health and spatial resolution of printed structures. Our combination of 3D printing technology with biological systems enables a sustainable approach for the production of numerous new materials. PMID:28225616

  9. A Straightforward Approach for 3D Bacterial Printing.

    PubMed

    Lehner, Benjamin A E; Schmieden, Dominik T; Meyer, Anne S

    2017-07-21

    Sustainable and personally tailored materials production is an emerging challenge to society. Living organisms can produce and pattern an extraordinarily wide range of different molecules in a sustainable way. These natural systems offer an abundant source of inspiration for the development of new environmentally friendly materials production techniques. In this paper, we describe the first steps toward the 3-dimensional printing of bacterial cultures for materials production and patterning. This methodology combines the capability of bacteria to form new materials with the reproducibility and tailored approach of 3D printing systems. For this purpose, a commercial 3D printer was modified for bacterial systems, and new alginate-based bioink chemistry was developed. Printing temperature, printhead speed, and bioink extrusion rate were all adapted and customized to maximize bacterial health and spatial resolution of printed structures. Our combination of 3D printing technology with biological systems enables a sustainable approach for the production of numerous new materials.

  10. Screening of marine bacterial producers of polyunsaturated fatty acids and optimisation of production.

    PubMed

    Abd El Razak, Ahmed; Ward, Alan C; Glassey, Jarka

    2014-02-01

    Water samples from three different environments including Mid Atlantic Ridge, Red Sea and Mediterranean Sea were screened in order to isolate new polyunsaturated fatty acids (PUFAs) bacterial producers especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Two hundred and fifty-one isolates were screened for PUFA production and among them the highest number of producers was isolated from the Mid-Atlantic Ridge followed by the Red Sea while no producers were found in the Mediterranean Sea samples. The screening strategy included a simple colourimetric method followed by a confirmation via GC/MS. Among the tested producers, an isolate named 66 was found to be a potentially high PUFA producer producing relatively high levels of EPA in particular. A Plackett-Burman statistical design of experiments was applied to screen a wide number of media components identifying glycerol and whey as components of a production medium. The potential low-cost production medium was optimised by applying a response surface methodology to obtain the highest productivity converting industrial by-products into value-added products. The maximum achieved productivity of EPA was 20 mg/g, 45 mg/l, representing 11% of the total fatty acids, which is approximately five times more than the amount produced prior to optimisation. The production medium composition was 10.79 g/l whey and 6.87 g/l glycerol. To our knowledge, this is the first investigation of potential bacteria PUFA producers from Mediterranean and Red Seas providing an evaluation of a colourimetric screening method as means of rapid screening of a large number of isolates.

  11. An active bacterial community linked to high chl-a concentrations in Antarctic winter-pack ice and evidence for the development of an anaerobic sea-ice bacterial community.

    PubMed

    Eronen-Rasimus, Eeva; Luhtanen, Anne-Mari; Rintala, Janne-Markus; Delille, Bruno; Dieckmann, Gerhard; Karkman, Antti; Tison, Jean-Louis

    2017-10-01

    Antarctic sea-ice bacterial community composition and dynamics in various developmental stages were investigated during the austral winter in 2013. Thick snow cover likely insulated the ice, leading to high (<4 μg l -1 ) chlorophyll-a (chl-a) concentrations and consequent bacterial production. Typical sea-ice bacterial genera, for example, Octadecabacter, Polaribacter and Glaciecola, often abundant in spring and summer during the sea-ice algal bloom, predominated in the communities. The variability in bacterial community composition in the different ice types was mainly explained by the chl-a concentrations, suggesting that as in spring and summer sea ice, the sea-ice bacteria and algae may also be coupled during the Antarctic winter. Coupling between the bacterial community and sea-ice algae was further supported by significant correlations between bacterial abundance and production with chl-a. In addition, sulphate-reducing bacteria (for example, Desulforhopalus) together with odour of H 2 S were observed in thick, apparently anoxic ice, suggesting that the development of the anaerobic bacterial community may occur in sea ice under suitable conditions. In all, the results show that bacterial community in Antarctic sea ice can stay active throughout the winter period and thus possible future warming of sea ice and consequent increase in bacterial production may lead to changes in bacteria-mediated processes in the Antarctic sea-ice zone.

  12. Glibenclamide reduces pro-inflammatory cytokine production by neutrophils of diabetes patients in response to bacterial infection

    NASA Astrophysics Data System (ADS)

    Kewcharoenwong, Chidchamai; Rinchai, Darawan; Utispan, Kusumawadee; Suwannasaen, Duangchan; Bancroft, Gregory J.; Ato, Manabu; Lertmemongkolchai, Ganjana

    2013-11-01

    Type 2 diabetes mellitus is a major risk factor for melioidosis, which is caused by Burkholderia pseudomallei. Our previous study has shown that polymorphonuclear neutrophils (PMNs) from diabetic subjects exhibited decreased functions in response to B. pseudomallei. Here we investigated the mechanisms regulating cytokine secretion of PMNs from diabetic patients which might contribute to patient susceptibility to bacterial infections. Purified PMNs from diabetic patients who had been treated with glibenclamide (an ATP-sensitive potassium channel blocker for anti-diabetes therapy), showed reduction of interleukin (IL)-1β and IL-8 secretion when exposed to B. pseudomallei. Additionally, reduction of these pro-inflammatory cytokines occurred when PMNs from diabetic patients were treated in vitro with glibenclamide. These findings suggest that glibenclamide might be responsible for the increased susceptibility of diabetic patients, with poor glycemic control, to bacterial infections as a result of its effect on reducing IL-1β production by PMNs.

  13. Significant alteration of soil bacterial communities and organic carbon decomposition by different long-term fertilization management conditions of extremely low-productivity arable soil in South China.

    PubMed

    Xun, Weibing; Zhao, Jun; Xue, Chao; Zhang, Guishan; Ran, Wei; Wang, Boren; Shen, Qirong; Zhang, Ruifu

    2016-06-01

    Different fertilization managements of red soil, a kind of Ferralic Cambisol, strongly affected the soil properties and associated microbial communities. The association of the soil microbial community and functionality with long-term fertilization management in the unique low-productivity red soil ecosystem is important for both soil microbial ecology and agricultural production. Here, 454 pyrosequencing analysis of 16S recombinant ribonucleic acid genes and GeoChip4-NimbleGen-based functional gene analysis were used to study the soil bacterial community composition and functional genes involved in soil organic carbon degradation. Long-term nitrogen-containing chemical fertilization-induced soil acidification and fertility decline and significantly altered the soil bacterial community, whereas long-term organic fertilization and fallow management improved the soil quality and maintained the bacterial diversity. Short-term quicklime remediation of the acidified soils did not change the bacterial communities. Organic fertilization and fallow management supported eutrophic ecosystems, in which copiotrophic taxa increased in relative abundance and have a higher intensity of labile-C-degrading genes. However, long-term nitrogen-containing chemical fertilization treatments supported oligotrophic ecosystems, in which oligotrophic taxa increased in relative abundance and have a higher intensity of recalcitrant-C-degrading genes but a lower intensity of labile-C-degrading genes. Quicklime application increased the relative abundance of copiotrophic taxa and crop production, although these effects were utterly inadequate. This study provides insights into the interaction of soil bacterial communities, soil functionality and long-term fertilization management in the red soil ecosystem; these insights are important for improving the fertility of unique low-productivity red soil. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation

    USDA-ARS?s Scientific Manuscript database

    Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grin...

  15. A duplex PCR-based assay for measuring the amount of bacterial contamination in a nucleic acid extract from a culture of free-living protists.

    PubMed

    Marron, Alan O; Akam, Michael; Walker, Giselle

    2013-01-01

    Cultures of heterotrophic protists often require co-culturing with bacteria to act as a source of nutrition. Such cultures will contain varying levels of intrinsic bacterial contamination that can interfere with molecular research and cause problems with the collection of sufficient material for sequencing. Measuring the levels of bacterial contamination for the purposes of molecular biology research is non-trivial, and can be complicated by the presence of a diverse bacterial flora, or by differences in the relative nucleic acid yield per bacterial or eukaryotic cell. Here we describe a duplex PCR-based assay that can be used to measure the levels of contamination from marine bacteria in a culture of loricate choanoflagellates. By comparison to a standard culture of known target sequence content, the assay can be used to quantify the relative proportions of bacterial and choanoflagellate material in DNA or RNA samples extracted from a culture. We apply the assay to compare methods of purifying choanoflagellate cultures prior to DNA extraction, to determine their effectiveness in reducing bacterial contamination. Together with measurements of the total nucleic acid concentration, the assay can then be used as the basis for determining the absolute amounts of choanoflagellate DNA or RNA present in a sample. The assay protocol we describe here is a simple and relatively inexpensive method of measuring contamination levels in nucleic acid samples. This provides a new way to establish quantification and purification protocols for molecular biology and genomics in novel heterotrophic protist species. Guidelines are provided to develop a similar protocol for use with any protistan culture. This assay method is recommended where qPCR equipment is unavailable, where qPCR is not viable because of the nature of the bacterial contamination or starting material, or where prior sequence information is insufficient to develop qPCR protocols.

  16. Production of added value bacterial lipids through valorisation of hydrocarbon-contaminated cork waste.

    PubMed

    Castro, A R; Guimarães, M; Oliveira, J V; Pereira, M A

    2017-12-15

    This work demonstrates that cork used as oil-spill sorbents, contaminated with liquid hydrocarbons, herein demonstrated with hexadecane, can be biologically treated by Rhodococcus opacus B4 with concomitant lipids production. R. opacus B4 consumed up to 96% of hexadecane (C16) impregnated in natural and regranulated cork sorbents after 48h incubation, producing 0.59±0.06g of triacylglycerol (TAG) g -1 of C16 consumed with a TAG content of 0.60±0.06gg -1 of cellular dry weight (CDW) and 0.54±0.05g TAG g -1 of C16 consumed with a TAG content of 0.77±0.04gg -1 (CDW), respectively. TAG was mainly composed by fatty acids of 16 and 18 carbon chains demonstrating the feasibility of using it as raw material for biodiesel production. In addition, the obtained lipid-rich biomass (whole cells) can be used for biomethane production, at a yield of 0.4L CH 4 g -1 (CDW). The obtained results support a novel approach for management of oil-spill contaminated cork sorbents through its valorisation by producing bacterial lipids, which can be used as feedstocks for biofuels production. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Mechanical Homogenization Increases Bacterial Homogeneity in Sputum

    PubMed Central

    Stokell, Joshua R.; Khan, Ammad

    2014-01-01

    Sputum obtained from patients with cystic fibrosis (CF) is highly viscous and often heterogeneous in bacterial distribution. Adding dithiothreitol (DTT) is the standard method for liquefaction prior to processing sputum for molecular detection assays. To determine if DTT treatment homogenizes the bacterial distribution within sputum, we measured the difference in mean total bacterial abundance and abundance of Burkholderia multivorans between aliquots of DTT-treated sputum samples with and without a mechanical homogenization (MH) step using a high-speed dispersing element. Additionally, we measured the effect of MH on bacterial abundance. We found a significant difference between the mean bacterial abundances in aliquots that were subjected to only DTT treatment and those of the aliquots which included an MH step (all bacteria, P = 0.04; B. multivorans, P = 0.05). There was no significant effect of MH on bacterial abundance in sputum. Although our results are from a single CF patient, they indicate that mechanical homogenization increases the homogeneity of bacteria in sputum. PMID:24759710

  18. Statistical optimization of culture conditions for bacterial cellulose production using Box-Behnken design.

    PubMed

    Bae, Sangok; Shoda, Makoto

    2005-04-05

    Culture conditions in a jar fermentor for bacterial cellulose (BC) production from A. xylinum BPR2001 were optimized by statistical analysis using Box-Behnken design. Response surface methodology was used to predict the levels of the factors, fructose (X1), corn steep liquor (CSL) (X2), dissolved oxygen (DO) (X3), and agar concentration (X4). Total 27 experimental runs by combination of each factor were carried out in a 10-L jar fermentor, and a three-dimensional response surface was generated to determine the effect of the factors and to find out the optimum concentration of each factor for maximum BC production and BC yield. The fructose and agar concentration highly influenced the BC production and BC yield. However, the optimum conditions according to changes in CSL and DO concentrations were predicted at almost central values of tested ranges. The predicted results showed that BC production was 14.3 g/L under the condition of 4.99% fructose, 2.85% CSL, 28.33% DO, and 0.38% agar concentration. On the other hand, BC yield was predicted in 0.34 g/g under the condition of 3.63% fructose, 2.90% CSL, 31.14% DO, and 0.42% agar concentration. Under optimized culture conditions, improvement of BC production and BC yield were experimentally confirmed, which increased 76% and 57%, respectively, compared to BC production and BC yield before optimizing the culture conditions. Copyright (c) 2005 Wiley Periodicals, Inc.

  19. Simultaneous biogas upgrading and biochemicals production using anaerobic bacterial mixed cultures.

    PubMed

    Omar, Basma; Abou-Shanab, Reda; El-Gammal, Maie; Fotidis, Ioannis A; Kougias, Panagiotis G; Zhang, Yifeng; Angelidaki, Irini

    2018-05-29

    A novel biological process to upgrade biogas was developed and optimised during the current study. In this process, CO 2 in the biogas and externally provided H 2 were fermented under mesophilic conditions to volatile fatty acids (VFAs), which are building blocks of higher-value biofuels. Meanwhile, the biogas was upgraded to biomethane (CH 4 >95%), which can be used as a vehicle fuel or injected into the natural gas grid. To establish an efficient fermentative microbial platform, a thermal (at two different temperatures of 70 °C and 90 °C) and a chemical pretreatment method using 2-bromoethanesulfonate were investigated initially to inhibit methanogenesis and enrich the acetogenic bacterial inoculum. Subsequently, the effect of different H 2 :CO 2 ratios on the efficiency of biogas upgrading and production of VFAs were further explored. The composition of the microbial community under different treatment methods and gas ratios has also been unravelled using 16S rRNA analysis. The chemical treatment of the inoculum had successfully blocked the activity of methanogens and enhanced the VFAs production, especially acetate. The chemical treatment led to a significantly better acetate production (291 mg HAc/L) compared to the thermal treatment. Based upon 16S rRNA gene sequencing, it was found that H 2 -utilizing methanogens were the dominant species in the thermally treated inoculum, while a significantly lower abundance of methanogens was observed in the chemically treated inoculum. The highest biogas content (96% (v/v)) and acetate production were achieved for 2H 2 :1CO 2 ratio (v/v), with Acetoanaerobium noterae, as the dominant homoacetogenic hydrogen scavenger. Results from the present study can pave the way towards more development with respect to microorganisms and conditions for high efficient VFAs production and biogas upgrading. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. MemStar: a one-shot Escherichia coli-based approach for high-level bacterial membrane protein production.

    PubMed

    Lee, Chiara; Kang, Hae Joo; Hjelm, Anna; Qureshi, Abdul Aziz; Nji, Emmanuel; Choudhury, Hassanul; Beis, Konstantinos; de Gier, Jan-Willem; Drew, David

    2014-10-16

    Optimising membrane protein production yields in Escherichiacoli can be time- and resource-consuming. Here, we present a simple and effective Membrane protein Single shot amplification recipe: MemStar. This one-shot amplification recipe is based on the E. coli strain Lemo21(DE3), the PASM-5052 auto-induction medium and, contradictorily, an IPTG induction step. Using MemStar, production yields for most bacterial membrane proteins tested were improved to reach an average of 5 mg L(-1) per OD600 unit, which is significantly higher than yields obtained with other common production strategies. With MemStar, we have been able to obtain new structural information for several transporters, including the sodium/proton antiporter NapA. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  1. Conventional and nonconventional strategies for controlling bacterial contamination in fuel ethanol fermentations.

    PubMed

    Ceccato-Antonini, Sandra Regina

    2018-05-25

    Ethanol bio-production in Brazil has some unique characteristics that inevitably lead to bacterial contamination, which results in the production of organic acids and biofilms and flocculation that impair the fermentation yield by affecting yeast viability and diverting sugars to metabolites other than ethanol. The ethanol-producing units commonly give an acid treatment to the cells after each fermentative cycle to decrease the bacterial number, which is not always effective. An alternative strategy must be employed to avoid bacterial multiplication but must be compatible with economic, health and environmental aspects. This review analyzes the issue of bacterial contamination in sugarcane-based fuel ethanol fermentation, and the potential strategies that may be utilized to control bacterial growth besides acid treatment and antibiotics. We have emphasized the efficiency and suitability of chemical products other than acids and those derived from natural sources in industrial conditions. In addition, we have also presented bacteriocins, bacteriophages, and beneficial bacteria as non-conventional antimicrobial agents to mitigate bacterial contamination in the bioethanol industry.

  2. Productivity and health: best practices for better measures of productivity.

    PubMed

    Schwartz, Steven M; Riedel, John

    2010-09-01

    Interest in quantifying the relationship between health status and lost productivity has accelerated among employers, researchers, and benefits advisors. Our objective was to engage a dialogue to highlight important productivity measurement issues for consideration in an overall business strategy. Critical review of selected topical literature. Four functions of productivity measurement are described: 1) the purposes of a measurement initiative, 2) norms and benchmarking, 3) health and productivity cost estimators, and 4) reporting results. Each function is described in detail; challenges are noted; examples are provided. This article supports the Integrated Benefits Institute consensus statements on productivity, underscoring the need to develop a conceptual framework of productivity measurement that guides the maturation of instruments and sets forth recommendations for their application consistent with the descriptive, comparative, and evaluative functions that foster health, well-being, and work performance.

  3. Bacterial enzymes involved in lignin degradation.

    PubMed

    de Gonzalo, Gonzalo; Colpa, Dana I; Habib, Mohamed H M; Fraaije, Marco W

    2016-10-20

    Lignin forms a large part of plant biomass. It is a highly heterogeneous polymer of 4-hydroxyphenylpropanoid units and is embedded within polysaccharide polymers forming lignocellulose. Lignin provides strength and rigidity to plants and is rather resilient towards degradation. To improve the (bio)processing of lignocellulosic feedstocks, more effective degradation methods of lignin are in demand. Nature has found ways to fully degrade lignin through the production of dedicated ligninolytic enzyme systems. While such enzymes have been well thoroughly studied for ligninolytic fungi, only in recent years biochemical studies on bacterial enzymes capable of lignin modification have intensified. This has revealed several types of enzymes available to bacteria that enable them to act on lignin. Two major classes of bacterial lignin-modifying enzymes are DyP-type peroxidases and laccases. Yet, recently also several other bacterial enzymes have been discovered that seem to play a role in lignin modifications. In the present review, we provide an overview of recent advances in the identification and use of bacterial enzymes acting on lignin or lignin-derived products. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  4. Quantitative PCR Method for Diagnosis of Citrus Bacterial Canker†

    PubMed Central

    Cubero, J.; Graham, J. H.; Gottwald, T. R.

    2001-01-01

    For diagnosis of citrus bacterial canker by PCR, an internal standard is employed to ensure the quality of the DNA extraction and that proper requisites exist for the amplification reaction. The ratio of PCR products from the internal standard and bacterial target is used to estimate the initial bacterial concentration in citrus tissues with lesions. PMID:11375206

  5. Recent trends in control methods for bacterial wilt diseases caused by Ralstonia solanacearum.

    PubMed

    Yuliar; Nion, Yanetri Asi; Toyota, Koki

    2015-01-01

    Previous studies have described the development of control methods against bacterial wilt diseases caused by Ralstonia solanacearum. This review focused on recent advances in control measures, such as biological, physical, chemical, cultural, and integral measures, as well as biocontrol efficacy and suppression mechanisms. Biological control agents (BCAs) have been dominated by bacteria (90%) and fungi (10%). Avirulent strains of R. solanacearum, Pseudomonas spp., Bacillus spp., and Streptomyces spp. are well-known BCAs. New or uncommon BCAs have also been identified such as Acinetobacter sp., Burkholderia sp., and Paenibacillus sp. Inoculation methods for BCAs affect biocontrol efficacy, such as pouring or drenching soil, dipping of roots, and seed coatings. The amendment of different organic matter, such as plant residue, animal waste, and simple organic compounds, have frequently been reported to suppress bacterial wilt diseases. The combined application of BCAs and their substrates was shown to more effectively suppress bacterial wilt in the tomato. Suppression mechanisms are typically attributed to the antibacterial metabolites produced by BCAs or those present in natural products; however, the number of studies related to host resistance to the pathogen is increasing. Enhanced/modified soil microbial communities are also indirectly involved in disease suppression. New promising types of control measures include biological soil disinfection using substrates that release volatile compounds. This review described recent advances in different control measures. We focused on the importance of integrated pest management (IPM) for bacterial wilt diseases.

  6. Recent Trends in Control Methods for Bacterial Wilt Diseases Caused by Ralstonia solanacearum

    PubMed Central

    Yuliar; Nion, Yanetri Asi; Toyota, Koki

    2015-01-01

    Previous studies have described the development of control methods against bacterial wilt diseases caused by Ralstonia solanacearum. This review focused on recent advances in control measures, such as biological, physical, chemical, cultural, and integral measures, as well as biocontrol efficacy and suppression mechanisms. Biological control agents (BCAs) have been dominated by bacteria (90%) and fungi (10%). Avirulent strains of R. solanacearum, Pseudomonas spp., Bacillus spp., and Streptomyces spp. are well-known BCAs. New or uncommon BCAs have also been identified such as Acinetobacter sp., Burkholderia sp., and Paenibacillus sp. Inoculation methods for BCAs affect biocontrol efficacy, such as pouring or drenching soil, dipping of roots, and seed coatings. The amendment of different organic matter, such as plant residue, animal waste, and simple organic compounds, have frequently been reported to suppress bacterial wilt diseases. The combined application of BCAs and their substrates was shown to more effectively suppress bacterial wilt in the tomato. Suppression mechanisms are typically attributed to the antibacterial metabolites produced by BCAs or those present in natural products; however, the number of studies related to host resistance to the pathogen is increasing. Enhanced/modified soil microbial communities are also indirectly involved in disease suppression. New promising types of control measures include biological soil disinfection using substrates that release volatile compounds. This review described recent advances in different control measures. We focused on the importance of integrated pest management (IPM) for bacterial wilt diseases. PMID:25762345

  7. Virulence of Aeromonas hydrophila to channel catfish Ictalurus punctatus fingerlings in the presence and absence of bacterial extracellular products

    USDA-ARS?s Scientific Manuscript database

    Virulence of three 2009 West Alabama isolates (AL09-71, AL09-72, and AL09-73) of Aeromonas hydrophila in the presence or absence of extracellular products (ECP) from overnight bacterial culture to channel catfish fingerlings (4.6 +/- 1.3g) was investigated by both bath immersion and intraperitoneal ...

  8. The measurement of bacterial translation by photon correlation spectroscopy.

    PubMed Central

    Stock, G B; Jenkins, T C

    1978-01-01

    Photon correlation spectroscopy is shown to be a practical technique for the accurate determination of translational speeds of bacteria. Though other attempts have been made to use light scattering as a probe of various aspects of bacterial motility, no other comprehensive studies to establish firmly the basic capabilities and limitations of the technique have been published. The intrinsic accuracy of the assay of translational speeds by photon correlation spectroscopy is investigated by analysis of synthetic autocorrelation data; consistently accurate estimates of the mean and second moment of the speed distribution can be calculated. Extensive analyses of experimental preparations of Salmonella typhimurium examine the possible sources of experimental difficulty with the assay. Cinematography confirms the bacterial speed estimates obtained by photon correlation techniques. PMID:346073

  9. National measures of forest productivity for timber

    Treesearch

    Peter J. Ince; H. Edward Dickerhoof; H. Fred Kaiser

    1989-01-01

    This report presents national measures of forest productivity for timber. These measures reveal trends in the relationship between quantity of timber produced by forests and the quantity of forest resources employed in timber production. Timber production is measured by net annual growth of timber and annual timber removals. Measures of timber productivity include...

  10. Measuring healthcare productivity - from unit to system level.

    PubMed

    Kämäräinen, Vesa Johannes; Peltokorpi, Antti; Torkki, Paulus; Tallbacka, Kaj

    2016-04-18

    Purpose - Healthcare productivity is a growing issue in most Western countries where healthcare expenditure is rapidly increasing. Therefore, accurate productivity metrics are essential to avoid sub-optimization within a healthcare system. The purpose of this paper is to focus on healthcare production system productivity measurement. Design/methodology/approach - Traditionally, healthcare productivity has been studied and measured independently at the unit, organization and system level. Suggesting that productivity measurement should be done in different levels, while simultaneously linking productivity measurement to incentives, this study presents the challenges of productivity measurement at the different levels. The study introduces different methods to measure productivity in healthcare. In addition, it provides background information on the methods used to measure productivity and the parameters used in these methods. A pilot investigation of productivity measurement is used to illustrate the challenges of measurement, to test the developed measures and to prove the practical information for managers. Findings - The study introduces different approaches and methods to measure productivity in healthcare. Practical implications - A pilot investigation of productivity measurement is used to illustrate the challenges of measurement, to test the developed measures and to prove the practical benefits for managers. Originality/value - The authors focus on the measurement of the whole healthcare production system and try to avoid sub-optimization. Additionally considering an individual patient approach, productivity measurement is examined at the unit level, the organizational level and the system level.

  11. Bacterial Diterpene Synthases: New Opportunities for Mechanistic Enzymology and Engineered Biosynthesis

    PubMed Central

    Smanski, Michael J.; Peterson, Ryan M.; Huang, Sheng-Xiong; Shen, Ben

    2012-01-01

    Diterpenoid biosynthesis has been extensively studied in plants and fungi, yet cloning and engineering diterpenoid pathways in these organisms remain challenging. Bacteria are emerging as prolific producers of diterpenoid natural products, and bacterial diterpene synthases are poised to make significant contributions to our understanding of terpenoid biosynthesis. Here we will first survey diterpenoid natural products of bacterial origin and briefly review their biosynthesis with emphasis on diterpene synthases (DTSs) that channel geranylgeranyl diphosphate to various diterpenoid scaffolds. We will then highlight differences of DTSs of bacterial and higher organism origins and discuss the challenges in discovering novel bacterial DTSs. We will conclude by discussing new opportunities for DTS mechanistic enzymology and applications of bacterial DTS in biocatalysis and metabolic pathway engineering. PMID:22445175

  12. A Mammalian Siderophore Synthesized by an Enzyme with a Bacterial Homologue Involved in Enterobactin Production

    PubMed Central

    Devireddy, Laxminarayana R.; Hart, Daniel O.; Goetz, David; Green, Michael R.

    2010-01-01

    SUMMARY Intracellular iron homeostasis is critical for survival and proliferation. Lipocalin 24p3 is an iron trafficking protein that binds iron through association with a bacterial siderophore, such as enterobactin, or a postulated mammalian siderophore. Here we show that the iron-binding moiety of the 24p3-associated mammalian siderophore is 2,5-dihydroxybenzoic acid (2,5-DHBA), which is similar to 2,3-DHBA, the iron-binding component of enterobactin. We find that the murine enzyme responsible for 2,5-DHBA synthesis is the homologue of bacterial EntA, which catalyzes 2,3-DHBA production during enterobactin biosynthesis. RNA interference-mediated knockdown of the murine homologue of EntA results in siderophore depletion. Mammalian cells lacking the siderophore accumulate abnormally high amounts of cytoplasmic iron, resulting in elevated levels of reactive oxygen species, whereas the mitochondria are iron deficient. Siderophore-depleted mammalian cells and zebrafish embryos fail to synthesize heme, an iron-dependent mitochondrial process. Our results reveal features of intracellular iron homeostasis that are conserved from bacteria through humans. PMID:20550936

  13. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

    PubMed Central

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-01-01

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

  14. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain.

    PubMed

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Abbott, James; Micklem, Chris N; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-06-14

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology.

  15. Bacterial Infection of Fly Ovaries Reduces Egg Production and Induces Local Hemocyte Activation

    PubMed Central

    Brandt, Stephanie M.; Schneider, David S.

    2009-01-01

    Summary Morbidity, the state of being diseased, is an important aspect of pathogenesis that has gone relatively unstudied in fruit flies. Our interest is in characterizing how bacterial pathogenesis affects various physiologies of the fly. We chose to examine the fly ovary because we found bacterial infection had a striking effect on fly reproduction. We observed decreased egg laying after bacterial infection that correlated with increased bacterial virulence. We also found that bacteria colonized the ovary in a previously undescribed manner; bacteria were found in the posterior of the ovary, adjacent to the lateral oviduct. This local infection in the ovary resulted in melanization and activation of the cellular immune response at the site of infection. PMID:17400292

  16. A Hybrid DNA Extraction Method for the Qualitative and Quantitative Assessment of Bacterial Communities from Poultry Production Samples

    PubMed Central

    Rothrock, Michael J.; Hiett, Kelli L.; Gamble, John; Caudill, Andrew C.; Cicconi-Hogan, Kellie M.; Caporaso, J. Gregory

    2014-01-01

    The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses performed. Considering that the use of new bacterial community analysis techniques (e.g., microbiomics, metagenomics) is becoming more prevalent in the agricultural and environmental sciences and many environmental samples within these disciplines can be physiochemically and microbiologically unique (e.g., fecal and litter/bedding samples from the poultry production spectrum), appropriate and effective DNA extraction methods need to be carefully chosen. Therefore, a novel semi-automated hybrid DNA extraction method was developed specifically for use with environmental poultry production samples. This method is a combination of the two major types of DNA extraction: mechanical and enzymatic. A two-step intense mechanical homogenization step (using bead-beating specifically formulated for environmental samples) was added to the beginning of the “gold standard” enzymatic DNA extraction method for fecal samples to enhance the removal of bacteria and DNA from the sample matrix and improve the recovery of Gram-positive bacterial community members. Once the enzymatic extraction portion of the hybrid method was initiated, the remaining purification process was automated using a robotic workstation to increase sample throughput and decrease sample processing error. In comparison to the strict mechanical and enzymatic DNA extraction methods, this novel hybrid method provided the best overall combined performance when considering quantitative (using 16S rRNA qPCR) and qualitative (using microbiomics) estimates of the total bacterial communities when processing poultry feces and litter samples. PMID:25548939

  17. Elucidating Duramycin's Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope.

    PubMed

    Hasim, Sahar; Allison, David P; Mendez, Berlin; Farmer, Abigail T; Pelletier, Dale A; Retterer, Scott T; Campagna, Shawn R; Reynolds, Todd B; Doktycz, Mitchel J

    2018-01-01

    The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus -derived bacterial isolates to determine species selectivity. Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin's mode of action and a better understanding of its selectivity.

  18. Applications of bacterial cellulose and its composites in biomedicine.

    PubMed

    Rajwade, J M; Paknikar, K M; Kumbhar, J V

    2015-03-01

    Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.

  19. Bacterial Degradation of Nitrogenous Energetic Compounds (NEC) in Coastal Waters and Sediments

    DTIC Science & Technology

    2008-09-10

    2006) Enzymatic immobilization of 2,4,6-trinitrotoluene (TNT) biodegradation products onto model humic substances. Enzyme Microbial Technol 39:1197...11 2.3 Heterotrophic bacterial production ...collected May 2006: A) Average (AVG) rates of TNT incorporation and bacterial production (μg C L-1 d-1); and, B) TNT incorporation normalized for

  20. A physiologically based kinetic model for bacterial sulfide oxidation.

    PubMed

    Klok, Johannes B M; de Graaff, Marco; van den Bosch, Pim L F; Boelee, Nadine C; Keesman, Karel J; Janssen, Albert J H

    2013-02-01

    In the biotechnological process for hydrogen sulfide removal from gas streams, a variety of oxidation products can be formed. Under natron-alkaline conditions, sulfide is oxidized by haloalkaliphilic sulfide oxidizing bacteria via flavocytochrome c oxidoreductase. From previous studies, it was concluded that the oxidation-reduction state of cytochrome c is a direct measure for the bacterial end-product formation. Given this physiological feature, incorporation of the oxidation state of cytochrome c in a mathematical model for the bacterial oxidation kinetics will yield a physiologically based model structure. This paper presents a physiologically based model, describing the dynamic formation of the various end-products in the biodesulfurization process. It consists of three elements: 1) Michaelis-Menten kinetics combined with 2) a cytochrome c driven mechanism describing 3) the rate determining enzymes of the respiratory system of haloalkaliphilic sulfide oxidizing bacteria. The proposed model is successfully validated against independent data obtained from biological respiration tests and bench scale gas-lift reactor experiments. The results demonstrate that the model is a powerful tool to describe product formation for haloalkaliphilic biomass under dynamic conditions. The model predicts a maximum S⁰ formation of about 98 mol%. A future challenge is the optimization of this bioprocess by improving the dissolved oxygen control strategy and reactor design. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Towards revealing the structure of bacterial inclusion bodies.

    PubMed

    Wang, Lei

    2009-01-01

    Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6-12 nm, they are comprised of residue-specific cross-beta structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies.

  2. Activity of Uncleaved Caspase-8 Controls Anti-bacterial Immune Defense and TLR-Induced Cytokine Production Independent of Cell Death.

    PubMed

    Philip, Naomi H; DeLaney, Alexandra; Peterson, Lance W; Santos-Marrero, Melanie; Grier, Jennifer T; Sun, Yan; Wynosky-Dolfi, Meghan A; Zwack, Erin E; Hu, Baofeng; Olsen, Tayla M; Rongvaux, Anthony; Pope, Scott D; López, Carolina B; Oberst, Andrew; Beiting, Daniel P; Henao-Mejia, Jorge; Brodsky, Igor E

    2016-10-01

    Caspases regulate cell death programs in response to environmental stresses, including infection and inflammation, and are therefore critical for the proper operation of the mammalian immune system. Caspase-8 is necessary for optimal production of inflammatory cytokines and host defense against infection by multiple pathogens including Yersinia, but whether this is due to death of infected cells or an intrinsic role of caspase-8 in TLR-induced gene expression is unknown. Caspase-8 activation at death signaling complexes results in its autoprocessing and subsequent cleavage and activation of its downstream apoptotic targets. Whether caspase-8 activity is also important for inflammatory gene expression during bacterial infection has not been investigated. Here, we report that caspase-8 plays an essential cell-intrinsic role in innate inflammatory cytokine production in vivo during Yersinia infection. Unexpectedly, we found that caspase-8 enzymatic activity regulates gene expression in response to bacterial infection as well as TLR signaling independently of apoptosis. Using newly-generated mice in which caspase-8 autoprocessing is ablated (Casp8DA/DA), we now demonstrate that caspase-8 enzymatic activity, but not autoprocessing, mediates induction of inflammatory cytokines by bacterial infection and a wide variety of TLR stimuli. Because unprocessed caspase-8 functions in an enzymatic complex with its homolog cFLIP, our findings implicate the caspase-8/cFLIP heterodimer in control of inflammatory cytokines during microbial infection, and provide new insight into regulation of antibacterial immune defense.

  3. Macrophage activation induced by Brucella DNA suppresses bacterial intracellular replication via enhancing NO production.

    PubMed

    Liu, Ning; Wang, Lin; Sun, Changjiang; Yang, Li; Tang, Bin; Sun, Wanchun; Peng, Qisheng

    2015-12-01

    Brucella DNA can be sensed by TLR9 on endosomal membrane and by cytosolic AIM2-inflammasome to induce proinflammatory cytokine production that contributes to partially activate innate immunity. Additionally, Brucella DNA has been identified to be able to act as a major bacterial component to induce type I IFN. However, the role of Brucella DNA in Brucella intracellular growth remains unknown. Here, we showed that stimulation with Brucella DNA promote macrophage activation in TLR9-dependent manner. Activated macrophages can suppresses wild type Brucella intracellular replication at early stage of infection via enhancing NO production. We also reported that activated macrophage promotes bactericidal function of macrophages infected with VirB-deficient Brucella at the early or late stage of infection. This study uncovers a novel function of Brucella DNA, which can help us further elucidate the mechanism of Brucella intracellular survival. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Heterotrophic bacterioplankton in the Arabian Sea:. Basinwide response to year-round high primary productivity

    NASA Astrophysics Data System (ADS)

    Ducklow, H. W.; Smith, D. C.; Campbell, L.; Landry, M. R.; Quinby, H. L.; Steward, G. F.; Azam, F.

    Heterotrophic bacterial abundance and productivity were measured during five and four cruises, respectively, in the northwest Arabian Sea as part of the US JGOFS Process Study, which provided a new view of seasonal bacterial dynamics in that part of the basin influenced by monsoonal forcing. In this paper, surface layer data are used to address two questions concerning the influence of the monsoon cycle on bacterial dynamics: (1) Is there a bacterial bloom in the SW Monsoon? and (2) Is bacterial production low during the oligotrophic Spring Intermonsoon? An extensive comparison of epifluorescence microscopy and flow cytometry, unprecedented at this scale, detected essentially the same heterotrophic bacterial populations and distributions, with some between-cruise differences. Use of the two methods allowed us to extend our observations in space and time. Bacterial productivity, both in the surface layer and integrated over the euphotic zone, was elevated less than 2-fold during the Southwest Monsoon. Levels of bacterial abundance and production were low during the Northeast Monsoon, then increased in March during the Spring Intermonsoon. There was some stimulation of abundance or production inshore in response to coastal upwelling. In general, the basin was enriched in bacterial biomass >5×10 8 cells l -1 throughout the year, relative to other tropical regimes, presumably in response to overall high PP and DOC levels. Seasonally uniform DOC levels may be regulated in part by intense bacterial utilization rates, but also reflect seasonal consistency in PP.

  5. Alternative indicators for measuring hospital productivity.

    PubMed

    Serway, G D; Strum, D W; Haug, W F

    1987-08-01

    This article explores the premise that the appropriateness and usefulness of typical hospital productivity measures have been affected by three changes in delivery: Organizational restructuring and other definition and data source changes that make full-time equivalent employee (FTE) measurements ambiguous. Transition to prospective payment (diagnosis-related groups). Increase in capitation (prepaid, at risk) programs. The effects of these changes on productivity management indicate the need for alternative productivity indicators. Several productivity measures that complement these changes in internal operations and the external hospital business environment are presented. These are based on an analysis of four hospitals within a multihospital system, and an illustration and interpretation of an array of measures, based on ten months of actual data, is provided. In conclusion, the recommendation is made for hospital management to collect an expanded set of productivity measures and review them in light of changing expense and revenue management schemes inherent in new payment modes.

