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Sample records for affect microbial growth

  1. Fractal scaling of microbial colonies affects growth

    NASA Astrophysics Data System (ADS)

    Károlyi, György

    2005-03-01

    The growth dynamics of filamentary microbial colonies is investigated. Fractality of the fungal or actinomycetes colonies is shown both theoretically and in numerical experiments to play an important role. The growth observed in real colonies is described by the assumption of time-dependent fractality related to the different ages of various parts of the colony. The theoretical results are compared to a simulation based on branching random walks.

  2. Rumen degradable protein supply affects microbial efficiency in continuous culture and growth in steers.

    PubMed

    Brooks, M A; Harvey, R M; Johnson, N F; Kerley, M S

    2012-12-01

    We hypothesized that microbial efficiency and output from fermentation in the rumen would be optimized when peptide supply was balanced with peptide requirement of ruminal microflora. This study was conducted to measure response of varying rumen degradable peptide (RDPep) supply on ruminal fermentation characteristics and steer growth. A continuous culture experiment was conducted with diets formulated to achieve a predicted RDPep balance (RDPep supplied above RDPep required) of -0.30 to 1.45% CP with rumen degradable N (RDN) balance (RDN supplied above RDN required) above dietary ammonia-N requirement of microbes. Two additional treatments had RDPep balances of -0.30 and 0.78% CP with insufficient ammonia-N supply to meet microbial requirements. Single-flow fermenters (N = 24; n = 6) were inoculated with rumen fluid and maintained anaerobically at 39°C with a 0.06 h(-1) dilution rate. Inadequate RDN decreased OM digestion and microbial N flow, and increased rumen undegradable N (P < 0.01). Microbial efficiency decreased in RDN-deficient diets and was greatest when RDPep balance did not excessively exceed microbial requirement of RDPep predicted (P < 0.01). A growth study was conducted with 49 yearling, crossbred, Angus steers (initial BW 370 ± 34 kg). Animals were assigned to 1 of 4 treatment groups by BW and further divided into 3 pens with 4 steers per pen to achieve similar initial pen weights. Treatments consisted of 4 isonitrogenous diets balanced for RDN but varying in predicted RDPep balance (0.55%, -0.02%, -0.25%, and -0.65% CP). Animals were maintained on treatment for 70 d with individual BW taken on d 0, 1, 21, 42, 70, and 71. Final BW decreased linearly with decreasing RDPep (P = 0.05). Average daily gain and G:F displayed a quadratic effect with greater ADG and G:F at greater and lesser RDPep levels (P = 0.02). We concluded that balancing RDPep supply to predicted requirement improved fermentation efficiency and microbial output, which in turn

  3. Wash operations affect water quality and packaged fresh-cut romaine lettuce quality and microbial growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Washing during the preparation of fresh-cut produce is an important step to maintaining the quality and safety of the finished products. It is often the only step aimed at reducing microbial populations and removing tissue fluids from cut produce. However, little is known about the effects of washi...

  4. Dissipation and effects of tricyclazole on soil microbial communities and rice growth as affected by amendment with alperujo compost.

    PubMed

    García-Jaramillo, M; Redondo-Gómez, S; Barcia-Piedras, J M; Aguilar, M; Jurado, V; Hermosín, M C; Cox, L

    2016-04-15

    The presence of pesticides in surface and groundwater has grown considerably in the last decades as a consequence of the intensive farming activity. Several studies have shown the benefits of using organic amendments to prevent losses of pesticides from runoff or leaching. A particular soil from the Guadalquivir valley was placed in open air ponds and amended at 1 or 2% (w/w) with alperujo compost (AC), a byproduct from the olive oil industry. Tricyclazole dissipation, rice growth and microbial diversity were monitored along an entire rice growing season. An increase in the net photosynthetic rate of Oryza sativa plants grown in the ponds with AC was observed. These plants produced between 1100 and 1300kgha(-1) more rice than plants from the unamended ponds. No significant differences were observed in tricyclazole dissipation, monitored for a month in soil, surface and drainage water, between the amended and unamended ponds. The structure and diversity of bacteria and fungi communities were also studied by the use of the polymerase chain reaction denaturing gel electrophoresis (PCR-DGGE) from DNA extracted directly from soil samples. The banding pattern was similar for all treatments, although the density of bands varied throughout the time. Apparently, tricyclazole did not affect the structure and diversity of bacteria and fungi communities, and this was attributed to its low bioavailability. Rice cultivation under paddy field conditions may be more efficient under the effects of this compost, due to its positive effects on soil properties, rice yield, and soil microbial diversity. PMID:26849328

  5. Growth of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, native microbial load, and Pseudomonas fluorescens 2-79

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incidence of human illness associated with the consumption of fresh sprouts has increased very sharply during the past decade. The objective of this study was to investigate the growth dynamics of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, native microbial load, an...

  6. New microbial growth factor

    NASA Technical Reports Server (NTRS)

    Bok, S. H.; Casida, L. E., Jr.