  6. Paediatric Crohn disease patients with stricturing behaviour exhibit ileal granulocyte–macrophage colony-stimulating factor (GM-CSF) autoantibody production and reduced neutrophil bacterial killing and GM-CSF bioactivity

    PubMed Central

    Jurickova, I; Collins, M H; Chalk, C; Seese, A; Bezold, R; Lake, K; Allmen, D; Frischer, J S; Falcone, R A; Trapnell, B C; Denson, L A

    2013-01-01

    Granulocyte–macrophage colony-stimulating factor (GM-CSF) autoantibodies are associated with stricturing behaviour in Crohn disease (CD). We hypothesized that CD ileal lamina propria mononuclear cells (LPMC) would produce GM-CSF autoantibodies and peripheral blood (PB) samples would contain GM-CSF neutralizing capacity (NC). Paediatric CD and control PBMC and ileal biopsies or LPMC were isolated and cultured and GM-CSF, immunoglobulin (Ig)G and GM-CSF autoantibodies production were measured by enzyme-linked immunosorbent assay (ELISA). Basal and GM-CSF-primed neutrophil bacterial killing and signal transducer and activator of transcription 5 (STAT5) tyrosine phosphorylation (pSTAT5) were measured by flow cytometry. GM-CSF autoantibodies were enriched within total IgG for LPMC isolated from CD ileal strictures and proximal margins compared to control ileum. Neutrophil bacterial killing was reduced in CD patients compared to controls. Within CD, neutrophil GM-CSF-dependent STAT5 activation and bacterial killing were reduced as GM-CSF autoantibodies increased. GM-CSF stimulation of pSTAT5 did not vary between controls and CD patients in washed PB granulocytes in which serum was removed. However, GM-CSF stimulation of pSTAT5 was reduced in whole PB samples from CD patients. These data were used to calculate the GM-CSF NC. CD patients with GM-CSF NC greater than 25% exhibited a fourfold higher rate of stricturing behaviour and surgery. The likelihood ratio (95% confidence interval) for stricturing behaviour for patients with elevation in both GM-CSF autoantibodies and GM-CSF NC was equal to 5 (2, 11). GM-CSF autoantibodies are produced by LPMC isolated from CD ileal resection specimens and are associated with reduced neutrophil bacterial killing. CD peripheral blood contains GM-CSF NC, which is associated with increased rates of stricturing behaviour. PMID:23600834

  7. Contribution of Progranulin to Protective Lung Immunity During Bacterial Pneumonia.

    PubMed

    Zou, Shan; Luo, Qin; Song, Zhixin; Zhang, Liping; Xia, Yun; Xu, Huajian; Xiang, Yu; Yin, Yibing; Cao, Ju

    2017-06-01

    Progranulin (PGRN) is an important immunomodulatory factor in a variety of inflammatory diseases. However, its role in pulmonary immunity against bacterial infection remains unknown. Pneumonia was induced in PGRN-deficient and normal wild-type mice using Pseudomonas aeruginosa or Staphylococcus aureus, and we assessed the effects of PGRN on survival, bacterial burden, cytokine and chemokine production, and pulmonary leukocyte recruitment after bacterial pneumonia. Patients with community-acquired pneumonia displayed elevated PGRN levels. Likewise, mice with Gram-negative and Gram-positive pneumonia had increased PGRN production in the lung and circulation. Progranulin deficiency led to increased bacterial growth and dissemination accompanied by enhanced lung injury and mortality in bacterial pneumonia, which was associated with impaired recruitment of macrophages and neutrophils in the lung. The reduced number of pulmonary macrophages and neutrophils observed in PGRN-deficient mice was related to a reduction of CCL2 and CXCL1 in the lungs after bacterial pneumonia. Importantly, therapeutic administration of PGRN improved mortality in severe bacterial pneumonia. This study supports a novel role for PGRN in pulmonary immunity and suggests that treatment with PGRN may be a viable therapy for bacterial pneumonia. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  8. Factors contributing to bacterial bulb rots of onion

    USDA-ARS?s Scientific Manuscript database

    The incidence of bacterial rots of onion bulbs is increasing and has become a serious problem for growers. This increase is likely due to a combination of factors, such as high bacterial populations in soils and irrigation water, heavy rains flooding production fields, higher temperatures, etc. It m...

  9. Gastrointestinal complaints in runners are not due to small intestinal bacterial overgrowth

    PubMed Central

    2011-01-01

    Background Gastrointestinal complaints are common among long distance runners. We hypothesised that small intestinal bacterial overgrowth (SIBO) is present in long distance runners frequently afflicted with gastrointestinal complaints. Findings Seven long distance runners (5 female, mean age 29.1 years) with gastrointestinal complaints during and immediately after exercise without known gastrointestinal diseases performed Glucose hydrogen breath tests for detection of SIBO one week after a lactose hydrogen breath test checking for lactose intolerance. The most frequent symptoms were diarrhea (5/7, 71%) and flatulence (6/7, 86%). The study was conducted at a laboratory. In none of the subjects a pathological hydrogen production was observed after the intake of glucose. Only in one athlete a pathological hydrogen production was measured after the intake of lactose suggesting lactose intolerance. Conclusions Gastrointestinal disorders in the examined long distance runners were not associated with small intestinal bacterial overgrowth. PMID:21794099

  10. Glycerol as an additional carbon source for bacterial cellulose synthesis

    NASA Astrophysics Data System (ADS)

    Agustin, Y. E.; Padmawijaya, K. S.; Rixwari, H. F.; Yuniharto, V. A. S.

    2018-03-01

    Bacterial cellulose, the fermentation result of Acetobacter xylinus can be produced when glycerol was used as an additional carbon source. In this research, bacterial cellulose produced in two different fermentation medium, Hestrin and Scharmm (HS) medium and HS medium with additional MgSO4. Concentration of glycerol that used in this research were 0%; 5%; 10%; and 15% (v/v). The optimum conditions of bacterial cellulose production on each experiment variations determined by characterization of the mechanical properties, including thickness, tensile strength and elongation. Fourier Transform Infra Red Spectroscopy (FTIR) revealed the characterization of bacterial cellulose. Results showed that the growth rate of bacterial cellulose in HS-MgSO4-glycerol medium was faster than in HS-glycerol medium. Increasing concentrations of glycerol will lower the value of tensile strength and elongation. Elongation test showed that the elongation bacterial cellulose (BC) with the addition of 4.95% (v/v) glycerol in the HS-MgSO4 medium is the highest elongation value. The optimum bacterial cellulose production was achieved when 4.95% (v/v) of glycerol added into HS-MgSO4 medium with stress at break of 116.885 MPa and 4.214% elongation.

  11. Limitation of Bacterial Growth by Dissolved Organic Matter and Iron in the Southern Ocean†

    PubMed Central

    Church, Matthew J.; Hutchins, David A.; Ducklow, Hugh W.

    2000-01-01

    The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42°S and 55°S along 141°E. Bacterial abundance, mean cell volume, and [3H]thymidine and [3H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favorably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilization may be partly constrained by iron availability in the HNLC Southern Ocean. PMID:10653704

  12. Production of long chain alkyl esters from carbon dioxide and electricity by a two-stage bacterial process.

    PubMed

    Lehtinen, Tapio; Efimova, Elena; Tremblay, Pier-Luc; Santala, Suvi; Zhang, Tian; Santala, Ville

    2017-11-01

    Microbial electrosynthesis (MES) is a promising technology for the reduction of carbon dioxide into value-added multicarbon molecules. In order to broaden the product profile of MES processes, we developed a two-stage process for microbial conversion of carbon dioxide and electricity into long chain alkyl esters. In the first stage, the carbon dioxide is reduced to organic compounds, mainly acetate, in a MES process by Sporomusa ovata. In the second stage, the liquid end-products of the MES process are converted to the final product by a second microorganism, Acinetobacter baylyi in an aerobic bioprocess. In this proof-of-principle study, we demonstrate for the first time the bacterial production of long alkyl esters (wax esters) from carbon dioxide and electricity as the sole sources of carbon and energy. The process holds potential for the efficient production of carbon-neutral chemicals or biofuels. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. An overview of food safety and bacterial foodborne zoonoses in food production animals in the Caribbean region.

    PubMed

    Guerra, Maria Manuela Mendes; de Almeida, Andre M; Willingham, Arve Lee

    2016-08-01

    Foodborne diseases (FBDs) in the Caribbean have a high economic burden. Public health and tourism concerns rise along with the increasing number of cases and outbreaks registered over the last 20 years. Salmonella spp., Shigella spp., and Campylobacter spp. are the main bacteria associated with these incidents. In spite of undertaking limited surveillance on FBD in the region, records related to bacterial foodborne zoonoses in food-producing animals and their associated epidemiologic significance are poorly documented, giving rise to concerns about the importance of the livestock, food animal product sectors, and consumption patterns. In this review, we report the available published literature over the last 20 years on selected bacterial foodborne zoonoses in the Caribbean region and also address other food safety-related aspects (e.g., FBD food attribution, importance, surveillance), mainly aiming at recognizing data gaps and identifying possible research approaches in the animal health sector.

  14. 30 CFR 250.1633 - Production measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Production measurement. 250.1633 Section 250... SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Sulphur Operations § 250.1633 Production measurement. (a) General. Measurement equipment and security procedures shall be designed, installed, used, maintained, and...

  15. Pesticide Side Effects in an Agricultural Soil Ecosystem as Measured by amoA Expression Quantification and Bacterial Diversity Changes

    PubMed Central

    Feld, Louise; Hjelmsø, Mathis Hjort; Nielsen, Morten Schostag; Jacobsen, Anne Dorthe; Rønn, Regin; Ekelund, Flemming; Krogh, Paul Henning; Strobel, Bjarne Westergaard; Jacobsen, Carsten Suhr

    2015-01-01

    Background and Methods Assessing the effects of pesticide hazards on microbiological processes in the soil is currently based on analyses that provide limited insight into the ongoing processes. This study proposes a more comprehensive approach. The side effects of pesticides may appear as changes in the expression of specific microbial genes or as changes in diversity. To assess the impact of pesticides on gene expression, we focused on the amoA gene, which is involved in ammonia oxidation. We prepared soil microcosms and exposed them to dazomet, mancozeb or no pesticide. We hypothesized that the amount of amoA transcript decreases upon pesticide application, and to test this hypothesis, we used reverse-transcription qPCR. We also hypothesized that bacterial diversity is affected by pesticides. This hypothesis was investigated via 454 sequencing and diversity analysis of the 16S ribosomal RNA and RNA genes, representing the active and total soil bacterial communities, respectively. Results and Conclusion Treatment with dazomet reduced both the bacterial and archaeal amoA transcript numbers by more than two log units and produced long-term effects for more than 28 days. Mancozeb also inhibited the numbers of amoA transcripts, but only transiently. The bacterial and archaeal amoA transcripts were both sensitive bioindicators of pesticide side effects. Additionally, the numbers of bacterial amoA transcripts correlated with nitrate production in N-amended microcosms. Dazomet reduced the total bacterial numbers by one log unit, but the population size was restored after twelve days. The diversity of the active soil bacteria also seemed to be re-established after twelve days. However, the total bacterial diversity as reflected in the 16S ribosomal RNA gene sequences was largely dominated by Firmicutes and Proteobacteria at day twelve, likely reflecting a halt in the growth of early opportunists and the re-establishment of a more diverse population. We observed no

  16. Implementation of secondary bacterial culture testing of platelets to mitigate residual risk of septic transfusion reactions.

    PubMed

    Bloch, Evan M; Marshall, Christi E; Boyd, Joan S; Shifflett, Lisa; Tobian, Aaron A R; Gehrie, Eric A; Ness, Paul M

    2018-04-01

    Bacterial contamination of platelets remains a major transfusion-associated risk despite long-standing safety measures in the United States. We evaluated an approach using secondary bacterial culture (SBC) to contend with residual risk of bacterial contamination. Phased implementation of SBC was initiated in October 2016 for platelets (all apheresis collected) received at our institution from the blood donor center (Day 3 post collection). Platelet products were sampled aseptically (5 mL inoculated into an aerobic bottle [BacT/ALERT BPA, BioMerieux, Inc.]) by the blood bank staff upon receipt, using a sterile connection device and sampling kit. The platelet sample was inoculated into an aerobic blood culture bottle and incubated at 35°C for 3 days. The cost of SBC was calculated on the basis of consumables and labor costs at time of implementation. In the 13 months following implementation (October 6, 2016, to November 30, 2017), 23,044/24,653 (93.47%) platelet products underwent SBC. A total of eight positive cultures were detected (incidence 1 in 2881 platelet products), seven of which were positive within 24 hours of SBC. Coagulase negative Staphyloccus spp. were identified in four cases. Five of the eight cases were probable true positive (repeat reactive) and interdicted (cost per averted case was US$77,935). The remaining three cases were indeterminate. No septic transfusion reactions were reported during the observation period. We demonstrate the feasibility of SBC of apheresis platelets to mitigate bacterial risk. SBC is lower cost than alternative measures (e.g., pathogen reduction and point-of-release testing) and can be integrated into workflow at hospital transfusion services. © 2018 AABB.

  17. Intermittent fasting promotes bacterial clearance and intestinal IgA production in Salmonella typhimurium-infected mice.

    PubMed

    Godínez-Victoria, M; Campos-Rodriguez, R; Rivera-Aguilar, V; Lara-Padilla, E; Pacheco-Yepez, J; Jarillo-Luna, R A; Drago-Serrano, M E

    2014-05-01

    The impact of intermittent fasting versus ad libitum feeding during Salmonella typhimurium infection was evaluated in terms of duodenum IgA levels, bacterial clearance and intestinal and extra-intestinal infection susceptibility. Mice that were intermittently fasted for 12 weeks or fed ad libitum were infected with S. typhimurium and assessed at 7 and 14 days post-infection. Next, we evaluated bacterial load in the faeces, Peyer's patches, spleen and liver by plate counting, as well as total and specific intestinal IgA and plasmatic corticosterone levels (by immunoenzymatic assay) and lamina propria IgA levels in plasma cells (by cytofluorometry). Polymeric immunoglobulin receptor, α- and J-chains, Pax-5 factor, pro-inflammatory cytokine (tumour necrosis factor-α and interferon-γ) and anti-inflammatory cytokine (transforming growth factor-β) mRNA levels were assessed in mucosal and liver samples (by real-time PCR). Compared with the infected ad libitum mice, the intermittently fasted infected animals had (1) lower intestinal and systemic bacterial loads; (2) higher SIgA and IgA plasma cell levels; (3) higher mRNA expression of most intestinal parameters; and (4) increased or decreased corticosterone levels on day 7 and 14 post-infection, respectively. No contribution of liver IgA was observed at the intestinal level. Apparently, the changes following metabolic stress induced by intermittent fasting during food deprivation days increased the resistance to S. typhimurium infection by triggering intestinal IgA production and presumably, pathogen elimination by phagocytic inflammatory cells. © 2014 John Wiley & Sons Ltd.

  18. Can the Bacterial Community of a High Arctic Glacier Surface Escape Viral Control?

    PubMed Central

    Rassner, Sara M. E.; Anesio, Alexandre M.; Girdwood, Susan E.; Hell, Katherina; Gokul, Jarishma K.; Whitworth, David E.; Edwards, Arwyn

    2016-01-01

    Glacial ice surfaces represent a seasonally evolving three-dimensional photic zone which accumulates microbial biomass and potentiates positive feedbacks in ice melt. Since viruses are abundant in glacial systems and may exert controls on supraglacial bacterial production, we examined whether changes in resource availability would promote changes in the bacterial community and the dynamics between viruses and bacteria of meltwater from the photic zone of a Svalbard glacier. Our results indicated that, under ambient nutrient conditions, low estimated viral decay rates account for a strong viral control of bacterial productivity, incurring a potent viral shunt of a third of bacterial carbon in the supraglacial microbial loop. Moreover, it appears that virus particles are very stable in supraglacial meltwater, raising the prospect that viruses liberated in melt are viable downstream. However, manipulating resource availability as dissolved organic carbon, nitrogen, and phosphorous in experimental microcosms demonstrates that the photic zone bacterial communities can escape viral control. This is evidenced by a marked decline in virus-to-bacterium ratio (VBR) concomitant with increased bacterial productivity and number. Pyrosequencing shows a few bacterial taxa, principally Janthinobacterium sp., dominate both the source meltwater and microcosm communities. Combined, our results suggest that viruses maintain high VBR to promote contact with low-density hosts, by the manufacture of robust particles, but that this necessitates a trade-off which limits viral production. Consequently, dominant bacterial taxa appear to access resources to evade viral control. We propose that a delicate interplay of bacterial and viral strategies affects biogeochemical cycling upon glaciers and, ultimately, downstream ecosystems. PMID:27446002

  19. Production and purification of anti-bacterial biometabolite from wild-type Lactobacillus, isolated from fermented bamboo shoot: future suggestions and a proposed system for secondary metabolite onsite recovery during continuous fermentation.

    PubMed

    Badwaik, Laxmikant S; Borah, Pallab Kumar; Deka, Sankar C

    2015-02-01

    Wild-type lactobacillus isolated form Khorisa, a fermented bamboo shoot product of Assam, India were evaluated for production anti-bacterial secondary biometabolites, against Staphylococcus aureus. Submerged fermentation technique was used for the production of secondary anti-microbial biometabolite by a single wild-type lactobacillus strain, which tested positive for the release of anti-bacterial factor(s). Crude cell-free supernatant was obtained, followed by extraction in water-immiscible solvents viz., chloroform, hexane, petroleum ether. Chloroform extract of cell-free crude supernatant showed maximum yield (0.054 g/ml) and inhibited all indicator bacterial strains viz., Escherichia coli, Staphylococcus aureus, and Bacillus cereus. Yields of hexane and petroleum ether extract were 0.052 and 0.026 g/ml, respectively. Minimum lethal dose concentration assay of the chloroform extract showed LDmin values at 27, 1.68, and 1.68 mg/ml for E. coli, S. aureus, and B. cereus, respectively. Kill time for all the indicator bacterial strains were less than 12 h. The efficacy of the anti-bacterial substance seemed to depend on the presence of organic acids, particularly lactic acid. Conceptual-based suggestion for the development of an onsite secondary metabolites recovery system during continuous fermentation has also been attempted.

  20. Assessment of bacterial inoculant formulated with Paraburkholderia tropica to enhance wheat productivity.

    PubMed

    Bernabeu, Pamela Romina; García, Sabrina Soledad; López, Ana Clara; Vio, Santiago Adolfo; Carrasco, Natalia; Boiardi, José Luis; Luna, María Flavia

    2018-05-25

    Paraburkholderia tropica is an endophytic nitrogen-fixing bacterium isolated from the rhizosphere, rhizoplane, and internal tissues of sugarcane and corn plants in different geographical regions. Other plant-growth-promoting abilities, such as phosphate solubilization and antifungal activity, have also been reported for this bacterium. With an aim at investigating the potential use of P. tropica as an inoculant for improving the performance of wheat crop, in this work we evaluated an experimental inoculant formulated with P. tropica MTo-293 with respect to root colonization, the practical aspects of its application, and the effects under field conditions when applied to wheat seeds. Bacterial colonization was monitored by culture dependent techniques and the wheat yield determined by quantifying the total grain production in two different seasons. Rhizoplane and endophytic colonization in wheat roots was achieved efficiently (on average, 8 and 4 log colony-forming units/g fresh weight, respectively) even at relatively low concentrations of viable bacteria in the inoculum under controlled conditions. P. tropica was compatible with a widely used fungicide, maintained viability for 48 h once applied to seeds, and was also able to colonize wheat roots efficiently. Furthermore, we were able to formulate an inoculant that maintained bacterial viability for relatively long time periods. Preliminary field assays were realized, and even though the average yields values for the inoculated treatments remained above the uninoculated ones, no significant effects of inoculation were detected with or without fertilization. The correct physiologic behavior of P. tropica suggests the necessity to continue with field experiments under different conditions.

  1. Bacterial membrane proteomics.

    PubMed

    Poetsch, Ansgar; Wolters, Dirk

    2008-10-01

    About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

  2. The relationship between rumen bacterial growth, intake of dry matter, digestible organic matter and volatile fatty acid production in buffalo (Bos bubalis) calves.

    PubMed

    Singh, U B; Verma, D N; Varma, A; Ranjhan, S K

    1977-11-01

    1. The production rates of bacteria in the rumen of buffalo (Bos bubalis) calves were estimated using an isotope-dilution technique. A series of fifteen experiments was done with animals given green maize and nine experiments with animals given cowpea (Vigna unguiculata). 2. The turnover time ranged from 205 to 567 min in the group given green maize and from 330 to 648 min in animals offered cowpea. The production rates of bacteria were (mean +/- SE; g/d) 145.77 +/- 7.240 and 237.09 +/- 11.847 in animals given green maize and cowpea respectively. 3. There was a significant correlation between bacterial production rates and dry matter intake, digestible organic matter and total volatile fatty acids formed in the rumen. 4. Regression equations obtained for the two foodstuffs were different suggesting that the bacterial growth rate may vary depending upon the quantity and quality of foodstuff digested and possibly the ratio nitrogen:energy of the foodstuff.

  3. Measuring test productivity - The elusive dream

    NASA Astrophysics Data System (ADS)

    Ward, D. T.; Cross, E. J., Jr.

    1983-11-01

    The paper summarizes definitions and terminology relating to measurement of Test and Evaluation productivity before settling on the appropriate criteria for such a measurement model. A productivity measurement scheme suited for use by Test and Evaluation organizations is suggested. This mathematical model is a simplified version of one proposed by the American Productivity Center and applied to an aircraft maintenance facility by Fletcher. It includes only four primary variables: safety, schedule, cost, and deficiencies reported with varying degrees of objectivity and subjectivity involved in quantifying them. A hypothetical example of a fighter aircraft flight test program is used to illustrate the application of the productivity measurement model. The proposed model is intended to serve as a first iteration procedure and should be tested against real test programs to verify and refine it.

  4. Measuring and improving productivity in general radiology.

    PubMed

    Wilt, Michelle A; Miranda, Rafael; Johnson, C Daniel; Love, Peggy Sue

    2010-10-01

    The aim of this study was to determine a method of measuring productivity among general radiographers in a moderate-sized hospital and to improve and sustain productivity within that work area. The average times needed to perform the 13 most common examinations were measured. Performance of the various examinations was tracked and multiplied by the time allocated per procedure; this measure was divided by the length of the work shift to determine productivity. Productivity measures were shared among the work group, and decisions to improve productivity (eg, whether to fill open positions) were made by group members. Average time spent per examination type was calculated (range, 10 minutes to 1 hour 16 minutes). At baseline (February 2008), group productivity was 50%. Productivity increased during the first year of monitoring and was sustained through November 2009 (productivity range, 57%-63%). Yearly savings from not filling open positions were estimated to be $174,000. Productivity in a general radiology work area can be measured. Consensus among the work group helped increase productivity and assess progress. This methodology, if widely adopted, could be standardized and used to compare productivity across departments and institutions. Copyright © 2010 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  5. Effects of different fermentation methods on bacterial cellulose and acid production by Gluconacetobacter xylinus in Cantonese-style rice vinegar.

    PubMed

    Fu, Liang; Chen, Siqian; Yi, Jiulong; Hou, Zongxia

    2014-07-01

    A strain of acidogenic bacterium was isolated from the fermentation liquid of Cantonese-style rice vinegar produced by traditional surface fermentation. 16S rDNA identification confirmed the bacterium as Gluconacetobacter xylinus, which synthesizes bacterial cellulose, and the acid productivity of the strain was investigated. In the study, the effects of the membrane integrity and the comparison of the air-liquid interface membrane with immerged membrane on total acidity, cellulose production, alcohol dehydrogenase (ADH) activity and number of bacteria were investigated. The cellulose membrane and the bacteria were observed under SEM for discussing their relationship. The correlations between oxygen consumption and total acid production rate were compared in surface and shake flask fermentation. The results showed the average acid productivity of the strain was 0.02g/(100mL/h), and the integrity of cellulose membrane in surface fermentation had an important effect on total acidity and cellulose production. With a higher membrane integrity, the total acidity after 144 h of fermentation was 3.75 g/100 mL, and the cellulose production was 1.71 g/100 mL after 360 h of fermentation. However, when the membrane was crushed by mechanical force, the total acidity and the cellulose production were as low as 0.36 g/100 mL and 0.14 g/100 mL, respectively. When the cellulose membrane was forced under the surface of fermentation liquid, the total acid production rate was extremely low, but the activity of ADH in the cellulose membrane was basically the same with the one above the liquid surface. The bacteria were mainly distributed in the cellulose membrane during the fermentation. The bacterial counts in surface fermentation were more than in the shake flask fermentation and G. xylinus consumed the substrate faster, in surface fermentation than in shake flask fermentation. The oxygen consumption rate and total acid production rate of surface fermentation were respectively 26

  6. Towards revealing the structure of bacterial inclusion bodies

    PubMed Central

    2009-01-01

    Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6–12 nm, they are comprised of residue-specific cross-β structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies. PMID:19806034

  7. A uniform bacterial growth potential assay for different water types.

    PubMed

    Farhat, Nadia; Hammes, Frederik; Prest, Emmanuelle; Vrouwenvelder, Johannes

    2018-06-06

    The bacterial growth potential is important to understand and manage bacterial regrowth-related water quality concerns. Bacterial growth potential depends on growth promoting/limiting compounds, therefore, nutrient availability is the key factor governing bacterial growth potential. Selecting proper tools for bacterial growth measurement is essential for routine implementation of the growth potential measurement. This study proposes a growth potential assay that is universal and can be used for different water types and soil extract without restrictions of pure culture or cultivability of the bacterial strain. The proposed assay measures the sample bacterial growth potential by using the indigenous community as inocula. Flow cytometry (FCM) and adenosine tri-phosphate (ATP) were used to evaluate the growth potential of six different microbial communities indigenous to the sample being analyzed, with increasing carbon concentrations. Bottled mineral water, non-chlorinated tap water, seawater, river water, wastewater effluent and a soil organic carbon extract were analyzed. Results showed that indigenous bacterial communities followed normal batch growth kinetics when grown on naturally present organic carbon. Indigenous bacterial growth could detect spiked organic carbon concentrations as low as 10 μg/L. The indigenous community in all samples responded proportionally to the increase in acetate-carbon and proportional growth could be measured with both FCM and ATP. Bacterial growth was proportional to the carbon concentration but not the same proportion factor for the different water samples tested. The effect of inoculating the same water with different indigenous microbial communities on the growth potential was also examined. The FCM results showed that the highest increase in total bacterial cell concentration was obtained with bacteria indigenous to the water sample. The growth potential assay using indigenous bacterial community revealed consistent results

  8. Comparison of the efficiency of bacterial and fungal laccases in delignification and detoxification of steam-pretreated lignocellulosic biomass for bioethanol production.

    PubMed

    De La Torre, María; Martín-Sampedro, Raquel; Fillat, Úrsula; Eugenio, María E; Blánquez, Alba; Hernández, Manuel; Arias, María E; Ibarra, David

    2017-11-01

    This study evaluates the potential of a bacterial laccase from Streptomyces ipomoeae (SilA) for delignification and detoxification of steam-exploded wheat straw, in comparison with a commercial fungal laccase from Trametes villosa. When alkali extraction followed by SilA laccase treatment was applied to the water insoluble solids fraction, a slight reduction in lignin content was detected, and after a saccharification step, an increase in both glucose and xylose production (16 and 6%, respectively) was observed. These effects were not produced with T. villosa laccase. Concerning to the fermentation process, the treatment of the steam-exploded whole slurry with both laccases produced a decrease in the phenol content by up to 35 and 71% with bacterial and fungal laccases, respectively. The phenols reduction resulted in an improved performance of Saccharomyces cerevisiae during a simultaneous saccharification and fermentation (SSF) process, improving ethanol production rate. This enhancement was more marked with a presaccharification step prior to the SSF process.

  9. Probing Prokaryotic Social Behaviors with Bacterial “Lobster Traps”

    PubMed Central

    Connell, Jodi L.; Wessel, Aimee K.; Parsek, Matthew R.; Ellington, Andrew D.; Whiteley, Marvin; Shear, Jason B.

    2010-01-01

    Bacteria are social organisms that display distinct behaviors/phenotypes when present in groups. These behaviors include the abilities to construct antibiotic-resistant sessile biofilm communities and to communicate with small signaling molecules (quorum sensing [QS]). Our understanding of biofilms and QS arises primarily from in vitro studies of bacterial communities containing large numbers of cells, often greater than 108 bacteria; however, in nature, bacteria often reside in dense clusters (aggregates) consisting of significantly fewer cells. Indeed, bacterial clusters containing 101 to 105 cells are important for transmission of many bacterial pathogens. Here, we describe a versatile strategy for conducting mechanistic studies to interrogate the molecular processes controlling antibiotic resistance and QS-mediated virulence factor production in high-density bacterial clusters. This strategy involves enclosing a single bacterium within three-dimensional picoliter-scale microcavities (referred to as bacterial “lobster traps”) defined by walls that are permeable to nutrients, waste products, and other bioactive small molecules. Within these traps, bacteria divide normally into extremely dense (1012 cells/ml) clonal populations with final population sizes similar to that observed in naturally occurring bacterial clusters. Using these traps, we provide strong evidence that within low-cell-number/high-density bacterial clusters, QS is modulated not only by bacterial density but also by population size and flow rate of the surrounding medium. We also demonstrate that antibiotic resistance develops as cell density increases, with as few as ~150 confined bacteria exhibiting an antibiotic-resistant phenotype similar to biofilm bacteria. Together, these findings provide key insights into clinically relevant phenotypes in low-cell-number/high-density bacterial populations. PMID:21060734

  10. Role of quorum sensing in bacterial infections

    PubMed Central

    Castillo-Juárez, Israel; Maeda, Toshinari; Mandujano-Tinoco, Edna Ayerim; Tomás, María; Pérez-Eretza, Berenice; García-Contreras, Silvia Julieta; Wood, Thomas K; García-Contreras, Rodolfo

    2015-01-01

    Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed. PMID:26244150

  11. Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

    NASA Astrophysics Data System (ADS)

    Agogué, Hélène; Mallet, Clarisse; Orvain, Francis; De Crignis, Margot; Mornet, Françoise; Dupuy, Christine

    2014-09-01

    In intertidal mudflats, during low tide exposure, microphytobenthos (MPB) migrate vertically through the surface sediment and form, with the heterotrophic bacteria, a transient biofilm. Inside this biofilm, multiple interactions exist between MPB and bacteria. These micro-organisms secrete a wide range of extracellular polymeric substances (EPS), which are major components of the biofilm matrix. In this study, we used a tidal mesocosm experiment in order to decipher the interactions of the MPB-EPS-bacteria complex within the biofilm. We tried to determine if the EPS could control bacterial activities and/or production and/or richness according to the age of the biofilm and to the immersion/emersion period. The dynamics of biomasses of MPB and prokaryotes, the bacterial production, the hydrolysis of predominating organic constituents in the dissolved organic carbon (DOC) pool (i.e., carbohydrates and polypeptides), and the bacterial structure were studied in relation to the different EPS fractions (carbohydrates and proteins: colloidal and bound) dynamics during 8 days. Our experiment had emphasized the influence of the environmental conditions (light, immersion/emersion) on the interactions within the biofilm and also on the effects on biofilm aging. Bacterial production was always inhibited by the bound EPS-carbohydrate, especially during low tide. Our results suggest that the concentration and composition of EPS had a major role in the bacterial/MPB interactions: these interactions can be either positive or negative in order to regulate the productive phases of MPB and bacteria.

  12. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    NASA Astrophysics Data System (ADS)

    Saha, Saswati; Gupta, Bhaskar; Gupta, Kamala; Chaudhuri, Mahua Ghosh

    2016-11-01

    Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10-25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration) regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  13. Bacterial adenosine triphosphate as a measure of urinary tract infection

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Picciolo, G. L.

    1971-01-01

    Procedure detects and counts bacteria present in urine samples. Method also determines bacterial levels in other aqueous body fluids including lymph fluid, plasma, blood, spinal fluid, saliva and mucous.

  14. Bacterial carbohydrate-degrading capacity in foal faeces: changes from birth to pre-weaning and the impact of maternal supplementation with fermented feed products.

    PubMed

    Faubladier, Céline; Julliand, Véronique; Danel, Justine; Philippeau, Christelle

    2013-09-28

    The present study aimed at (1) describing age-related changes in faecal bacterial functional groups involved in carbohydrate degradation and in their activities in foals (n 10) from birth (day (d) 0) to 6 months (d180) and (2) investigating the effect of maternal supplementation (five mares per treatment) from d - 45 to d60 with fermented feed products on response trends over time of the foal bacterial carbohydratedegrading capacity. Maternal supplementation with fermented feed products stimulated foal growth from d0 to d60 and had an impact on the establishment of some digestive bacterial groups and their activities in foals from d0 to d5 but not in the longer term. Irrespective of the maternal treatment, total bacteria, total anaerobic, lactate-utilising and amylolytic bacteria were established immediately after birth (P<0·05) and were active as shown by the significant increase in total volatile fatty acids. In the foals of supplemented mares, total anaerobes and lactate utilisers were established rapidly between d0 and d2 (P=0·021 and 0·066, respectively) and the increase in the percentage of propionate occurred earlier (P=0·013). Maternal supplementation had no effect on the establishment of fibrolytic bacteria and their activity. Cellulolytic bacteria and Fibrobacter succinogenes first appeared at d2 and d5, and increased progressively, reaching stable values at d30 and d60, respectively. From the second week of life, the increase in the molar percentage of acetate and the ratio (acetate + butyrate):propionate (P<0·05) suggested that fibrolytic activity had begun. From d60, only minor changes in bacterial composition and activities occurred, showing that the bacterial carbohydrate-degrading capacity was established at 2 months of age.

  15. Use of Response Surface Methodology to Optimize Culture Conditions for Hydrogen Production by an Anaerobic Bacterial Strain from Soluble Starch

    NASA Astrophysics Data System (ADS)

    Kieu, Hoa Thi Quynh; Nguyen, Yen Thi; Dang, Yen Thi; Nguyen, Binh Thanh

    2016-05-01

    Biohydrogen is a clean source of energy that produces no harmful byproducts during combustion, being a potential sustainable energy carrier for the future. Therefore, biohydrogen produced by anaerobic bacteria via dark fermentation has attracted attention worldwide as a renewable energy source. However, the hydrogen production capability of these bacteria depends on major factors such as substrate, iron-containing hydrogenase, reduction agent, pH, and temperature. In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by an anaerobic bacterial strain isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8 g L-1 to 12 g L-1), ferrous iron concentration (100 mg L-1 to 200 mg L-1), and l-cysteine concentration (300 mg L-1 to 500 mg L-1). RSM analysis showed that all three factors significantly influenced hydrogen production. Among them, the ferrous iron concentration presented the greatest influence. The optimum hydrogen concentration of 1030 mL L-1 medium was obtained with 10 g L-1 soluble starch, 150 mg L-1 ferrous iron, and 400 mg L-1 l-cysteine after 48 h of anaerobic fermentation. The hydrogen concentration produced by the PL strain was doubled after using RSM. The obtained results indicate that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacterial strain. Hydrogen production from low-cost organic substrates such as soluble starch using anaerobic fermentation methods may be one of the most promising approaches.

  16. Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

    DOE PAGES

    Hasim, Sahar; Allison, David P.; Mendez, Berlin; ...

    2018-02-14

    The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

  17. Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hasim, Sahar; Allison, David P.; Mendez, Berlin

    The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

  18. Seasonal dynamics of bacterial biomass and production in a coastal arctic ecosystem: Franklin Bay, western Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Garneau, Marie-Ã. Ve; Roy, SéBastien; Lovejoy, Connie; Gratton, Yves; Vincent, Warwick F.

    2008-07-01

    The Canadian Arctic Shelf Exchange Study (CASES) included the overwintering deployment of a research platform in Franklin Bay (70°N, 126°W) and provided a unique seasonal record of bacterial dynamics in a coastal region of the Arctic Ocean. Our objectives were (1) to relate seasonal bacterial abundance (BA) and production (BP) to physico-chemical characteristics and (2) to quantify the annual bacterial carbon flux. BA was estimated by epifluorescence microscopy and BP was estimated from 3H-leucine and 3H-thymidine assays. Mean BA values for the water column ranged from 1.0 (December) to 6.8 × 105 cells mL-1 (July). Integral BP varied from 1 (February) to 80 mg C m-2 d-1 (July). During winter-spring, BP was uncorrelated with chlorophyll a (Chl a), but these variables were significantly correlated during summer-autumn (rs = 0.68, p < 0.001, N = 38), suggesting that BP was subject to bottom-up control by carbon supply. Integrated BP data showed three distinct periods: fall-winter, late winter-late spring, and summer. A baseline level of BB and BP was maintained throughout late winter-late spring despite the persistent cold and darkness, with irregular fluctuations that may be related to hydrodynamic events. During this period, BP rates were correlated with colored dissolved organic matter (CDOM) but not Chl a (rs BP.CDOM∣Chl a = 0.20, p < 0.05, N = 176). Annual BP was estimated as 6 g C m-2 a-1, implying a total BP of 4.8 × 1010 g C a-1 for the Franklin Bay region. These results show that bacterial processes continue throughout all seasons and make a large contribution to the total biological carbon flux in this coastal arctic ecosystem.

  19. Noninvasive Measurement of Bacterial Intracellular pH on a Single-Cell Level with Green Fluorescent Protein and Fluorescence Ratio Imaging Microscopy

    PubMed Central

    Olsen, Katja N.; Budde, Birgitte B.; Siegumfeldt, Henrik; Rechinger, K. Björn; Jakobsen, Mogens; Ingmer, Hanne

    2002-01-01

    We show that a pH-sensitive derivative of the green fluorescent protein, designated ratiometric GFP, can be used to measure intracellular pH (pHi) in both gram-positive and gram-negative bacterial cells. In cells expressing ratiometric GFP, the excitation ratio (fluorescence intensity at 410 and 430 nm) is correlated to the pHi, allowing fast and noninvasive determination of pHi that is ideally suited for direct analysis of individual bacterial cells present in complex environments. PMID:12147523

  20. Phenotypic Signatures Arising from Unbalanced Bacterial Growth

    PubMed Central

    Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

    2014-01-01

    Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains. PMID:25101949

  1. Phenotypic signatures arising from unbalanced bacterial growth.

    PubMed

    Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

    2014-08-01

    Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify "phenotypic signatures" by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains.

  2. Consolidation of archaeological gypsum plaster by bacterial biomineralization of calcium carbonate.

    PubMed

    Jroundi, Fadwa; Gonzalez-Muñoz, Maria Teresa; Garcia-Bueno, Ana; Rodriguez-Navarro, Carlos

    2014-09-01

    Gypsum plasterworks and decorative surfaces are easily degraded, especially when exposed to humidity, and thus they require protection and/or consolidation. However, the conservation of historical gypsum-based structural and decorative materials by conventional organic and inorganic consolidants shows limited efficacy. Here, a new method based on the bioconsolidation capacity of carbonatogenic bacteria inhabiting the material was assayed on historical gypsum plasters and compared with conventional consolidation treatments (ethyl silicate; methylacrylate-ethylmethacrylate copolymer and polyvinyl butyral). Conventional products do not reach in-depth consolidation, typically forming a thin impervious surface layer which blocks pores. In contrast, the bacterial treatment produces vaterite (CaCO3) biocement, which does not block pores and produces a good level of consolidation, both at the surface and in-depth, as shown by drilling resistance measurement system analyses. Transmission electron microscopy analyses show that bacterial vaterite cement formed via oriented aggregation of CaCO3 nanoparticles (∼20nm in size), resulting in mesocrystals which incorporate bacterial biopolymers. Such a biocomposite has superior mechanical properties, thus explaining the fact that drilling resistance of bioconsolidated gypsum plasters is within the range of inorganic calcite materials of equivalent porosity, despite the fact that the bacterial vaterite cement accounts for only a 0.02 solid volume fraction. Bacterial bioconsolidation is proposed for the effective consolidation of this type of material. The potential applications of bacterial calcium carbonate consolidation of gypsum biomaterials used as bone graft substitutes are discussed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Phage selection for bacterial cheats leads to population decline

    PubMed Central

    Vasse, Marie; Torres-Barceló, Clara; Hochberg, Michael E.

    2015-01-01

    While predators and parasites are known for their effects on bacterial population biology, their impact on the dynamics of bacterial social evolution remains largely unclear. Siderophores are iron-chelating molecules that are key to the survival of certain bacterial species in iron-limited environments, but their production can be subject to cheating by non-producing genotypes. In a selection experiment conducted over approximately 20 bacterial generations and involving 140 populations of the pathogenic bacterium Pseudomonas aeruginosa PAO1, we assessed the impact of a lytic phage on competition between siderophore producers and non-producers. We show that the presence of lytic phages favours the non-producing genotype in competition, regardless of whether iron use relies on siderophores. Interestingly, phage pressure resulted in higher siderophore production, which constitutes a cost to the producers and may explain why they were outcompeted by non-producers. By the end of the experiment, however, cheating load reduced the fitness of mixed populations relative to producer monocultures, and only monocultures of producers managed to grow in the presence of phage in situations where siderophores were necessary to access iron. These results suggest that public goods production may be modulated in the presence of natural enemies with consequences for the evolution of social strategies. PMID:26538598

  4. QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

    PubMed

    Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

    2016-12-01

    In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

  5. Enhanced Mucosal Antibody Production and Protection against Respiratory Infections Following an Orally Administered Bacterial Extract

    PubMed Central

    Pasquali, Christian; Salami, Olawale; Taneja, Manisha; Gollwitzer, Eva S.; Trompette, Aurelien; Pattaroni, Céline; Yadava, Koshika; Bauer, Jacques; Marsland, Benjamin J.

    2014-01-01

    Secondary bacterial infections following influenza infection are a pressing problem facing respiratory medicine. Although antibiotic treatment has been highly successful over recent decades, fatalities due to secondary bacterial infections remain one of the leading causes of death associated with influenza. We have assessed whether administration of a bacterial extract alone is sufficient to potentiate immune responses and protect against primary infection with influenza, and secondary infections with either Streptococcus pneumoniae or Klebsiella pneumoniae in mice. We show that oral administration with the bacterial extract, OM-85, leads to a maturation of dendritic cells and B-cells characterized by increases in MHC II, CD86, and CD40, and a reduction in ICOSL. Improved immune responsiveness against influenza virus reduced the threshold of susceptibility to secondary bacterial infections, and thus protected the mice. The protection was associated with enhanced polyclonal B-cell activation and release of antibodies that were effective at neutralizing the virus. Taken together, these data show that oral administration of bacterial extracts provides sufficient mucosal immune stimulation to protect mice against a respiratory tract viral infection and associated sequelae. PMID:25593914

  6. Characterization of Bacterial Cellulose by Gluconacetobacter hansenii CGMCC 3917.

    PubMed

    Feng, Xianchao; Ullah, Niamat; Wang, Xuejiao; Sun, Xuchun; Li, Chenyi; Bai, Yun; Chen, Lin; Li, Zhixi

    2015-10-01

    In this study, comprehensive characterization and drying methods on properties of bacterial cellulose were analyzed. Bacterial cellulose was prepared by Gluconacetobacter hansenii CGMCC 3917, which was mutated by high hydrostatic pressure (HHP) treatment. Bacterial cellulose is mainly comprised of cellulose Iα with high crystallinity and purity. High-water holding and absorption capacity were examined by reticulated structure. Thermogravimetric analysis showed high thermal stability. High tensile strength and Young's modulus indicated its mechanical properties. The rheological analysis showed that bacterial cellulose had good consistency and viscosity. These results indicated that bacterial cellulose is a potential food additive and also could be used for a food packaging material. The high textural stability during freeze-thaw cycles makes bacterial cellulose an effective additive for frozen food products. In addition, the properties of bacterial cellulose can be affected by drying methods. Our results suggest that the bacterial cellulose produced from HHP-mutant strain has an effective characterization, which can be used for a wide range of applications in food industry. © 2015 Institute of Food Technologists®

  7. Community-acquired bacterial meningitis.

    PubMed

    van de Beek, Diederik; Brouwer, Matthijs; Hasbun, Rodrigo; Koedel, Uwe; Whitney, Cynthia G; Wijdicks, Eelco

    2016-11-03

    Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma (nosocomial bacterial meningitis). Despite advances in treatment and vaccinations, community-acquired bacterial meningitis remains one of the most important infectious diseases worldwide. Streptococcus pneumoniae and Neisseria meningitidis are the most common causative bacteria and are associated with high mortality and morbidity; vaccines targeting these organisms, which have designs similar to the successful vaccine that targets Haemophilus influenzae type b meningitis, are now being used in many routine vaccination programmes. Experimental and genetic association studies have increased our knowledge about the pathogenesis of bacterial meningitis. Early antibiotic treatment improves the outcome, but the growing emergence of drug resistance as well as shifts in the distribution of serotypes and groups are fuelling further development of new vaccines and treatment strategies. Corticosteroids were found to be beneficial in high-income countries depending on the bacterial species. Further improvements in the outcome are likely to come from dampening the host inflammatory response and implementing preventive measures, especially the development of new vaccines.

  8. Upgrading the hydrolytic potential of immobilized bacterial pretreatment to boost biogas production.

    PubMed

    Ushani, U; Kavitha, S; Johnson, M; Yeom, Ick Tae; Banu, J Rajesh

    2017-01-01

    In this study, surfactant dioctyl sodium sulphosuccinate (DOSS)-mediated immobilized bacterial pretreatment of waste activated sludge (WAS) was experimentally proved to be an efficient and economically feasible process for enhancing the biodegradability of WAS. The maximal floc disruption with negligible cell cleavage was achieved at surfactant dosage of 0.009 g/g SS. Results of the outcome of bacterial pretreatment of sludge biomass revealed that chemical oxygen demand (COD) solubilization for deflocculated (EPS removed-bacterially pretreated) sludge was 20 %, which was higher than that of flocculated (14 %) or control (5 %). The pretreatment was swift in deflocculated sludge with a rate constant of about 0.064 h -1 . Biochemical methane potential (BMP) assay resulted in significant methane yield at 0.24 gCOD/gCOD for deflocculated sludge. Economic assessment of the proposed method showed a net profit of about 57.39 USD/ton of sludge.

  9. Bacterial cellulose production from cotton-based waste textiles: enzymatic saccharification enhanced by ionic liquid pretreatment.

    PubMed

    Hong, Feng; Guo, Xiang; Zhang, Shuo; Han, Shi-fen; Yang, Guang; Jönsson, Leif J

    2012-01-01

    Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5-7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Urban aerosols harbor diverse and dynamic bacterial populations

    PubMed Central

    Brodie, Eoin L.; DeSantis, Todd Z.; Parker, Jordan P. Moberg; Zubietta, Ingrid X.; Piceno, Yvette M.; Andersen, Gary L.

    2007-01-01

    Considering the importance of its potential implications for human health, agricultural productivity, and ecosystem stability, surprisingly little is known regarding the composition or dynamics of the atmosphere's microbial inhabitants. Using a custom high-density DNA microarray, we detected and monitored bacterial populations in two U.S. cities over 17 weeks. These urban aerosols contained at least 1,800 diverse bacterial types, a richness approaching that of some soil bacterial communities. We also reveal the consistent presence of bacterial families with pathogenic members including environmental relatives of select agents of bioterrorism significance. Finally, using multivariate regression techniques, we demonstrate that temporal and meteorological influences can be stronger factors than location in shaping the biological composition of the air we breathe. PMID:17182744

  11. Biliary bacterial factors determine the path of gallstone formation.

    PubMed

    Stewart, Lygia; Grifiss, J McLeod; Jarvis, Gary A; Way, Lawrence W

    2006-11-01

    Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation. A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed. Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons). Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.

  12. Contractor Productivity Measurement Practices.

    DTIC Science & Technology

    1983-10-01

    addresses defense contractor productivity measurement is a high-risk effort in terms of probability of success, but it has tremendous potential benefitis to...total cost and is decreasing regularly with the advent of automation and robotics . Figure 3, extracted from the Air Force PACER PRICE program, shows...increase in manufacturing overhead and other indirect rates as the capital/labor mix increases from low to high. 3. Productivity and Other Indices

  13. Biological evaluation of hyperforin and its hydrogenated analogue on bacterial growth and biofilm production.

    PubMed

    Schiavone, Brigida Immacolata Pia; Rosato, Antonio; Marilena, Muraglia; Gibbons, Simon; Bombardelli, Ezio; Verotta, Luisella; Franchini, Carlo; Corbo, Filomena

    2013-09-27

    Bacterial biofilms are organized communities of microorganisms, embedded in a self-produced matrix, growing on a biotic surface and resistant to many antimicrobial agents when associated with a medical device. These biofilms require the development of new strategies for the prevention and treatment of infectious disease, including the potential use of natural products. One interesting natural product example is Hypericum, a plant genus that contains species known to have antimicrobial properties. The major constituent of Hypericum perforatum is an unstable compound named hyperforin (1); for this reason it was not believed to play a significant role in the pharmacological effects. In this investigation a hydrogenated hyperforin analogue (2) was tested on several ATCC and clinical isolate strains, in their planktonic and biofilm form (Staphylococcus aureus, MRSA, and Enterococcus faecalis). Compound 2 was effective against planktonic and biofilm cultures, probably due to higher stability, showing the percentage of cells killed in the range from 45% to 52%. These results are noteworthy from the point of view of future development of these polyprenylated phloroglucinols as potential antibiotics.

  14. Using wastewater after lipid fermentation as substrate for bacterial cellulose production by Gluconacetobacter xylinus.

    PubMed

    Huang, Chao; Guo, Hai-Jun; Xiong, Lian; Wang, Bo; Shi, Si-Lan; Chen, Xue-Fang; Lin, Xiao-Qing; Wang, Can; Luo, Jun; Chen, Xin-De

    2016-01-20

    In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Amylase production potentials of bacterial isolates obtained from the gut of Oryctes rhinoceros larvae

    NASA Astrophysics Data System (ADS)

    Aryati, P. C.; Pangastuti, A.; Sari, S. L. A.

    2017-04-01

    Amylase is one of the main enzymes used in industry, such as food, detergent, textile, and pharmaceutical industry. Amylase can be produced by plants, animals, and microorganisms. However, bacterial and fungal amylases have dominated application in industries. This research was aimed to determine amylolytic activity of bacteria isolated from the gut of Oryctes rhinoceros larvae. Based on clear zone formation, 9 from 11 isolates showed amylolytic activity. Isolates with the widest clear zone, i.e Bacillus subtilis GOR1, Bacillus cereus GOR3, and Bacillus pumilus GOR2, were screened for amylolytic activity based on reduction sugar production. The result showed that Bacillus subtilis GOR1 was the most potential as amylase producer, showed by the widest clear zone 5.224 cm2 and highest reduction sugar production 0.0235 mg/ml. Highest amylase specific activity (0.1447 U/mg protein) was obtained at 60°C and pH 7. Amylase activity was stable for 3 hours at 60°C with residual activity respectively was 59.7%.

  16. Limited Bacterial Diversity within a Treatment Plant Receiving Antibiotic-Containing Waste from Bulk Drug Production.

    PubMed

    Marathe, Nachiket P; Shetty, Sudarshan A; Shouche, Yogesh S; Larsson, D G Joakim

    2016-01-01

    Biological treatment of waste water from bulk drug production, contaminated with high levels of fluoroquinolone antibiotics, can lead to massive enrichment of antibiotic resistant bacteria, resistance genes and associated mobile elements, as previously shown. Such strong selection may be boosted by the use of activated sludge (AS) technology, where microbes that are able to thrive on the chemicals within the wastewater are reintroduced at an earlier stage of the process to further enhance degradation of incoming chemicals. The microbial community structure within such a treatment plant is, however, largely unclear. In this study, Illumina-based 16S rRNA amplicon sequencing was applied to investigate the bacterial communities of different stages from an Indian treatment plant operated by Patancheru Environment Technology Limited (PETL) in Hyderabad, India. The plant receives waste water with high levels of fluoroquinolones and applies AS technology. A total of 1,019,400 sequences from samples of different stages of the treatment process were analyzed. In total 202, 303, 732, 652, 947 and 864 operational taxonomic units (OTUs) were obtained at 3% distance cutoff in the equilibrator, aeration tanks 1 and 2, settling tank, secondary sludge and old sludge samples from PETL, respectively. Proteobacteria was the most dominant phyla in all samples with Gammaproteobacteria and Betaproteobacteria being the dominant classes. Alcaligenaceae and Pseudomonadaceae, bacterial families from PETL previously reported to be highly multidrug resistant, were the dominant families in aeration tank samples. Despite regular addition of human sewage (approximately 20%) to uphold microbial activity, the bacterial diversity within aeration tanks from PETL was considerably lower than corresponding samples from seven, regular municipal waste water treatment plants. The strong selection pressure from antibiotics present may be one important factor in structuring the microbial community in PETL

  17. Limited Bacterial Diversity within a Treatment Plant Receiving Antibiotic-Containing Waste from Bulk Drug Production

    PubMed Central

    Shouche, Yogesh S.; Larsson, D. G. Joakim

    2016-01-01

    Biological treatment of waste water from bulk drug production, contaminated with high levels of fluoroquinolone antibiotics, can lead to massive enrichment of antibiotic resistant bacteria, resistance genes and associated mobile elements, as previously shown. Such strong selection may be boosted by the use of activated sludge (AS) technology, where microbes that are able to thrive on the chemicals within the wastewater are reintroduced at an earlier stage of the process to further enhance degradation of incoming chemicals. The microbial community structure within such a treatment plant is, however, largely unclear. In this study, Illumina-based 16S rRNA amplicon sequencing was applied to investigate the bacterial communities of different stages from an Indian treatment plant operated by Patancheru Environment Technology Limited (PETL) in Hyderabad, India. The plant receives waste water with high levels of fluoroquinolones and applies AS technology. A total of 1,019,400 sequences from samples of different stages of the treatment process were analyzed. In total 202, 303, 732, 652, 947 and 864 operational taxonomic units (OTUs) were obtained at 3% distance cutoff in the equilibrator, aeration tanks 1 and 2, settling tank, secondary sludge and old sludge samples from PETL, respectively. Proteobacteria was the most dominant phyla in all samples with Gammaproteobacteria and Betaproteobacteria being the dominant classes. Alcaligenaceae and Pseudomonadaceae, bacterial families from PETL previously reported to be highly multidrug resistant, were the dominant families in aeration tank samples. Despite regular addition of human sewage (approximately 20%) to uphold microbial activity, the bacterial diversity within aeration tanks from PETL was considerably lower than corresponding samples from seven, regular municipal waste water treatment plants. The strong selection pressure from antibiotics present may be one important factor in structuring the microbial community in PETL

  18. Effects on enteric methane production and bacterial and archaeal communities by the addition of cashew nut shell extract or glycerol-an in vitro evaluation.

    PubMed

    Danielsson, Rebecca; Werner-Omazic, Anna; Ramin, Mohammad; Schnürer, Anna; Griinari, Mikko; Dicksved, Johan; Bertilsson, Jan

    2014-09-01

    The objective of the study was to evaluate the effect of cashew nut shell extract (CNSE) and glycerol (purity >99%) on enteric methane (CH4) production and microbial communities in an automated gas in vitro system. Microbial communities from the in vitro system were compared with samples from the donor cows, in vivo. Inoculated rumen fluid was mixed with a diet with a 60:40 forage:concentrate ratio and, in total, 5 different treatments were set up: 5mg of CNSE (CNSE-L), 10mg of CNSE (CNSE-H), 15mmol of glycerol/L (glycerol-L), and 30mmol of glycerol/L (glycerol-H), and a control without feed additive. Gas samples were taken at 2, 4, 8, 24, 32, and 48h of incubation, and the CH4 concentration was measured. Samples of rumen fluid were taken for volatile fatty acid analysis and for microbial sequence analyses after 8, 24, and 48h of incubation. In vivo rumen samples from the cows were taken 2h after the morning feeding at 3 consecutive days to compare the in vitro system with in vivo conditions. The gas data and data from microbial sequence analysis (454 sequencing) were analyzed using a mixed model and principal components analysis. These analyses illustrated that CH4 production was reduced with the CNSE treatment, by 8 and 18%, respectively, for the L and H concentration. Glycerol instead increased CH4 production by 8 and 12%, respectively, for the L and H concentration. The inhibition with CNSE could be due to the observed shift in bacterial population, possibly resulting in decreased production of hydrogen or formate, the methanogenic substrates. Alternatively the response could be explained by a shift in the methanogenic community. In the glycerol treatments, no main differences in bacterial or archaeal population were detected compared with the in vivo control. Thus, the increase in CH4 production may be explained by the increase in substrate in the in vitro system. The reduced CH4 production in vitro with CNSE suggests that CNSE can be a promising inhibitor of

  19. Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater.

    PubMed

    Kragh, Theis; Søndergaard, Morten; Tranvik, Lars

    2008-05-01

    This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used to calculate bacterial growth efficiency (BGE). Bacterial degradation of DOC increased with increasing exposure to simulated sunlight and availability of phosphorus and no detectable growth occurred on DOC that was not pre-exposed to simulated sunlight. The outcome of photochemical degradation of DOC changed with increasing availability of phosphorus, resulting in an increase in BGE from about 5% to 30%. Thus, the availability of phosphorus has major implications for the quantitative transfer of carbon in microbial food webs.

  20. Influence of substrate mineralogy on bacterial mineralization of calcium carbonate: implications for stone conservation.

    PubMed

    Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-06-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed.

  1. Influence of Substrate Mineralogy on Bacterial Mineralization of Calcium Carbonate: Implications for Stone Conservation

    PubMed Central

    Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-01-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed. PMID:22447589

  2. Measuring Net Investment and Productivity in Timber Production

    Treesearch

    David N. Wear

    1994-01-01

    An index number approach is developed for measuring changes in inputs, outputs, and total factor productivity in a timber-producing sector. These methods are applied to timber production in the U.S. South for the period 1952 to 1985. Results suggest that development of the sector may be described by an adjustment phase between 1952 and 1962 and a growth phase between...

  3. Carbon dioxide sequestration by chemolithotrophic oleaginous bacteria for production and optimization of polyhydroxyalkanoate.

    PubMed

    Kumar, Manish; Gupta, Asmita; Thakur, Indu Shekhar

    2016-08-01

    The present work involved screening of a previously reported carbon concentrating oleaginous bacterial strain Serratia sp. ISTD04 for production of PHA and optimization of process parameters for enhanced PHA and biomass generation. The selected bacterial strain was screened for PHA production based on Nile red staining followed by visualization under fluorescence microscope. Spectrofluorometric measurement of Nile red fluorescence of the bacterial culture was also done. Confirmatory analysis of PHA accumulation by GC-MS revealed the presence of 3-hydroxyvalerate. Detection of characteristic peaks in the FT-IR spectrum further confirmed the production of PHA by the bacterium. Response Surface Methodology was used for optimization of pH and carbon sources' concentrations for higher PHA production. There was almost a 2 fold increase in the production of PHA following optimization as compared to un-optimized condition. The study thus establishes the production of PHA by Serratia sp. ISTD04. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Multi-parameter flow cytometry as a process analytical technology (PAT) approach for the assessment of bacterial ghost production.

    PubMed

    Langemann, Timo; Mayr, Ulrike Beate; Meitz, Andrea; Lubitz, Werner; Herwig, Christoph

    2016-01-01

    Flow cytometry (FCM) is a tool for the analysis of single-cell properties in a cell suspension. In this contribution, we present an improved FCM method for the assessment of E-lysis in Enterobacteriaceae. The result of the E-lysis process is empty bacterial envelopes-called bacterial ghosts (BGs)-that constitute potential products in the pharmaceutical field. BGs have reduced light scattering properties when compared with intact cells. In combination with viability information obtained from staining samples with the membrane potential-sensitive fluorescent dye bis-(1,3-dibutylarbituric acid) trimethine oxonol (DiBAC4(3)), the presented method allows to differentiate between populations of viable cells, dead cells, and BGs. Using a second fluorescent dye RH414 as a membrane marker, non-cellular background was excluded from the data which greatly improved the quality of the results. Using true volumetric absolute counting, the FCM data correlated well with cell count data obtained from colony-forming units (CFU) for viable populations. Applicability of the method to several Enterobacteriaceae (different Escherichia coli strains, Salmonella typhimurium, Shigella flexneri 2a) could be shown. The method was validated as a resilient process analytical technology (PAT) tool for the assessment of E-lysis and for particle counting during 20-l batch processes for the production of Escherichia coli Nissle 1917 BGs.

  5. Surface chemical studies on selective separation of pyrite and galena in the presence of bacterial cells and metabolic products of Paenibacillus polymyxa.

    PubMed

    Patra, Partha; Natarajan, K A

    2006-06-15

    Selective separation of pyrite and galena from mixture of the two minerals was achieved through interaction with cells and metabolic products from a culture of Paenibacillus polymyxa. Adsorption of cells and metabolic products onto minerals and electrokinetic studies of minerals after interaction with cells and metabolic products were carried out to examine the resulting surface modification on the mineral surfaces. Flocculation and flotation techniques were successfully applied in the selective separation of minerals after bacterial interaction. The effect of varying conditions for production of extracellular polysaccharides and protein provided an insight into the possible mechanism involved in microbially induced flocculation and flotation of pyrite and galena.

  6. Identification and Antimicrobial Resistance of Bacteria Isolated from Probiotic Products Used in Shrimp Culture.

    PubMed

    Noor Uddin, Gazi Md; Larsen, Marianne Halberg; Christensen, Henrik; Aarestrup, Frank M; Phu, Tran Minh; Dalsgaard, Anders

    2015-01-01

    through scientific-based efficacy trials and product labels should allow identification of individual bacterial strains and inform the farmer on specific purpose, dosage and correct application measures.

  7. Changes in Soil Bacterial Communities and Diversity in ...

    EPA Pesticide Factsheets

    Silver-induced selective pressure is becoming increasingly important due to the growing use of silver (Ag) as an antimicrobial agent in biomedical and commercial products. With demonstrated links between environmental resistomes and clinical pathogens, it is important to identify microbial profiles related to silver tolerance/resistance. We investigated the effects of ionic Ag stress on soil bacterial communities and identified resistant/persistant bacterial populations. Silver treatments of 50 - 400 mg Ag kg-1 soil were established in five soils. Chemical lability measurements using diffusive gradients in thin-film devices confirmed that significant (albeit decreasing) labile Ag concentrations were present throughout the 9-month incubation period. Synchrotron X-ray absorption near edge structure spectroscopy demonstrate that this decreasing lability was due to changes in Ag speciation to less soluble forms such as Ag0 and Ag2S. Real-time PCR and Illumina MiSeq screening of 16S rRNA bacterial genes showed β-diversity in response to Ag pressure, and immediate and significant reductions in 16S rRNA gene counts with varying degrees of recovery. These effects were more strongly influenced by exposure time than by Ag dose at these rates. Ag-selected dominant OTUs principally resided in known persister taxa (mainly Gram positive), including metal-tolerant bacteria and slow-growing Mycobacteria. Soil microbial communities have been implicated as sources of an

  8. Temperature effects on net greenhouse gas production and bacterial communities in arctic thaw ponds.

    PubMed

    Negandhi, Karita; Laurion, Isabelle; Lovejoy, Connie

    2016-08-01

    One consequence of High Arctic permafrost thawing is the formation of small ponds, which release greenhouse gases (GHG) from stored carbon through microbial activity. Under a climate with higher summer air temperatures and longer ice-free seasons, sediments of shallow ponds are likely to become warmer, which could influence enzyme kinetics or select for less cryophilic microbes. There is little data on the direct temperature effects on GHG production and consumption or on microbial communities' composition in Arctic ponds. We investigated GHG production over 16 days at 4°C and 9°C in sediments collected from four thaw ponds. Consistent with an enzymatic response, production rates of CO2 and CH4 were significantly greater at higher temperatures, with Q10 varying from 1.2 to 2.5. The bacterial community composition from one pond was followed through the incubation by targeting the V6-V8 variable regions of the 16S rRNA gene and 16S rRNA. Several rare taxa detected from rRNA accounted for significant community compositional changes. At the higher temperature, the relative community contribution from Bacteroidetes decreased by 15% with compensating increases in Betaproteobacteria, Alphaproteobacteria, Firmicutes, Acidobacteria, Verrucomicrobia and Actinobacteria. The increase in experimental GHG production accompanied by changes in community indicates an additional factor to consider in sediment environments when evaluating future climate scenarios. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Statistical optimization of medium composition for bacterial cellulose production by Gluconacetobacter hansenii UAC09 using coffee cherry husk extract--an agro-industry waste.

    PubMed

    Rani, Mahadevaswamy Usha; Rastogi, Navin K; Appaiah, K A Anu

    2011-07-01

    During the production of grape wine, the formation of thick leathery pellicle/bacterial cellulose (BC) at the airliquid interface was due to the bacterium, which was isolated and identified as Gluconacetobacter hansenii UAC09. Cultural conditions for bacterial cellulose production from G. hansenii UAC09 were optimized by central composite rotatable experimental design. To economize the BC production, coffee cherry husk (CCH) extract and corn steep liquor (CSL) were used as less expensive sources of carbon and nitrogen, respectively. CCH and CSL are byproducts from the coffee processing and starch processing industry, respectively. The interactions between pH (4.5- 8.5), CSL (2-10%), alcohol (0.5-2%), acetic acid (0.5- 2%), and water dilution rate to CCH ratio (1:1 to 1:5) were studied using response surface methodology. The optimum conditions for maximum BC production were pH (6.64), CSL (10%), alcohol (0.5%), acetic acid (1.13%), and water to CCH ratio (1:1). After 2 weeks of fermentation, the amount of BC produced was 6.24 g/l. This yield was comparable to the predicted value of 6.09 g/l. This is the first report on the optimization of the fermentation medium by RSM using CCH extract as the carbon source for BC production by G. hansenii UAC09.

  10. Simultaneous measurement of bacterial flagellar rotation rate and swimming speed.

    PubMed Central

    Magariyama, Y; Sugiyama, S; Muramoto, K; Kawagishi, I; Imae, Y; Kudo, S

    1995-01-01

    Swimming speeds and flagellar rotation rates of individual free-swimming Vibrio alginolyticus cells were measured simultaneously by laser dark-field microscopy at 25, 30, and 35 degrees C. A roughly linear relation between swimming speed and flagellar rotation rate was observed. The ratio of swimming speed to flagellar rotation rate was 0.113 microns, which indicated that a cell progressed by 7% of pitch of flagellar helix during one flagellar rotation. At each temperature, however, swimming speed had a tendency to saturate at high flagellar rotation rate. That is, the cell with a faster-rotating flagellum did not always swim faster. To analyze the bacterial motion, we proposed a model in which the torque characteristics of the flagellar motor were considered. The model could be analytically solved, and it qualitatively explained the experimental results. The discrepancy between the experimental and the calculated ratios of swimming speed to flagellar rotation rate was about 20%. The apparent saturation in swimming speed was considered to be caused by shorter flagella that rotated faster but produced less propelling force. Images FIGURE 1 FIGURE 4 PMID:8580359

  11. The quest for bacterial allergens.

    PubMed

    Nordengrün, Maria; Michalik, Stephan; Völker, Uwe; Bröker, Barbara M; Gómez-Gascón, Lidia

    2018-04-26

    Allergies are complex diseases featuring local tissue inflammation, which is characterized by an exaggerated type 2 immune response to environmental compounds known as allergens. Pollens, environmental fungi, and house dust mites are examples of common allergens. Bacteria have a dual role in allergy. Usually, they are associated with protection, however, certain bacterial species promote the development and exacerbation of allergic inflammation. Notably, IgE antibodies specific for bacterial antigens are found in the sera of allergic individuals. This implies that some bacterial factors are allergens, eliciting a specific type 2 immune response. However, to date, only a few of these are molecularly defined. This review summarizes the current knowledge about known bacterial allergens, and it provides an overview of the available techniques for the discovery of new allergens as well as for measuring the immune responses directed against them. Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.

  12. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    PubMed

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Investigation of multimodal forward scatter phenotyping from bacterial colonies

    NASA Astrophysics Data System (ADS)

    Kim, Huisung

    A rapid, label-free, and elastic light scattering (ELS) based bacterial colony phenotyping technology, bacterial rapid detection using optical scattering technology (BARDOT) provides a successful classification of several bacterial genus and species. For a thorough understanding of the phenomena and overcoming the limitations of the previous design, five additional modalities from a bacterial colony: 3D morphology, spatial optical density (OD) distribution, spectral forward scattering pattern, spectral OD, and surface backward reflection pattern are proposed to enhance the classification/identification ratio, and the feasibilities of each modality are verified. For the verification, three different instruments: integrated colony morphology analyzer (ICMA), multi-spectral BARDOT (MS-BARDOT) , and multi-modal BARDOT (MM-BARDOT) are proposed and developed. The ICMA can measure 3D morphology and spatial OD distribution of the colony simultaneously. A commercialized confocal displacement meter is used to measure the profiles of the bacterial colonies, together with a custom built optical density measurement unit to interrogate the biophysics behind the collective behavior of a bacterial colony. The system delivers essential information related to the quantitative growth dynamics (height, diameter, aspect ratio, optical density) of the bacterial colony, as well as, a relationship in between the morphological characteristics of the bacterial colony and its forward scattering pattern. Two different genera: Escherichia coli O157:H7 EDL933, and Staphylococcus aureus ATCC 25923 are selected for the analysis of the spatially resolved growth dynamics, while, Bacillus spp. such as B. subtilis ATCC 6633, B. cereus ATCC 14579, B. thuringiensis DUP6044, B. polymyxa B719W, and B. megaterium DSP 81319, are interrogated since some of the Bacillus spp. provides strikingly different characteristics of ELS patterns, and the origin of the speckle patterns are successfully correlated with

  14. Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO2/CH4 Production Ratios

    PubMed Central

    Eiler, Alexander; Biasi, Christina; Tuittila, Eeva-Stiina; Yrjälä, Kim; Fritze, Hannu

    2016-01-01

    ABSTRACT Northern peatlands in general have high methane (CH4) emissions, but individual peatlands show considerable variation as CH4 sources. Particularly in nutrient-poor peatlands, CH4 production can be low and exceeded by carbon dioxide (CO2) production from unresolved anaerobic processes. To clarify the role anaerobic bacterial degraders play in this variation, we compared consumers of cellobiose-derived carbon in two fens differing in nutrient status and the ratio of CO2 to CH4 produced. After [13C]cellobiose amendment, the mesotrophic fen produced equal amounts of CH4 and CO2. The oligotrophic fen had lower CH4 production but produced 3 to 59 times more CO2 than CH4. RNA stable-isotope probing revealed that in the mesotrophic fen with higher CH4 production, cellobiose-derived carbon was mainly assimilated by various recognized fermenters of Firmicutes and by Proteobacteria. The oligotrophic peat with excess CO2 production revealed a wider variety of cellobiose-C consumers, including Firmicutes and Proteobacteria, but also more unconventional degraders, such as Telmatobacter-related Acidobacteria and subphylum 3 of Verrucomicrobia. Prominent and potentially fermentative Planctomycetes and Chloroflexi did not appear to process cellobiose-C. Our results show that anaerobic degradation resulting in different levels of CH4 production can involve distinct sets of bacterial degraders. By distinguishing cellobiose degraders from the total community, this study contributes to defining anaerobic bacteria that process cellulose-derived carbon in peat. Several of the identified degraders, particularly fermenters and potential Fe(III) or humic substance reducers in the oligotrophic peat, represent promising candidates for resolving the origin of excess CO2 production in peatlands. IMPORTANCE Peatlands are major sources of the greenhouse gas methane (CH4), yet in many peatlands, CO2 production from unresolved anaerobic processes exceeds CH4 production. Anaerobic

  15. Distinct Anaerobic Bacterial Consumers of Cellobiose-Derived Carbon in Boreal Fens with Different CO2/CH4 Production Ratios.

    PubMed

    Juottonen, Heli; Eiler, Alexander; Biasi, Christina; Tuittila, Eeva-Stiina; Yrjälä, Kim; Fritze, Hannu

    2017-02-15

    Northern peatlands in general have high methane (CH 4 ) emissions, but individual peatlands show considerable variation as CH 4 sources. Particularly in nutrient-poor peatlands, CH 4 production can be low and exceeded by carbon dioxide (CO 2 ) production from unresolved anaerobic processes. To clarify the role anaerobic bacterial degraders play in this variation, we compared consumers of cellobiose-derived carbon in two fens differing in nutrient status and the ratio of CO 2 to CH 4 produced. After [ 13 C]cellobiose amendment, the mesotrophic fen produced equal amounts of CH 4 and CO 2 The oligotrophic fen had lower CH 4 production but produced 3 to 59 times more CO 2 than CH 4 RNA stable-isotope probing revealed that in the mesotrophic fen with higher CH 4 production, cellobiose-derived carbon was mainly assimilated by various recognized fermenters of Firmicutes and by Proteobacteria The oligotrophic peat with excess CO 2 production revealed a wider variety of cellobiose-C consumers, including Firmicutes and Proteobacteria, but also more unconventional degraders, such as Telmatobacter-related Acidobacteria and subphylum 3 of Verrucomicrobia Prominent and potentially fermentative Planctomycetes and Chloroflexi did not appear to process cellobiose-C. Our results show that anaerobic degradation resulting in different levels of CH 4 production can involve distinct sets of bacterial degraders. By distinguishing cellobiose degraders from the total community, this study contributes to defining anaerobic bacteria that process cellulose-derived carbon in peat. Several of the identified degraders, particularly fermenters and potential Fe(III) or humic substance reducers in the oligotrophic peat, represent promising candidates for resolving the origin of excess CO 2 production in peatlands. Peatlands are major sources of the greenhouse gas methane (CH 4 ), yet in many peatlands, CO 2 production from unresolved anaerobic processes exceeds CH 4 production. Anaerobic

  16. Arsenic uptake in bacterial calcite

    NASA Astrophysics Data System (ADS)

    Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

    2018-02-01

    Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03 Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

  17. Estimation of lactic acid bacterial cell number by DNA quantification.

    PubMed

    Ishii, Masaki; Matsumoto, Yasuhiko; Sekimizu, Kazuhisa

    2018-01-01

    Lactic acid bacteria are provided by fermented foods, beverages, medicines, and supplements. Because the beneficial effects of medicines and supplements containing functional lactic acid bacteria are related to the bacterial cell number, it is important to establish a simple method for estimating the total number of lactic acid bacterial cells in the products for quality control. Almost all of the lactic acid bacteria in the products are dead, however, making it difficult to estimate the total number of lactic acid bacterial cells in the products using a standard colony-counting method. Here we estimated the total lactic acid bacterial cell number in samples containing dead bacteria by quantifying the DNA. The number of viable Enterococcus faecalis 0831-07 cells decreased to less than 1 × 10 -8 by 15 min of heat treatment at 80°C. The amount of extracted DNA from heat-treated cells was 78% that of non-heated cells. The number of viable Lactobacillus paraplantarum 11-1 cells decreased to 1 × 10 -4 after 4 days culture. The amount of extracted DNA of the long-cultured cells, however, was maintained at 97%. These results suggest that cell number of lactic acid bacteria killed by heat-treatment or long-term culture can be estimated by DNA quantification.

  18. Bacterially mediated mineralization of vaterite

    NASA Astrophysics Data System (ADS)

    Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

    2007-03-01

    Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

  19. Formation of bacterial nanocells

    NASA Astrophysics Data System (ADS)

    Vainshtein, Mikhail; Kudryashova, Ekaterina; Suzina, Natalia; Ariskina, Elena; Voronkov, Vadim

    1998-07-01

    Existence of nanobacteria received increasing attention both in environmental microbiology/geomicro-biology and in medical microbiology. In order to study a production of nanoforms by typical bacterial cells. Effects of different physical factors were investigated. Treatment of bacterial cultures with microwave radiation, or culturing in field of electric current resulted in formation a few types of nanocells. The number and type of nanoforms were determined with type and dose of the treatment. The produced nanoforms were: i) globules, ii) clusters of the globules--probably produced by liaison, iii) nanocells coated with membrane. The viability of the globules is an object opened for doubts. The nanocells discovered multiplication and growth on solidified nutrient media. The authors suggest that formation of nanocells is a common response of bacteria to stress-actions produced by different agents.

  20. Soil bacterial community shifts associated with sugarcane straw removal

    NASA Astrophysics Data System (ADS)

    Pimentel, Laisa; Gumiere, Thiago; Andreote, Fernando; Cerri, Carlos

    2017-04-01

    In Brazil, the adoption of the mechanical unburned sugarcane harvest potentially increase the quantity of residue left in the field after harvesting. Economically, this material has a high potential for second generation ethanol (2G) production. However, crop residues have an essential role in diverse properties and processes in the soil. The greater part of the uncertainties about straw removal for 2G ethanol production is based on its effects in soil microbial community. In this sense, it is important to identify the main impacts of sugarcane straw removal on soil microbial community. Therefore, we conducted a field study, during one year, in Valparaíso (São Paulo state - Brazil) to evaluate the effects of straw decomposition on soil bacterial community. Specifically, we wanted: i) to compare the rates of straw removal and ii) to evaluate the effects of straw decomposition on soil bacterial groups over one year. The experiment was in a randomized block design with treatments arranged in strip plot. The treatments are different rates of sugarcane straw removal, namely: no removal, 50, 75 and 100% of straw removal. Soil sampling was carried out at 0, 4, 8 and 12 months after the sugarcane harvest (August 2015). Total DNA was extracted from soil using the PowersoilTM DNA Isolation kit. And the abundance of bacterial in each soil sample was estimated via quantification of 16S rRNA gene. The composition of the bacterial communities was estimated via terminal restriction fragment length polymorphism (T-RFLP) analysis, and the T-RF sizes were performed on a 3500 Genetic Analyzer. Finally, the results were examined with GeneMapper 4.1 software. There was bacterial community shifts through the time and among the rates of sugarcane straw removal. Bacterial community was firstly determined by the time scale, which explained 29.16% of total variation. Rates of straw removal explained 11.55% of shifts on bacterial community. Distribution through the time is an important

  1. Effect of Different Carbon Sources on Bacterial Nanocellulose Production and Structure Using the Low pH Resistant Strain Komagataeibacter Medellinensis

    PubMed Central

    Molina-Ramírez, Carlos; Castro, Margarita; Osorio, Marlon; Torres-Taborda, Mabel; Gómez, Beatriz; Zuluaga, Robin; Gómez, Catalina; Gañán, Piedad; Rojas, Orlando J.; Castro, Cristina

    2017-01-01

    Bacterial cellulose (BC) is a polymer obtained by fermentation with microorganism of different genera. Recently, new producer species have been discovered, which require identification of the most important variables affecting cellulose production. In this work, the influence of different carbon sources in BC production by a novel low pH-resistant strain Komagataeibacter medellinensis was established. The Hestrin-Schramm culture medium was used as a reference and was compared to other media comprising glucose, fructose, and sucrose, used as carbon sources at three concentrations (1, 2, and 3% w/v). The BC yield and dynamics of carbon consumption were determined at given fermentation times during cellulose production. While the carbon source did not influence the BC structural characteristics, different production levels were determined: glucose > sucrose > fructose. These results highlight considerations to improve BC industrial production and to establish the BC property space for applications in different fields. PMID:28773001

  2. Bacterial endophytes enhance competition by invasive plants.

    PubMed

    Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

    2013-09-01

    Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

  3. Induction of antiphospholipid antibodies by immunization with synthetic viral and bacterial peptides.

    PubMed

    Gharavi, E E; Chaimovich, H; Cucurull, E; Celli, C M; Tang, H; Wilson, W A; Gharavi, A E

    1999-01-01

    We previously induced pathogenic antibodies against anionic phospholipids (PL) in experimental animals by immunization with lipid-free purified human beta2glycoprotein I (beta2GPI). We hypothesized that antiphospholipid antibodies (aPL) are induced by in vivo binding of foreign beta2GPI to self-PL, thus forming an immunogenic complex against which aPL antibodies are produced. If this hypothesis is true, other PL-binding proteins that are products of ubiquitous viral/bacterial agents may also induce aPL. To test this hypothesis, groups of NIH/Swiss mice were immunized with synthetic peptides of viral and bacterial origin that share structural similarity with the putative PL-binding region of beta2GPI. Compared with the control groups, animals immunized with the peptides produced significantly higher levels of aPL and anti-beta2GPI antibodies. These findings demonstrate that some PL-binding viral and bacterial proteins function like beta2GPI in inducing aPL and anti-beta2GPI production, and are consistent with a role for such viral and bacterial proteins in inducing aPL antibody production in humans.