    1977-01-01

    A screening procedure was used to isolate from soil a Penicillium sp., two bacterial isolates, and a Streptomyces sp. that produced a previously unknown microbial growth factor. This factor was an absolute growth requirement for three soil bacteria. The Penicillium sp. and one of the bacteria requiring the factor, an Arthrobacter sp., were selected for more extensive study concerning the production and characteristics of the growth factor. It did not seem to be related to the siderochromes. It was not present in soil extract, rumen fluid, or any other medium component tested. It appears to be a glycoprotein of high molecular weight and has high specific activity. When added to the diets for a meadow-vole mammalian test system, it caused an increased consumption of diet without a concurrent increase in rate of weight gain.

  7. Teaching Microbial Growth by Simulation.

    ERIC Educational Resources Information Center

    Ruiz, A. Fernandez; And Others

    1989-01-01

    Presented is a simulation program for Apple II computer which assays the effects of a series of variables on bacterial growth and interactions between microbial populations. Results of evaluation of the program with students are summarized. (CW)

  8. Modeling microbial growth and dynamics.

    PubMed

    Esser, Daniel S; Leveau, Johan H J; Meyer, Katrin M

    2015-11-01

    Modeling has become an important tool for widening our understanding of microbial growth in the context of applied microbiology and related to such processes as safe food production, wastewater treatment, bioremediation, or microbe-mediated mining. Various modeling techniques, such as primary, secondary and tertiary mathematical models, phenomenological models, mechanistic or kinetic models, reactive transport models, Bayesian network models, artificial neural networks, as well as agent-, individual-, and particle-based models have been applied to model microbial growth and activity in many applied fields. In this mini-review, we summarize the basic concepts of these models using examples and applications from food safety and wastewater treatment systems. We further review recent developments in other applied fields focusing on models that explicitly include spatial relationships. Using these examples, we point out the conceptual similarities across fields of application and encourage the combined use of different modeling techniques in hybrid models as well as their cross-disciplinary exchange. For instance, pattern-oriented modeling has its origin in ecology but may be employed to parameterize microbial growth models when experimental data are scarce. Models could also be used as virtual laboratories to optimize experimental design analogous to the virtual ecologist approach. Future microbial growth models will likely become more complex to benefit from the rich toolbox that is now available to microbial growth modelers. PMID:26298697

  9. Substrate and nutrient limitation regulating microbial growth in soil

    NASA Astrophysics Data System (ADS)

    Bååth, Erland

    2015-04-01

    Microbial activity and growth in soil is regulated by several abiotic factors, including temperature, moisture and pH as the most important ones. At the same time nutrient conditions and substrate availability will also determine microbial growth. Amount of substrate will not only affect overall microbial growth, but also affect the balance of fungal and bacterial growth. The type of substrate will also affect the latter. Furthermore, according to Liebig law of limiting factors, we would expect one nutrient to be the main limiting one for microbial growth in soil. When this nutrient is added, the initial second liming factor will become the main one, adding complexity to the microbial response after adding different substrates. I will initially describe different ways of determining limiting factors for bacterial growth in soil, especially a rapid method estimating bacterial growth, using the leucine incorporation technique, after adding C (as glucose), N (as ammonium nitrate) and P (as phosphate). Scenarios of different limitations will be covered, with the bacterial growth response compared with fungal growth and total activity (respiration). The "degree of limitation", as well as the main limiting nutrient, can be altered by adding substrate of different stoichiometric composition. However, the organism group responding after alleviating the nutrient limitation can differ depending on the type of substrate added. There will also be situations, where fungi and bacteria appear to be limited by different nutrients. Finally, I will describe interactions between abiotic factors and the response of the soil microbiota to alleviation of limiting factors.

  10. Conditioning biomass for microbial growth

    SciTech Connect

    Bodie, Elizabeth A; England, George

    2015-03-31

    The present invention relates to methods for improving the yield of microbial processes that use lignocellulose biomass as a nutrient source. The methods comprise conditioning a composition comprising lignocellulose biomass with an enzyme composition that comprises a phenol oxidizing enzyme. The conditioned composition can support a higher rate of growth of microorganisms in a process. In one embodiment, a laccase composition is used to condition lignocellulose biomass derived from non-woody plants, such as corn and sugar cane. The invention also encompasses methods for culturing microorganisms that are sensitive to inhibitory compounds in lignocellulose biomass. The invention further provides methods of making a product by culturing the production microorganisms in conditioned lignocellulose biomass.

  11. Well having inhibited microbial growth

    DOEpatents

    Lee, Brady D.; Dooley, Kirk J.

    2006-08-15

    The invention includes methods of inhibiting microbial growth in a well. A packing material containing a mixture of a first material and an antimicrobial agent is provided to at least partially fill a well bore. One or more access tubes are provided in an annular space around a casing within the well bore. The access tubes have a first terminal opening located at or above a ground surface and have a length that extends from the first terminal opening at least part of the depth of the well bore. The access tubes have a second terminal opening located within the well bore. An antimicrobial material is supplied into the well bore through the first terminal opening of the access tubes. The invention also includes well constructs.