  4. A method to isolate bacterial communities and characterize ecosystems from food products: Validation and utilization in as a reproducible chicken meat model.

    PubMed

    Rouger, Amélie; Remenant, Benoit; Prévost, Hervé; Zagorec, Monique

    2017-04-17

    Influenced by production and storage processes and by seasonal changes the diversity of meat products microbiota can be very variable. Because microbiotas influence meat quality and safety, characterizing and understanding their dynamics during processing and storage is important for proposing innovative and efficient storage conditions. Challenge tests are usually performed using meat from the same batch, inoculated at high levels with one or few strains. Such experiments do not reflect the true microbial situation, and the global ecosystem is not taken into account. Our purpose was to constitute live stocks of chicken meat microbiotas to create standard and reproducible ecosystems. We searched for the best method to collect contaminating bacterial communities from chicken cuts to store as frozen aliquots. We tested several methods to extract DNA of these stored communities for subsequent PCR amplification. We determined the best moment to collect bacteria in sufficient amounts during the product shelf life. Results showed that the rinsing method associated to the use of Mobio DNA extraction kit was the most reliable method to collect bacteria and obtain DNA for subsequent PCR amplification. Then, 23 different chicken meat microbiotas were collected using this procedure. Microbiota aliquots were stored at -80°C without important loss of viability. Their characterization by cultural methods confirmed the large variability (richness and abundance) of bacterial communities present on chicken cuts. Four of these bacterial communities were used to estimate their ability to regrow on meat matrices. Challenge tests performed on sterile matrices showed that these microbiotas were successfully inoculated and could overgrow the natural microbiota of chicken meat. They can therefore be used for performing reproducible challenge tests mimicking a true meat ecosystem and enabling the possibility to test the influence of various processing or storage conditions on complex meat

  5. Bacterial contaminants from frozen puff pastry production process and their growth inhibition by antimicrobial substances from lactic acid bacteria.

    PubMed

    Rumjuankiat, Kittaporn; Keawsompong, Suttipun; Nitisinprasert, Sunee

    2017-05-01

    Seventy-five bacterial contaminants which still persisted to cleaning system from three puff pastry production lines (dough forming, layer and filling forming, and shock freezing) were identified using 16S rDNA as seven genera of Bacillus , Corynebacterium , Dermacoccus , Enterobacter , Klebsiella, Pseudomonas , and Staphylococcus with detection frequencies of 24.00, 2.66, 1.33, 37.33, 1.33, 2.66, and 30.66, respectively. Seventeen species were discovered while only 11 species Bacillus cereus, B. subtilis, B. pumilus, Corynebacterium striatum , Dermacoccus barathri , Enterobacter asburiae, Staphylococcus kloosii, S. haemolyticus, S. hominis, S. warneri , and S. aureus were detected at the end of production. Based on their abundance, the highest abundance of E. asburiae could be used as a biomarker for product quality. While a low abundance of the mesophile pathogen C. striatum , which causes respiratory and nervous infection and appeared only at the shock freezing step was firstly reported for its detection in bakery product. Six antimicrobial substances (AMSs) from lactic acid bacteria, FF1-4, FF1-7, PFUR-242, PFUR-255, PP-174, and nisin A were tested for their inhibition activities against the contaminants. The three most effective were FF1-7, PP-174, and nisin A exhibiting wide inhibition spectra of 88.00%, 85.33%, and 86.66%, respectively. The potential of a disinfectant solution containing 800 AU/ml of PP-174 and nisin A against the most resistant strains of Enterobacter , Staphylococcus , Bacillus and Klebsiella was determined on artificially contaminated conveyor belt coupons at 0, 4, 8, 12, and 16 hr. The survival levels of the test strains were below 1 log CFU/coupon at 0 hr. The results suggested that a combined solution of PP-174 and nisin A may be beneficial as a sanitizer to inhibit bacterial contaminants in the frozen puff pastry industry.

  6. Bacterial diversity of oil palm Elaeis guineensis basal stems

    NASA Astrophysics Data System (ADS)

    Amran, Afzufira; Jangi, Mohd Sanusi; Aqma, Wan Syaidatul; Yusof, Nurul Yuziana Mohd; Bakar, Mohd Faizal Abu; Isa, Mohd Noor Mat

    2016-11-01

    Oil palm, Elaeis guineensis is one of the major industrial production crops in Malaysia. Basal stem rot, caused by the white fungus, Ganoderma boninense, is a disease that reduces oil palm yields in most production areas of the world. Understanding of bacterial community that is associated with Ganoderma infection will shed light on how this bacterial community contributes toward the severity of the infection. In this preliminary study, we assessed the bacterial community that inhabit the basal stems of E. guineensis based on 16S rRNA gene as a marker using next generation sequencing platform. This result showed that a total of 84,372 operational taxonomic-units (OTUs) were identified within six samples analyzed. A total 55,049 OTUs were assigned to known taxonomy whereas 29,323 were unassigned. Cyanobacteria, Bacteroidetes, Firmicutes and Proteobacteria were the most abundant phyla found in all six samples and the unique taxonomy assigned for each infected and healthy samples were also identified. The findings from this study will further enhance our knowledge in the interaction of bacterial communities against Ganoderma infection within the oil palm host plant and for a better management of the basal stems rot disease.

  7. Dynamic responses of the benthic bacterial community at the Western English Channel observatory site L4 are driven by deposition of fresh phytodetritus

    NASA Astrophysics Data System (ADS)

    Tait, Karen; Airs, Ruth L.; Widdicombe, Claire E.; Tarran, Glen A.; Jones, Mark R.; Widdicombe, Stephen

    2015-09-01

    The impact of the seasonal deposition of phytoplankton and phytodetritus on surface sediment bacterial abundance and community composition was investigated at the Western English Channel site L4. Sediment and water samples were collected from January to September in 2012, increasing in frequency during periods of high water column phytoplankton abundance. Compared to the past two decades, the spring bloom in 2012 was both unusually long in duration and contained higher than average biomass. Within spring months, the phytoplankton bloom was well mixed through the water column and showed accumulations near the sea bed, as evidenced by flow cytometry measurements of nanoeukaryotes, water column chlorophyll a and the appearance of pelagic phytoplankton at the sediment. Measurements of chlorophyll and chlorophyll degradation products indicated phytoplankton material was heavily degraded after it reached the sediment surface: the nature of the chlorophyll degradation products (predominantly pheophorbide, pyropheophorbide and hydroxychlorophyllone) was indicative of grazing activity. The abundance of bacterial 16S rRNA genes g-1 sediment (used as a proxy for bacterial biomass) increased markedly with the onset of the phytoplankton bloom, and correlated with measurements of chlorophyll at the surface sediment. Together, this suggests that bacteria may have responded to nutrients released via grazing activity. In depth sequencing of the 16S rRNA genes indicated that the composition of the bacterial community shifted rapidly through-out the prolonged spring bloom period. This was primarily due to an increase in the relative sequence abundance of Flavobacteria.

  8. A Host-Produced Autoinducer-2 Mimic Activates Bacterial Quorum Sensing.

    PubMed

    Ismail, Anisa S; Valastyan, Julie S; Bassler, Bonnie L

    2016-04-13

    Host-microbial symbioses are vital to health; nonetheless, little is known about the role crosskingdom signaling plays in these relationships. In a process called quorum sensing, bacteria communicate with one another using extracellular signal molecules called autoinducers. One autoinducer, AI-2, is proposed to promote interspecies bacterial communication, including in the mammalian gut. We show that mammalian epithelia produce an AI-2 mimic activity in response to bacteria or tight-junction disruption. This AI-2 mimic is detected by the bacterial AI-2 receptor, LuxP/LsrB, and can activate quorum-sensing-controlled gene expression, including in the enteric pathogen Salmonella typhimurium. AI-2 mimic activity is induced when epithelia are directly or indirectly exposed to bacteria, suggesting that a secreted bacterial component(s) stimulates its production. Mutagenesis revealed genes required for bacteria to both detect and stimulate production of the AI-2 mimic. These findings uncover a potential role for the mammalian AI-2 mimic in fostering crosskingdom signaling and host-bacterial symbioses. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Comparison of rumen bacterial communities in dairy herds of different production.

    PubMed

    Indugu, Nagaraju; Vecchiarelli, Bonnie; Baker, Linda D; Ferguson, James D; Vanamala, Jairam K P; Pitta, Dipti W

    2017-08-30

    The purpose of this study was to compare the rumen bacterial composition in high and low yielding dairy cows within and between two dairy herds. Eighty five Holstein dairy cows in mid-lactation (79-179 days in milk) were selected from two farms: Farm 12 (M305 = 12,300 kg; n = 47; 24 primiparous cows, 23 multiparous cows) and Farm 9 (M305 = 9700 kg; n = 38; 19 primiparous cows, 19 multiparous cows). Each study cow was sampled once using the stomach tube method and processed for 16S rRNA gene amplicon sequencing using the Ion Torrent (PGM) platform. Differences in bacterial communities between farms were greater (Adonis: R 2  = 0.16; p < 0.001) than within farm. Five bacterial lineages, namely Prevotella (48-52%), unclassified Bacteroidales (10-12%), unclassified bacteria (5-8%), unclassified Succinivibrionaceae (1-7%) and unclassified Prevotellaceae (4-5%) were observed to differentiate the community clustering patterns among the two farms. A notable finding is the greater (p < 0.05) contribution of Succinivibrionaceae lineages in Farm 12 compared to Farm 9. Furthermore, in Farm 12, Succinivibrionaceae lineages were higher (p < 0.05) in the high yielding cows compared to the low yielding cows in both primiparous and multiparous groups. Prevotella, S24-7 and Succinivibrionaceae lineages were found in greater abundance on Farm 12 and were positively correlated with milk yield. Differences in rumen bacterial populations observed between the two farms can be attributed to dietary composition, particularly differences in forage type and proportion in the diets. A combination of corn silage and alfalfa silage may have contributed to the increased proportion of Proteobacteria in Farm 12. It was concluded that Farm 12 had a greater proportion of specialist bacteria that have the potential to enhance rumen fermentative digestion of feedstuffs to support higher milk yields.

  10. Exploiting Quorum Sensing To Confuse Bacterial Pathogens

    PubMed Central

    LaSarre, Breah

    2013-01-01

    SUMMARY Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals. PMID:23471618

  11. Rifaximin has minor effects on bacterial composition, inflammation, and bacterial translocation in cirrhosis: A randomized trial.

    PubMed

    Kimer, Nina; Pedersen, Julie S; Tavenier, Juliette; Christensen, Jeffrey E; Busk, Troels M; Hobolth, Lise; Krag, Aleksander; Al-Soud, Waleed Abu; Mortensen, Martin S; Sørensen, Søren J; Møller, Søren; Bendtsen, Flemming

    2018-01-01

    Decompensated cirrhosis is characterized by disturbed hemodynamics, immune dysfunction, and high risk of infections. Translocation of viable bacteria and bacterial products from the gut to the blood is considered a key driver in this process. Intestinal decontamination with rifaximin may reduce bacterial translocation (BT) and decrease inflammation. A randomized, placebo-controlled trial investigated the effects of rifaximin on inflammation and BT in decompensated cirrhosis. Fifty-four out-patients with cirrhosis and ascites were randomized, mean age 56 years (± 8.4), and model for end-stage liver disease score 12 (± 3.9). Patients received rifaximin 550-mg BD (n = 36) or placebo BD (n = 18). Blood and fecal (n = 15) sampling were conducted at baseline and after 4 weeks. Bacterial DNA in blood was determined by real-time qPCR 16S rRNA gene quantification. Bacterial composition in feces was analyzed by 16S rRNA gene sequencing. Circulating markers of inflammation, including tumor necrosis factor alpha, interleukins 6, 10, and 18, stromal cell-derived factor 1-α, transforming growth factor β-1, and high sensitivity C-reactive protein, were unaltered by rifaximin treatment. Rifaximin altered abundance of bacterial taxa in blood marginally, only a decrease in Pseudomonadales was observed. In feces, rifaximin decreased bacterial richness, but effect on particular species was not observed. Subgroup analyses on patients with severely disturbed hemodynamics (n = 34) or activated lipopolysaccharide binding protein (n = 37) revealed no effect of rifaximin. Four weeks of treatment with rifaximin had no impact on the inflammatory state and only minor effects on BT and intestinal bacterial composition in stable, decompensated cirrhosis (NCT01769040). © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  12. Bacterial expression of self-assembling peptide hydrogelators

    NASA Astrophysics Data System (ADS)

    Sonmez, Cem

    For tissue regeneration and drug delivery applications, various architectures are explored to serve as biomaterial tools. Via de novo design, functional peptide hydrogel materials have been developed as scaffolds for biomedical applications. The objective of this study is to investigate bacterial expression as an alternative method to chemical synthesis for the recombinant production of self-assembling peptides that can form rigid hydrogels under physiological conditions. The Schneider and Pochan Labs have designed and characterized a 20 amino acid beta-hairpin forming amphiphilic peptide containing a D-residue in its turn region (MAX1). As a result, this peptide must be prepared chemically. Peptide engineering, using the sequence of MAX1 as a template, afforded a small family of peptides for expression (EX peptides) that have different turn sequences consisting of natural amino acids and amenable to bacterial expression. Each sequence was initially chemically synthesized to quickly assess the material properties of its corresponding gel. One model peptide EX1, was chosen to start the bacterial expression studies. DNA constructs facilitating the expression of EX1 were designed in such that the peptide could be expressed with different fusion partners and subsequently cleaved by enzymatic or chemical means to afford the free peptide. Optimization studies were performed to increase the yield of pure peptide that ultimately allowed 50 mg of pure peptide to be harvested from one liter of culture, providing an alternate means to produce this hydrogel-forming peptide. Recombinant production of other self-assembling hairpins with different turn sequences was also successful using this optimized protocol. The studies demonstrate that new beta-hairpin self-assembling peptides that are amenable to bacterial production and form rigid hydrogels at physiological conditions can be designed and produced by fermentation in good yield at significantly reduced cost when compared to

  13. Hadron production measurements for neutrino physics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Panman, Jaap

    2008-02-21

    One of the limiting factors for the precision of neutrino oscillation experiments is the uncertainty in the composition and spectrum of the neutrino flux. Recently, dedicated hadron production experiments have been taking data and are being planned to supply measurements which can significantly reduce these uncertainties. The HARP experiment has presented results on the measurements of the double-differential production cross-section of charged pions in proton interactions with beryllium, carbon, aluminium, copper, tin, tantalum and lead targets. These results are relevant for a detailed understanding of neutrino flux in accelerator neutrino experiments K2K (p-Al data) and MiniBooNE/SciBooNE (p-Be data), for amore » better prediction of atmospheric neutrino fluxes (p-C, {pi}{sup +}-C and {pi}{sup -}-C data) as well as for a systematic improvement of hadron production models. The E910 experiment at BNL has recently published their p-Be data. NA49 has measured pion production spectra in p-C interactions and a new experiment, NA61, is starting to take data using essentially the same detector. NA61 plans to measure production spectra for the T2K experiment and for the calculation of extended air showers. MIPP has taken data with a copy of the NuMI target and is progressing in the analysis of these data. An upgrade of the readout of this experiment can greatly increase its potential.« less

  14. Exploring lot-to-lot variation in spoilage bacterial communities on commercial modified atmosphere packaged beef.

    PubMed

    Säde, Elina; Penttinen, Katri; Björkroth, Johanna; Hultman, Jenni

    2017-04-01

    Understanding the factors influencing meat bacterial communities is important as these communities are largely responsible for meat spoilage. The composition and structure of a bacterial community on a high-O 2 modified-atmosphere packaged beef product were examined after packaging, on the use-by date and two days after, to determine whether the communities at each stage were similar to those in samples taken from different production lots. Furthermore, we examined whether the taxa associated with product spoilage were distributed across production lots. Results from 16S rRNA amplicon sequencing showed that while the early samples harbored distinct bacterial communities, after 8-12 days storage at 6 °C the communities were similar to those in samples from different lots, comprising mainly of common meat spoilage bacteria Carnobacterium spp., Brochothrix spp., Leuconostoc spp. and Lactococcus spp. Interestingly, abundant operational taxonomic units associated with product spoilage were shared between the production lots, suggesting that the bacteria enable to spoil the product were constant contaminants in the production chain. A characteristic succession pattern and the distribution of common spoilage bacteria between lots suggest that both the packaging type and the initial community structure influenced the development of the spoilage bacterial community. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. [USE OF LASER RAMAN-LUMINESCENT TECHNOLOGIES FOR EVALUATION OF QUALITY OF MEAT PRODUCTS AND DETERMINATION OF THE DEGREE OF THEIR BACTERIAL CONTAMINATION].

    PubMed

    Kukushkin, V I; Satusheva, E V; Aleksandrov, M T; Morozova, O A; Pashkov, E P; Ambartsumyan, O A; Amosova, V A

    2015-01-01

    Determination of the effect of microorganisms on spoilage of meat products during various temperature regimes of storage by integral indexes of luminescent lines in their spectra and development of an algorithm of microorganism indication by an express method using laser Raman-luminescent spectroscopy. Minced meat from beef and pork was used. Determination of quantity of mesophilic aerobic and opportunistic-anaerobic microorganisms was carried out by serial 10-fold dilutions with subsequent parallel seeding into Rida count total 24 plates and Petri dishes with 5% blood agar. Sample study was carried out in luminescent software-hardware complex Enspectr L405 (a variant of Enspectr M software-hardware complexes). Meat spoilage was established to be caused to a large degree by Pseudomonas genus (P. fluorescens, P. putida, P. fragi et al.) bacterial growth. Raman-luminescent spectra of bacteria that compose microflora, characterizing and accompanying beef and pork spoilage, were measured and recorded into a database. The results obtained will allow to use this technique in the future for both express-indication and differentiation of microorganisms and express-evaluation of quality of meat products at all stages of their manufacturing, storage, transport and realization.

  16. An operon for production of bioactive gibberellin A4 phytohormone with wide distribution in the bacterial rice leaf streak pathogen Xanthomonas oryzae pv. oryzicola

    PubMed Central

    Nagel, Raimund; Turrini, Paula C. G.; Nett, Ryan S.; Leach, Jan E.; Verdier, Valérie; Van Sluys, Marie-Anne; Peters, Reuben J.

    2016-01-01

    Summary Phytopathogens have developed elaborate mechanisms to attenuate the defense response of their host plants, including convergent evolution of complex pathways for production of the gibberellin (GA) phytohormones, which were actually first isolated from the rice fungal pathogen Gibberella fujikuroi. The rice bacterial pathogen Xanthomonas oryzae pv. oryzicola (Xoc) has been demonstrated to contain a biosynthetic operon with cyclases capable of producing the universal GA precursor ent-kaurene. Genetic (knock-out) studies indicate that the derived diterpenoid serves as a virulence factor for this rice leaf streak pathogen, serving to reduce the jasmonic acid (JA) mediated defense response.Here the function of the remaining genes in the Xoc operon are elucidated and the distribution of the operon in X. oryzae investigated in over 100 isolates.The Xoc operon leads to production of the bioactive GA4, an additional step beyond production of the penultimate precursor GA9 mediated by the homologous operons recently characterized from rhizobia. Moreover, this GA biosynthetic operon was found to be widespread in Xoc (>90%), but absent in the other major oryzae pathovar.These results indicate selective pressure for production of GA4 in the distinct lifestyle of Xoc, and the importance of GA to both fungal and bacterial pathogens of rice. PMID:28134995

  17. Interspecies chemical communication in bacterial development.

    PubMed

    Straight, Paul D; Kolter, Roberto

    2009-01-01

    Our view of bacteria, from the earliest observations through the heyday of antibiotic discovery, has shifted dramatically. We recognize communities of bacteria as integral and functionally important components of diverse habitats, ranging from soil collectives to the human microbiome. To function as productive communities, bacteria coordinate metabolic functions, often requiring shifts in growth and development. The hallmark of cellular development, which we characterize as physiological change in response to environmental stimuli, is a defining feature of many bacterial interspecies interactions. Bacterial communities rely on chemical exchanges to provide the cues for developmental change. Traditional methods in microbiology focus on isolation and characterization of bacteria in monoculture, separating the organisms from the surroundings in which interspecies chemical communication has relevance. Developing multispecies experimental systems that incorporate knowledge of bacterial physiology and metabolism with insights from biodiversity and metagenomics shows great promise for understanding interspecies chemical communication in the microbial world.

  18. Bacterial Responses to Reactive Chlorine Species

    PubMed Central

    Gray, Michael J.; Wholey, Wei-Yun; Jakob, Ursula

    2013-01-01

    Hypochlorous acid (HOCl), the active ingredient of household bleach, is the most common disinfectant in medical, industrial, and domestic use and plays an important role in microbial killing in the innate immune system. Given the critical importance of the antimicrobial properties of chlorine to public health, it is surprising how little is known about the ways in which bacteria sense and respond to reactive chlorine species (RCS). Although the literature on bacterial responses to reactive oxygen species (ROS) is enormous, work addressing bacterial responses to RCS has begun only recently. Transcriptomic and proteomic studies now provide new insights into how bacteria mount defenses against this important class of antimicrobial compounds. In this review, we summarize the current knowledge, emphasizing the overlaps between RCS stress responses and other more well-characterized bacterial defense systems, and identify outstanding questions that represent productive avenues for future research. PMID:23768204

  19. Strontium Incorporation Into Calcite Generated by Bacterial Ureolysis

    NASA Astrophysics Data System (ADS)

    Fujita, Y.; Ingram, J. A.; Cortez, M. M.; Redden, G. D.; Smith, R. W.

    2002-12-01

    Strontium incorporation into calcite generated by bacterial ureolytic activity was investigated as part of a larger effort to evaluate the use of in situ urea hydrolysis for accelerating co-precipitation of trace metals and radionuclides in contaminated aquifers. 90Sr, a uranium fission product with a half-life of 29 years, is a significant subsurface contaminant at several Department of Energy facilities and could be immobilized using this remediation strategy. Experiments were conducted in a medium designed to simulate the groundwater of the Snake River Plain Aquifer in eastern Idaho, amended with strontium. Initially the solution was undersaturated with respect to calcite. As a model ureolytic organism, we used Bacillus pasteurii, a well-characterized bacterium known for high urease activity and previously shown to induce calcite precipitation in urea-amended medium. To gain information on the effect of the bacterial surfaces, we also looked at precipitation in the presence of a bacterial species that did not hydrolyze urea, as well as in the absence of bacteria. In the absence of bacterial ureolysis, carbonate precipitation was induced by addition of ammonium carbonate. All products were identified as calcite by X-ray diffraction. Strontium uptake was observed in all cases, but was greatest in the system including bacterial ureolysis. Sputter depth element profiling by time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed this finding, showing highest Sr:Ca ratios in the bacterially generated calcite throughout the depth (~350 nm) investigated. Environmental Scanning Electron Microscopy (ESEM) of the solids revealed regular crystals containing the outlines of embedded or entombed bacterial cells, suggesting that calcite precipitated directly on the cell surfaces when present. Analysis by X-ray Absorption Near Edge Spectroscopy (XANES) indicated that in both the biotically and abiotically generated calcites the Sr was incorporated into the calcite

  20. Studies on the factors modulating indole-3-acetic acid production in endophytic bacterial isolates from Piper nigrum and molecular analysis of ipdc gene.

    PubMed

    Jasim, B; Jimtha John, C; Shimil, V; Jyothis, M; Radhakrishnan, E K

    2014-09-01

    The study mainly aimed quantitative analysis of IAA produced by endophytic bacteria under various conditions including the presence of extract from Piper nigrum. Analysis of genetic basis of IAA production was also conducted by studying the presence and diversity of the ipdc gene among the selected isolates. Five endophytic bacteria isolated previously from P. nigrum were used for the study. The effect of temperature, pH, agitation, tryptophan concentration and plant extract on modulating IAA production of selected isolates was analysed by colorimetric method. Comparative and quantitative analysis of IAA production by colorimetric isolates under optimal culture condition was analysed by HPTLC method. Presence of ipdc gene and thereby biosynthetic basis of IAA production among the selected isolates were studied by PCR-based amplification and subsequent insilico analysis of sequence obtained. Among the selected bacterial isolates from P. nigrum, isolate PnB 8 (Klebsiella pneumoniae) was found to have the maximum yield of IAA under various conditions optimized and was confirmed by colorimetric, HPLC and HPTLC analysis. Very interestingly, the study showed stimulating effect of phytochemicals from P. nigrum on IAA production by endophytic bacteria isolated from same plant. This study is unique because of the selection of endophytes from same source for comparative and quantitative analysis of IAA production under various conditions. Study on stimulatory effect of phytochemicals on bacterial IAA production as explained in the study is a novel approach. Studies on molecular basis of IAA production which was confirmed by sequence analysis of ipdc gene make the study scientifically attractive. Even though microbial production of IAA is well known, current report on detailed optimization, effect of plant extract and molecular confirmation of IAA biosynthesis is comparatively novel in its approach. © 2014 The Society for Applied Microbiology.

  1. Arsenic uptake in bacterial calcite

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco

    Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and Xray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the cmore » axis (by 0.03Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.« less

  2. Bacterial siderophores efficiently provide iron to iron-starved tomato plants in hydroponics culture.

    PubMed

    Radzki, W; Gutierrez Mañero, F J; Algar, E; Lucas García, J A; García-Villaraco, A; Ramos Solano, B

    2013-09-01

    Iron is one of the essential elements for a proper plant development. Providing plants with an accessible form of iron is crucial when it is scant or unavailable in soils. Chemical chelates are the only current alternative and are highly stable in soils, therefore, posing a threat to drinking water. The aim of this investigation was to quantify siderophores produced by two bacterial strains and to determine if these bacterial siderophores would palliate chlorotic symptoms of iron-starved tomato plants. For this purpose, siderophore production in MM9 medium by two selected bacterial strains was quantified, and the best was used for biological assay. Bacterial culture media free of bacteria (S) and with bacterial cells (BS), both supplemented with Fe were delivered to 12-week-old plants grown under iron starvation in hydroponic conditions; controls with full Hoagland solution, iron-free Hoagland solution and water were also conducted. Treatments were applied twice along the experiment, with a week in between. At harvest, plant yield, chlorophyll content and nutritional status in leaves were measured. Both the bacterial siderophore treatments significantly increased plant yield, chlorophyll and iron content over the positive controls with full Hoagland solution, indicating that siderophores are effective in providing Fe to the plant, either with or without the presence of bacteria. In summary, siderophores from strain Chryseobacterium C138 are effective in supplying Fe to iron-starved tomato plants by the roots, either with or without the presence of bacteria. Based on the amount of siderophores produced, an effective and economically feasible organic Fe chelator could be developed.

  3. Phylogenetic structure of soil bacterial communities predicts ecosystem functioning.

    PubMed

    Pérez-Valera, Eduardo; Goberna, Marta; Verdú, Miguel

    2015-05-01

    Quantifying diversity with phylogeny-informed metrics helps understand the effects of diversity on ecosystem functioning (EF). The sign of these effects remains controversial because phylogenetic diversity and taxonomic identity may interactively influence EF. Positive relationships, traditionally attributed to complementarity effects, seem unimportant in natural soil bacterial communities. Negative relationships could be attributed to fitness differences leading to the overrepresentation of few productive clades, a mechanism recently invoked to assemble soil bacteria communities. We tested in two ecosystems contrasting in terms of environmental heterogeneity whether two metrics of phylogenetic community structure, a simpler measure of phylogenetic diversity (NRI) and a more complex metric incorporating taxonomic identity (PCPS), correctly predict microbially mediated EF. We show that the relationship between phylogenetic diversity and EF depends on the taxonomic identity of the main coexisting lineages. Phylogenetic diversity was negatively related to EF in soils where a marked fertility gradient exists and a single and productive clade (Proteobacteria) outcompete other clades in the most fertile plots. However, phylogenetic diversity was unrelated to EF in soils where the fertility gradient is less marked and Proteobacteria coexist with other abundant lineages. Including the taxonomic identity of bacterial lineages in metrics of phylogenetic community structure allows the prediction of EF in both ecosystems. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Non-homogeneous flow profiles in sheared bacterial suspensions

    NASA Astrophysics Data System (ADS)

    Samanta, Devranjan; Cheng, Xiang

    Bacterial suspensions under shear exhibit interesting rheological behaviors including the remarkable ``superfluidic'' state with vanishing viscosity at low shear rates. Theoretical studies have shown that such ``superfluidic'' state is linked with non-homogeneous shear flows, which are induced by coupling between nematic order of active fluids and hydrodynamics of shear flows. However, although bulk rheology of bacterial suspensions has been experimentally studied, shear profiles within bacterial suspensions have not been explored so far. Here, we experimentally investigate the flow behaviors of E. coli suspensions under planar oscillatory shear. Using confocal microscopy and PIV, we measure velocity profiles across gap between two shear plates. We find that with increasing shear rates, high-concentration bacterial suspensions exhibit an array of non-homogeneous flow behaviors like yield-stress flows and shear banding. We show that these non-homogeneous flows are due to collective motion of bacterial suspensions. The phase diagram of sheared bacterial suspensions is systematically mapped as functions of shear rates an bacterial concentrations. Our experiments provide new insights into rheology of bacterial suspensions and shed light on shear induced dynamics of active fluids. Chemical Engineering and Material Science department.

  5. The antimicrobial activity of honey against common equine wound bacterial isolates.

    PubMed

    Carnwath, R; Graham, E M; Reynolds, K; Pollock, P J

    2014-01-01

    Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and non-irradiated commercial medical grade honeys, supermarket honeys, and honeys from local beekeepers. To exclude contaminated honeys from the project, all honeys were cultured aerobically for evidence of bacterial contamination. Aerobic bacteria or fungi were recovered from 18 products. The antimicrobial activity of the remaining 11 products was assessed against 10 wound bacteria, recovered from the wounds of horses, including methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. Eight products were effective against all 10 bacterial isolates at concentrations varying from <2% to 16% (v/v). Overall, the Scottish Heather Honey was the best performing product, and inhibited the growth of all 10 bacterial isolates at concentrations ranging from <2% to 6% (v/v). Although Manuka has been the most studied honey to date, other sources may have valuable antimicrobial properties. Since some honeys were found to be contaminated with aerobic bacteria or fungi, non-sterile honeys may not be suitable for wound treatment. Further assessment of gamma-irradiated honeys from the best performing honeys would be useful. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Acetaldehyde production by major oral microbes.

    PubMed

    Moritani, K; Takeshita, T; Shibata, Y; Ninomiya, T; Kiyohara, Y; Yamashita, Y

    2015-09-01

    To assess acetaldehyde (ACH) production by bacteria constituting the oral microbiota and the inhibitory effects of sugar alcohols on ACH production. The predominant bacterial components of the salivary microbiota of 166 orally healthy subjects were determined by barcoded pyrosequencing analysis of the 16S rRNA gene. Bacterial ACH production from ethanol or glucose was measured using gas chromatography. In addition, inhibition by four sugars and five sugar alcohols of ACH production was assayed. Forty-one species from 16 genera were selected as predominant and prevalent bacteria based on the following criteria: identification in ≥95% of the subjects, ≥1% of mean relative abundance or ≥5% of maximum relative abundance. All Neisseria species tested produced conspicuous amounts of ACH from ethanol, as did Rothia mucilaginosa, Streptococcus mitis and Prevotella histicola exhibited the ability to produce ACH. In addition, xylitol and sorbitol inhibited ACH production by Neisseria mucosa by more than 90%. The oral microbiota of orally healthy subjects comprises considerable amounts of bacteria possessing the ability to produce ACH, an oral carcinogen. Consumption of sugar alcohols may regulate ACH production by oral microbes. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Bacterial DNA Detected in Japanese Rice Wines and the Fermentation Starters.

    PubMed

    Terasaki, Momoka; Fukuyama, Akari; Takahashi, Yurika; Yamada, Masato; Nishida, Hiromi

    2017-12-01

    As Japanese rice wine (sake) brewing is not done aseptically, bacterial contamination is conceivable during the process of sake production. There are two types of the fermentation starter, sokujo-moto and yamahai-moto (kimoto). We identified bacterial DNA found in various sakes, the sokujo-moto and the yamahai-moto making just after sake yeast addition. Each sake has a unique variety of bacterial DNA not observed in other sakes. Although most bacterial DNA sequences detected in the sokujo-moto were found in sakes of different sake breweries, most bacterial DNA sequences detected in the yamahai-moto at the early stage of the starter fermentation were not detected in any sakes. Our findings demonstrate that various bacteria grow and then die during the process of sake brewing, as indicated by the presence of trace levels of bacterial DNA.

  8. Comparison between the evaluation of bacterial regrowth capability in a turbidimeter and biodegradable dissolved organic carbon bioreactor measurements in water.

    PubMed

    Kott, Y; Ribas, F; Frías, J; Lucena, F

    1997-09-01

    In recent years, two different approaches to the study of biodegradable organic matter in distribution systems have been followed. The assimilable organic carbon (AOC) indicates the portion of the dissolved organic matter used by bacteria and converted to biomass, which is directly measured as total bacteria, active bacteria or colony-forming units and indirectly as ATP or increase in turbidity. In contrast, the biodegradable dissolved organic carbon (BDOC) is the portion of the dissolved organic carbon that can be mineralized by heterotrophic microorganisms, and it is measured as the difference between the inflow and the outflow of a bioreactor. In this study, at different steps in a water treatment plant, the bacterial regrowth capability was determined by the AOC method that measures the maximum growth rate by using a computerized Monitek turbidimeter. The BDOC was determined using a plug flow bioreactor. Measurements of colony-forming units and total organic carbon (TOC) evolution in a turbidimeter and of colony-forming units at the inflow/outflow of the bioreactor were also performed, calculating at all sampling points the coefficient yield (Y = cfu/delta TOC) in both systems. The correlations between the results from the bioreactor and turbidimeter have been calculated; a high correlation level was observed between BDOC values and all the other parameters, except for Y calculated from bacterial suspension measured in the turbidimeter.

  9. Bacterial prostatitis.

    PubMed

    Gill, Bradley C; Shoskes, Daniel A

    2016-02-01

    The review provides the infectious disease community with a urologic perspective on bacterial prostatitis. Specifically, the article briefly reviews the categorization of prostatitis by type and provides a distillation of new findings published on bacterial prostatitis over the past year. It also highlights key points from the established literature. Cross-sectional prostate imaging is becoming more common and may lead to more incidental diagnoses of acute bacterial prostatitis. As drug resistance remains problematic in this condition, the reemergence of older antibiotics such as fosfomycin, has proven beneficial. With regard to chronic bacterial prostatitis, no clear clinical risk factors emerged in a large epidemiological study. However, bacterial biofilm formation has been associated with more severe cases. Surgery has a limited role in bacterial prostatitis and should be reserved for draining of a prostatic abscess or the removal of infected prostatic stones. Prostatitis remains a common and bothersome clinical condition. Antibiotic therapy remains the basis of treatment for both acute and chronic bacterial prostatitis. Further research into improving prostatitis treatment is indicated.

  10. Bacterial Sialidase

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

  11. Assessing the Robustness of Complete Bacterial Genome Segmentations

    NASA Astrophysics Data System (ADS)

    Devillers, Hugo; Chiapello, Hélène; Schbath, Sophie; El Karoui, Meriem

    Comparison of closely related bacterial genomes has revealed the presence of highly conserved sequences forming a "backbone" that is interrupted by numerous, less conserved, DNA fragments. Segmentation of bacterial genomes into backbone and variable regions is particularly useful to investigate bacterial genome evolution. Several software tools have been designed to compare complete bacterial chromosomes and a few online databases store pre-computed genome comparisons. However, very few statistical methods are available to evaluate the reliability of these software tools and to compare the results obtained with them. To fill this gap, we have developed two local scores to measure the robustness of bacterial genome segmentations. Our method uses a simulation procedure based on random perturbations of the compared genomes. The scores presented in this paper are simple to implement and our results show that they allow to discriminate easily between robust and non-robust bacterial genome segmentations when using aligners such as MAUVE and MGA.

  12. Effect of bacterial inoculants on phytomining of metals from waste incineration bottom ash.

    PubMed

    Rosenkranz, Theresa; Kidd, Petra; Puschenreiter, Markus

    2018-03-01

    Waste incineration bottom ash is considered a secondary resource for valuable trace elements (TE), which is currently neglected in most European countries. Phytomining could potentially recover valuable TE from such waste materials but is still at an exploratory stage with many challenges. The use of bioaugmentation to improve plant growth and TE accumulation of metal-tolerant high biomass plants growing on waste incineration bottom ash was evaluated. Bacterial strains that were previously isolated from rhizosphere, roots and contaminated soil were selected according to their plant growth promoting characteristics and tolerance to the bottom ash substrate. Those selected bacterial strains were tested for their beneficial effects on Nicotiana tabacum and Salix smithiana with regards to phytomining. The rhizobacterial strain Rhodococcus erythropolis P30 enhanced the shoot dry weight of N. tabacum by on average 57% compared to the control plants. Several bacterial inoculants enhanced biomass production and the nutritional status of S. smithiana. Moreover, those bacterial strains previously described to enhance biomass production of N. tabacum and members of the Salicaceae on TE-contaminated soils, also enhanced biomass production of these species on bottom ash. However, bacterial inoculants could not enhance trace element accumulation in plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Bacterial Production of Site Specific 13C Labeled Phenylalanine and Methodology for High Level Incorporation into Bacterially Expressed Recombinant Proteins

    PubMed Central

    Ramaraju, Bhargavi; McFeeters, Hana; Vogler, Bernhard; McFeeters, Robert L.