  12. A thermodynamic theory of microbial growth.

    PubMed

    Desmond-Le Quéméner, Elie; Bouchez, Théodore

    2014-08-01

    Our ability to model the growth of microbes only relies on empirical laws, fundamentally restricting our understanding and predictive capacity in many environmental systems. In particular, the link between energy balances and growth dynamics is still not understood. Here we demonstrate a microbial growth equation relying on an explicit theoretical ground sustained by Boltzmann statistics, thus establishing a relationship between microbial growth rate and available energy. The validity of our equation was then questioned by analyzing the microbial isotopic fractionation phenomenon, which can be viewed as a kinetic consequence of the differences in energy contents of isotopic isomers used for growth. We illustrate how the associated theoretical predictions are actually consistent with recent experimental evidences. Our work links microbial population dynamics to the thermodynamic driving forces of the ecosystem, which opens the door to many biotechnological and ecological developments. PMID:24522260

  13. Can transgenic maize affect soil microbial communities?

    PubMed

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-09-29

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  14. Can Transgenic Maize Affect Soil Microbial Communities?

    PubMed Central

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-01-01

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  15. Microbial Growth under Supercritical CO2

    PubMed Central

    Peet, Kyle C.; Freedman, Adam J. E.; Hernandez, Hector H.; Britto, Vanya; Boreham, Chris; Ajo-Franklin, Jonathan B.

    2015-01-01

    Growth of microorganisms in environments containing CO2 above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO2 (scCO2) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO2. Analysis of 16S rRNA genes from scCO2 enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO2 headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO2 headspace. In addition to these isolates, several Bacillus type strains grew under scCO2, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO2 and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO2 (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO2 in the deep subsurface. PMID:25681188

  16. Factors Affecting Soil Microbial Community Structure in Tomato Cropping Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil and rhizosphere microbial communities in agroecosystems may be affected by soil, climate, plant species, and management. We identified some of the most important factors controlling microbial biomass and community structure in an agroecosystem utilizing tomato plants with the following nine tre...

  17. Nanomechanical sensors for single microbial cell growth monitoring

    NASA Astrophysics Data System (ADS)

    Maloney, Niall; Lukacs, Gyongyi; Jensen, Jason; Hegner, Martin

    2014-06-01

    A nanomechanical technique for rapid real time detection and monitoring of microorganism growth will significantly reduce costs and diagnosis times in industrial and clinical settings. Owing to their label free detection mechanism and unprecedented sensitivity to the mass and elastic modulus of biological structures, dynamically operated cantilever arrays provide an opportunity to rapidly detect and track the evolution of microbial growth. Here we report the monitoring of the growth of single Aspergillus niger spores via the multimode response of microcantilevers. The fungal hyphal structure affects the cantilevers' nanomechanical properties as it propagates along the sensor. We demonstrate, for the first time, the mapping of cellular events with great accuracy using a cantilever frequency response. Imaging of growth conditions on the cantilever, which is performed in parallel, allows for verification of these results. Theoretical comparison and finite element modelling confirm experimental findings and allow for determination of the hyphal elastic modulus.A nanomechanical technique for rapid real time detection and monitoring of microorganism growth will significantly reduce costs and diagnosis times in industrial and clinical settings. Owing to their label free detection mechanism and unprecedented sensitivity to the mass and elastic modulus of biological structures, dynamically operated cantilever arrays provide an opportunity to rapidly detect and track the evolution of microbial growth. Here we report the monitoring of the growth of single Aspergillus niger spores via the multimode response of microcantilevers. The fungal hyphal structure affects the cantilevers' nanomechanical properties as it propagates along the sensor. We demonstrate, for the first time, the mapping of cellular events with great accuracy using a cantilever frequency response. Imaging of growth conditions on the cantilever, which is performed in parallel, allows for verification of these

  18. Bioflumology: Microbial mat growth in flumes

    NASA Astrophysics Data System (ADS)

    Airo, A.; Weigert, S.; Beck, C.

    2014-04-01

    The emergence of oxygenic photosynthesis resulted in a transformational change of Earth's geochemical cycles and the subsequent evolution of life. However, it remains vigorously debated when this metabolic ability had evolved in cyanobacteria. This is largely because studies of Archean microfossil morphology, molecular biomarkers, and isotopic characteristics are frequently ambiguous. However, the high degree of morphological similarities between modern photosynthetic and Archean fossil mats has been interpreted to indicate phototactic microbial behavior or oxygenic photosynthesis. In order to better evaluate the relationship between mat morphology and metabolism, we here present a laboratory set-up for conducting month-long experiments in several sterilizable circular flumes designed to allow single-species cyanobacterial growth under adjustable fluid-flow conditions and protected from contamination.

  19. Altered precipitation regime affects the function and composition of soil microbial communities on multiple time scales.

    PubMed

    Zeglin, L H; Bottomley, P J; Jumpponen, A; Rice, C W; Arango, M; Lindsley, A; McGowan, A; Mfombep, P; Myrold, D D

    2013-10-01

    Climate change models predict that future precipitation patterns will entail lower-frequency but larger rainfall events, increasing the duration of dry soil conditions. Resulting shifts in microbial C cycling activity could affect soil C storage. Further, microbial response to rainfall events may be constrained by the physiological or nutrient limitation stress of extended drought periods; thus seasonal or multiannual precipitation regimes may influence microbial activity following soil wet-up. We quantified rainfall-driven dynamics of microbial processes that affect soil C loss and retention, and microbial community composition, in soils from a long-term (14-year) field experiment contrasting "Ambient" and "Altered" (extended intervals between rainfalls) precipitation regimes. We collected soil before, the day following, and five days following 2.5-cm rainfall events during both moist and dry periods (June and September 2011; soil water potential = -0.01 and -0.83 MPa, respectively), and measured microbial respiration, microbial biomass, organic matter decomposition potential (extracellular enzyme activities), and microbial community composition (phospholipid fatty acids). The equivalent rainfall events caused equivalent microbial respiration responses in both treatments. In contrast, microbial biomass was higher and increased after rainfall in the Altered treatment soils only, thus microbial C use efficiency (CUE) was higher in Altered than Ambient treatments (0.70 +/- 0.03 > 0.46 +/- 0.10). CUE was also higher in dry (September) soils. C-acquiring enzyme activities (beta-glucosidase, cellobiohydrolase, and phenol oxidase) increased after rainfall in moist (June), but not dry (September) soils. Both microbial biomass C:N ratios and fungal:bacterial ratios were higher at lower soil water contents, suggesting a functional and/or population-level shift in the microbiota at low soil water contents, and microbial community composition also differed following wet

  20. Dynamics of microbial growth and coexistence on variably saturated rough surfaces.

    PubMed

    Long, Tao; Or, Dani

    2009-08-01

    The high degree of microbial diversity found in soils is attributed to the highly heterogeneous pore space and the dynamic aqueous microenvironments. Previous studies have shown that spatial and temporal variations in aqueous diffusion pathways play an important role in shaping microbial habitats and biological activity in unsaturated porous media. A new modeling framework was developed for the quantitative description of diffusion-dominated microbial interactions focusing on competitive growth of two microbial species inhabiting partially saturated rough surfaces. Surface heterogeneity was represented by patches with different porosities and water retention properties, yielding heterogeneous distribution of water contents that varies with changes in relative humidity or soil matric potential. Nutrient diffusion and microbial growth on the variably hydrated and heterogeneous surface was modeled using a hybrid method that combines a reaction diffusion method for nutrient field with individual based model for microbial growth and expansion. The model elucidated the effects of hydration dynamics and heterogeneity on nutrient fluxes and mobility affecting microbial population growth, expansion, and coexistence at the microscale. In contrast with single species dominance under wet conditions, results demonstrated prolonged coexistence of two competing species under drier conditions where nutrient diffusion and microbial movement were both limited. The uneven distribution of resources and diffusion pathways in heterogeneous surfaces highlighted the importance of position in the landscape for survival that may compensate for competitive disadvantages conferred by physiological traits. Increased motility was beneficial for expansion and survival. Temporal variations in hydration conditions resulted in fluctuations in microbial growth rate and population size. Population growth dynamics of the dominant species under wet-dry cycles were similar to growth under average value

  1. Microbial Growth and Carbon Use Efficiency in the Rhizosphere and Root-Free Soil

    PubMed Central

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Anderson, Traute-Heidi; Kuzyakov, Yakov

    2014-01-01

    Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE)–the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in soil microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the soil under Beta vulgaris. All measurements were done in root-free and rhizosphere soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free soil. The effects of N and C availability on CUE in rhizosphere and root-free soil are discussed. PMID:24722409

  2. Microbial composition affects the functioning of estuarine sediments

    PubMed Central

    Reed, Heather E; Martiny, Jennifer BH

    2013-01-01

    Although microorganisms largely drive many ecosystem processes, the relationship between microbial composition and their functioning remains unclear. To tease apart the effects of composition and the environment directly, microbial composition must be manipulated and maintained, ideally in a natural ecosystem. In this study, we aimed to test whether variability in microbial composition affects functional processes in a field setting, by reciprocally transplanting riverbed sediments between low- and high-salinity locations along the Nonesuch River (Maine, USA). We placed the sediments into microbial ‘cages' to prevent the migration of microorganisms, while allowing the sediments to experience the abiotic conditions of the surroundings. We performed two experiments, short- (1 week) and long-term (7 weeks) reciprocal transplants, after which we assayed a variety of functional processes in the cages. In both experiments, we examined the composition of bacteria generally (targeting the 16S rDNA gene) and sulfate-reducing bacteria (SRB) specifically (targeting the dsrAB gene) using terminal restriction fragment length polymorphism (T-RFLP). In the short-term experiment, sediment processes (CO2 production, CH4 flux, nitrification and enzyme activities) depended on both the sediment's origin (reflecting differences in microbial composition between salt and freshwater sediments) and the surrounding environment. In the long-term experiment, general bacterial composition (but not SRB composition) shifted in response to their new environment, and this composition was significantly correlated with sediment functioning. Further, sediment origin had a diminished effect, relative to the short-term experiment, on sediment processes. Overall, this study provides direct evidence that microbial composition directly affects functional processes in these sediments. PMID:23235294

  3. Microbial Growth Inside Insulated External Walls as an Indoor Air Biocontamination Source

    PubMed Central

    Pessi, Anna-Mari; Suonketo, Jommi; Pentti, Matti; Kurkilahti, Mika; Peltola, Kaija; Rantio-Lehtimäki, Auli

    2002-01-01

    The association between moisture-related microbial growth (mesophilic fungi and bacteria) within insulated exterior walls and microbial concentrations in the indoor air was studied. The studied apartment buildings with precast concrete external walls were situated in a subarctic zone. Actinomycetes in the insulation layer were found to have increased concentrations in the indoor air. The moisture content of the indoor air significantly affected all measurable airborne concentrations. PMID:11823245

  4. Spatial & Temporal Geophysical Monitoring of Microbial Growth and Biofilm Formation

    EPA Science Inventory

    Previous studies have examined the effect of biogenic gases and biomineralization on the acoustic properties of porous media. In this study, we investigated the spatiotemporal effect of microbial growth and biofilm formation on compressional waves and complex conductivity in sand...