    2016-01-01

    Nuclear magnetic resonance spectroscopy studies of ever larger systems have benefited from many different forms of isotope labeling, in particular, site specific isotopic labeling. Site specific 13C labeling of methyl groups has become an established means of probing systems not amenable to traditional methodology. However useful, methyl reporter sites can be limited in number and/or location. Therefore, new complementary site specific isotope labeling strategies are valuable. Aromatic amino acids make excellent probes since they are often found at important interaction interfaces and play significant structural roles. Aromatic side chains have many of the same advantages as methyl containing amino acids including distinct 13C chemical shifts and multiple magnetically equivalent 1H positions. Herein we report economical bacterial production and one-step purification of phenylalanine with 13C incorporation at the Cα, Cγ and Cε positions, resulting in two isolated 1H-13C spin systems. We also present methodology to maximize incorporation of phenylalanine into recombinantly overexpressed proteins in bacteria and demonstrate compatibility with ILV-methyl labeling. Inexpensive, site specific isotope labeled phenylalanine adds another dimension to biomolecular NMR, opening new avenues of study. PMID:28028744

  14. Bacterial Cell Production from Hexadecane at High Temperatures

    PubMed Central

    Sukatsch, Dieter A.; Johnson, Marvin J.

    1972-01-01

    On mineral medium with hexadecane as the sole carbon source, stable mixed bacterial enrichment cultures were obtained from soil inoculum at 25, 35, 45, 55, and 65 C. Cell yields (grams of dry cells per gram of hexadecane) were determined for each of the enrichment cultures grown at the temperature at which they were enriched, and also for the 55 and 65 C cultures grown at various temperatures. In all cases, cell yields decreased with increasing growth temperature. The highest yield obtained at 65 C was 0.26, and the lowest yield obtained at 25 or 35 C was 1.02. Slower growth was observed at higher temperatures. PMID:5021971

  15. Analysis of the Impact of Rosuvastatin on Bacterial Mevalonate Production Using a UPLC-Mass Spectrometry Approach.

    PubMed

    Nolan, J A; Kinsella, M; Hill, C; Joyce, S A; Gahan, C G M

    2016-07-01

    Statins are widely prescribed cholesterol-lowering medications and act through inhibition of the human enzyme 3-methylglutaryl coenzyme A reductase (HMG-R) which produces mevalonate (MVAL), a key substrate for cholesterol biosynthesis. Some important microbial species also express an isoform of HMG-R; however, the nature of the interaction between statins and bacteria is currently unclear and studies would benefit from protocols to quantify MVAL in complex microbial environments. The objective of this study was to develop a protocol for the analytical quantification of MVAL in bacterial systems and to utilise this approach to analyse the effects of Rosuvastatin (RSV) on bacterial MVAL formation. To determine the effective concentration range of RSV, we examined the dose-dependent inhibition of growth in the HMG-R(+) bacterial pathogens Listeria monocytogenes, Staphylococcus aureus and Enterococcus faecium at various concentrations of pure RSV. Growth inhibition generally correlated with a reduction in bacterial MVAL levels, particularly in culture supernatants at high RSV concentrations, as determined using our ultra-performance liquid chromatography mass spectrometry protocol. This work therefore outlines a refined protocol for the analysis of MVAL in microbial cultures and provides evidence for statin-mediated inhibition of bacterial HMG-R. Furthermore, we show that MVAL is readily transported and secreted from bacterial cells into the growth media.

  16. Effect of redox conditions on bacterial and fungal biomass and carbon dioxide production in Louisiana coastal swamp forest sediment.

    PubMed

    Seo, Dong Cheol; DeLaune, Ronald D

    2010-08-01

    Fungal and bacterial carbon dioxide (CO2) production/emission was determined under a range of redox conditions in sediment from a Louisiana swamp forest used for wastewater treatment. Sediment was incubated in microcosms at 6 Eh levels (-200, -100, 0, +100, +250 and +400 mV) covering the anaerobic range found in wetland soil and sediment. Carbon dioxide production was determined by the substrate-induced respiration (SIR) inhibition method. Cycloheximide (C15H23NO4) was used as the fungal inhibitor and streptomycin (C21H39N7O12) as the bacterial inhibitor. Under moderately reducing conditions (Eh > +250 mV), fungi contributed more than bacteria to the CO2 production. Under highly reducing conditions (Eh < or = 0 mV), bacteria contributed more than fungi to the total CO2 production. The fungi/bacteria (F/B) ratios varied between 0.71-1.16 for microbial biomass C, and 0.54-0.94 for microbial biomass N. Under moderately reducing conditions (Eh > or = +100 mV), the F/B ratios for microbial biomass C and N were higher than that for highly reducing conditions (Eh < or = 0 mV). In moderately reducing conditions (Eh > or = +100 mV), the C/N microbial biomass ratio for fungi (C/N: 13.54-14.26) was slightly higher than for bacteria (C/N: 9.61-12.07). Under highly reducing redox conditions (Eh < or = 0 mV), the C/N microbial biomass ratio for fungi (C/N: 10.79-12.41) was higher than for bacteria (C/N: 8.21-9.14). For bacteria and fungi, the C/N microbial biomass ratios under moderately reducing conditions were higher than that in highly reducing conditions. Fungal CO2 production from swamp forest could be of greater ecological significance under moderately reducing sediment conditions contributing to the greenhouse effect (GHE) and the global warming potential (GWP). However, increases in coastal submergence associated with global sea level rise and resultant decrease in sediment redox potential from increased flooding would likely shift CO2 production to bacteria rather than

  17. Total Organic Carbon Distribution and Bacterial Cycling Across A Geostrophic Front In Mediterranean Sea. Implications For The Western Basin Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Sempere, R.; van Wambeke, F.; Bianchi, M.; Dafner, E.; Lefevre, D.; Bruyant, F.; Prieur, L.

    We investigated the dynamic of the total organic carbon (TOC) pool and the role it played in the carbon cycle during winter 1997-1998 in the Almeria-Oran jet-front (AOF) system resulting from the spreading of Atlantic surface water through the Gibraltar Strait in the Alboran Sea (Southwestern Mediterranean Sea). We determined TOC by using high temperature combustion technique (HTC) and bacterial produc- tion (BP; via [3H] leucine incorporation) during two legs in the frontal area. We also estimated labile TOC (l-TOC) and bacterial growth efficiency (BGE) by performing TOC biodegradation experiments on board during the cruise whereas water column semi-labile (sl-TOC), and refractory-TOC were determined from TOC profile exami- nation. These results are discussed in relation with current velocity measured by using accoustic doppler current profiler (ADCP). Lowest TOC stocks (6330-6853 mmol C m-2) over 0-100 m were measured in the northern side of the geostrophic Jet which is also the highest dynamic area (horizontal speed of 80 cm s-1 in the first 100 m di- rected eastward). Our results indicated variable turnover times of sl-TOC across the Jet-Front system, which might be explained by different coupling of primary produc- tion and bacterial production observed in these areas. We also estimated TOC and sl-TOC transports within the Jet core off the Alboran Sea as well as potential CO2 production through bacterial respiration produced from sl-TOC assimilation by het- erotrophic bacteria.

  18. Germplasm Evaluation for Resistance and Monitoring Bacterial Panicle Blight Disease of Rice in Arkansas, 2016

    USDA-ARS?s Scientific Manuscript database

    Bacterial panicle blight (BPB), caused by a bacterial pathogen, mainly Burkholderia glumae, has posed a higher level of threat to rice production worldwide in recent years. Here we report the response of over 300 entries evaluated by artificially inoculating with a bacterial suspension under field c...

  19. Colourful parrot feathers resist bacterial degradation

    PubMed Central

    Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

    2011-01-01

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

  20. Properties and applications of undecylprodigiosin and other bacterial prodigiosins.

    PubMed

    Stankovic, Nada; Senerovic, Lidija; Ilic-Tomic, Tatjana; Vasiljevic, Branka; Nikodinovic-Runic, Jasmina

    2014-05-01

    The growing demand to fulfill the needs of present-day medicine in terms of novel effective molecules has lead to reexamining some of the old and known bacterial secondary metabolites. Bacterial prodigiosins (prodiginines) have a long history of being re markable multipurpose compounds, best examined for their anticancer and antimalarial activities. Production of prodigiosin in the most common producer strain Serratia marcescens has been described in great detail. However, few reports have discussed the ecophysiological roles of these molecules in the producing strains, as well as their antibiotic and UV-protective properties. This review describes recent advances in the production process, biosynthesis, properties, and applications of bacterial prodigiosins. Special emphasis is put on undecylprodigiosin which has generally been a less studied member of the prodigiosin family. In addition, it has been suggested that proteins involved in undecylprodigiosin synthesis, RedG and RedH, could be a useful addition to the biocatalytic toolbox being able to mediate regio- and stereoselective oxidative cyclization. Judging by the number of recent references (216 for the 2007-2013 period), it has become clear that undecylprodigiosin and other bacterial prodigiosins still hold surprises in terms of valuable properties and applicative potential to medical and other industrial fields and that they still deserve continuing research curiosity.

  1. Proteome analysis of Arabidopsis seedlings exposed to bacterial volatiles.

    PubMed

    Kwon, Young Sang; Ryu, Choong-Min; Lee, Soohyun; Park, Hyo Bee; Han, Ki Soo; Lee, Jung Han; Lee, Kyunghee; Chung, Woo Sik; Jeong, Mi-Jeong; Kim, Hee Kyu; Bae, Dong-Won

    2010-11-01

    Plant root-associated bacteria (rhizobacteria) elicit plant basal immunity referred to as induced systemic resistance (ISR) against multiple pathogens. Among multi-bacterial determinants involving such ISR, the induction of ISR and promotion of growth by bacterial volatile compounds was previously reported. To exploit global de novo expression of plant proteins by bacterial volatiles, proteomic analysis was performed after exposure of Arabidopsis plants to the rhizobacterium Bacillus subtilis GB03. Ethylene biosynthesis enzymes were significantly up-regulated. Analysis by quantitative reverse transcriptase polymerase chain reaction confirmed that ethylene biosynthesis-related genes SAM-2, ACS4, ACS12, and ACO2 as well as ethylene response genes, ERF1, GST2, and CHIB were up-regulated by the exposure to bacterial volatiles. More interestingly, the emission of bacterial volatiles significantly up-regulated both key defense mechanisms mediated by jasmonic acid and salicylic acid signaling pathways. In addition, high accumulation of antioxidant proteins also provided evidence of decreased sensitivity to reactive oxygen species during the elicitation of ISR by bacterial volatiles. The present results suggest that the proteomic analysis of plant defense responses in bacterial volatile-mediated ISR can reveal the mechanisms of plant basal defenses orchestrated by endogenous ethylene production pathways and the generation of reactive oxygen species.

  2. Virulence and Immunomodulatory Roles of Bacterial Outer Membrane Vesicles

    PubMed Central

    Ellis, Terri N.; Kuehn, Meta J.

    2010-01-01

    Summary: Outer membrane (OM) vesicles are ubiquitously produced by Gram-negative bacteria during all stages of bacterial growth. OM vesicles are naturally secreted by both pathogenic and nonpathogenic bacteria. Strong experimental evidence exists to categorize OM vesicle production as a type of Gram-negative bacterial virulence factor. A growing body of data demonstrates an association of active virulence factors and toxins with vesicles, suggesting that they play a role in pathogenesis. One of the most popular and best-studied pathogenic functions for membrane vesicles is to serve as natural vehicles for the intercellular transport of virulence factors and other materials directly into host cells. The production of OM vesicles has been identified as an independent bacterial stress response pathway that is activated when bacteria encounter environmental stress, such as what might be experienced during the colonization of host tissues. Their detection in infected human tissues reinforces this theory. Various other virulence factors are also associated with OM vesicles, including adhesins and degradative enzymes. As a result, OM vesicles are heavily laden with pathogen-associated molecular patterns (PAMPs), virulence factors, and other OM components that can impact the course of infection by having toxigenic effects or by the activation of the innate immune response. However, infected hosts can also benefit from OM vesicle production by stimulating their ability to mount an effective defense. Vesicles display antigens and can elicit potent inflammatory and immune responses. In sum, OM vesicles are likely to play a significant role in the virulence of Gram-negative bacterial pathogens. PMID:20197500

  3. Jellyfish modulate bacterial dynamic and community structure.

    PubMed

    Tinta, Tinkara; Kogovšek, Tjaša; Malej, Alenka; Turk, Valentina

    2012-01-01

    Jellyfish blooms have increased in coastal areas around the world and the outbreaks have become longer and more frequent over the past few decades. The Mediterranean Sea is among the heavily affected regions and the common bloom-forming taxa are scyphozoans Aurelia aurita s.l., Pelagia noctiluca, and Rhizostoma pulmo. Jellyfish have few natural predators, therefore their carcasses at the termination of a bloom represent an organic-rich substrate that supports rapid bacterial growth, and may have a large impact on the surrounding environment. The focus of this study was to explore whether jellyfish substrate have an impact on bacterial community phylotype selection. We conducted in situ jellyfish-enrichment experiment with three different jellyfish species. Bacterial dynamic together with nutrients were monitored to assess decaying jellyfish-bacteria dynamics. Our results show that jellyfish biomass is characterized by protein rich organic matter, which is highly bioavailable to 'jellyfish-associated' and 'free-living' bacteria, and triggers rapid shifts in bacterial population dynamics and composition. Based on 16S rRNA clone libraries and denaturing gradient gel electrophoresis (DGGE) analysis, we observed a rapid shift in community composition from unculturable Alphaproteobacteria to culturable species of Gammaproteobacteria and Flavobacteria. The results of sequence analyses of bacterial isolates and of total bacterial community determined by culture independent genetic analysis showed the dominance of the Pseudoalteromonadaceae and the Vibrionaceae families. Elevated levels of dissolved proteins, dissolved organic and inorganic nutrient release, bacterial abundance and carbon production as well as ammonium concentrations characterized the degradation process. The biochemical composition of jellyfish species may influence changes in the amount of accumulated dissolved organic and inorganic nutrients. Our results can contribute insights into possible changes in

  4. Evaluation of quantitative PCR measurement of bacterial colonization of epithelial cells.

    PubMed

    Schmidt, Marcin T; Olejnik-Schmidt, Agnieszka K; Myszka, Kamila; Borkowska, Monika; Grajek, Włodzimierz

    2010-01-01

    Microbial colonization is an important step in establishing pathogenic or probiotic relations to host cells and in biofilm formation on industrial or medical devices. The aim of this work was to verify the applicability of quantitative PCR (Real-Time PCR) to measure bacterial colonization of epithelial cells. Salmonella enterica and Caco-2 intestinal epithelial cell line was used as a model. To verify sensitivity of the assay a competition of the pathogen cells to probiotic microorganism was tested. The qPCR method was compared to plate count and radiolabel approach, which are well established techniques in this area of research. The three methods returned similar results. The best quantification accuracy had radiolabel method, followed by qPCR. The plate count results showed coefficient of variation two-times higher than this of qPCR. The quantitative PCR proved to be a reliable method for enumeration of microbes in colonization assay. It has several advantages that make it very useful in case of analyzing mixed populations, where several different species or even strains can be monitored at the same time.

  5. An operon for production of bioactive gibberellin A4 phytohormone with wide distribution in the bacterial rice leaf streak pathogen Xanthomonas oryzae pv. oryzicola.

    PubMed

    Nagel, Raimund; Turrini, Paula C G; Nett, Ryan S; Leach, Jan E; Verdier, Valérie; Van Sluys, Marie-Anne; Peters, Reuben J

    2017-05-01

    Phytopathogens have developed elaborate mechanisms to attenuate the defense response of their host plants, including convergent evolution of complex pathways for production of the GA phytohormones, which were actually first isolated from the rice fungal pathogen Gibberella fujikuroi. The rice bacterial pathogen Xanthomonas oryzae pv. oryzicola (Xoc) has been demonstrated to contain a biosynthetic operon with cyclases capable of producing the universal GA precursor ent-kaurene. Genetic (knock-out) studies indicate that the derived diterpenoid serves as a virulence factor for this rice leaf streak pathogen, serving to reduce the jasmonic acid-mediated defense response. Here the functions of the remaining genes in the Xoc operon are elucidated and the distribution of the operon in X. oryzae is investigated in over 100 isolates. The Xoc operon leads to production of the bioactive GA 4 , an additional step beyond production of the penultimate precursor GA 9 mediated by the homologous operons recently characterized from rhizobia. Moreover, this GA biosynthetic operon was found to be widespread in Xoc (> 90%), but absent in the other major X. oryzae pathovar. These results indicate selective pressure for production of GA 4 in the distinct lifestyle of Xoc, and the importance of GA to both fungal and bacterial pathogens of rice. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  6. Bacterial trajectories tracked with time-lapse video-microscopy reveal the impact of manganese biomineralization on bacterial sedimentation.

    NASA Astrophysics Data System (ADS)

    Kerboas, Camille; Pena, Jasquelin; De Anna, Pietro

    2017-04-01

    In aquatic and subsurface environments, sedimentation may influence bacterial transport. Microorganisms that carry out biomineralization reactions may exhibit distinct transport properties from non-biomineralizing organisms due an apparent increase in density caused by biomineral production. For several decades, the biomineralization of manganese (Mn) has been recognized to be a major environmental process, whereby Mn oxide (MnO2(s)) minerals participate in a plethora of biogeochemical processes including contaminant adsorption, organic matter oxidation. Typically, manganese biomineralization proceeds through the enzymatic oxidation of aqueous Mn2+ to Mn4+ and precipitation of MnO2(s) in a biofilm matrix outside the bacterial cell. Here, we present a study of the impact of biomineralization on the sedimentation properties of bacteria at small scales (over mm distances) under hydrostatic conditions. We hypothesize that bacteria will sediment faster when biomineralization is active due to encrustation of the organisms by mineral particles. To test this hypothesis, we tracked the vertical notion of individual bacteria (Pseudomonas putida GB-1) using time-lapse video-microscopy. We compared the sedimentation velocity of bacteria in the case where significant biomineralization had occurred, as inferred from bulk measurements of solid phase Mn, with the sinking velocity of bacteria grown without Mn. We calibrated the proposed method by comparing velocity measurements of sinking polystyrene micro-sphere of known density and size with Stokes law, obtaining results that were accurate within 1% of the theoretical value (29.4 nm/s). We also measured a diffusion coefficient of 7x10-13 m2/s for the particles. Following this approach, we measured the sedimentation velocity of P. putida with and without MnO2(s). Our results show that biomineralization leads to faster sedimentation of the bacteria. In natural environments, biomineralization reactions may increase the sinking

  7. Diversity, Productivity, and Stability of an Industrial Microbial Ecosystem

    PubMed Central

    Tang, Pei-Zhong; Becker, Scott; Hoang, Tony; Bilgin, Damla; Lim, Yan Wei; Peterson, Todd C.; Mayfield, Stephen; Haerizadeh, Farzad; Shurin, Jonathan B.; Bafna, Vineet; McBride, Robert

    2016-01-01

    Managing ecosystems to maintain biodiversity may be one approach to ensuring their dynamic stability, productivity, and delivery of vital services. The applicability of this approach to industrial ecosystems that harness the metabolic activities of microbes has been proposed but has never been tested at relevant scales. We used a tag-sequencing approach with bacterial small subunit rRNA (16S) genes and eukaryotic internal transcribed spacer 2 (ITS2) to measuring the taxonomic composition and diversity of bacteria and eukaryotes in an open pond managed for bioenergy production by microalgae over a year. Periods of high eukaryotic diversity were associated with high and more-stable biomass productivity. In addition, bacterial diversity and eukaryotic diversity were inversely correlated over time, possibly due to their opposite responses to temperature. The results indicate that maintaining diverse communities may be essential to engineering stable and productive bioenergy ecosystems using microorganisms. PMID:26896141

  8. Leaky RAG Deficiency in Adult Patients with Impaired Antibody Production against Bacterial Polysaccharide Antigens

    PubMed Central

    Geier, Christoph B.; Piller, Alexander; Linder, Angela; Sauerwein, Kai M. T.; Eibl, Martha M.; Wolf, Hermann M.

    2015-01-01

    Loss of function mutations in the recombination activating genes RAG1 and RAG2 have been reported to cause a T-B-NK+ type of severe combined immunodeficiency. In addition identification of hypomorphic mutations in RAG1 and RAG2 has led to an expansion of the spectrum of disease to include Omenn syndrome, early onset autoimmunity, granuloma, chronic cytomegalovirus- or EBV-infection with expansion of gamma/delta T-cells, idiophatic CD4 lymphopenia and a phenotype resembling common variable immunodeficiency. Herein we describe a novel presentation of leaky RAG1 and RAG2 deficiency in two unrelated adult patients with impaired antibody production against bacterial polysaccharide antigens. Clinical manifestation included recurrent pneumonia, sinusitis, otitis media and in one patient recurrent cutaneous vasculitis. Both patients harbored a combination of a null mutation on one allele with a novel hypomorphic RAG1/2 mutation on the other allele. One of these novel mutations affected the start codon of RAG1 and resulted in an aberrant gene and protein expression. The second novel RAG2 mutation leads to a truncated RAG2 protein, lacking the C-terminus with intact core RAG2 and reduced VDJ recombination capacity as previously described in a mouse model. Both patients presented with severely decreased numbers of naïve CD4+ T cells and defective T independent IgG responses to bacterial polysaccharide antigens, while T cell-dependent IgG antibody formation e.g. after tetanus or TBEV vaccination was intact. In conclusion, hypomorphic mutations in genes responsible for SCID should be considered in adults with predominantly antibody deficiency. PMID:26186701

  9. Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

    PubMed

    Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María Del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio; Muñoz-Rojas, Jesús

    2017-01-01

    Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

  10. Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth

    PubMed Central

    Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio

    2017-01-01

    Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications. PMID:29117218

  11. Development of a multispectral light-scatter sensor for bacterial colonies

    USDA-ARS?s Scientific Manuscript database

    We report a multispectral elastic-light-scatter instrument that can simultaneously detect three-wavelength scatter patterns and associated optical densities from individual bacterial colonies, overcoming the limits of the single-wavelength predecessor. Absorption measurements on liquid bacterial sam...

  12. Bacterial bioluminescence onset and quenching: a dynamical model for a quorum sensing-mediated property

    PubMed Central

    Side, Domenico Delle; Nassisi, Vincenzo; Pennetta, Cecilia; Alifano, Pietro; Di Salvo, Marco; Talà, Adelfia; Chechkin, Aleksei; Seno, Flavio

    2017-01-01

    We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distributions of photon emission times, previously measured for bacterial colonies of Vibrio jasicida, a luminescent bacterium belonging to the Harveyi clade, growing in a highly drying environment. A distinctive and novel feature of the proposed model is bioluminescence ‘quenching’ after a given time elapsed from activation. Using an advanced fitting procedure based on the simulated annealing algorithm, we are able to infer from the experimental observations the biochemical parameters used in the model. Such parameters are in good agreement with the literature data. As a further result, we find that, at least in our experimental conditions, light emission in bioluminescent bacteria appears to originate from a subtle balance between colony growth and quorum activation due to autoinducers diffusion, with the two phenomena occurring on the same time scale. This finding is consistent with a negative feedback mechanism previously reported for Vibrio harveyi. PMID:29308273

  13. Bacterial bioluminescence onset and quenching: a dynamical model for a quorum sensing-mediated property.

    PubMed

    Side, Domenico Delle; Nassisi, Vincenzo; Pennetta, Cecilia; Alifano, Pietro; Di Salvo, Marco; Talà, Adelfia; Chechkin, Aleksei; Seno, Flavio; Trovato, Antonio

    2017-12-01

    We present an effective dynamical model for the onset of bacterial bioluminescence, one of the most studied quorum sensing-mediated traits. Our model is built upon simple equations that describe the growth of the bacterial colony, the production and accumulation of autoinducer signal molecules, their sensing within bacterial cells, and the ensuing quorum activation mechanism that triggers bioluminescent emission. The model is directly tested to quantitatively reproduce the experimental distributions of photon emission times, previously measured for bacterial colonies of Vibrio jasicida , a luminescent bacterium belonging to the Harveyi clade, growing in a highly drying environment. A distinctive and novel feature of the proposed model is bioluminescence 'quenching' after a given time elapsed from activation. Using an advanced fitting procedure based on the simulated annealing algorithm, we are able to infer from the experimental observations the biochemical parameters used in the model. Such parameters are in good agreement with the literature data. As a further result, we find that, at least in our experimental conditions, light emission in bioluminescent bacteria appears to originate from a subtle balance between colony growth and quorum activation due to autoinducers diffusion, with the two phenomena occurring on the same time scale. This finding is consistent with a negative feedback mechanism previously reported for Vibrio harveyi .

  14. Gallstones containing bacteria are biofilms: bacterial slime production and ability to form pigment solids determines infection severity and bacteremia.

    PubMed

    Stewart, Lygia; Griffiss, J McLeod; Jarvis, Gary A; Way, Lawrence W

    2007-08-01

    Gallstone bacteria provide a reservoir for biliary infections. Slime production facilitates adherence, whereas beta-glucuronidase and phospholipase generate colonization surface. These factors facilitate gallstone formation, but their influence on infection severity is unknown. Two hundred ninety-two patients were studied. Gallstones, bile, and blood (as applicable) were cultured. Bacteria were tested for beta-glucuronidase/phospholipase production and quantitative slime production. Infection severity was correlated with bacterial factors. Bacteria were present in 43% of cases, 13% with bacteremia. Severe infections correlated directly with beta-glucuronidase/phospholipase (55% with vs 13% without, P < 0.0001), but inversely with slime production (55 vs 8%, slime <75 or >75, P = 0.008). Low slime production and beta-glucuronidase/phospholipase production were additive: Severe infections were present in 76% with both, but 10% with either or none (P < 0.0001). beta-Glucuronidase/phospholipase production facilitated bactibilia (86% with vs 62% without, P = 0.03). Slime production was 19 (+/-8) vs 50 (+/-10) for bacteria that did or did not cause bacteremia (P = 0.004). No bacteria with slime >75 demonstrated bacteremia. Bacteria-laden gallstones are biofilms whose characteristics influence illness severity. Factors creating colonization surface (beta-glucuronidase/phospholipase) facilitated bacteremia and severe infections; but abundant slime production, while facilitating colonization, inhibited detachment and cholangiovenous reflux. This shows how properties of the gallstone biofilm determine the severity of the associated illness.

  15. Global Patterns of Bacterial Beta-Diversity in Seafloor and Seawater Ecosystems

    PubMed Central

    Zinger, Lucie; Amaral-Zettler, Linda A.; Fuhrman, Jed A.; Horner-Devine, M. Claire; Huse, Susan M.; Welch, David B. Mark; Martiny, Jennifer B. H.; Sogin, Mitchell; Boetius, Antje; Ramette, Alban

    2011-01-01

    Background Marine microbial communities have been essential contributors to global biomass, nutrient cycling, and biodiversity since the early history of Earth, but so far their community distribution patterns remain unknown in most marine ecosystems. Methodology/Principal Findings The synthesis of 9.6 million bacterial V6-rRNA amplicons for 509 samples that span the global ocean's surface to the deep-sea floor shows that pelagic and benthic communities greatly differ, at all taxonomic levels, and share <10% bacterial types defined at 3% sequence similarity level. Surface and deep water, coastal and open ocean, and anoxic and oxic ecosystems host distinct communities that reflect productivity, land influences and other environmental constraints such as oxygen availability. The high variability of bacterial community composition specific to vent and coastal ecosystems reflects the heterogeneity and dynamic nature of these habitats. Both pelagic and benthic bacterial community distributions correlate with surface water productivity, reflecting the coupling between both realms by particle export. Also, differences in physical mixing may play a fundamental role in the distribution patterns of marine bacteria, as benthic communities showed a higher dissimilarity with increasing distance than pelagic communities. Conclusions/Significance This first synthesis of global bacterial distribution across different ecosystems of the World's oceans shows remarkable horizontal and vertical large-scale patterns in bacterial communities. This opens interesting perspectives for the definition of biogeographical biomes for bacteria of ocean waters and the seabed. PMID:21931760

  16. Bacterial Production of Poly(3-hydroxybutyrate): An Undergraduate Student Laboratory Experiment

    ERIC Educational Resources Information Center

    Burns, Kristi L.; Oldham, Charlie D.; May, Sheldon W.

    2009-01-01

    As part of a multidisciplinary course that is cross-listed between five departments, we developed an undergraduate student laboratory experiment for culturing, isolating, and purifying the biopolymer, poly(3-hydroxybutyrate), PHB. This biopolyester accumulates in the cytoplasm of bacterial cells under specific growth conditions, and it has…

  17. Enhancement of biogas production from microalgal biomass through cellulolytic bacterial pretreatment.

    PubMed

    Kavitha, S; Subbulakshmi, P; Rajesh Banu, J; Gobi, Muthukaruppan; Tae Yeom, Ick

    2017-06-01

    Generation of bioenergy from microalgal biomass has been a focus of interest in recent years. The recalcitrant nature of microalgal biomass owing to its high cellulose content limits methane generation. Thus, the present study investigates the effect of bacterial-based biological pretreatment on liquefaction of the microalga Chlorella vulgaris prior to anaerobic biodegradation to gain insights into energy efficient biomethanation. Liquefaction of microalgae resulted in a higher biomass stress index of about 18% in the experimental (pretreated with cellulose-secreting bacteria) vs. 11.8% in the control (non-pretreated) group. Mathematical modelling of the biomethanation studies implied that bacterial pretreatment had a greater influence on sustainable methane recovery, with a methane yield of about 0.08 (g Chemical Oxygen Demand/g Chemical Oxygen Demand), than did control pretreatment, with a yield of 0.04 (g Chemical Oxygen Demand/g Chemical Oxygen Demand). Energetic analysis of the proposed method of pretreatment showed a positive energy ratio of 1.04. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

    PubMed Central

    Limoli, Dominique H.; Jones, Christopher J.; Wozniak, Daniel J.

    2015-01-01

    Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms. PMID:26185074

  19. Bacterial Extracellular Polysaccharides in Biofilm Formation and Function.

    PubMed

    Limoli, Dominique H; Jones, Christopher J; Wozniak, Daniel J

    2015-06-01

    Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.

  20. Bacterial diversity characterization in petroleum samples from Brazilian reservoirs

    PubMed Central

    de Oliveira, Valéria Maia; Sette, Lara Durães; Simioni, Karen Christina Marques; dos Santos Neto, Eugênio Vaz

    2008-01-01

    This study aimed at evaluating potential differences among the bacterial communities from formation water and oil samples originated from biodegraded and non-biodegraded Brazilian petroleum reservoirs by using a PCR-DGGE based approach. Environmental DNA was isolated and used in PCR reactions with bacterial primers, followed by separation of 16S rDNA fragments in the DGGE. PCR products were also cloned and sequenced, aiming at the taxonomic affiliation of the community members. The fingerprints obtained allowed the direct comparison among the bacterial communities from oil samples presenting distinct degrees of biodegradation, as well as between the communities of formation water and oil sample from the non-biodegraded reservoir. Very similar DGGE band profiles were observed for all samples, and the diversity of the predominant bacterial phylotypes was shown to be low. Cloning and sequencing results revealed major differences between formation water and oil samples from the non-biodegraded reservoir. Bacillus sp. and Halanaerobium sp. were shown to be the predominant components of the bacterial community from the formation water sample, whereas the oil sample also included Alicyclobacillus acidoterrestris, Rhodococcus sp., Streptomyces sp. and Acidithiobacillus ferrooxidans. The PCR-DGGE technique, combined with cloning and sequencing of PCR products, revealed the presence of taxonomic groups not found previously in these samples when using cultivation-based methods and 16S rRNA gene library assembly, confirming the need of a polyphasic study in order to improve the knowledge of the extent of microbial diversity in such extreme environments. PMID:24031244

  1. Phytoplankton production systems in a shellfish hatchery: variations of the bacterial load and diversity of vibrios.

    PubMed

    Dubert, J; Fernández-Pardo, A; Nóvoa, S; Barja, J L; Prado, S

    2015-06-01

    Outbreaks of disease caused by some Vibrio species represent the main production bottleneck in shellfish hatcheries. Although the phytoplankton used as food is one of the main sources of bacteria, studies of the associated bacterial populations, specifically vibrios, are scarce. The aim of the study was the microbiological monitoring of the microalgae as the first step in assessing the risk disease for bivalve cultures. Two phytoplankton production systems were sampled weekly throughout 1-year period in a bivalve hatchery. Quantitative analysis revealed high levels of marine heterotrophic bacteria in both systems throughout the study. Presumptive vibrios were detected occasionally and at low concentrations. In most of the cases, they belonged to the Splendidus and Harveyi clades. The early detection of vibrios in the microalgae may be the key for a successful bivalve culture. Their abundance and diversity were affected by factors related to the hatchery environment. This work represents the first long study where the presence of vibrios was evaluated rigorously in phytoplankton production systems and provides a suitable microbiological protocol to control and guarantee the quality of the algal cultures to avoid the risk of transferring potential pathogens to shellfish larvae and/or broodstock. © 2015 The Society for Applied Microbiology.

  2. Hemoadsorption corrects hyperresistinemia and restores anti-bacterial neutrophil function.

    PubMed

    Bonavia, Anthony; Miller, Lauren; Kellum, John A; Singbartl, Kai

    2017-12-01

    Mounting evidence suggests that sepsis-induced morbidity and mortality are due to both immune activation and immunosuppression. Resistin is an inflammatory cytokine and uremic toxin. Septic hyperresistinemia (plasma resistin >20 ng/ml) has been associated with greater disease severity and worse outcomes, and it is further exacerbated by concomitant acute kidney injury (AKI). Septic hyperresistinemia disturbs actin polymerization in neutrophils leading to impaired neutrophil migration, a crucial first-line mechanism in host defense to bacterial infection. Our experimental objective was to study the effects of hyperresistinemia on other F-actin-dependent neutrophil defense mechanisms, in particular intracellular bacterial clearance and generation of reactive oxygen species (ROS). We also sought to examine the effects of hemoadsorption on hyperresistinemia and neutrophil dysfunction. Thirteen patients with septic shock and six control patients were analyzed for serum resistin levels and their effects on neutrophil migration. In vitro, following incubation with resistin-spiked serum samples, Pseudomonas aeruginosa clearance and ROS generation in neutrophils were measured. Phosphorylation of 3-phosphoinositide-dependent protein kinase-1 (PDPK1) was assessed using flow cytometry. In vitro hemoadsorption with both Amberchrome™ columns (AC) and CytoSorb® cartridges (CC) were used to test correction of hyperresistinemia. We further tested AC for their effect on cell migration and ROS generation and CC for their effect on bacterial clearance. Patients with septic shock had higher serum resistin levels than control ICU patients and showed a strong, negative correlation between hyperresistinemia and neutrophil transwell migration (ρ= - 0.915, p < 0.001). In vitro, neutrophils exposed to hyperresistinemia exhibited twofold lower intracellular bacterial clearance rates compared to controls. Resistin impaired intracellular signaling and ROS production in a dose

  3. Surface-attached and suspended bacterial community structure as affected by C/N ratios: relationship between bacteria and fish production.

    PubMed

    Yu, Ermeng; Xie, Jun; Wang, Jinlin; Ako, Harry; Wang, Guangjun; Chen, Zhanghe; Liu, Yongfeng

    2016-07-01

    Bacteria play crucial roles in the combined system of substrate addition and C/N control, which has been demonstrated to improve aquaculture production. However, the complexity of surface-attached bacteria on substrates and suspended bacteria in the water column hamper further application of this system. This study firstly applied this combined system into the culture of grass carp, and then explored the relationship between microbial complexes from surface-attached and suspended bacteria in this system and the production of grass carp. In addition, this study investigated bacterial community structures as affected by four C/N ratios using Illumina sequencing technology. The results demonstrated that the weight gain rate and specific growth rate of grass carp in the CN20 group (C/N ratio 20:1) were the highest (P < 0.05), and dietary supplementation of the microbial complex had positive effects on the growth of grass carp (P < 0.05). Sequencing data revealed that, (1) the proportions of Verrucomicrobiae and Rhodobacter (surface-attached), sediminibacterium (suspended), and emticicia (surface-attached and suspended) were much higher in the CN20 group compared with those in the other groups (P < 0.05); (2) Rhodobacter, Flavobacterium, Acinetobacter, Pseudomonas, Planctomyces, and Cloacibacterium might be important for the microbial colonization on substrates; (3) as the C/N ratio increased, proportions of Hydrogenophaga (surface-attached and suspended), Zoogloea, and Flectobacillus (suspended) increased, but proportions of Bacillus, Clavibacter, and Cellvibro (surface-attached and suspended) decreased. In summary, a combined system of substrate addition and C/N control increased the production of grass carp, and Verrucomicrobiae and Rhodobacter in the surface-attached bacterial community were potential probiotic bacteria that contributed to the enhanced growth of grass carp.

  4. Future direction in marine bacterial agarases for industrial applications.

    PubMed

    Jahromi, Saeid Tamadoni; Barzkar, Noora

    2018-06-16

    The marine ecosystem has been known to be a rich source of novel enzymes. Agarase is a key enzyme that can hydrolyze agar in the marine environment. Marine bacterial agarase has been isolated from various sources, such as sediments, coastal water, and deep sea and from the surface of crustaceans and seaweeds. This review presents an account of the agarase production of marine bacteria. General information about agar, agarase, isolation, and purification of marine bacterial agarases; the biochemical properties of native agarase from marine bacteria; the biochemical properties of recombinant marine bacterial agarases from engineered microorganisms; and the industrial future of marine bacterial agarases is analyzed. With recent biotechnological processes, researchers need novel functional enzymes like agarase from marine resources, such as marine bacteria, that can be used for diverse applications in the biotechnological industry. Marine bacterial agarases might be of significant interest to the industry because they are safe and are a natural source. This review highlights the potential of marine bacteria as important sources of agarase for application in various industries.

  5. Physiological changes induced in four bacterial strains following oxidative stress.

    PubMed

    Baatout, S; De Boever, P; Mergeay, M

    2006-01-01

    In order to study the behaviour and resistance of bacteria under extreme conditions, physiological changes associated with oxidative stress were monitored using flow cytometry. The study was conducted to assess the maintenance of membrane integrity and potential as well as the esterase activity, the intracellular pH and the production of superoxide anions in four bacterial strains (Ralstonia metallidurans, Escherichia coli, Shewanella oneidensis and Deinococcus radiodurans). The strains were chosen for their potential usefulness in bioremediation. Suspensions of R. metallidurans, E. coli, S. oneidensis and D. radiodurans were submitted to 1 h oxidative stress (H2O2 at various concentrations from 0 to 880 mM). Cell membrane permeability (propidium iodide) and potential (rhodamine-123, 3,3'-dihexyloxacarbocyanine iodide), intracellular esterase activity (fluorescein diacetate), intracellular reactive oxygen species concentration (hydroethidine) and intracellular pH (carboxyflurorescein diacetate succinimidyl ester (5(6)) were monitored to evaluate the physiological state and the overall fitness of individual bacterial cells under oxidative stress. The four bacterial strains exhibited varying sensitivities towards H2O2. However, for all bacterial strains, some physiological damage could already be observed from 13.25 mM H2O2 onwards, in particular with regard to their membrane permeability. Depending on the bacterial strains, moderate to high physiological damage could be observed between 13.25 mM and 220 mM H2O2. Membrane potential, esterase activity, intracellular pH and production of superoxide anion production were considerably modified at high H2O2 concentrations in all four strains. In conclusion, we show that a range of significant physiological alterations occurs when bacteria are challenged with H2O2 and fluorescent staining methods coupled with flow cytometry are useful for monitoring the changes induced not only by oxidative stress but also by other

  6. Transient changes in milk production efficiency and bacterial community composition resulting from near-total exchange of ruminal contents between high- and low-efficiency Holstein cows

    USDA-ARS?s Scientific Manuscript database

    The objectives of this study were to determine if milk production efficiency (MPE) is altered by near-total exchange of ruminal contents between high- (HE) and low-MPE (LE) cows and to characterize ruminal bacterial community composition (BCC) prior to exchange and over time post-exchange. Three pai...