  5. Inhibition of microbial growth on chitosan membranes by plasma treatment.

    PubMed

    de Oliveira Cardoso Macêdo, Marina; de Macêdo, Haroldo Reis Alves; Gomes, Dayanne Lopes; de Freitas Daudt, Natália; Rocha, Hugo Alexandre Oliveira; Alves, Clodomiro

    2013-11-01

    The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site, and it also affects the bulk properties of the polymers. The use of gas plasma is an elegant alternative sterilization technique. The plasma promotes efficient inactivation of the microorganisms, minimizes damage to the materials, and presents very little danger for personnel and the environment. In this study we used plasma for microbial inhibition of chitosan membranes. The membranes were treated with oxygen, methane, or argon plasma for different time periods (15, 30, 45, or 60 min). For inhibition of microbial growth with oxygen plasma, the time needed was 60 min. For the methane plasma, samples were successfully treated after 30, 45, and 60 min. For argon plasma, all treatment periods were effective. PMID:24251774

  6. Microbial growth and physiology in space - A review

    NASA Technical Reports Server (NTRS)

    Cioletti, Louis A.; Mishra, S. K.; Pierson, Duane L.

    1991-01-01

    An overview of microbial behavior in closed environments is given with attention to data related to simulated microgravity and actual space flight. Microbes are described in terms of antibiotic sensitivity, subcellular structure, and physiology, and the combined effects are considered of weightlessness and cosmic radiation on human immunity to such microorganisms. Space flight results report such effects as increased phage induction, accelerated microbial growth rates, and the increased risk of disease communication and microbial exchange aboard confining spacecraft. Ultrastructural changes are also noted in the nuclei, cell membranes, and cytoplasmic streaming, and it appears that antibiotic sensitivity is reduced under both actual and simulated conditions of spaceflight.

  7. Estimating phosphorus availability for microbial growth in an emerging landscape

    USGS Publications Warehouse

    Schmidt, S.K.; Cleveland, C.C.; Nemergut, D.R.; Reed, S.C.; King, A.J.; Sowell, P.

    2011-01-01

    Estimating phosphorus (P) availability is difficult—particularly in infertile soils such as those exposed after glacial recession—because standard P extraction methods may not mimic biological acquisition pathways. We developed an approach, based on microbial CO2 production kinetics and conserved carbon:phosphorus (C:P) ratios, to estimate the amount of P available for microbial growth in soils and compared this method to traditional, operationally-defined indicators of P availability. Along a primary succession gradient in the High Andes of Perú, P additions stimulated the growth-related (logistic) kinetics of glutamate mineralization in soils that had been deglaciated from 0 to 5 years suggesting that microbial growth was limited by soil P availability. We then used a logistic model to estimate the amount of C incorporated into biomass in P-limited soils, allowing us to estimate total microbial P uptake based on a conservative C:P ratio of 28:1 (mass:mass). Using this approach, we estimated that there was < 1 μg/g of microbial-available P in recently de-glaciated soils in both years of this study. These estimates fell well below estimates of available soil P obtained using traditional extraction procedures. Our results give both theoretical and practical insights into the kinetics of C and P utilization in young soils, as well as show changes in microbial P availability during early stages of soil development.

  8. Microbial Carbon Cycling in Permafrost-Affected Soils

    SciTech Connect

    Vishnivetskaya, T.; Liebner, Susanne; Wilhelm, Ronald; Wagner, Dirk

    2011-01-01

    The Arctic plays a key role in Earth s climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, present studies concentrate on investigations of microbial controls of greenhouse gas fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. Permafrost-affected soils can function as both a source and a sink for carbon dioxide and methane. Under anaerobic conditions, caused by flooding of the active layer and the effect of backwater above the permafrost table, the mineralization of organic matter can only be realized stepwise by specialized microorganisms. Important intermediates of the organic matter decomposition are hydrogen, carbon dioxide and acetate, which can be further reduced to methane by methanogenic archaea. Evolution of methane fluxes across the subsurface/atmosphere boundary will thereby strongly depend on the activity of anaerobic methanogenic archaea and obligately aerobic methane oxidizing proteobacteria, which are known to be abundant and to significantly reduce methane emissions in permafrost-affected soils. Therefore current studies on methane-cycling microorganisms are the object of particular attention in permafrost studies, because of their key role in the Arctic methane cycle and consequently of their significance for the global methane budget.

  9. Optimization of biomass composition explains microbial growth-stoichiometry relationships

    USGS Publications Warehouse

    Franklin, O.; Hall, E.K.; Kaiser, C.; Battin, T.J.; Richter, A.

    2011-01-01

    Integrating microbial physiology and biomass stoichiometry opens far-reaching possibilities for linking microbial dynamics to ecosystem processes. For example, the growth-rate hypothesis (GRH) predicts positive correlations among growth rate, RNA content, and biomass phosphorus (P) content. Such relationships have been used to infer patterns of microbial activity, resource availability, and nutrient recycling in ecosystems. However, for microorganisms it is unclear under which resource conditions the GRH applies. We developed a model to test whether the response of microbial biomass stoichiometry to variable resource stoichiometry can be explained by a trade-off among cellular components that maximizes growth. The results show mechanistically why the GRH is valid under P limitation but not under N limitation. We also show why variability of growth rate-biomass stoichiometry relationships is lower under P limitation than under N or C limitation. These theoretical results are supported by experimental data on macromolecular composition (RNA, DNA, and protein) and biomass stoichiometry from two different bacteria. In addition, compared to a model with strictly homeostatic biomass, the optimization mechanism we suggest results in increased microbial N and P mineralization during organic-matter decomposition. Therefore, this mechanism may also have important implications for our understanding of nutrient cycling in ecosystems.

  10. The role of microbial signals in plant growth and development

    PubMed Central

    Ortíz-Castro, Randy; Contreras-Cornejo, Hexon Angel; Macías-Rodríguez, Lourdes

    2009-01-01

    Plant growth and development involves a tight coordination of the spatial and temporal organization of cell division, cell expansion and cell differentiation. Orchestration of these events requires the exchange of signaling molecules between the root and shoot, which can be affected by both biotic and abiotic factors. The interactions that occur between plants and their associated microorganisms have long been of interest, as knowledge of these processes could lead to the development of novel agricultural applications. Plants produce a wide range of organic compounds including sugars, organic acids and vitamins, which can be used as nutrients or signals by microbial populations. On the other hand, microorganisms release phytohormones, small molecules or volatile compounds, which may act directly or indirectly to activate plant immunity or regulate plant growth and morphogenesis. In this review, we focus on recent developments in the identification of signals from free-living bacteria and fungi that interact with plants in a beneficial way. Evidence has accumulated indicating that classic plant signals such as auxins and cytokinins can be produced by microorganisms to efficiently colonize the root and modulate root system architecture. Other classes of signals, including N-acyl-L-homoserine lactones, which are used by bacteria for cell-to-cell communication, can be perceived by plants to modulate gene expression, metabolism and growth. Finally, we discuss the role played by volatile organic compounds released by certain plant growth-promoting rhizobacteria in plant immunity and developmental processes. The picture that emerges is one in which plants and microbes communicate themselves through transkingdom signaling systems involving classic and novel signals. PMID:19820333

  11. Solutes determine the temperature windows for microbial survival and growth

    PubMed Central

    Chin, Jason P.; Megaw, Julianne; Magill, Caroline L.; Nowotarski, Krzysztof; Williams, Jim P.; Bhaganna, Prashanth; Linton, Mark; Patterson, Margaret F.; Underwood, Graham J. C.; Mswaka, Allen Y.; Hallsworth, John E.

    2010-01-01

    Microbial cells, and ultimately the Earth's biosphere, function within a narrow range of physicochemical conditions. For the majority of ecosystems, productivity is cold-limited, and it is microbes that represent the failure point. This study was carried out to determine if naturally occurring solutes can extend the temperature windows for activity of microorganisms. We found that substances known to disorder cellular macromolecules (chaotropes) did expand microbial growth windows, fungi preferentially accumulated chaotropic metabolites at low temperature, and chemical activities of solutes determined microbial survival at extremes of temperature as well as pressure. This information can enhance the precision of models used to predict if extraterrestrial and other hostile environments are able to support life; furthermore, chaotropes may be used to extend the growth windows for key microbes, such as saprotrophs, in cold ecosystems and manmade biomes. PMID:20404182

  12. Dynamic speckle study of microbial growth

    NASA Astrophysics Data System (ADS)

    Vincitorio, F. M.; Mulone, C.; Marcuzzi, P. A.; Budini, N.; Freyre, C.; Lopez, A. J.; Ramil, A.

    2015-08-01

    In this work we present a characterization of yeast dynamic speckle activity during growth in an isolated agar culture medium. We found that it is possible to detect the growth of the microorganisms even before they turn out to be visible. By observing the time evolution of the speckle activity at different regions of the culture medium we could extract a map of the growth process, which served to analyze how the yeast develops and spreads over the agar's medium. An interesting point of this study concerns with the influence of the laser light on the yeast growth rate. We have found that yeast finds hard to develop at regions with higher laser light illumination, although we used a synchronous system to capture the speckle pattern. The results obtained in this work would serve us as a starting point to fabricate a detector of growing microorganism colonies, with obvious interesting applications in diverse areas.

  13. Acoustic and Electrical Property Changes Due to Microbial Growth and Biofilm Formation in Porous Media

    EPA Science Inventory

    A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times f...