  7. Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis

    PubMed Central

    Liu, Xiaokun; Grabherr, Heini M; Willmann, Roland; Kolb, Dagmar; Brunner, Frédéric; Bertsche, Ute; Kühner, Daniel; Franz-Wachtel, Mirita; Amin, Bushra; Felix, Georg; Ongena, Marc; Nürnberger, Thorsten; Gust, Andrea A

    2014-01-01

    Peptidoglycans (PGNs) are immunogenic bacterial surface patterns that trigger immune activation in metazoans and plants. It is generally unknown how complex bacterial structures such as PGNs are perceived by plant pattern recognition receptors (PRRs) and whether host hydrolytic activities facilitate decomposition of bacterial matrices and generation of soluble PRR ligands. Here we show that Arabidopsis thaliana, upon bacterial infection or exposure to microbial patterns, produces a metazoan lysozyme-like hydrolase (lysozyme 1, LYS1). LYS1 activity releases soluble PGN fragments from insoluble bacterial cell walls and cleavage products are able to trigger responses typically associated with plant immunity. Importantly, LYS1 mutant genotypes exhibit super-susceptibility to bacterial infections similar to that observed on PGN receptor mutants. We propose that plants employ hydrolytic activities for the decomposition of complex bacterial structures, and that soluble pattern generation might aid PRR-mediated immune activation in cell layers adjacent to infection sites. DOI: http://dx.doi.org/10.7554/eLife.01990.001 PMID:24957336

  8. ATLAS measurement of Electroweak Vector Boson production

    NASA Astrophysics Data System (ADS)

    Vittori, C.; Atlas Collaboration

    2017-01-01

    The measurements of the Drell-Yan production of W and Z /γ* bosons at the LHC provide a benchmark of our understanding of the perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed new high precision measurements of the double differential cross-sections as a function of the dilepton mass and rapidity. The measurements are compared to state of calculations at NNLO in QCD and constrain the photon content of the proton. The angular distributions of the Drell-Yan lepton pairs around the Z-boson mass peak probe the underlying QCD dynamics of the Z-boson production mechanisms. The complete set of angular coefficients describing these distributions is presented and compared to theoretical predictions highlighting different approaches of the QCD and EW modelling. First precise inclusive measurements of W and Z production at 13 TeV are presented. W / Z and W+ /W- ratios profit from a cancellation of experimental uncertainties.

  9. Exploitation of algal-bacterial associations in a two-stage biohydrogen and biogas generation process.

    PubMed

    Wirth, Roland; Lakatos, Gergely; Maróti, Gergely; Bagi, Zoltán; Minárovics, János; Nagy, Katalin; Kondorosi, Éva; Rákhely, Gábor; Kovács, Kornél L

    2015-01-01

    The growing concern regarding the use of agricultural land for the production of biomass for food/feed or energy is dictating the search for alternative biomass sources. Photosynthetic microorganisms grown on marginal or deserted land present a promising alternative to the cultivation of energy plants and thereby may dampen the 'food or fuel' dispute. Microalgae offer diverse utilization routes. A two-stage energetic utilization, using a natural mixed population of algae (Chlamydomonas sp. and Scenedesmus sp.) and mutualistic bacteria (primarily Rhizobium sp.), was tested for coupled biohydrogen and biogas production. The microalgal-bacterial biomass generated hydrogen without sulfur deprivation. Algal hydrogen production in the mixed population started earlier but lasted for a shorter period relative to the benchmark approach. The residual biomass after hydrogen production was used for biogas generation and was compared with the biogas production from maize silage. The gas evolved from the microbial biomass was enriched in methane, but the specific gas production was lower than that of maize silage. Sustainable biogas production from the microbial biomass proceeded without noticeable difficulties in continuously stirred fed-batch laboratory-size reactors for an extended period of time. Co-fermentation of the microbial biomass and maize silage improved the biogas production: The metagenomic results indicated that pronounced changes took place in the domain Bacteria, primarily due to the introduction of a considerable bacterial biomass into the system with the substrate; this effect was partially compensated in the case of co-fermentation. The bacteria living in syntrophy with the algae apparently persisted in the anaerobic reactor and predominated in the bacterial population. The Archaea community remained virtually unaffected by the changes in the substrate biomass composition. Through elimination of cost- and labor-demanding sulfur deprivation, sustainable

  10. Primary and heterotrophic productivity relate to multikingdom diversity in a hypersaline mat

    PubMed Central

    Brislawn, Colin J.; Dana, Karl; Flores-Wentz, Tobias; Cory, Alexandra B.; Fansler, Sarah J.; Fredrickson, James K.; Moran, James J.

    2017-01-01

    Abstract Benthic microbial ecosystems are widespread yet knowledge gaps still remain on the relationships between the diversity of species across kingdoms and productivity. Here, we ask two fundamental questions: (i) How does species diversity relate to the rates of primary and heterotrophic productivity? (ii) How do diel variations in light-energy inputs influence productivity and microbiome diversity? To answer these questions, microbial mats from a magnesium sulfate hypersaline lake were used to establish microcosms. Both the number and relatedness between bacterial and eukaryotic taxa in the microbiome were assayed via amplicon-based sequencing of 16S and 18S rRNA genes over two diel cycles. These results correlated with biomass productivity obtained from substrate-specific 13C stable isotope tracers that enabled comparisons between primary and heterotrophic productivity. Both bacterial and eukaryotic species richness and evenness were related only to the rates of 13C-labeled glucose and acetate biomass incorporation. Interestingly, measures of these heterotrophic relationships changed from positive and negative correlations depending on carbon derived from glucose or acetate, respectively. The bacterial and eukaryotic diversity of this ecosystem is also controlled, in part, from energy constraints imposed by changing irradiance over a diel cycle. PMID:29045626

  11. [Bacterial meningitis].

    PubMed

    Brouwer, M C; van de Beek, D

    2012-05-01

    Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria meningtidis group C and Streptococcus pneumoniae. Due to these vaccines, meningitis is now predominantly a disease occurring in adults, caused especially by Streptococcus pneumoniae, while it was formerly a child disease which was largely caused by Haemophilus influenzae. Bacterial meningitis is often difficult to recognize since the classical presentation with neck stiffness, reduced awareness and fever occurs in less than half of the patients. The only way to diagnose or exclude bacterial meningitis is by performing low-threshold cerebrospinal fluid examination with a suspicion of bacterial meningitis. The treatment consists of the prescription of antibiotics and dexamethasone.

  12. Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Mehrübeoglu, Mehrube; Buck, Gregory W.; Livingston, Daniel W.

    2014-09-01

    Detection and identification of bacteria are important for health and safety. Hyperspectral imaging offers the potential to capture unique spectral patterns and spatial information from bacteria which can then be used to detect and differentiate bacterial species. Here, hyperspectral imaging has been used to characterize different bacterial colonies and investigate their growth over time. Six bacterial species (Pseudomonas fluorescens, Escherichia coli, Serratia marcescens, Salmonella enterica, Staphylococcus aureus, Enterobacter aerogenes) were grown on tryptic soy agar plates. Hyperspectral data were acquired immediately after, 24 hours after, and 96 hours after incubation. Spectral signatures from bacterial colonies demonstrated repeatable measurements for five out of six species. Spatial variations as well as changes in spectral signatures were observed across temporal measurements within and among species at multiple wavelengths due to strengthening or weakening reflectance signals from growing bacterial colonies based on their pigmentation. Between-class differences and within-class similarities were the most prominent in hyperspectral data collected 96 hours after incubation.

  13. Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells.

    PubMed

    Peternel, Spela; Komel, Radovan

    2010-09-10

    In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry.To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process.To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared.During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation.During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity.High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells.

  14. Bacterial Sphingomyelinases and Phospholipases as Virulence Factors

    PubMed Central

    Flores-Díaz, Marietta; Monturiol-Gross, Laura; Naylor, Claire

    2016-01-01

    SUMMARY Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases. PMID:27307578

  15. Two cases of bacterial meningitis accompanied by thalidomide therapy in patients with multiple myeloma: is thalidomide associated with bacterial meningitis?

    PubMed

    Pasa, Semir; Altintas, Abdullah; Cil, Timucin; Ustun, Cemal; Bayan, Kadim; Danis, Ramazan; Urakci, Zuhat; Tuzun, Yekta; Ayyildiz, Orhan

    2009-01-01

    Morbidity and mortality in multiple myeloma is often attributed to life-threatening infections. A defect in humoral immunity has been proposed for the predisposition to bacterial infections. Most of the infections are of bacterial origin, and the most serious are septicemia, meningitis, and pneumonia. Thalidomide is a drug with pleiotropic effects. The immunomodulatory effects of thalidomide are at least partially mediated through its ability to down-regulate the pathogenic over-production of tumor necrosis factor-alpha (TNF-alpha). TNF-alpha is a cytokine that plays a central role in the regulation of the host immune and inflammatory response to infection. In the central nervous system, TNF-alpha is involved in induction of a fever response and triggers the release of other cytokines, and may also influence transport of compounds into the brain, leading to cerebrospinal fluid leukocytosis, increased protein influx, and lactate accumulation. Thalidomide has been shown to down-regulate the production of TNF-alpha. On the other hand, knowledge of the effects of thalidomide on granulocyte functions is limited. Thalidomide has been shown to attenuate neutrophil adhesion and chemotaxis. We present herein two cases of Streptococcus pneumoniae bacterial meningitis that developed soon after the initiation of thalidomide treatment, and discuss the effect of thalidomide on the immune system. Although, it is not clear whether thalidomide caused the development of the bacterial infections and meningitis, or what its pathogenetic mechanisms are, physicians should be alert for signs and symptoms of meningitis in patients with multiple myeloma who are treated with thalidomide, especially those in neutropenic states.

  16. Photochemical alteration of dissolved organic matter and the subsequent effects on bacterial carbon cycling and diversity.

    PubMed

    Lønborg, Christian; Nieto-Cid, Mar; Hernando-Morales, Victor; Hernández-Ruiz, Marta; Teira, Eva; Álvarez-Salgado, Xosé Antón

    2016-05-01

    The impact of solar radiation on dissolved organic matter (DOM) derived from 3 different sources (seawater, eelgrass leaves and river water) and the effect on the bacterial carbon cycling and diversity were investigated. Seawater with DOM from the sources was first either kept in the dark or exposed to sunlight (4 days), after which a bacterial inoculum was added and incubated for 4 additional days. Sunlight exposure reduced the coloured DOM and carbon signals, which was followed by a production of inorganic nutrients. Bacterial carbon cycling was higher in the dark compared with the light treatment in seawater and river samples, while higher levels were found in the sunlight-exposed eelgrass experiment. Sunlight pre-exposure stimulated the bacterial growth efficiency in the seawater experiments, while no impact was found in the other experiments. We suggest that these responses are connected to differences in substrate composition and the production of free radicals. The bacterial community that developed in the dark and sunlight pre-treated samples differed in the seawater and river experiments. Our findings suggest that impact of sunlight exposure on the bacterial carbon transfer and diversity depends on the DOM source and on the sunlight-induced production of inorganic nutrients. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Measurement of lipocalin-2 and syndecan-4 levels to differentiate bacterial from viral infection in children with community-acquired pneumonia.

    PubMed

    Esposito, Susanna; Bianchini, Sonia; Gambino, Monia; Madini, Barbara; Di Pietro, Giada; Umbrello, Giulia; Presicce, Maria Lory; Ruggiero, Luca; Terranova, Leonardo; Principi, Nicola

    2016-07-20

    In this study, we evaluated the lipocalin-2 (LIP2) and syndecan-4 (SYN4) levels in children who were hospitalized for radiologically confirmed CAP in order to differentiate bacterial from viral infection. The results regarding the LIP2 and SYN4 diagnostic outcomes were compared with the white blood cell (WBC) count and C reactive protein (CRP) levels. A total of 110 children <14 years old who were hospitalized for radiologically confirmed CAP were enrolled. Serum samples were obtained upon admission and on day 5 to measure the levels of LIP2, SYN4, and CRP as well as the WBC. Polymerase chain reaction of the respiratory secretions and tests on blood samples were performed to detect respiratory viruses, Streptococcus pneumoniae, and Mycoplasma pneumoniae. CAP was considered to be due to a probable bacterial infection in 74 children (67.3 %) and due to a probable viral infection in 16 children (14.5 %). Overall, 84 children (76.4 %) were diagnosed with severe CAP. The mean values of the WBC count and the LIP2 and SYN4 levels did not differ among the probable bacterial, probable viral, and undetermined cases. However, the CRP serum concentrations were significantly higher in children with probable bacterial CAP than in those with probable viral disease (32.2 ± 55.5 mg/L vs 9.4 ± 17.0 mg/L, p < 0.05). The WBC count was the best predictor of severe CAP, but the differences among the studied variables were marginal. The WBC count was significantly lower on day 5 in children with probable bacterial CAP (p < 0.01) and in those with an undetermined etiology (p < 0.01). The CRP and LIP2 levels were significantly lower 5 days after enrollment in all of the studied groups, independent of the supposed etiology of CAP (p < 0.01 for all comparisons). No statistically significant variation was observed for SYN4. Measuring the LIP2 and SYN4 levels does not appear to solve the problem of the poor reliability of routine laboratory tests in defining

  18. Evaluation of environmental bacterial communities as a factor affecting the growth of duckweed Lemna minor.

    PubMed

    Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

    2017-01-01

    Duckweed (family Lemnaceae ) has recently been recognized as an ideal biomass feedstock for biofuel production due to its rapid growth and high starch content, which inspired interest in improving their productivity. Since microbes that co-exist with plants are known to have significant effects on their growth according to the previous studies for terrestrial plants, this study has attempted to understand the plant-microbial interactions of a duckweed, Lemna minor , focusing on the growth promotion/inhibition effects so as to assess the possibility of accelerated duckweed production by modifying co-existing bacterial community. Co-cultivation of aseptic L. minor and bacterial communities collected from various aquatic environments resulted in changes in duckweed growth ranging from -24 to +14% compared to aseptic control. A number of bacterial strains were isolated from both growth-promoting and growth-inhibitory communities, and examined for their co-existing effects on duckweed growth. Irrespective of the source, each strain showed promotive, inhibitory, or neutral effects when individually co-cultured with L. minor . To further analyze the interactions among these bacterial strains in a community, binary combinations of promotive and inhibitory strains were co-cultured with aseptic L. minor , resulting in that combinations of promotive-promotive or inhibitory-inhibitory strains generally showed effects similar to those of individual strains. However, combinations of promotive-inhibitory strains tended to show inhibitory effects while only Aquitalea magnusonii H3 exerted its plant growth-promoting effect in all combinations tested. Significant change in biomass production was observed when duckweed was co-cultivated with environmental bacterial communities. Promotive, neutral, and inhibitory bacteria in the community would synergistically determine the effects. The results indicate the possibility of improving duckweed biomass production via regulation of co

  19. Probiotics - a helpful additional therapy for bacterial vaginosis

    PubMed Central

    Bodean, O; Munteanu, O; Cirstoiu, C; Secara, D; Cirstoiu, M

    2013-01-01

    Abstract Background: Bacterial vaginosis is a condition of unknown etiology, associated with an imbalance of the normal vaginal microbiota, characterized by a high recurrence rate despite of classical therapy solutions. Probiotics are microorganisms, which taken in adequate amounts, are proven to bring health benefits in human and animal bodies, by re-establishing the normal flora at different levels. Objective: The present article studies the possibility of using probiotic treatment as an adjuvant therapy for nonspecific vaginosis and reducing its recurrence rate. Methods: We have evaluated the evolution of patients with bacterial vaginosis who received the classical antibiotic therapy and a probiotic product. The study group consisted of 173 non-pregnant, sexually active patients, 20-45 years old, with no additional health problems and no contraceptive undergoing treatment, which have been admitted to the department of Obstetrics and Gynecology of the Bucharest Emergency University Hospital between 1.01.2012-31.12.2012.The bacteriological evaluation was made on cervical and vaginal cultures. Results: From a total of 173 patients, those who used probiotics oral capsules while taking an antibiotic had lower recurrence rates. More than a half of women who did not use any probiotic product had 3 or more relapse episodes per year. Vaginal capsules with probiotics have also proven to be useful in lowering the recurrence rate, but research is still needed. Conclusion: Probiotic products are proven to be a helpful adjuvant therapy for bacterial vaginosis, with no adverse outcomes. PMID:24868256

  20. Probiotics--a helpful additional therapy for bacterial vaginosis.

    PubMed

    Bodean, O; Munteanu, O; Cirstoiu, C; Secara, D; Cirstoiu, M

    2013-01-01

    Bacterial vaginosis is a condition of unknown etiology, associated with an imbalance of the normal vaginal microbiota, characterized by a high recurrence rate despite of classical therapy solutions. Probiotics are microorganisms, which taken in adequate amounts, are proven to bring health benefits in human and animal bodies, by re-establishing the normal flora at different levels. The present article studies the possibility of using probiotic treatment as an adjuvant therapy for nonspecific vaginosis and reducing its recurrence rate. We have evaluated the evolution of patients with bacterial vaginosis who received the classical antibiotic therapy and a probiotic product. The study group consisted of 173 non-pregnant, sexually active patients, 20-45 years old, with no additional health problems and no contraceptive undergoing treatment, which have been admitted to the department of Obstetrics and Gynecology of the Bucharest Emergency University Hospital between 1.01.2012-31.12.2012.The bacteriological evaluation was made on cervical and vaginal cultures. From a total of 173 patients, those who used probiotics oral capsules while taking an antibiotic had lower recurrence rates. More than a half of women who did not use any probiotic product had 3 or more relapse episodes per year. Vaginal capsules with probiotics have also proven to be useful in lowering the recurrence rate, but research is still needed. Probiotic products are proven to be a helpful adjuvant therapy for bacterial vaginosis, with no adverse outcomes.

  1. Structure-Function Analysis of a Broad Specificity Populus trichocarpa Endo-β-glucanase Reveals an Evolutionary Link between Bacterial Licheninases and Plant XTH Gene Products*

    PubMed Central

    Eklöf, Jens M.; Shojania, Shaheen; Okon, Mark; McIntosh, Lawrence P.; Brumer, Harry

    2013-01-01

    The large xyloglucan endotransglycosylase/hydrolase (XTH) gene family continues to be the focus of much attention in studies of plant cell wall morphogenesis due to the unique catalytic functions of the enzymes it encodes. The XTH gene products compose a subfamily of glycoside hydrolase family 16 (GH16), which also comprises a broad range of microbial endoglucanases and endogalactanases, as well as yeast cell wall chitin/β-glucan transglycosylases. Previous whole-family phylogenetic analyses have suggested that the closest relatives to the XTH gene products are the bacterial licheninases (EC 3.2.1.73), which specifically hydrolyze linear mixed linkage β(1→3)/β(1→4)-glucans. In addition to their specificity for the highly branched xyloglucan polysaccharide, XTH gene products are distinguished from the licheninases and other GH16 enzyme subfamilies by significant active site loop alterations and a large C-terminal extension. Given these differences, the molecular evolution of the XTH gene products in GH16 has remained enigmatic. Here, we present the biochemical and structural analysis of a unique, mixed function endoglucanase from black cottonwood (Populus trichocarpa), which reveals a small, newly recognized subfamily of GH16 members intermediate between the bacterial licheninases and plant XTH gene products. We postulate that this clade comprises an important link in the evolution of the large plant XTH gene families from a putative microbial ancestor. As such, this analysis provides new insights into the diversification of GH16 and further unites the apparently disparate members of this important family of proteins. PMID:23572521

  2. Bacterial DNA-induced NK cell IFN-gamma production is dependent on macrophage secretion of IL-12.

    PubMed

    Chace, J H; Hooker, N A; Mildenstein, K L; Krieg, A M; Cowdery, J S

    1997-08-01

    Bacterial DNA (bDNA) activates B cells and macrophages and can augment inflammatory responses by inducing release of proinflammatory cytokines. We found that bDNA stimulation of mouse spleen cells induced NK cell IFN-gamma production that was dependent upon the presence of unmethylated CpG motifs, and oligonucleotides with internal CpG motifs could also induce splenocytes to secrete IFN-gamma. The bDNA-induced IFN-gamma response was strictly macrophages dependent. While splenocytes from SCID mice secreted IFN-gamma in response to bDNA, depletion of macrophages eliminated this response. Additionally, purified NK cells did not respond to bDNA; however, addition of macrophages restored the NK cell IFN-gamma response. Coculture of NK cells with preactivated macrophages further increased bDNA-induced NK cell IFN-gamma production. Anti-IL-12 or IL-10 inhibited bDNA-induced IFN-gamma response. Treatment of purified macrophages with bDNA resulted in IL-12 secretion accompanied by an increase in IL-12 p40 mRNA level. Although isolated NK cells did not make IFN-gamma in response to bDNA, NK cells costimulated with IL-12 gained the ability to respond to bDNA. These experiments show that bDNA induces macrophage IL-12 production which, in turn, stimulates NK cell IFN-gamma production. Macrophage-derived IL-12 renders NK cells responsive to bDNA permitting an even greater IFN-gamma response to bDNA.

  3. Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass

    PubMed Central

    Minty, Jeremy J.; Singer, Marc E.; Scholz, Scott A.; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E.; Liao, James C.; Lin, Xiaoxia Nina

    2013-01-01

    Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system’s performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator–cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals. PMID:23959872

  4. Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass.

    PubMed

    Minty, Jeremy J; Singer, Marc E; Scholz, Scott A; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E; Liao, James C; Lin, Xiaoxia Nina

    2013-09-03

    Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system's performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator-cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals.

  5. Diversity, Productivity, and Stability of an Industrial Microbial Ecosystem.

    PubMed

    Beyter, Doruk; Tang, Pei-Zhong; Becker, Scott; Hoang, Tony; Bilgin, Damla; Lim, Yan Wei; Peterson, Todd C; Mayfield, Stephen; Haerizadeh, Farzad; Shurin, Jonathan B; Bafna, Vineet; McBride, Robert

    2016-04-01

    Managing ecosystems to maintain biodiversity may be one approach to ensuring their dynamic stability, productivity, and delivery of vital services. The applicability of this approach to industrial ecosystems that harness the metabolic activities of microbes has been proposed but has never been tested at relevant scales. We used a tag-sequencing approach with bacterial small subunit rRNA (16S) genes and eukaryotic internal transcribed spacer 2 (ITS2) to measuring the taxonomic composition and diversity of bacteria and eukaryotes in an open pond managed for bioenergy production by microalgae over a year. Periods of high eukaryotic diversity were associated with high and more-stable biomass productivity. In addition, bacterial diversity and eukaryotic diversity were inversely correlated over time, possibly due to their opposite responses to temperature. The results indicate that maintaining diverse communities may be essential to engineering stable and productive bioenergy ecosystems using microorganisms. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  6. Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

    2017-11-01

    Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p < 0.0001, n = 90) between the rates of community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth

  7. Global biogeographic sampling of bacterial secondary metabolism

    PubMed Central

    Charlop-Powers, Zachary; Owen, Jeremy G; Reddy, Boojala Vijay B; Ternei, Melinda A; Guimarães, Denise O; de Frias, Ulysses A; Pupo, Monica T; Seepe, Prudy; Feng, Zhiyang; Brady, Sean F

    2015-01-01

    Recent bacterial (meta)genome sequencing efforts suggest the existence of an enormous untapped reservoir of natural-product-encoding biosynthetic gene clusters in the environment. Here we use the pyro-sequencing of PCR amplicons derived from both nonribosomal peptide adenylation domains and polyketide ketosynthase domains to compare biosynthetic diversity in soil microbiomes from around the globe. We see large differences in domain populations from all except the most proximal and biome-similar samples, suggesting that most microbiomes will encode largely distinct collections of bacterial secondary metabolites. Our data indicate a correlation between two factors, geographic distance and biome-type, and the biosynthetic diversity found in soil environments. By assigning reads to known gene clusters we identify hotspots of biomedically relevant biosynthetic diversity. These observations not only provide new insights into the natural world, they also provide a road map for guiding future natural products discovery efforts. DOI: http://dx.doi.org/10.7554/eLife.05048.001 PMID:25599565

  8. Real-time detection of antibiotic activity by measuring nanometer-scale bacterial deformation

    NASA Astrophysics Data System (ADS)

    Iriya, Rafael; Syal, Karan; Jing, Wenwen; Mo, Manni; Yu, Hui; Haydel, Shelley E.; Wang, Shaopeng; Tao, Nongjian

    2017-12-01

    Diagnosing antibiotic-resistant bacteria currently requires sensitive detection of phenotypic changes associated with antibiotic action on bacteria. Here, we present an optical imaging-based approach to quantify bacterial membrane deformation as a phenotypic feature in real-time with a nanometer scale (˜9 nm) detection limit. Using this approach, we found two types of antibiotic-induced membrane deformations in different bacterial strains: polymyxin B induced relatively uniform spatial deformation of Escherichia coli O157:H7 cells leading to change in cellular volume and ampicillin-induced localized spatial deformation leading to the formation of bulges or protrusions on uropathogenic E. coli CFT073 cells. We anticipate that the approach will contribute to understanding of antibiotic phenotypic effects on bacteria with a potential for applications in rapid antibiotic susceptibility testing.

  9. The influence of dissolved organic carbon on bacterial phosphorus uptake and bacteria-phytoplankton dynamics in two Minnesota lakes

    USGS Publications Warehouse

    Stets, E.G.; Cotner, J.B.

    2008-01-01

    The balance of production in any ecosystem is dependent on the flow of limiting nutrients into either the autotrophic or heterotrophic components of the food web. To understand one of the important controls on the flow of inorganic nutrients between phytoplankton and bacterioplankton in lakes, we manipulated dissolved organic carbon (DOC) in two lakes of different trophic status. We hypothesized that labile DOC additions would increase bacterial phosphorus (P) uptake and decrease the response of phytoplankton to nutrient additions. Supplemental nutrients and carbon (C), nitrogen (N, 1.6 ??mol NH4Cl L-1 d-1), P (0.1 ??mol KH 2PO4 L-1 d-1), and DOC (glucose, 15 ??mol C L-1 d-1) were added twice daily to 8-liter experimental units. We tested the effect of added DOC on chlorophyll concentration, bacterial production, biomass, and P uptake using size-fractionated 33P-PO4 uptake. In the oligotrophic lake, DOC additions stimulated bacterial production and increased bacterial biomass-specific P uptake. Bacteria consumed added DOC, and chlorophyll concentrations were significantly lower in carboys receiving DOC additions. In the eutrophic lake, DOC additions had less of a stimulatory effect on bacterial production and biomass-specific P uptake. DOC accumulated over the time period, and there was little evidence for a DOC-induced decrease in phytoplankton biomass. Bacterial growth approached the calculated ??max and yet did not accumulate biomass, indicating significant biomass losses, which may have constrained bacterial DOC consumption. Excess bacterial DOC consumption in oligotrophic lakes may result in greater bacterial P affinity and enhanced nutrient uptake by the heterotrophic compartment of the food web. On the other hand, constraints on bacterial biomass accumulation in eutrophic lakes, from either viral lysis or bacterial grazing, can allow labile DOC to accumulate, thereby negating the effect of excess DOC on the planktonic food web. ?? 2008, by the American

  10. Strategies for managing rival bacterial communities: Lessons from burying beetles.

    PubMed

    Duarte, Ana; Welch, Martin; Swannack, Chris; Wagner, Josef; Kilner, Rebecca M

    2018-03-01

    the production of antimicrobials themselves. Whether these alterations to the bacterial community are adaptive from the beetle's perspective, or are simply a by-product of the way in which the beetles prepare the carcass for reproduction, remains to be determined in future work. In general, our work suggests that animals might use more sophisticated techniques for attacking and disrupting rival microbial communities than is currently appreciated. © 2017 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

  11. The Impact of Oxygen on Bacterial Enteric Pathogens.

    PubMed

    Wallace, N; Zani, A; Abrams, E; Sun, Y

    2016-01-01

    Bacterial enteric pathogens are responsible for a tremendous amount of foodborne illnesses every year through the consumption of contaminated food products. During their transit from contaminated food sources to the host gastrointestinal tract, these pathogens are exposed and must adapt to fluctuating oxygen levels to successfully colonize the host and cause diseases. However, the majority of enteric infection research has been conducted under aerobic conditions. To raise awareness of the importance in understanding the impact of oxygen, or lack of oxygen, on enteric pathogenesis, we describe in this review the metabolic and physiological responses of nine bacterial enteric pathogens exposed to environments with different oxygen levels. We further discuss the effects of oxygen levels on virulence regulation to establish potential connections between metabolic adaptations and bacterial pathogenesis. While not providing an exhaustive list of all bacterial pathogens, we highlight key differences and similarities among nine facultative anaerobic and microaerobic pathogens in this review to argue for a more in-depth understanding of the diverse impact oxygen levels have on enteric pathogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Collective Functionality through Bacterial Individuality

    NASA Astrophysics Data System (ADS)

    Ackermann, Martin

    According to the conventional view, the properties of an organism are a product of nature and nurture - of its genes and the environment it lives in. Recent experiments with unicellular organisms have challenged this view: several molecular mechanisms generate phenotypic variation independently of environmental signals, leading to variation in clonal groups. My presentation will focus on the causes and consequences of this microbial individuality. Using examples from bacterial genetic model systems, I will first discuss different molecular and cellular mechanisms that give rise to bacterial individuality. Then, I will discuss the consequences of individuality, and focus on how phenotypic variation in clonal populations of bacteria can promote interactions between individuals, lead to the division of labor, and allow clonal groups of bacteria to cope with environmental uncertainty. Variation between individuals thus provides clonal groups with collective functionality.

  13. Hemojuvelin regulates the innate immune response to peritoneal bacterial infection in mice.

    PubMed

    Wu, Qian; Shen, Yuanyuan; Tao, Yunlong; Wei, Jiayu; Wang, Hao; An, Peng; Zhang, Zhuzhen; Gao, Hong; Zhou, Tianhua; Wang, Fudi; Min, Junxia

    2017-01-01

    Hereditary hemochromatosis and iron imbalance are associated with susceptibility to bacterial infection; however, the underlying mechanisms are poorly understood. Here, we performed in vivo bacterial infection screening using several mouse models of hemochromatosis, including Hfe ( Hfe -/- ), hemojuvelin ( Hjv -/- ), and macrophage-specific ferroportin-1 ( Fpn1 fl/fl ; LysM-Cre + ) knockout mice. We found that Hjv -/- mice, but not Hfe -/- or Fpn1 fl/fl ; LysM-Cre + mice, are highly susceptible to peritoneal infection by both Gram-negative and Gram-positive bacteria. Interestingly, phagocytic cells in the peritoneum of Hjv -/- mice have reduced bacterial clearance, IFN-γ secretion, and nitric oxide production; in contrast, both cell migration and phagocytosis are normal. Expressing Hjv in RAW264.7 cells increased the level of phosphorylated Stat1 and nitric oxide production. Moreover, macrophage-specific Hjv knockout mice are susceptible to bacterial infection. Finally, we found that Hjv facilitates the secretion of IFN-γ via the IL-12/Jak2/Stat4 signaling pathway. Together, these findings reveal a novel protective role of Hjv in the early stages of antimicrobial defense.

  14. Characterization of the Bacteroides fragilis bfr Gene Product Identifies a Bacterial DPS-Like Protein and Suggests Evolutionary Links in the Ferritin Superfamily

    PubMed Central

    Gauss, George H.; Reott, Michael A.; Rocha, Edson R.; Young, Mark J.; Douglas, Trevor

    2012-01-01

    A factor contributing to the pathogenicity of Bacteroides fragilis, the most common anaerobic species isolated from clinical infections, is the bacterium's extreme aerotolerance, which allows survival in oxygenated tissues prior to anaerobic abscess formation. We investigated the role of the bacterioferritin-related (bfr) gene in the B. fragilis oxidative stress response. The bfr mRNA levels are increased in stationary phase or in response to O2 or iron. In addition, bfr null mutants exhibit reduced aerotolerance, and the bfr gene product protects DNA from hydroxyl radical cleavage in vitro. Crystallographic studies revealed a protein with a dodecameric structure and greater similarity to an archaeal DNA protection in starved cells (DPS)-like protein than to the 24-subunit bacterioferritins. Similarity to the DPS-like (DPSL) protein extends to the subunit and includes a pair of conserved cysteine residues juxtaposed to a buried dimetal binding site within the four-helix bundle. Compared to archaeal DPSLs, however, this bacterial DPSL protein contains several unique features, including a significantly different conformation in the C-terminal tail that alters the number and location of pores leading to the central cavity and a conserved metal binding site on the interior surface of the dodecamer. Combined, these characteristics confirm this new class of miniferritin in the bacterial domain, delineate the similarities and differences between bacterial DPSL proteins and their archaeal homologs, allow corrected annotations for B. fragilis bfr and other dpsl genes within the bacterial domain, and suggest an evolutionary link within the ferritin superfamily that connects dodecameric DPS to the (bacterio)ferritin 24-mer. PMID:22020642

  15. Questions about the behaviour of bacterial pathogens in vivo.

    PubMed Central

    Smith, H

    2000-01-01

    Bacterial pathogens cause disease in man and animals. They have unique biological properties, which enable them to colonize mucous surfaces, penetrate them, grow in the environment of the host, inhibit or avoid host defences and damage the host. The bacterial products responsible for these five biological requirements are the determinants of pathogenicity (virulence determinants). Current knowledge comes from studies in vitro, but now interest is increasing in how bacteria behave and produce virulence determinants within the infected host. There are three aspects to elucidate: bacterial activities, the host factors that affect them and the metabolic interactions between the two. The first is relatively easy to accomplish and, recently, new methods for doing this have been devised. The second is not easy because of the complexity of the environment in vivo and its ever-changing face. Nevertheless, some information can be gained from the literature and by new methodology. The third aspect is very difficult to study effectively unless some events in vivo can be simulated in vitro. The objectives of the Discussion Meeting were to describe the new methods and to show how they, and conventional studies, are revealing the activities of bacterial pathogens in vivo. This paper sets the scene by raising some questions and suggesting, with examples, how they might be answered. Bacterial growth in vivo is the primary requirement for pathogenicity. Without growth, determinants of the other four requirements are not formed. Results from the new methods are underlining this point. The important questions are as follows. What is the pattern of a developing infection and the growth rates and population sizes of the bacteria at different stages? What nutrients are present in vivo and how do they change as infection progresses and relate to growth rates and population sizes? How are these nutrients metabolized and by what bacterial mechanisms? Which bacterial processes handle

  16. Hydration dynamics promote bacterial coexistence on rough surfaces

    PubMed Central

    Wang, Gang; Or, Dani

    2013-01-01

    Identification of mechanisms that promote and maintain the immense microbial diversity found in soil is a central challenge for contemporary microbial ecology. Quantitative tools for systematic integration of complex biophysical and trophic processes at spatial scales, relevant for individual cell interactions, are essential for making progress. We report a modeling study of competing bacterial populations cohabiting soil surfaces subjected to highly dynamic hydration conditions. The model explicitly tracks growth, motion and life histories of individual bacterial cells on surfaces spanning dynamic aqueous networks that shape heterogeneous nutrient fields. The range of hydration conditions that confer physical advantages for rapidly growing species and support competitive exclusion is surprisingly narrow. The rapid fragmentation of soil aqueous phase under most natural conditions suppresses bacterial growth and cell dispersion, thereby balancing conditions experienced by competing populations with diverse physiological traits. In addition, hydration fluctuations intensify localized interactions that promote coexistence through disproportional effects within densely populated regions during dry periods. Consequently, bacterial population dynamics is affected well beyond responses predicted from equivalent and uniform hydration conditions. New insights on hydration dynamics could be considered in future designs of soil bioremediation activities, affect longevity of dry food products, and advance basic understanding of bacterial diversity dynamics and its role in global biogeochemical cycles. PMID:23051694

  17. Effects of partial mixed rations and supplement amounts on milk production and composition, ruminal fermentation, bacterial communities, and ruminal acidosis.

    PubMed

    Golder, H M; Denman, S E; McSweeney, C; Wales, W J; Auldist, M J; Wright, M M; Marett, L C; Greenwood, J S; Hannah, M C; Celi, P; Bramley, E; Lean, I J

    2014-09-01

    and quadratically increased with supplement feeding amount. The Bacteroidetes and Firmicutes were the dominant bacterial phyla identified. The Prevotellaceae, Ruminococcaceae, and Lachnospiraceae were the dominant bacterial families, regardless of feeding group, and were influenced by feeding strategy, supplement feeding amount, or both. The Veillonellaceae family decreased in relative abundance in PMR-fed cows compared with controls, and the Streptococcaeae and Lactobacillaceae families were present in only minor relative abundances, regardless of feeding group. Despite large among- and within-group variation in bacterial community composition, distinct bacterial communities occurred among feeding strategies, supplement amounts, and sample times and were associated with ruminal fermentation measures. Control cows fed 16kg of DM of total supplement per day had the most distinct ruminal bacterial community composition. Bacterial community composition was most significantly associated with supplement feeding amount and ammonia, butyrate, valerate, and propionate concentrations. Feeding supplements in a PMR reduced the incidence of ruminal acidosis and altered ruminal bacterial communities, regardless of supplement feeding amount, but did not result in increased milk measures compared with isoenergetic control diets component-fed to late-lactation cows. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  18. Corticosteroids for Bacterial Keratitis

    PubMed Central

    Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

    2013-01-01

    Objective To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Methods Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. Main Outcome Measures The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Results Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (−0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, −0.31 to −0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (−0.37 to −0.04; P = .02). Conclusions We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Application to Clinical Practice Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. PMID:21987582

  19. Temporal Relationships Exist Between Cecum, Ileum, and Litter Bacterial Microbiomes in a Commercial Turkey Flock, and Subtherapeutic Penicillin Treatment Impacts Ileum Bacterial Community Establishment

    PubMed Central

    Danzeisen, Jessica L.; Clayton, Jonathan B.; Huang, Hu; Knights, Dan; McComb, Brian; Hayer, Shivdeep S.; Johnson, Timothy J.

    2015-01-01

    Gut health is paramount for commercial poultry production, and improved methods to assess gut health are critically needed to better understand how the avian gastrointestinal tract matures over time. One important aspect of gut health is the totality of bacterial populations inhabiting different sites of the avian gastrointestinal tract, and associations of these populations with the poultry farm environment, since these bacteria are thought to drive metabolism and prime the developing host immune system. In this study, a single flock of commercial turkeys was followed over the course of 12 weeks to examine bacterial microbiome inhabiting the ceca, ileum, and corresponding poultry litter. Furthermore, the effects of low-dose, growth-promoting penicillin treatment (50 g/ton) in feed on the ileum bacterial microbiome were also examined during the early brood period. The cecum and ileum bacterial communities of turkeys were distinct, yet shifted in parallel to one another over time during bird maturation. Corresponding poultry litter was also distinct yet more closely represented the ileal bacterial populations than cecal bacterial populations, and also changed parallel to ileum bacterial populations over time. Penicillin applied at low dose in feed significantly enhanced early weight gain in commercial poults, and this correlated with predictable shifts in the ileum bacterial populations in control versus treatment groups. Overall, this study identified the dynamics of the turkey gastrointestinal microbiome during development, correlations between bacterial populations in the gastrointestinal tract and the litter environment, and the impact of low-dose penicillin on modulation of bacterial communities in the ileum. Such modulations provide a target for alternatives to low-dose antibiotics. PMID:26664983

  20. Bacterial abundance and activity in deep-sea sediments from the eastern North Atlantic

    NASA Astrophysics Data System (ADS)

    Eardly, D. F.; Carton, M. W.; Gallagher, J. M.; Patching, J. W.