  14. Microbial physiology and ecology of slow growth.

    PubMed Central

    Koch, A L

    1997-01-01

    The uptake capabilities of the cell have evolved to permit growth at very low external nutrient concentrations. How are these capabilities controlled when the substrate concentrations are not extremely low and the uptake systems could import substrate much more rapidly than the metabolic capabilities of the cell might be able to handle? To answer this question, earlier theories for the kinetics of uptake through the cell envelope and steady-state systems of metabolic enzymes are discussed and a computer simulation is presented. The problems to the cell of fluctuating levels of nutrient and too much substrate during continuous culture are discussed. Too much substrate can lead to oligotrophy, substrate-accelerated death, entry into the viable but not culturable state, and lactose killing. The relationship between uptake and growth is considered. Finally, too little substrate may lead to catastrophic attempts at mounting molecular syntheses that cannot be completed. PMID:9293184

  15. Modeling microbial dynamics in heterogeneous environments: Growth on soil carbon sources

    SciTech Connect

    Resat, Haluk; Bailey, Vanessa L.; McCue, Lee Ann; Konopka, Allan

    2012-01-01

    We have developed a new hybrid model to study how microbial dynamics are affected by the heterogeneity in the physical structure of the environment. The modeling framework can represent porous media such as soil. The individual based biological model can explicitly simulate microbial diversity, and cell metabolism is regulated via optimal allocation of cellular resources to enzyme synthesis, control of growth rate by protein synthesis capacity, and shifts to dormancy. This model was developed to study how microbial community functioning is influenced by local environmental conditions and by the functional attributes of individual microbes. Different strategies for acquisition of carbon from polymeric cellulose were investigated. Bacteria that express membrane-associated hydrolase had different growth and survival dynamics in soil pores than bacteria that release extracellular hydrolases. The kinetic differences may suggest different functional roles for these two classes of microbes in cellulose utilization. Our model predicted an emergent behavior in which co-existence led to higher cellulose utilization efficiency and reduced stochasticity. Microbial community dynamics were simulated at two spatial scales: micro-pores that resemble 6-20 {micro}m size portions of the soil physical structure and in 111 {micro}m size soil aggregates with a random pore structure. Trends in dynamic properties were very similar at these two scales, implying that micro-scale studies can be useful approximations to aggregate scale studies when local effects on microbial dynamics are studied.

  16. Microbial growth and physiology: a call for better craftsmanship

    PubMed Central

    Egli, Thomas

    2015-01-01

    Virtually every microbiological experiment starts with the cultivation of microbes. Consequently, as originally pointed out by Monod (1949), handling microbial cultures is a fundamental methodology of microbiology and mastering different cultivation techniques should be part of every microbiologist’s craftsmanship. This is particularly important for research in microbial physiology, as the composition and behavior of microbes is strongly dependent on their growth environment. It has been pointed out repeatedly by eminent microbiologists that we should give more attention to the media and culturing conditions. However, this is obviously not adhered to with sufficient rigor as mistakes in basic cultivation principles are frequently found in the published research literature. The most frequent mistakes are the use of inappropriate growth media and little or no control of the specific growth rate, and some examples will be discussed here in detail. Therefore, this is a call for better microbiological craftsmanship when cultivating microbial cultures for physiological experiments. This call is not only addressed to researchers but it is probably even more important for the teaching of our discipline. PMID:25926822

  17. Biochar affects soil organic matter cycling and microbial functions but does not alter microbial community structure in a paddy soil.

    PubMed

    Tian, Jing; Wang, Jingyuan; Dippold, Michaela; Gao, Yang; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2016-06-15

    The application of biochar (BC) in conjunction with mineral fertilizers is one of the most promising management practices recommended to improve soil quality. However, the interactive mechanisms of BC and mineral fertilizer addition affecting microbial communities and functions associated with soil organic matter (SOM) cycling are poorly understood. We investigated the SOM in physical and chemical fractions, microbial community structure (using phospholipid fatty acid analysis, PLFA) and functions (by analyzing enzymes involved in C and N cycling and Biolog) in a 6-year field experiment with BC and NPK amendment. BC application increased total soil C and particulate organic C for 47.4-50.4% and 63.7-74.6%, respectively. The effects of BC on the microbial community and C-cycling enzymes were dependent on fertilization. Addition of BC alone did not change the microbial community compared with the control, but altered the microbial community structure in conjunction with NPK fertilization. SOM fractions accounted for 55% of the variance in the PLFA-related microbial community structure. The particulate organic N explained the largest variation in the microbial community structure. Microbial metabolic activity strongly increased after BC addition, particularly the utilization of amino acids and amines due to an increase in the activity of proteolytic (l-leucine aminopeptidase) enzymes. These results indicate that microorganisms start to mine N from the SOM to compensate for high C:N ratios after BC application, which consequently accelerate cycling of stable N. Concluding, BC in combination with NPK fertilizer application strongly affected microbial community composition and functions, which consequently influenced SOM cycling. PMID:26974565

  18. Community history affects the predictability of microbial ecosystem development

    PubMed Central

    Pagaling, Eulyn; Strathdee, Fiona; Spears, Bryan M; Cates, Michael E; Allen, Rosalind J; Free, Andrew

    2014-01-01

    Microbial communities mediate crucial biogeochemical, biomedical and biotechnological processes, yet our understanding of their assembly, and our ability to control its outcome, remain poor. Existing evidence presents conflicting views on whether microbial ecosystem assembly is predictable, or inherently unpredictable. We address this issue using a well-controlled laboratory model system, in which source microbial communities colonize a pristine environment to form complex, nutrient-cycling ecosystems. When the source communities colonize a novel environment, final community composition and function (as measured by redox potential) are unpredictable, although a signature of the community's previous history is maintained. However, when the source communities are pre-conditioned to their new habitat, community development is more reproducible. This situation contrasts with some studies of communities of macro-organisms, where strong selection under novel environmental conditions leads to reproducible community structure, whereas communities under weaker selection show more variability. Our results suggest that the microbial rare biosphere may have an important role in the predictability of microbial community development, and that pre-conditioning may help to reduce unpredictability in the design of microbial communities for biotechnological applications. PMID:23985743

  19. INVESTIGATING THE EFFECT OF MICROBIAL GROWTH AND BIOFILM FORMATION ON SEISMIC WAVE PROPAGATION IN SEDIMENT

    EPA Science Inventory

    Previous laboratory investigations have demonstrated that the seismic methods are sensitive to microbially-induced changes in porous media through the generation of biogenic gases and biomineralization. The seismic signatures associated with microbial growth and biofilm formation...