    Results are presented from four cruises to the Porcupine Abyssal Plain (PAP site) that took place during the BENGAL project from September 1996 to March 1998, and two cruises to the PAP and an oligotrophic site (EUMELI) that took place during the DEEPSEAS project between September 1993 and March 1994. Bacterial abundances in sediment and sediment contact water were measured by epifluorescence microscopy. Bacterial activity was determined by 3H-thymidine incorporation as a measure of DNA synthesis, and by 3H-leucine incorporation as a measure of protein synthesis. Activities were measured under atmospheric and in situ pressures and temperatures. Bacterial activity was usually higher in samples incubated at in situ pressure than those incubated at atmospheric pressure indicating that a barophilic community was dominant. Inter-cruise comparisons of abundance and activity during the BENGAL project showed no firm evidence of there being a seasonal response in the benthic microbial community to any episodic phytodetritus event. This was probably because of inter-annual variations in the quality and quantity of phytodetritus deposition at the PAP site, the rapid remineralization of fresh organic material by the microbial communities and the timing of cruises to the study area. 3H-thymidine and 3H-leucine incorporation in sediments was higher during the BENGAL period than the DEEPSEAS programme. A methodological change in the 3H-thymidine incorporation technique for sediments may explain the differences in DNA synthesis observed between the two projects, whereas the lower levels of protein synthesis observed during the DEEPSEAS programme probably reflected both inter-annual variations in activity at the PAP site and the lower productivity that prevailed at surface at the EUMELI oligotrophic site. Rates of 3H-thymidine incorporation in sediment contact water were similar during both projects.

  1. Consequences of packaging on bacterial growth. Meat is an ecological niche.

    PubMed

    Labadie, J

    1999-07-01

    Meat is a good support for bacterial growth and particularly for bacteria which are specific of meat and meat products. Little is known about the physiological and biochemical factors which could explain why some bacterial species are only isolated from meat. This review tentatively points out, from an ecological point of view, some of these factors in Gram negative and Gram positive micro-organisms influencing storage life.

  2. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

    PubMed Central

    Álvarez, Belén; Biosca, Elena G.

    2017-01-01

    Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field. PMID:28769942

  3. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture.

    PubMed

    Álvarez, Belén; Biosca, Elena G

    2017-01-01

    Bacterial wilt diseases caused by Ralstonia solanacearum , R. pseudosolanacearum , and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis , not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta . Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

  4. The participation of outer membrane proteins in the bacterial sensitivity to nanosilver.

    PubMed

    Kędziora, Anna; Krzyżewska, Eva; Dudek, Bartłomiej; Bugla-Płoskońska, Gabriela

    2016-06-13

    The presented study is to analyze the participation of outer membrane proteins of Gram- negative bacteria in sensitivity to silver nanomaterials. The mechanism of interaction of silver with the bacterial cell is best described in this group of microorganisms. There are several theories regarding the effectiveness of antimicrobial ions and nanosilver, and at the indicated differences in the way they work. Outer membrane proteins of Gram-negative bacteria are involved in the procurement of silver from the environment and contribute to the development mechanisms of resistance to nanometals. They are measurable parameter in the field of cell phenotypic response to the presence of Gram-negative bacteria in the environment silver nanoforms: its properties, chemical composition, content or times of action. Proteomic methods (including two dimensional electrophoresis and MALDI‑TOF MS) are therefore relevant techniques for determining the susceptibility of bacteria to silver and the changes taking place in the outer membrane under the influence: uptime/exposure and physical and chemical parameters of silver nanomaterials. Many products containing nanosilver is still in the research phase in terms of physico‑chemical characteristics and biological activity, others have been already implemented in many industries. During the very fast nanotechnology developing and introduction to the market products based on the nanosilver the bacterial answer to nanosilver is needed.

  5. Application of customised bacterial inoculants for grass haylage production and its effectiveness on nutrient composition and fermentation quality of haylage.

    PubMed

    Soundharrajan, Ilavenil; Kim, Da Hye; Srisesharam, Srigopalram; Kuppusamy, Palaniselvam; Park, Hyung Soo; Yoon, Yong Hee; Kim, Won Ho; Song, Young Gil; Choi, Ki Choon

    2017-10-01

    The present study aimed to investigate the efficacy of customised Lactobacillus plantarum KCC-10, KCC-19 and K-46 on nutrient composition and fermentation quality of low moisture Italian ryegrass (IRG) forage. An addition of customised bacterial inoculants (CBI) did not affect the nutrient compositions and digestibility rates of haylage. The lactic acid content was higher in CBI-inoculated haylage, whereas the amount of acetic acid and butyric acid production was significantly reduced than the control. CBI-inoculated haylage exhibited higher numbers of bacterial colonies that reduced the pH of the haylage. Low pH in haylage is an important criterion for preventing undesirable microbial growth and improves fermentation quality of haylage. PCR studies indicated that the DNA of L. plantarum was predominantly amplified. It evidenced that the CBI is the main reason behind the improvement of haylage fermentation as compared to control. Overall results suggested that KCC-10, KCC-19 and K-46 are considered as potent strains for improving fermentation quality of low moisture forage and preserve its stability for a long time.

  6. Importance of particle-associated bacterial heterotrophy in a coastal Arctic ecosystem

    NASA Astrophysics Data System (ADS)

    Garneau, Marie-Ève; Vincent, Warwick F.; Terrado, Ramon; Lovejoy, Connie

    2009-01-01

    The large quantities of particles delivered by the Mackenzie River to the coastal Beaufort Sea (Arctic Ocean) have implications for the spatial distribution, composition and productivity of its bacterial communities. Our objectives in this study were: (1) to assess the contribution of particle-associated bacteria (fraction ≥ 3 µm) to total bacterial production and their relationships with changing environmental conditions along a surface water transect; (2) to examine how particle-based heterotrophy changes over the annual cycle (Nov 2003-Aug 2004); and (3) to determine whether particle-associated bacterial assemblages differ in composition from the free-living communities (fraction < 3 µm). Our transect results showed that particle-associated bacteria contributed a variable percentage of leucine-based (BP-Leu) and thymidine-based (BP-TdR) bacterial production, with values up to 98% at the inshore, low salinity stations. The relative contribution of particle-associated bacteria to total BP-Leu was positively correlated with temperature and particulate organic material (POM) concentration. The annual dataset showed low activities of particle-associated bacteria during late fall and most of the winter, and a period of high particle-associated activity in spring and summer, likely related to the seasonal inputs of riverine POM. Results from catalyzed reporter deposition for fluorescence in situ hybridization (CARD-FISH) confirmed the dominance of Bacteria and presence of Archaea (43-84% and 0.2-5.5% of DAPI counts, respectively), which were evenly distributed throughout the Mackenzie Shelf, and not significantly related to environmental variables. Denaturing gradient gel electrophoresis (DGGE) revealed changes in the bacterial community structure among riverine, estuarine and marine stations, with separation according to temperature and salinity. There was evidence of differences between the particle-associated and free-living bacterial assemblages at the

  7. The papain inhibitor (SPI) of Streptomyces mobaraensis inhibits bacterial cysteine proteases and is an antagonist of bacterial growth.

    PubMed

    Zindel, Stephan; Kaman, Wendy E; Fröls, Sabrina; Pfeifer, Felicitas; Peters, Anna; Hays, John P; Fuchsbauer, Hans-Lothar

    2013-07-01

    A novel papain inhibitory protein (SPI) from Streptomyces mobaraensis was studied to measure its inhibitory effect on bacterial cysteine protease activity (Staphylococcus aureus SspB) and culture supernatants (Porphyromonas gingivalis, Bacillus anthracis). Further, growth of Bacillus anthracis, Staphylococcus aureus, Pseudomonas aeruginosa, and Vibrio cholerae was completely inhibited by 10 μM SPI. At this concentration of SPI, no cytotoxicity was observed. We conclude that SPI inhibits bacterial virulence factors and has the potential to become a novel therapeutic treatment against a range of unrelated pathogenic bacteria.

  8. A marine bacterial adhesion microplate test using the DAPI fluorescent dye: a new method to screen antifouling agents.

    PubMed

    Leroy, C; Delbarre-Ladrat, C; Ghillebaert, F; Rochet, M J; Compère, C; Combes, D

    2007-04-01

    To develop a method to screen antifouling agents against marine bacterial adhesion as a sensitive, rapid and quantitative microplate fluorescent test. Our experimental method is based on a natural biofilm formed by mono-incubation of the marine bacterium Pseudoalteromonas sp. D41 in sterile natural sea water in a 96-well polystyrene microplate. The 4'6-diamidino-2-phenylindole dye was used to quantify adhered bacteria in each well. The total measured fluorescence in the wells was correlated with the amount of bacteria showing a detection limit of one bacterium per 5 microm(2) and quantifying 2 x 10(7) to 2 x 10(8) bacteria adhered per cm(2). The antifouling properties of three commercial surface-active agents and chlorine were tested by this method in the prevention of adhesion and also in the detachment of already adhered bacteria. The marine bacterial adhesion inhibition rate depending on the agent concentration showed a sigmoid shaped dose-response curve. This test is well adapted for a rapid and quantitative first screening of antifouling agents directly in seawater in the early steps of marine biofilm formation. In contrast to the usual screenings of antifouling products which detect a bactericidal activity, this test is more appropriate to screen antifouling agents for bacterial adhesion removal or bacterial adhesion inhibition activities. This screening test focuses on the antifouling properties of the products, especially the initial steps of marine biofilm formation.

  9. Prospective bacterial quorum sensing inhibitors from Indian medicinal plant extracts.

    PubMed

    Tiwary, B K; Ghosh, R; Moktan, S; Ranjan, V K; Dey, P; Choudhury, D; Dutta, S; Deb, D; Das, A P; Chakraborty, R

    2017-07-01

    As virulence of many pathogenic bacteria is regulated by the phenomenon of quorum sensing (QS), the present study aimed to find the QS-inhibiting (QS-I) property (if any) in 61 Indian medicinal plants. The presence of QS-I compound in the leaf extract was evaluated by its ability to inhibit production of pigment in Chromobacterium violaceum MTCC 2656 (violacein) and Pseudomonas aeruginosa MTCC 2297 (pyocyanin) or swarming of P. aeruginosa MTCC 2297. Extracts of three plants, Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis, have shown a dose-dependent inhibition of violacein production with no negative effect on bacterial growth. Inhibition of pyocyanin pigment production and swarming motility in P. aeruginosa MTCC 2297 was also shown. Based on the results obtained by gas chromatography-mass spectroscopy (GC-MS) and thin-layer chromatography-direct bioautography (TLC-DB), it was concluded that triterpenes and flavonoid compounds found in the three plant extracts could have QS-I activity. A novel alternative prospect to prevent bacterial infections without inhibiting the growth is to apply chemicals that inhibit quorum sensing mechanism of the pathogens. Antiquorum property of 61 medicinal plants was evaluated by the ability of their leaf extract(s) to inhibit production of pigment (violacein in Chromobacterium violaceum MTCC 2656, pyocyanin in Pseudomonas aeruginosa MTCC 2297) or swarming in P. aeruginosa MTCC 2297. The most prospective plants (for the development of quorum sensing inhibitor), showing inhibition of violacein production without affecting bacterial growth, were Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis. © 2017 The Society for Applied Microbiology.

  10. Nile Red Detection of Bacterial Hydrocarbons and Ketones in a High-Throughput Format

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pinzon, NM; Aukema, KG; Gralnick, JA

    A method for use in high-throughput screening of bacteria for the production of long-chain hydrocarbons and ketones by monitoring fluorescent light emission in the presence of Nile red is described. Nile red has previously been used to screen for polyhydroxybutyrate (PHB) and fatty acid esters, but this is the first report of screening for recombinant bacteria making hydrocarbons or ketones. The microtiter plate assay was evaluated using wild-type and recombinant strains of Shewanella oneidensis and Escherichia coli expressing the enzyme OleA, previously shown to initiate hydrocarbon biosynthesis. The strains expressing exogenous Stenotrophomonas maltophilia oleA, with increased levels of ketone productionmore » as determined by gas chromatography-mass spectrometry, were distinguished with Nile red fluorescence. Confocal microscopy images of S. oneidensis oleA-expressing strains stained with Nile red were consistent with a membrane localization of the ketones. This differed from Nile red staining of bacterial PHB or algal lipid droplets that showed intracellular inclusion bodies. These results demonstrated the applicability of Nile red in a high-throughput technique for the detection of bacterial hydrocarbons and ketones. IMPORTANCE In recent years, there has been renewed interest in advanced biofuel sources such as bacterial hydrocarbon production. Previous studies used solvent extraction of bacterial cultures followed by gas chromatography-mass spectrometry (GC-MS) to detect and quantify ketones and hydrocarbons (Beller HR, Goh EB, Keasling JD, Appl. Environ. Microbiol. 76: 1212-1223, 2010; Sukovich DJ, Seffernick JL, Richman JE, Gralnick JA, Wackett LP, Appl. Environ. Microbiol. 76: 3850-3862, 2010). While these analyses are powerful and accurate, their labor-intensive nature makes them intractable to high-throughput screening; therefore, methods for rapid identification of bacterial strains that are overproducing hydrocarbons are needed. The use of high

  11. Viral effects on bacterial respiration, production and growth efficiency: Consistent trends in the Southern Ocean and the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Bonilla-Findji, Osana; Malits, Andrea; Lefèvre, Dominique; Rochelle-Newall, Emma; Lemée, Rodolphe; Weinbauer, Markus G.; Gattuso, Jean-Pierre

    2008-03-01

    To investigate the potential effects of viruses on bacterial respiration (BR), production (BP) and growth efficiency (BGE), experiments were performed using natural microbial communities from the coastal Mediterranean Sea, from a typical high-nutrient low-chlorophyll (HNLC) region in the Southern Ocean and from a naturally iron (Fe)-fertilized algal bloom above the Kerguelen Plateau (Southern Ocean). Seawater was sequentially filtered and concentrated to produce a bacterial concentrate, a viral concentrate and a virus-free ultrafiltrate. The combination of all three fractions served as treatments with active viruses. Heating or microwaving was used to inactivate viruses for the control treatments. Despite the differences in the initial trophic state and community composition of the study sites, consistent trends were found. In the presence of active viruses, BR was stimulated (up to 113%), whereas BP and BGE were reduced (up to 51%). Our results suggest that viruses enhance the role of bacteria as oxidizers of organic matter, hence as producers of CO 2, and remineralizers of CO 2, N, P and Fe. In the context of Fe-fertilization, this has important implications for the final fate of organic carbon in marine systems.

  12. Lower Carboniferous Siderites: A Product of Bottom Seeps and Bacterial Metanogenesis (Subpolar Urals)

    NASA Astrophysics Data System (ADS)

    Antoshkina, A. I.; Ryabinkina, N. N.

    2018-02-01

    Complex modern micro- and spectroscopic methods for study of siderite concretions in the Lower Carboniferous terrigenous strata on the Kozhym River (Subpolar Urals) have shown that its formation was caused by destruction of clay minerals due to the activity of bacterial communities. The abundance of these bacteria was caused by gas-fluid seeps and bacterial methanogenesis processes in bottom deposits. In basins with normal marine fauna, this led to local desalination, hydrogen sulfide contamination, mass collapse of primary organisms, and the development of element-specific bacteria. The occurrence of these bacteria caused the formation of specific authigenic mineralization in the concretion of sideritic bacteriolites: the framboidal pyrite, sphalerite, galenite, barite, sulfoselenides, and tellurides.

  13. Forest strata drive spatial structure of bacterial and archaeal communities and microbial methane cycling in neotropical bromeliad wetlands

    NASA Astrophysics Data System (ADS)

    Martinson, Guntars; Brandt, Franziska; Conrad, Ralf

    2016-04-01

    Several thousands of tank bromeliads per hectare of neotropical forest create a unique wetland ecosystem that harbors diverse communities of archaea and bacteria and emit substantial amounts of methane. We studied spatial distribution of archaeal and bacterial communities, microbial methane cycling and their environmental drivers in tank bromeliad wetlands. We selected tank bromeliads of different species and functional types (terrestrial and canopy bromeliads) in a neotropical montane forest of Southern Ecuador and sampled the organic tank slurry. Archaeal and bacterial communities were characterized using terminal-restriction fragment length polymorphism (T-RFLP) and Illumina MiSeq sequencing, respectively, and linked with physico-chemical tank-slurry properties. Additionally, we performed tank-slurry incubations to measure methane production potential, stable carbon isotope fractionation and pathway of methane formation. Archaeal and bacterial community composition in bromeliad wetlands was dominated by methanogens and by Alphaproteobacteria, respectively, and did not differ between species but between functional types. Hydrogenotrophic Methanomicrobiales were the dominant methanogens among all bromeliads but the relative abundance of aceticlastic Methanosaetaceae increased in terrestrial bromeliads. Complementary, hydrogenotrophic methanogenesis was the dominant pathway of methane formation but the relative contribution of aceticlastic methanogenesis increased in terrestrial bromeliads and led to a concomitant increase in total methane production. Rhodospirillales were characteristic for canopy bromeliads, Planctomycetales and Actinomycetalis for terrestrial bromeliads. While nitrogen concentration and pH explained 32% of the archaeal community variability, 29% of the bacterial community variability was explained by nitrogen, acetate and propionate concentrations. Our study demonstrates that bromeliad functional types, associated with different forest strata

  14. Real-time detection of antibiotic activity by measuring nanometer-scale bacterial deformation.

    PubMed

    Iriya, Rafael; Syal, Karan; Jing, Wenwen; Mo, Manni; Yu, Hui; Haydel, Shelley E; Wang, Shaopeng; Tao, Nongjian

    2017-12-01

    Diagnosing antibiotic-resistant bacteria currently requires sensitive detection of phenotypic changes associated with antibiotic action on bacteria. Here, we present an optical imaging-based approach to quantify bacterial membrane deformation as a phenotypic feature in real-time with a nanometer scale (∼9  nm) detection limit. Using this approach, we found two types of antibiotic-induced membrane deformations in different bacterial strains: polymyxin B induced relatively uniform spatial deformation of Escherichia coli O157:H7 cells leading to change in cellular volume and ampicillin-induced localized spatial deformation leading to the formation of bulges or protrusions on uropathogenic E. coli CFT073 cells. We anticipate that the approach will contribute to understanding of antibiotic phenotypic effects on bacteria with a potential for applications in rapid antibiotic susceptibility testing. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  15. Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells

    PubMed Central

    2010-01-01

    Background In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry. To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process. To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. Results In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared. During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation. During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity. High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. Conclusions The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells. PMID:20831775

  16. Big Soda Lake (Nevada). 1. Pelagic bacterial heterotrophy and biomass

    USGS Publications Warehouse

    Zehr, Jon P.; Harvey, Ronald W.; Oremland, Ronald S.; Cloern, James E.; George, Leah H.; Lane, Judith L.

    1987-01-01

    Bacterial activities and abundance were measured seasonally in the water column of meromictic Big Soda Lake which is divided into three chemically distinct zones: aerobic mixolimnion, anaerobic mixolimnion, and anaerobic monimolimnion. Bacterial abundance ranged between 5 and 52 x 106 cells ml−1, with highest biomass at the interfaces between these zones: 2–4 mg C liter−1 in the photosynthetic bacterial layer (oxycline) and 0.8–2.0 mg C liter−1 in the chemocline. Bacterial cell size and morphology also varied with depth: small coccoid cells were dominant in the aerobic mixolimnion, whereas the monimolimnion had a more diverse population that included cocci, rods, and large filaments. Heterotrophic activity was measured by [methyl-3H]thymidine incorporation and [14C]glutamate uptake. Highest uptake rates were at or just below the photosynthetic bacterial layer and were attributable to small (<1 µm) heterotrophs rather than the larger photosynthetic bacteria. These high rates of heterotrophic uptake were apparently linked with fermentation; rates of other mineralization processes (e.g. sulfate reduction, methanogenesis, denitrification) in the anoxic mixolimnion were insignificant. Heterotrophic activity in the highly reduced monimolimnion was generally much lower than elsewhere in the water column. Therefore, although the monimolimnion contained most of the bacterial abundance and biomass (∼60%), most of the cells there were inactive.

  17. Metal adsorption onto bacterial surfaces: development of a predictive approach

    NASA Astrophysics Data System (ADS)

    Fein, Jeremy B.; Martin, Aaron M.; Wightman, Peter G.

    2001-12-01

    Aqueous metal cation adsorption onto bacterial surfaces can be successfully modeled by means of a surface complexation approach. However, relatively few stability constants for metal-bacterial surface complexes have been measured. In order to determine the bacterial adsorption behavior of cations that have not been studied in the laboratory, predictive techniques are required that enable estimation of the stability constants of bacterial surface complexes. In this study, we use a linear free-energy approach to compare previously measured stability constants for Bacillus subtilis metal-carboxyl surface complexes with aqueous metal-organic acid anion stability constants. The organic acids that we consider are acetic, oxalic, citric, and tiron. We add to this limited data set by conducting metal adsorption experiments onto Bacillus subtilis, determining bacterial surface stability constants for Co, Nd, Ni, Sr, and Zn. The adsorption behavior of each of the metals studied here was described well by considering metal-carboxyl bacterial surface complexation only, except for the Zn adsorption behavior, which required carboxyl and phosphoryl complexation to obtain a suitable fit to the data. The best correlation between bacterial carboxyl surface complexes and aqueous organic acid anion stability constants was obtained by means of metal-acetate aqueous complexes, with a linear correlation coefficient of 0.97. This correlation applies only to unhydrolyzed aqueous cations and only to carboxyl binding of those cations, and it does not predict the binding behavior under conditions where metal binding to other bacterial surface site types occurs. However, the relationship derived in this study permits estimation of the carboxyl site adsorption behavior of a wide range of aqueous metal cations for which there is an absence of experimental data. This technique, coupled with the observation of similar adsorption behaviors across bacterial species (Yee and Fein, 2001), enables

  18. Bacterial production of methyl ketones

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Beller, Harry R.; Goh, Ee-Been

    The present invention relates to methods and compositions for increasing production of methyl ketones in a genetically modified host cell that overproduces .beta.-ketoacyl-CoAs through a re-engineered .beta.-oxidation pathway and overexpresses FadM.

  19. Isolation and identification of biocellulose-producing bacterial strains from Malaysian acidic fruits.

    PubMed

    Voon, W W Y; Rukayadi, Y; Meor Hussin, A S

    2016-05-01

    Biocellulose (BC) is pure extracellular cellulose produced by several species of micro-organisms that has numerous applications in the food, biomedical and paper industries. However, the existing biocellulose-producing bacterial strain with high yield was limited. The aim of this study was to isolate and identify the potential biocellulose-producing bacterial isolates from Malaysian acidic fruits. One hundred and ninety-three bacterial isolates were obtained from 19 local acidic fruits collected in Malaysia and screened for their ability to produce BC. A total of 15 potential bacterial isolates were then cultured in standard Hestrin-Schramm (HS) medium statically at 30°C for 2 weeks to determine the BC production. The most potent bacterial isolates were identified using 16S rRNA gene sequence analysis, morphological and biochemical characteristics. Three new and potent biocellulose-producing bacterial strains were isolated from soursop fruit and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. Stenotrophomonas maltophilia WAUPM42 was the most potent biocellulose-producing bacterial strain that produced the highest amount of BC 0·58 g l(-1) in standard HS medium. Whereas, the isolates P. vagans WAUPM45 and B. fluminensis WAUPM53 showed 0·50 and 0·52 g l(-1) of BC production, respectively. Biocellulose (BC) is pure extracellular cellulose that is formed by many micro-organisms in the presence of carbon source and acidic condition. It can replace plant-based cellulose in multifarious applications due to its unique characteristics. In this study, three potential biocellulose-producing bacterial strains were obtained from Malaysian acidic fruits and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. This study reports for the first time the new biocellulose-producing bacterial strains isolated from Malaysian acidic fruits. © 2016 The

  20. Measuring the Adhesion Forces for the Multivalent Binding of Vancomycin-Conjugated Dendrimer to Bacterial Cell-Wall Peptide.

    PubMed

    Peterson, Elizabeth; Joseph, Christine; Peterson, Hannah; Bouwman, Rachael; Tang, Shengzhuang; Cannon, Jayme; Sinniah, Kumar; Choi, Seok Ki

    2018-06-19

    Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van) n ( n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy. The SPR experiment for these conjugates was performed in a biosensor chip surface immobilized with a bacterial cell-wall peptide Lys-d-Ala-d-Ala. Of these, G5(Van) 4 bound most tightly with a K D of 0.34 nM, which represents an increase in avidity by 2 or 3 orders of magnitude relative to a monovalent conjugate G5(Van) 1 or free vancomycin, respectively. By single-molecule force spectroscopy, we measured the adhesion force between G5(Van) n and the same cell-wall peptide immobilized on the surface. The distribution of adhesion forces increased in proportion to vancomycin valency with the mean force of 134 pN at n = 4 greater than 96 pN at n = 1 at a loading rate of 5200 pN/s. In summary, our results are strongly supportive of the positive correlation between the avidity and adhesion force in the multivalent interaction of vancomycin nanoconjugates.

  1. Production of polyhydroxyalkanoates (PHA) by bacterial consortium from excess sludge fermentation liquid at laboratory and pilot scales.

    PubMed

    Jia, Qianqian; Xiong, Huilei; Wang, Hui; Shi, Hanchang; Sheng, Xinying; Sun, Run; Chen, Guoqiang

    2014-11-01

    The generation of polyhydroxyalkanoates (PHA) from excess sludge fermentation liquid (SFL) was studied at lab and pilot scale. A PHA-accumulated bacterial consortium (S-150) was isolated from activated sludge using simulated SFL (S-SFL) contained high concentration volatile fatty acids (VFA) and nitrogen. The maximal PHA content accounted for 59.18% in S-SFL and dropped to 23.47% in actual SFL (L-SFL) of the dry cell weight (DCW) at lab scale. The pilot-scale integrated system comprised an anaerobic fermentation reactor (AFR), a ceramic membrane system (CMS) and a PHA production bio-reactor (PHAR). The PHA content from pilot-scale SFL (P-SFL) finally reached to 59.47% DCW with the maximal PHA yield coefficient (YP/S) of 0.17 g PHA/g COD. The results indicated that VFA-containing SFL was suitable for PHA production. The adverse impact of excess nitrogen and non-VFAs in SFL might be eliminated by pilot-scale domestication, which might resulted in community structure optimization and substrate selective ability improvement of S-150. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Semi-spontaneous oral text production: measurements in clinical practice.

    PubMed

    Lind, Marianne; Kristoffersen, Kristian Emil; Moen, Inger; Simonsen, Hanne Gram

    2009-12-01

    Functionally relevant assessment of the language production of speakers with aphasia should include assessment of connected speech production. Despite the ecological validity of everyday conversations, more controlled and monological types of texts may be easier to obtain and analyse in clinical practice. This article discusses some simple measurements for the analysis of semi-spontaneous oral text production by speakers with aphasia. Specifically, the measurements are related to the production of verbs and nouns, and the realization of different sentence types. The proposed measurements should be clinically relevant, easily applicable, and linguistically meaningful. The measurements have been applied to oral descriptions of the 'Cookie Theft' picture by eight monolingual Norwegian speakers, four with an anomic type of aphasia and four without any type of language impairment. Despite individual differences in both the clinical and the non-clinical group, most of the measurements seem to distinguish between speakers with and without aphasia.

  3. Using Amplicon Sequencing To Characterize and Monitor Bacterial Diversity in Drinking Water Distribution Systems

    PubMed Central

    Shaw, Jennifer L. A.; Weyrich, Laura S.; Sawade, Emma; Drikas, Mary; Cooper, Alan J.

    2015-01-01

    Drinking water assessments use a variety of microbial, physical, and chemical indicators to evaluate water treatment efficiency and product water quality. However, these indicators do not allow the complex biological communities, which can adversely impact the performance of drinking water distribution systems (DWDSs), to be characterized. Entire bacterial communities can be studied quickly and inexpensively using targeted metagenomic amplicon sequencing. Here, amplicon sequencing of the 16S rRNA gene region was performed alongside traditional water quality measures to assess the health, quality, and efficiency of two distinct, full-scale DWDSs: (i) a linear DWDS supplied with unfiltered water subjected to basic disinfection before distribution and (ii) a complex, branching DWDS treated by a four-stage water treatment plant (WTP) prior to disinfection and distribution. In both DWDSs bacterial communities differed significantly after disinfection, demonstrating the effectiveness of both treatment regimes. However, bacterial repopulation occurred further along in the DWDSs, and some end-user samples were more similar to the source water than to the postdisinfection water. Three sample locations appeared to be nitrified, displaying elevated nitrate levels and decreased ammonia levels, and nitrifying bacterial species, such as Nitrospira, were detected. Burkholderiales were abundant in samples containing large amounts of monochloramine, indicating resistance to disinfection. Genera known to contain pathogenic and fecal-associated species were also identified in several locations. From this study, we conclude that metagenomic amplicon sequencing is an informative method to support current compliance-based methods and can be used to reveal bacterial community interactions with the chemical and physical properties of DWDSs. PMID:26162884

  4. Real-time polymerase chain reaction in transfusion medicine: applications for detection of bacterial contamination in blood products.

    PubMed

    Dreier, Jens; Störmer, Melanie; Kleesiek, Knut

    2007-07-01

    Bacterial contamination of blood components, particularly of platelet concentrates (PCs), represents the greatest infectious risk in blood transfusion. Although the incidence of platelet bacterial contamination is approximately 1 per 2,000 U, the urgent need for a method for the routine screening of PCs to improve safety for patients had not been considered for a long time. Besides the culturing systems, which will remain the criterion standard, rapid methods for sterility screening will play a more important role in transfusion medicine in the future. In particular, nucleic acid amplification techniques (NATs) are powerful potential tools for bacterial screening assays. The combination of excellent sensitivity and specificity, reduced contamination risk, ease of performance, and speed has made real-time polymerase chain reaction (PCR) technology an appealing alternative to conventional culture-based testing methods. When using real-time PCR for the detection of bacterial contamination, several points have to be considered. The main focus is the choice of the target gene; the assay format; the nucleic acid extraction method, depending on the sample type; and the evaluation of an ideal sampling strategy. However, several factors such as the availability of bacterial-derived nucleic acid amplification reagents, the impracticability, and the cost have limited the use of NATs until now. Attempts to reduce the presence of contaminating nucleic acids from reagents in real-time PCR have been described, but none of these approaches have proven to be very effective or to lower the sensitivity of the assay. Recently, a number of broad-range NAT assays targeting the 16S ribosomal DNA or 23S ribosomal RNA for the detection of bacteria based on real-time technology have been reported. This review will give a short survey of current approaches to and the limitations of the application of real-time PCR for bacterial detection in blood components, with emphasis on the bacterial

  5. Solid-state NMR for bacterial biofilms

    NASA Astrophysics Data System (ADS)

    Reichhardt, Courtney; Cegelski, Lynette

    2014-04-01

    Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state nuclear magnetic resonance (NMR) is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an Escherichia coli biofilm and transformed our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area.

  6. Real-time measurement of UV-inactivated Escherichia coli bacterial particles by electrospray-assisted UVAPS spectrometry.

    PubMed

    Jung, Jae Hee; Lee, Jung Eun; Bae, Gwi Nam

    2011-08-01

    The ultraviolet aerodynamic particle sizer (UVAPS) is a novel commercially available aerosol spectrometer for real-time continuous monitoring of viable bioaerosols, based on fluorescence from living microorganisms. In a previous study, we developed an electrospray-assisted UVAPS using biological electrospray techniques, which have the advantage of generating non-agglomerated single particles by the repulsive electrical forces. With this electrospraying of suspensions containing microorganisms, the analytical system can supply more accurate and quantitative information about living microorganisms than with conventional aerosolization. Using electrospray-assisted UVAPS, we investigated the characteristics of bacterial particles with various viabilities in real-time. Escherichia coli was used as the test microorganism, and its initial viability was controlled by the degree of exposure to UV irradiation. In the stable cone-jet domain, the particle size distributions of test bacterial particles remained almost uniform regardless of the degree of UV inactivation. However, the fluorescence spectra of the bacterial particles changed with the degree of UV inactivation. The fluorescence characteristics of UV-inactivated bacterial particles tended to show a similar decline with viability, determined by the sampling and culture method, although the percentage showing fluorescence was higher than that showing viability. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Bacterial recognition of thermal glycation products derived from porcine serum albumin with lactose.

    PubMed

    Sarabia-Sainz, Andre-I; Ramos-Clamont, Gabriela; Winzerling, Joy; Vázquez-Moreno, Luz

    2011-01-01

    Recently, glyco-therapy is proposed to prevent the interaction of bacterial lectins with host ligands (glycoconjugates). This interaction represents the first step in infection. Neoglycans referred to as PSA-Lac (PSA-Glu (β1-4) Gal) were obtained by conjugation of porcine serum albumin (PSA) with lactose at 80 °C, 100 °C and 120 ºC. Characterization studies of the products showed that PSA could contain 1, 38 or 41 added lactoses, depending on the reaction temperature. These neoglycans were approximately 10 times more glycated than PSA-Lac obtained in previous work. Lactose conjugation occurred only at lysines and PSA-Lac contained terminal galactoses as confirmed by Ricinus communis lectin recognition. Furthermore, Escherichia coli K88+, K88ab, K88ac and K88ad adhesins showed affinity toward all PSA-Lac neoglycans, and the most effective was the PSA-Lac obtained after 100 ºC treatment. In vitro, this neoglycan partially inhibited the adhesion of E. coli K88+ to piglet mucin (its natural ligand). These results provide support for the hypothesis that glycated proteins can be used as an alternative for bioactive compounds for disease prevention.

  8. Control strategies against Campylobacter at the poultry production level: biosecurity measures, feed additives and vaccination.

    PubMed

    Meunier, M; Guyard-Nicodème, M; Dory, D; Chemaly, M

    2016-05-01

    Campylobacteriosis is the most prevalent bacterial foodborne gastroenteritis affecting humans in the European Union, and ranks second in the United States only behind salmonellosis. In Europe, there are about nine million cases of campylobacteriosis every year, making the disease a major public health issue. Human cases are mainly caused by the zoonotic pathogen Campylobacter jejuni. The main source of contamination is handling or consumption of poultry meat. Poultry constitutes the main reservoir of Campylobacter, substantial quantities of which are found in the intestines following rapid, intense colonization. Reducing Campylobacter levels in the poultry chain would decrease the incidence of human campylobacteriosis. As primary production is a crucial step in Campylobacter poultry contamination, controlling the infection at this level could impact the following links along the food chain (slaughter, retail and consumption). This review describes the control strategies implemented during the past few decades in primary poultry production, including the most recent studies. In fact, the implementation of biosecurity and hygiene measures is described, as well as the immune strategy with passive immunization and vaccination trials and the nutritional strategy with the administration of organic and fatty acids, essential oil and plant-derived compound, probiotics, bacteriocins and bacteriophages. © 2015 The Society for Applied Microbiology.

  9. Primary and heterotrophic productivity relate to multikingdom diversity in a hypersaline mat

    DOE PAGES

    Bernstein, Hans C.; Brislawn, Colin J.; Dana, Karl; ...

    2017-10-17

    Benthic microbial ecosystems are widespread yet knowledge gaps still remain on the relationships between the diversity of species across kingdoms and productivity. Here, we ask two fundamental questions: (i) How does species diversity relate to the rates of primary and heterotrophic productivity? (ii) How do diel variations in light-energy inputs influence productivity and microbiome diversity? To answer these questions, microbial mats from a magnesium sulfate hypersaline lake were used to establish microcosms. Both the number and relatedness between bacterial and eukaryotic taxa in the microbiome were assayed via amplicon-based sequencing of 16S and 18S rRNA genes over two diel cycles.more » These results correlated with biomass productivity obtained from substrate-specific 13C stable isotope tracers that enabled comparisons between primary and heterotrophic productivity. Both bacterial and eukaryotic species richness and evenness were related only to the rates of 13C-labeled glucose and acetate biomass incorporation. Interestingly, measures of these heterotrophic relationships changed from positive and negative correlations depending on carbon derived from glucose or acetate, respectively. The bacterial and eukaryotic diversity of this ecosystem is also controlled, in part, from energy constraints imposed by changing irradiance over a diel cycle.« less

  10. Primary and heterotrophic productivity relate to multikingdom diversity in a hypersaline mat

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bernstein, Hans C.; Brislawn, Colin J.; Dana, Karl

    Benthic microbial ecosystems are widespread yet knowledge gaps still remain on the relationships between the diversity of species across kingdoms and productivity. Here, we ask two fundamental questions: (i) How does species diversity relate to the rates of primary and heterotrophic productivity? (ii) How do diel variations in light-energy inputs influence productivity and microbiome diversity? To answer these questions, microbial mats from a magnesium sulfate hypersaline lake were used to establish microcosms. Both the number and relatedness between bacterial and eukaryotic taxa in the microbiome were assayed via amplicon-based sequencing of 16S and 18S rRNA genes over two diel cycles.more » These results correlated with biomass productivity obtained from substrate-specific 13C stable isotope tracers that enabled comparisons between primary and heterotrophic productivity. Both bacterial and eukaryotic species richness and evenness were related only to the rates of 13C-labeled glucose and acetate biomass incorporation. Interestingly, measures of these heterotrophic relationships changed from positive and negative correlations depending on carbon derived from glucose or acetate, respectively. The bacterial and eukaryotic diversity of this ecosystem is also controlled, in part, from energy constraints imposed by changing irradiance over a diel cycle.« less

  11. Measuring spatial variation in secondary production and food quality using a common consumer approach in Lake Erie

    USGS Publications Warehouse

    Larson, James H.; Richardson, William B.; Evans, Mary Anne; Schaeffer, Jeff; Wynne, Timothy; Bartsch, Michelle; Bartsch, Lynn; Nelson, J. C.; Vallazza, Jon M.

    2016-01-01

    Lake Erie is a large lake straddling the border of the U.S. and Canada that has become increasingly eutrophic in recent years. Eutrophication is particularly focused in the shallow western basin. The western basin of Lake Erie is hydrodynamically similar to a large estuary, with riverine inputs from the Detroit and Maumee Rivers mixing together and creating gradients in chemical and physical conditions. This study was driven by two questions: How does secondary production and food quality for consumers vary across this large mixing zone? and Are there correlations between cyanobacterial abundance and secondary production or food quality for consumers? Measuring spatial and temporal variation in secondary production and food quality is difficult for a variety of logistical reasons, so here a common consumer approach was used. In a common consumer approach, individuals of a single species are raised under similar conditions until placed in the field across environmental gradients of interest. After some period of exposure, the response of that common consumer is measured to provide an index of spatial variation in conditions. Here, a freshwater mussel (Lampsilis siliquoidea) was deployed at 32 locations that spanned habitat types and a gradient in cyanobacterial abundance in the western basin of Lake Erie to measure spatial variation in growth (an index of secondary production) and fatty acid (FA) content (an index of food quality). We found secondary production was highest within the Maumee rivermouth and lowest in the open waters of the lake. Mussel tissues in the Maumee rivermouth also included more eicosapentaenoic and docosapentaenoic fatty acids (EPA and DPA, respectively), but fewer bacterial FAs, suggesting more algae at the base of the food web in the Maumee rivermouth compared to open lake sites. The satellite-derived estimate of cyanobacterial abundance was not correlated to secondary production, but was positively related to EPA and DPA content in the

  12. Phylogenetic Profiles of In-House Microflora in Drains at a Food Production Facility: Comparison and Biocontrol Implications of Listeria-Positive and -Negative Bacterial Populations

    PubMed Central

    Solomon, Katie; Moore, John E.; Wall, Patrick G.; Fanning, Séamus

    2014-01-01

    Listeria species experience complex interactions with other microorganisms, which may promote growth and colonization of the organism in local environments or negatively affect them. This study investigated the microbial community at a food production facility, examining interactions between Listeria and the associated microbiome. Listeria species can be transferred between zones in the production environment by individuals or equipment, and drains may act as a reservoir for the organism, reflecting the microbial flora potentially in the production environment. Drains that were colonized by Listeria species and those determined to be free of Listeria were examined. In each case, 16S rRNA gene analysis was performed using the PhyloChip platform. Some general similarities in bacterial population structure were observed when Listeria-negative and -positive drain communities were compared, with some distinct differences also noted. These included increased populations of the genera Prevotella and Janthinobacterium associated with the absence of Listeria species, whereas Enterococcus and Rhodococcus were in higher abundance in drains colonized by Listeria species. Based on these results, a selection of bacterial species were grown in coculture biofilm with a Listeria monocytogenes strain identified as having colonized a drain at the facility. Mixed-species biofilm experiments showed that Janthinobacterium inhibited attachment and subsequent biofilm formation of L. monocytogenes; however, Enterococcus gallinarum significantly increased it. The results of this study suggest the microbial community in food processing facilities can impact the colonization of Listeria species and that influencing the microbiome in favor of antilisterial species may reduce the colonization of Listeria species and limit the likelihood of product/process contamination. PMID:24657862

  13. Bacterial meningitis.

    PubMed

    Heckenberg, Sebastiaan G B; Brouwer, Matthijs C; van de Beek, Diederik

    2014-01-01

    Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained, preceding any imaging studies. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, and an altered level of consciousness but signs may be scarce in children, in the elderly, and in meningococcal disease. Host genetic factors are major determinants of susceptibility to meningococcal and pneumococcal disease. Dexamethasone therapy has been implemented as adjunctive treatment of adults with pneumococcal meningitis. Adequate and prompt treatment of bacterial meningitis is critical to outcome. In this chapter we review the epidemiology, pathophysiology, and management of bacterial meningitis. © 2014 Elsevier B.V. All rights reserved.

  14. {sup 252}Cf-plasma desorption mass spectra of bacterial oligosaccharides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Elkin, Y.N.; Komandrova, N.A.; Tomshich, S.V.

    1994-07-20

    The possibility has been investigated of using the MSBKh instrument ({sup 252}Cf plasma desorption mass spectrometer) for studying the oligosaccharides of the O-specific chains of bacterial lipopolysaccharides. Experimental results on the ionization of galacturonic acid and of neutral and bacterial oligosaccharides containing NHR and COOH groups have been obtained and are discussed. The instrument has been used for estimating the compositions of fractions in the separation of degradation products of O-specific polysaccharide chains and establishing their structures.

  15. Isolation and functional characterization of bacterial endophytes from Carica papaya fruits.

    PubMed

    Krishnan, P; Bhat, R; Kush, A; Ravikumar, P

    2012-08-01

    To isolate and characterize the endophytes from papaya fruits and to determine the fermentative potential of the strains. Endophytes provide potential sources for novel natural products for the use in agriculture and nutrition. There is very limited information on isolation and characterization of bacterial endophytes from papaya. We describe isolation and characterization of eighteen endophytes of papaya fruit from four economically important papaya varieties viz 'Red lady', 'Solo', 'Coorg Honey' and 'Bangalore'. The phylogenetic analysis based on the 16S rRNA sequence revealed that isolated endophytes are genetically distinct and cluster as discrete clades in the dendrogram. The Bacillus species is a predominant bacterial endophyte across papaya varieties. The seeds and the endocarp of papaya fruits harbour Kocuria, Acinetobacter and Enterobacter species. The Staphylococcus species were detected in the fruit mesocarp of two papaya varieties used in the study. The endophytes isolated from papaya fruits were capable of producing extracellular enzymes like amylase, cellulase, pectinase and xylanase. Three isolates, Bacillus (PE-LR-1 and PE-LR-3) and Kocuria (PE-LR-2), were selected for fruit fermentation, and antioxidant potential of the fermented product was evaluated. PE-LR-3 fermented product has the free radical scavenging activity of 61·2% and a microbial cocktail of PE-LR-3 with Saccharomyces cerevisiae MTCC 2918 enhances the antioxidant potential to 75·7%. These findings suggest that different parts of papaya fruits harbour an array of bacterial endophytes that could be important agents in attributing the high nutritive status to the fruit and can serve as potent microbial cocktails for developing value-added fermented products of this important fruit. This study describes isolation of a bacterial endophyte from papaya fruit that is capable of improving the antioxidant potential of raw papaya after fermentation. No claim to Indian Government works Journal

  16. Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation.

    PubMed

    Rich, Joseph O; Leathers, Timothy D; Bischoff, Kenneth M; Anderson, Amber M; Nunnally, Melinda S

    2015-11-01

    Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grind corn fuel ethanol facility. Among eight sites sampled in the facility, the combined liquefaction stream and yeast propagation tank were consistently contaminated, leading to contamination of early fermentation tanks. Among 768 contaminants isolated, 92% were identified as Lactobacillus sp., with the most abundant species being Lactobacillus plantarum, Lactobacillus casei, Lactobacillus mucosae, and Lactobacillus fermentum. Seven percent of total isolates showed the ability to form biofilms in pure cultures, and 22% showed the capacity to significantly inhibit ethanol production. However, these traits were not correlated. Ethanol inhibition appeared to be related to acetic acid production by contaminants, particularly by obligately heterofermentative species such as L. fermentum and L. mucosae. Published by Elsevier Ltd.

  17. Effects of a herbicide mixture on primary and bacterial productivity in four prairie wetlands with varying salinities: an enclosure approach.

    PubMed

    Sura, Srinivas; Waiser, Marley J; Tumber, Vijay; Raina-Fulton, Renata; Cessna, Allan J

    2015-04-15

    Wetlands in the Prairie pothole region of Saskatchewan and Manitoba serve an important role in providing wildlife habitat, water storage and water filtration. They display a wide range of water quality parameters such as salinity, nutrients and major ions with sulfate as the dominant ion for the most saline wetlands. The differences in these water quality parameters among wetlands are reflected in the composition of aquatic plant communities and their productivity. Interspersed within an intensely managed agricultural landscape where pesticides are commonly used, mixtures of herbicides are often detected in these wetlands as well as in rivers, and drinking water reservoirs. One freshwater and three wetlands of varying salinity in the St. Denis National Wildlife Area, Saskatchewan, Canada were selected to study the effects of a mixture of eight herbicides (2,4-D, MCPA, dicamba, clopyralid, bromoxynil, mecoprop, dichlorprop, and glyphosate) on wetland microbial communities using an outdoor enclosure approach. Six enclosures (three controls and three treatments) were installed in each wetland and the herbicide mixture added to the treatment enclosures. The concentration of each herbicide in the enclosure water was that which would have resulted from a direct overspray of a 0.5-m deep wetland at its recommended field application rate. After herbicide addition, primary and bacterial productivity, and algal biomass were measured in both planktonic and benthic communities over 28 days. The herbicide mixture had a stimulatory effect on primary productivity in the nutrient-sufficient freshwater wetland while no stimulatory effect was observed in the nutrient-deficient saline wetlands. The differences observed in the effects of the herbicide mixture appear to be related to the nutrient bioavailability in these wetlands. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  18. Application of bacterial cytological profiling to crude natural product extracts reveals the antibacterial arsenal of Bacillus subtilis.

    PubMed

    Nonejuie, Poochit; Trial, Rachelle M; Newton, Gerald L; Lamsa, Anne; Ranmali Perera, Varahenage; Aguilar, Julieta; Liu, Wei-Ting; Dorrestein, Pieter C; Pogliano, Joe; Pogliano, Kit

    2016-05-01

    Although most clinically used antibiotics are derived from natural products, identifying new antibacterial molecules from natural product extracts is difficult due to the complexity of these extracts and the limited tools to correlate biological activity with specific molecules. Here, we show that bacterial cytological profiling (BCP) provides a rapid method for mechanism of action determination on plates and in complex natural product extracts and for activity-guided purification. We prepared an extract from Bacillus subtilis 3610 that killed the Escherichia coli lptD mutant and used BCP to observe two types of bioactivities in the unfractionated extract: inhibition of translation and permeablization of the cytoplasmic membrane. We used BCP to guide purification of the molecules responsible for each activity, identifying the translation inhibitors bacillaene and bacillaene B (glycosylated bacillaene) and demonstrating that two molecules contribute to cell permeabilitization, the bacteriocin subtilosin and the cyclic peptide sporulation killing factor. Our results suggest that bacillaene mediates translational arrest, and show that bacillaene B has a minimum inhibitory concentration 10 × higher than unmodified bacillaene. Finally, we show that BCP can be used to screen strains on an agar plate without the need for extract preparation, greatly saving time and improving throughput. Thus, BCP simplifies the isolation of novel natural products, by identifying strains, crude extracts and fractions with interesting bioactivities even when multiple activities are present, allowing investigators to focus labor-intensive steps on those with desired activities.

  19. Application of bacterial cytological profiling to crude natural product extracts reveals the antibacterial arsenal of Bacillus subtilis

    PubMed Central

    Nonejuie, Poochit; Trial, Rachelle M.; Newton, Gerald L.; Lamsa, Anne; Perera, Varahenage Ranmali; Aguilar, Julieta; Liu, Wei-Ting; Dorrestein, Pieter C.; Pogliano, Joe; Pogliano, Kit

    2016-01-01

    Although most clinically used antibiotics are derived from natural products, identifying new antibacterial molecules from natural product extracts is difficult due to the complexity of these extracts and the limited tools to correlate biological activity with specific molecules. Here, we show that bacterial cytological profiling (BCP) provides a rapid method for mechanism of action determination on plates and in complex natural product extracts and for activity-guided purification. We prepared an extract from Bacillus subtilis 3610 that killed the Escherichia coli lptD mutant and used BCP to observe two types of bioactivities in the unfractionated extract: inhibition of translation and permeablization of the cytoplasmic membrane. We used BCP to guide purification of the molecules responsible for each activity, identifying the translation inhibitors bacillaene and bacillaene B (glycosylated bacillaene) and demonstrating that two molecules contribute to cell permeabilitization, the bacteriocin subtilosin and the cyclic peptide sporulation killing factor. Our results suggest that bacillaene mediates translational arrest, and show that bacillaene B has a minimum inhibitory concentration 10 × higher than unmodified bacillaene. Finally, we show that BCP can be used to screen strains on an agar plate without the need for extract preparation, greatly saving time and improving throughput. Thus, BCP simplifies the isolation of novel natural products, by identifying strains, crude extracts and fractions with interesting bioactivities even when multiple activities are present, allowing investigators to focus labor-intensive steps on those with desired activities. PMID:26648120

  20. Inflammatory response in mixed viral-bacterial community-acquired pneumonia.

    PubMed

    Bello, Salvador; Mincholé, Elisa; Fandos, Sergio; Lasierra, Ana B; Ruiz, María A; Simon, Ana L; Panadero, Carolina; Lapresta, Carlos; Menendez, Rosario; Torres, Antoni

    2014-07-29

    The role of mixed pneumonia (virus+bacteria) in community-acquired pneumonia (CAP) has been described in recent years. However, it is not known whether the systemic inflammatory profile is different compared to monomicrobial CAP. We wanted to investigate this profile of mixed viral-bacterial infection and to compare it to monomicrobial bacterial or viral CAP. We measured baseline serum procalcitonin (PCT), C reactive protein (CRP), and white blood cell (WBC) count in 171 patients with CAP with definite etiology admitted to a tertiary hospital: 59 (34.5%) bacterial, 66 (39.%) viral and 46 (27%) mixed (viral-bacterial). Serum PCT levels were higher in mixed and bacterial CAP compared to viral CAP. CRP levels were higher in mixed CAP compared to the other groups. CRP was independently associated with mixed CAP. CRP levels below 26 mg/dL were indicative of an etiology other than mixed in 83% of cases, but the positive predictive value was 45%. PCT levels over 2.10 ng/mL had a positive predictive value for bacterial-involved CAP versus viral CAP of 78%, but the negative predictive value was 48%. Mixed CAP has a different inflammatory pattern compared to bacterial or viral CAP. High CRP levels may be useful for clinicians to suspect mixed CAP.

  1. R software package based statistical optimization of process components to simultaneously enhance the bacterial growth, laccase production and textile dye decolorization with cytotoxicity study

    PubMed Central

    Dudhagara, Pravin; Tank, Shantilal

    2018-01-01

    The thermophilic bacterium, Bacillus licheniformis U1 is used for the optimization of bacterial growth (R1), laccase production (R2) and synthetic disperse blue DBR textile dye decolorization (R3) in the present study. Preliminary optimization has been performed by one variable at time (OVAT) approach using four media components viz., dye concentration, copper sulphate concentration, pH, and inoculum size. Based on OVAT result further statistical optimization of R1, R2 and R3 performed by Box–Behnken design (BBD) using response surface methodology (RSM) in R software with R Commander package. The total 29 experimental runs conducted in the experimental design study towards the construction of a quadratic model. The model indicated that dye concentration 110 ppm, copper sulphate 0.2 mM, pH 7.5 and inoculum size 6% v/v were found to be optimum to maximize the laccase production and bacterial growth. Whereas, maximum dye decolorization achieved in media containing dye concentration 110 ppm, copper sulphate 0.6 mM, pH 6 and inoculum size 6% v/v. R package predicted R2 of R1, R2 and R3 were 0.9917, 0.9831 and 0.9703 respectively; likened to Design-Expert (Stat-Ease) (DOE) predicted R2 of R1, R2, and R3 were 0.9893, 0.9822 and 0.8442 respectively. The values obtained by R software were more precise, reliable and reproducible, compared to the DOE model. The laccase production was 1.80 fold increased, and 2.24 fold enhancement in dye decolorization was achieved using optimized medium than initial experiments. Moreover, the laccase-treated sample demonstrated the less cytotoxic effect on L132 and MCF-7 cell lines compared to untreated sample using MTT assay. Higher cell viability and lower cytotoxicity observed in a laccase-treated sample suggest the impending application of bacterial laccase in the reduction of toxicity of dye to design rapid biodegradation process. PMID:29718934

  2. Acute Bacterial Prostatitis: Diagnosis and Management.

    PubMed

    Coker, Timothy J; Dierfeldt, Daniel M

    2016-01-15

    Acute bacterial prostatitis is an acute infection of the prostate gland that causes pelvic pain and urinary tract symptoms, such as dysuria, urinary frequency, and urinary retention, and may lead to systemic symptoms, such as fevers, chills, nausea, emesis, and malaise. Although the true incidence is unknown, acute bacterial prostatitis is estimated to comprise approximately 10% of all cases of prostatitis. Most acute bacterial prostatitis infections are community acquired, but some occur after transurethral manipulation procedures, such as urethral catheterization and cystoscopy, or after transrectal prostate biopsy. The physical examination should include abdominal, genital, and digital rectal examination to assess for a tender, enlarged, or boggy prostate. Diagnosis is predominantly made based on history and physical examination, but may be aided by urinalysis. Urine cultures should be obtained in all patients who are suspected of having acute bacterial prostatitis to determine the responsible bacteria and its antibiotic sensitivity pattern. Additional laboratory studies can be obtained based on risk factors and severity of illness. Radiography is typically unnecessary. Most patients can be treated as outpatients with oral antibiotics and supportive measures. Hospitalization and broad-spectrum intravenous antibiotics should be considered in patients who are systemically ill, unable to voluntarily urinate, unable to tolerate oral intake, or have risk factors for antibiotic resistance. Typical antibiotic regimens include ceftriaxone and doxycycline, ciprofloxacin, and piperacillin/tazobactam. The risk of nosocomial bacterial prostatitis can be reduced by using antibiotics, such as ciprofloxacin, before transrectal prostate biopsy.

  3. [3H]Leucine incorporation method as a tool to measure secondary production by periphytic bacteria associated to the roots of floating aquatic macrophyte.

    PubMed

    Miranda, M R; Guimarães, J R D; Coelho-Souza, A S

    2007-10-01

    The present study assessed the application of [(3)H]Leucine incorporation into protein by periphytic bacteria associated with the roots of the floating aquatic macrophyte Eichornia crassipes. Basic assumptions underlying the method, such as linearity of leucine incorporation, saturation level of incorporation rates, incorporation into other macromolecules, specificity of incorporation for bacterial assemblages and [(3)H]Leucine degradation during samples storage were tested, and two procedures for extracting the incorporated leucine were compared. Both methods gave the same results, however, the hot TCA extraction method was less time consuming than the alkaline extraction method. Incorporation of [(3)H]Leucine was linear for up to 40 min. Saturation concentration of [(3)H]Leucine incorporation into protein was 1500 nM. An experiment with prokaryotic and eukaryotic inhibitors showed no significant [(3)H]Leucine incorporation into eukaryotes even in high leucine concentrations. No significant amounts of radiolabel were incorporated into other macromolecules. The maximum time of sample storage after the incubation is 15 days. The leucine incorporation method can be a reliable tool to measure bacterial production in the periphyton root-associated bacteria.

  4. Real time viability detection of bacterial spores

    DOEpatents

    Vanderberg, Laura A.; Herdendorf, Timothy J.; Obiso, Richard J.

    2003-07-29

    This invention relates to a process for detecting the presence of viable bacterial spores in a sample and to a spore detection system, the process including placing a sample in a germination medium for a period of time sufficient for commitment of any present viable bacterial spores to occur, mixing the sample with a solution of a lanthanide capable of forming a fluorescent complex with dipicolinic acid, and, measuring the sample for the presence of dipicolinic acid, and the system including a germination chamber having inlets from a sample chamber, a germinant chamber and a bleach chamber, the germination chamber further including an outlet through a filtering means, the outlet connected to a detection chamber, the detection chamber having an inlet from a fluorescence promoting metal chamber and the detection chamber including a spectral excitation source and a means of measuring emission spectra from a sample, the detection chamber further connected to a waste chamber. A germination reaction mixture useful for promoting commitment of any viable bacterial spores in a sample including a combination of L-alanine, L-asparagine and D-glucose is also described.

  5. Diagnosis of Meningococcal Meningitis by Broad-Range Bacterial PCR with Cerebrospinal Fluid

    PubMed Central

    Kotilainen, Pirkko; Jalava, Jari; Meurman, Olli; Lehtonen, Olli-Pekka; Rintala, Esa; Seppälä, Olli-Pekka; Eerola, Erkki; Nikkari, Simo

    1998-01-01

    We used broad-range bacterial PCR combined with DNA sequencing to examine prospectively cerebrospinal fluid (CSF) samples from patients with suspected meningitis. Fifty-six CSF samples from 46 patients were studied during the year 1995. Genes coding for bacterial 16S and/or 23S rRNA genes could be amplified from the CSF samples from five patients with a clinical picture consistent with acute bacterial meningitis. For these patients, the sequenced PCR product shared 98.3 to 100% homology with the Neisseria meningitidis sequence. For one patient, the diagnosis was initially made by PCR alone. Of the remaining 51 CSF samples, for 50 (98.0%) samples the negative PCR findings were in accordance with the negative findings by bacterial culture and Gram staining, as well as with the eventual clinical diagnosis for the patient. However, the PCR test failed to detect the bacterial rRNA gene in one CSF sample, the culture of which yielded Listeria monocytogenes. These results invite new research efforts to be focused on the application of PCR with broad-range bacterial primers to improve the etiologic diagnosis of bacterial meningitis. In a clinical setting, Gram staining and bacterial culture still remain the cornerstones of diagnosis. PMID:9665992

  6. Antibiotic-induced bacterial killing stimulates tumor necrosis factor-alpha release in whole blood.

    PubMed

    Arditi, M; Kabat, W; Yogev, R

    1993-01-01

    Rapid lysis of gram-negative bacteria is associated with considerable release of free endotoxin. Production of tumor necrosis factor (TNF) from adult whole blood ex vivo in response to bacterial products generated during antibiotic killing of Haemophilus influenzae type b (Hib) was investigated. Heparinized whole blood released TNF in a dose-dependent fashion in response to purified lipooligosaccharide of Hib. Bacteria (10(4)-10(7) cfu/mL) were placed into a Transwell filter insert (0.1 microns) and incubated with whole blood in the presence of various antibiotics. Exposure to ceftriaxone resulted in significantly greater release of TNF during killing of Hib than did exposure to imipenem, despite similar degrees of bacterial killing at 6 h. Polymyxin B inhibited the ceftriaxone-induced TNF release by 97%-99%, indicating that free endotoxin was the predominant stimulus for the increase in TNF release in this system. These observations suggest that ceftriaxone-induced killing of Hib results in bacterial cell wall products that are more proinflammatory than those produced by imipenem.

  7. Inheritance of bacterial spot resistance in Capsicum annuum var. annuum.

    PubMed

    Silva, L R A; Rodrigues, R; Pimenta, S; Correa, J W S; Araújo, M S B; Bento, C S; Sudré, C P

    2017-04-20

    Since 2008, Brazil is the largest consumer of agrochemicals, which increases production costs and risks of agricultural products, environment, and farmers' contamination. Sweet pepper, which is one of the main consumed vegetables in the country, is on top of the list of the most sprayed crops. The bacterial spot, caused by Xanthomonas spp, is one of the most damaging diseases of pepper crops. Genetic resistant consists of a suitable way of disease control, but development of durable resistant cultivars as well as understanding of plant-bacterium interaction is being a challenge for plant breeders and pathologists worldwide. Inheritance of disease resistance is often variable, depending on genetic background of the parents. The knowledge of the genetic base controlling such resistance is the first step in a breeding program aiming to develop new genotypes, bringing together resistance and other superior agronomic traits. This study reports the genetic basis of bacterial spot resistance in Capsicum annuum var. annuum using mean generation analysis from crosses between accessions UENF 2285 (susceptible) and UENF 1381 (resistant). The plants of each generation were grown in a greenhouse and leaflets were inoculated with bacterial strain ENA 4135 at 10 5 CFU/mL in 1.0 cm 2 of the mesophyll. Evaluations were performed using a scoring scale whose grades ranged from 1.0 (resistant) to 5.0 (susceptible), depending on symptom manifestation. Genetic control of bacterial spot has a quantitative aspect, with higher additive effect. The quantitative analysis showed that five genes were the minimum number controlling bacterial spot resistance. Additive effect was higher (6.06) than dominant (3.31) and explained 86.36% of total variation.

  8. Definition of a type of abnormal vaginal flora that is distinct from bacterial vaginosis: aerobic vaginitis.

    PubMed

    Donders, Gilbert G G; Vereecken, Annie; Bosmans, Eugene; Dekeersmaecker, Alfons; Salembier, Geert; Spitz, Bernard

    2002-01-01

    To define an entity of abnormal vaginal flora: aerobic vaginitis. Observational study. University Hospital Gasthuisberg, Leuven, Belgium. 631 women attending for routine prenatal care or attending vaginitis clinic. Samples were taken for fresh wet mount microscopy of vaginal fluid, vaginal cultures and measurement of lactate, succinate and cytokine levels in vaginal fluid. Smears deficient in lactobacilli and positive for clue cells were considered to indicate a diagnosis of bacterial vaginosis. Aerobic vaginitis was diagnosed if smears were deficient in lactobacilli, positive for cocci or coarse bacilli, positive for parabasal epithelial cells, and/or positive for vaginal leucocytes (plus their granular aspect). Genital complaints include red inflammation, yellow discharge, vaginal dyspareunia. Group B streptococci, escherichia coli, staphylococcus aureus and trichomonas vaginalis are frequently cultured. Vaginal lactate concentration is severely depressed in women with aerobic vaginitis, as in bacterial vaginosis, but vaginal succinate is not produced. Also in contrast to bacterial vaginosis, aerobic vaginitis produces a host immune response that leads to high production of interleukin-6, interleukin-1-beta and leukaemia inhibitory factor in the vaginal fluid. Aerobic vaginitis is associated with aerobic micro-organisms, mainly group B streptococci and E. coli. Its characteristics are different from those of bacterial vaginosis and elicit an important host response. The most severe form of aerobic vaginitis equals desquamative inflammatory vaginitis. In theory, aerobic vaginitis may be a better candidate than bacterial vaginosis as the cause of pregnancy complications, such as ascending chorioamnionitis, preterm rupture of the membranes and preterm delivery.

  9. The SPIDER fission fragment spectrometer for fission product yield measurements

    DOE PAGES

    Meierbachtol, K.; Tovesson, F.; Shields, D.; ...

    2015-04-01

    We developed the SPectrometer for Ion DEtermination in fission Research (SPIDER) for measuring mass yield distributions of fission products from spontaneous and neutron-induced fission. The 2E–2v method of measuring the kinetic energy (E) and velocity (v) of both outgoing fission products has been utilized, with the goal of measuring the mass of the fission products with an average resolution of 1 atomic mass unit (amu). Moreover, the SPIDER instrument, consisting of detector components for time-of-flight, trajectory, and energy measurements, has been assembled and tested using 229Th and 252Cf radioactive decay sources. For commissioning, the fully assembled system measured fission productsmore » from spontaneous fission of 252Cf. Individual measurement resolutions were met for time-of-flight (250 ps FWHM), spacial resolution (2 mm FHWM), and energy (92 keV FWHM for 8.376 MeV). Finally, these mass yield results measured from 252Cf spontaneous fission products are reported from an E–v measurement.« less

  10. Yearly variation of bacterial production in the Arraial do Cabo protection area (Cabo Frio upwelling region): An evidence of anthropogenic pressure

    PubMed Central

    Coelho-Souza, Sérgio A.; Pereira, Gilberto C.; Coutinho, Ricardo; Guimarães, Jean R.D.

    2013-01-01

    Arraial do Cabo is where upwelling occurs more intensively on the Brazilian coast. Although it is a protection area it suffers anthropogenic pressure such as harbor activities and sporadic sewage emissions. Short-time studies showed a high variability of bacterial production (BP) in this region but none of them evaluated BP during long periods in a large spatial scale including stations under different natural (upwelling and cold fronts) and anthropogenic pressures. During 2006, we sampled surface waters 10 times (5 in upwelling and 5 in subsidence periods) in 8 stations and we measured BP, temperature as well as the concentrations of inorganic nutrients, pigments and particulate organic matter (POM). BP was up to 400 times higher when sewage emissions were observed visually and it had a positive correlation with ammonia concentrations. Therefore, in 2007, we did two samples (each during upwelling and subsidence periods) during sewage emissions in five stations under different anthropogenic pressure and we also measured particles abundance by flow cytometry. The 12 samples in the most impacted area confirmed that BP was highest when ammonia was higher than 2 μM, also reporting the highest concentrations of chlorophyll a and suspended particles. However, considering all measured variables, upwelling was the main disturbing factor but the pressure of fronts should not be neglected since it had consequences in the auto-heterotrophic coupling, increasing the concentrations of non fluorescent particles and POM. Stations clustered in function of natural and anthropogenic pressures degrees and both determined the temporal-spatial variability. PMID:24688533

  11. Yearly variation of bacterial production in the Arraial do Cabo protection area (Cabo Frio upwelling region): an evidence of anthropogenic pressure.

    PubMed

    Coelho-Souza, Sérgio A; Pereira, Gilberto C; Coutinho, Ricardo; Guimarães, Jean R D

    2013-12-01

    Arraial do Cabo is where upwelling occurs more intensively on the Brazilian coast. Although it is a protection area it suffers anthropogenic pressure such as harbor activities and sporadic sewage emissions. Short-time studies showed a high variability of bacterial production (BP) in this region but none of them evaluated BP during long periods in a large spatial scale including stations under different natural (upwelling and cold fronts) and anthropogenic pressures. During 2006, we sampled surface waters 10 times (5 in upwelling and 5 in subsidence periods) in 8 stations and we measured BP, temperature as well as the concentrations of inorganic nutrients, pigments and particulate organic matter (POM). BP was up to 400 times higher when sewage emissions were observed visually and it had a positive correlation with ammonia concentrations. Therefore, in 2007, we did two samples (each during upwelling and subsidence periods) during sewage emissions in five stations under different anthropogenic pressure and we also measured particles abundance by flow cytometry. The 12 samples in the most impacted area confirmed that BP was highest when ammonia was higher than 2 μM, also reporting the highest concentrations of chlorophyll a and suspended particles. However, considering all measured variables, upwelling was the main disturbing factor but the pressure of fronts should not be neglected since it had consequences in the auto-heterotrophic coupling, increasing the concentrations of non fluorescent particles and POM. Stations clustered in function of natural and anthropogenic pressures degrees and both determined the temporal-spatial variability.

  12. Biotechnological Production of Caffeic Acid by Bacterial Cytochrome P450 CYP199A2

    PubMed Central

    Arai, Yuka; Kino, Kuniki

    2012-01-01

    Caffeic acid is a biologically active molecule that has various beneficial properties, including antioxidant, anticancer, and anti-inflammatory activities. In this study, we explored the catalytic potential of a bacterial cytochrome P450, CYP199A2, for the biotechnological production of caffeic acid. When the CYP199A2 enzyme was reacted with p-coumaric acid, it stoichiometrically produced caffeic acid. The crystal structure of CYP199A2 shows that Phe at position 185 is situated directly above, and only 6.35 Å from, the heme iron. This F185 residue was replaced with hydrophobic or hydroxylated amino acids using site-directed mutagenesis to create mutants with novel and improved catalytic properties. In whole-cell assays with the known substrate of CYP199A2, 2-naphthoic acid, only the wild-type enzyme hydroxylated 2-naphthoic acid at the C-7 and C-8 positions, whereas all of the active F185 mutants exhibited a preference for C-5 hydroxylation. Interestingly, several F185 mutants (F185V, F185L, F185I, F185G, and F185A mutants) also acquired the ability to hydroxylate cinnamic acid, which was not hydroxylated by the wild-type enzyme. These results demonstrate that F185 is an important residue that controls the regioselectivity and the substrate specificity of CYP199A2. Furthermore, Escherichia coli cells expressing the F185L mutant exhibited 5.5 times higher hydroxylation activity for p-coumaric acid than those expressing the wild-type enzyme. By using the F185L whole-cell catalyst, the production of caffeic acid reached 15 mM (2.8 g/liter), which is the highest level so far attained in biotechnological production of this compound. PMID:22729547

  13. [Bacterial contamination of stethoscopes in hospital].

    PubMed

    Davullu, Sevcan; Burger, Sandrine; Kessler, Brigitte; Meunier, Olivier

    2015-01-01

    Although many publications on the subject are available, only few campaigns for stethoscopes cleaning and disinfection are conducted. Stethoscope is a "not critical" reusable medical device and should benefit from a cleaning disinfection "low level" after each use. We studied the bacterial contamination of stethoscopes in our hospital and measured the role of bacterial reservoir and/or vector stethoscope could play. Mean microbial load was estimated at 1.550 CFU per stethoscope. Results obtained in our hospital and those of the literature, led us to propose a simple and efficient cleaning method. We believe motivate everyone to change their habits and carry out disinfection more frequent their very handling stethoscope.

  14. Live/Dead Bacterial Spore Assay Using DPA-Triggered Tb Luminescence

    NASA Technical Reports Server (NTRS)

    Ponce, Adrian

    2003-01-01

    A method of measuring the fraction of bacterial spores in a sample that remain viable exploits DPA-triggered luminescence of Tb(3+) and is based partly on the same principles as those described earlier. Unlike prior methods for performing such live/dead assays of bacterial spores, this method does not involve counting colonies formed by cultivation (which can take days), or counting of spores under a microscope, and works whether or not bacterial spores are attached to other small particles (i.e., dust), and can be implemented on a time scale of about 20 minutes.

  15. A method for the purification of bacterial flagellin that allows simple upscaling.

    PubMed

    Hiriart, Yanina; Errea, Agustina; González Maciel, Dolores; Lopez, Juan Carlos; Rumbo, Martin

    2012-01-01

    There is a growing interest in enterobacterial flagellins that may result in a demand to produce flagellin on an industrial scale for possible applications as an adjuvant, immunomodulatory agent or vaccine antigen. Traditionally, small-scale production of flagellin has occurred in the laboratory by flagellar shearing of bacterial surfaces and subsequent ultracentrifugation. The main drawback of this method is the need to use low-agitation cultures to avoid the loss of flagella due to shearing during culture. In the present work, we describe a scalable protocol for the production of flagellin with higher yields than traditional laboratory-scale protocols. The use of cross-flow filtration to concentrate bacterial cultures combines extensive shearing of flagella with a reduction in volume, greatly simplifying downstream processing. This technique also allows the use of highly-agitated culture conditions because any sheared flagella are retained in the bacterial concentrate. Flagella obtained with this procedure showed in vivo and in vitro innate activating capacities similar to those of flagella produced at laboratory scale. This procedure is flexible, allowing an increase in production scale, an enhancement of flagellin yield and no requirement for expensive equipment.

  16. Barium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies.

    PubMed

    Martinez-Ruiz, Francisca; Jroundi, Fadwa; Paytan, Adina; Guerra-Tschuschke, Isabel; Abad, María Del Mar; González-Muñoz, María Teresa

    2018-04-24

    Ba proxies have been broadly used to reconstruct past oceanic export production. However, the precise mechanisms underlying barite precipitation in undersaturated seawater are not known. The link between bacterial production and particulate Ba in the ocean suggests that bacteria may play a role. Here we show that under experimental conditions marine bacterial biofilms, particularly extracellular polymeric substances (EPS), are capable of bioaccumulating Ba, providing adequate conditions for barite precipitation. An amorphous P-rich phase is formed at the initial stages of Ba bioaccumulation, which evolves into barite crystals. This supports that in high productivity regions where large amounts of organic matter are subjected to bacterial degradation, the abundant EPS would serve to bind the necessary Ba and form nucleation sites leading to barite precipitation. This also provides new insights into barite precipitation and opens an exciting field to explore the role of EPS in mineral precipitation in the ocean.

  17. Applications of CRISPR/Cas System to Bacterial Metabolic Engineering.

    PubMed

    Cho, Suhyung; Shin, Jongoh; Cho, Byung-Kwan

    2018-04-05

    The clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR/Cas) adaptive immune system has been extensively used for gene editing, including gene deletion, insertion, and replacement in bacterial and eukaryotic cells owing to its simple, rapid, and efficient activities in unprecedented resolution. Furthermore, the CRISPR interference (CRISPRi) system including deactivated Cas9 (dCas9) with inactivated endonuclease activity has been further investigated for regulation of the target gene transiently or constitutively, avoiding cell death by disruption of genome. This review discusses the applications of CRISPR/Cas for genome editing in various bacterial systems and their applications. In particular, CRISPR technology has been used for the production of metabolites of high industrial significance, including biochemical, biofuel, and pharmaceutical products/precursors in bacteria. Here, we focus on methods to increase the productivity and yield/titer scan by controlling metabolic flux through individual or combinatorial use of CRISPR/Cas and CRISPRi systems with introduction of synthetic pathway in industrially common bacteria including Escherichia coli . Further, we discuss additional useful applications of the CRISPR/Cas system, including its use in functional genomics.

  18. Merging chemical ecology with bacterial genome mining for secondary metabolite discovery.

    PubMed

    Vizcaino, Maria I; Guo, Xun; Crawford, Jason M

    2014-02-01

    The integration of chemical ecology and bacterial genome mining can enhance the discovery of structurally diverse natural products in functional contexts. By examining bacterial secondary metabolism in the framework of its ecological niche, insights into the upregulation of orphan biosynthetic pathways and the enhancement of the enzyme substrate supply can be obtained, leading to the discovery of new secondary metabolic pathways that would otherwise be silent or undetected under typical laboratory cultivation conditions. Access to these new natural products (i.e., the chemotypes) facilitates experimental genotype-to-phenotype linkages. Here, we describe certain functional natural products produced by Xenorhabdus and Photorhabdus bacteria with experimentally linked biosynthetic gene clusters as illustrative examples of the synergy between chemical ecology and bacterial genome mining in connecting genotypes to phenotypes through chemotype characterization. These Gammaproteobacteria share a mutualistic relationship with nematodes and a pathogenic relationship with insects and, in select cases, humans. The natural products encoded by these bacteria distinguish their interactions with their animal hosts and other microorganisms in their multipartite symbiotic lifestyles. Though both genera have similar lifestyles, their genetic, chemical, and physiological attributes are distinct. Both undergo phenotypic variation and produce a profuse number of bioactive secondary metabolites. We provide further detail in the context of regulation, production, processing, and function for these genetically encoded small molecules with respect to their roles in mutualism and pathogenicity. These collective insights more widely promote the discovery of atypical orphan biosynthetic pathways encoding novel small molecules in symbiotic systems, which could open up new avenues for investigating and exploiting microbial chemical signaling in host-bacteria interactions.

  19. 77 FR 18916 - Production Measurement Documents Incorporated by Reference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-29

    ... products, or lubricating oils. Natural gas liquids and liquid petroleum gases are excluded from this... into the regulations governing oil, gas, and sulphur operations in the Outer Continental Shelf... measuring oil and gas production volumes. This rule will result in more accurate and efficient measurement...

  20. Bacterial community dynamics in a rumen fluid bioreactor during in-vitro cultivation.

    PubMed

    Zapletalová, Martina; Kašparovská, Jitka; Křížová, Ludmila; Kašparovský, Tomáš; Šerý, Omar; Lochman, Jan

    2016-09-20

    To study the various processes in the rumen the in vitro techniques are widely used to realize more controlled and reproducible conditions compared to in vivo experiments. Mostly, only the parameters like pH changes, volatile fatty acids content or metabolite production are monitored. In this study we examine the bacterial community dynamics of rumen fluid in course of ten day cultivation realize under standard conditions described in the literature. Whereas the pH values, total VFA content and A/P ratio in bioreactor were consistent with natural conditions in the rumen, the mean redox-potential values of -251 and -243mV were much more negative. For culture-independent assessment of bacterial community composition, the Illumina MiSeq results indicated that the community contained 292 bacterial genera. In course of ten days cultivation a significant changes in the microbial community were measured when Bacteroidetes to Firmicutes ratio changed from 3.2 to 1.2 and phyla Proteobacteria and Actinobacteria represented by genus Bifidobacterium and Olsenella significantly increased. The main responsible factor of these changes seems to be very low redox potential in bioreactor together with accumulation of simple carbohydrates in milieu as a result of limited excretion of fermented feed and absence of nutrient absorbing mechanisms. Copyright © 2016 Elsevier B.V. All rights reserved.