  20. Microbial growth and biofilm formation in geologic media is detected with complex conductivity measurements

    NASA Astrophysics Data System (ADS)

    Davis, Caroline A.; Atekwana, Estella; Atekwana, Eliot; Slater, Lee D.; Rossbach, Silvia; Mormile, Melanie R.

    2006-09-01

    Complex conductivity measurements (0.1-1000 Hz) were obtained from biostimulated sand-packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial cell concentrations extracted from sands. However, the real conductivity component showed no discernible relationship to microbial cell concentration. We suggest that the observed dynamic changes in the imaginary conductivity (σ″) arise from the growth and attachment of microbial cells and biofilms to sand surfaces. We conclude that complex conductivity techniques, specifically imaginary conductivity measurements are a proxy indicator for microbial growth and biofilm formation in porous media. Our results have implications for microbial enhanced oil recovery, CO2 sequestration, bioremediation, and astrobiology studies.

  1. Microbial growth and transport in saturated and unsaturated porous media

    NASA Astrophysics Data System (ADS)

    Hron, Pavel; Jost, Daniel; Bastian, Peter; Ippisch, Olaf

    2014-05-01

    There is a considerable ongoing effort aimed at understanding the behavior of microorganisms in porous media. Microbial activity is of significant interest in various environmental applications such as in situ bioremediation, protection of drinking water supplies and for subsurface geochemistry in general. The main limiting factors for bacterial growth are the availability of electron acceptors, nutrients and bio-available water. The capillary fringe, defined - in a wider sense than usual - as the region of the subsurface above the groundwater table, but still dominated by capillary rise, is a region where all these factors are abundantly available. It is thus a region where high microbial activity is to be expected. In a research unit 'Dynamic Capillary Fringes - A Multidisciplinary Approach (DyCap)' founded by the German Research Foundation (DFG), the growth of microorganisms in the capillary fringe was studied experimentally and with numerical simulations. Processes like component transport and diffusion, exchange between the liquid phase and the gas phase, microbial growth and cell attachment and detachment were incorporated into a numerical simulator. The growth of the facultative anaerobic Escherichia coli as a function of nutrient availability and oxygen concentration in the liquid phase is modeled with modified Monod-type models and modifications for the switch between aerobic and anaerobic growth. Laboratory batch experiments with aqueous solutions of bacteria have been carried out under various combinations of oxygen concentrations in the gas phase and added amounts of dissolved organic carbon to determine the growth model parameters by solution of a parameter estimation problem. For the transport of bacteria the adhesion to phase boundaries is also very important. As microorganisms are transported through porous media, they are removed from the pore fluid by physicochemical filtration (attachment to sediment grain surfaces) or are adhering to gas

  2. Do long-lived ants affect soil microbial communities?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was designed to test the hypothesis that desert ant species that build nests that remain viable at a particular point in space for more than a decade produce soil conditions that enhance microbial biomass and functional diversity. We studied the effects of a seed-harvester ant, Pogonomyrm...

  3. Electron donors and co-contaminants affect microbial community composition and activity in perchlorate degradation.

    PubMed

    Guan, Xiangyu; Xie, Yuxuan; Wang, Jinfeng; Wang, Jing; Liu, Fei

    2015-04-01

    Although microbial reduction of perchlorate (ClO4(-)) is a promising and effective method, our knowledge on the changes in microbial communities during ClO4(-) degradation is limited, especially when different electron donors are supplied and/or other contaminants are present. Here, we examined the effects of acetate and hydrogen as electron donors and nitrate and ammonium as co-contaminants on ClO4(-) degradation by anaerobic microcosms using six treatments. The process of degradation was divided into the lag stage (SI) and the accelerated stage (SII). Quantitative PCR was used to quantify four genes: pcrA (encoding perchlorate reductase), cld (encoding chlorite dismutase), nirS (encoding copper and cytochrome cd1 nitrite reductase), and 16S rRNA. While the degradation of ClO4(-) with acetate, nitrate, and ammonia system (PNA) was the fastest with the highest abundance of the four genes, it was the slowest in the autotrophic system (HYP). The pcrA gene accumulated in SI and played a key role in initiating the accelerated degradation of ClO4(-) when its abundance reached a peak. Degradation in SII was primarily maintained by the cld gene. Acetate inhibited the growth of perchlorate-reducing bacteria (PRB), but its effect was weakened by nitrate (NO3(-)), which promoted the growth of PRB in SI, and therefore, accelerated the ClO4(-) degradation rate. In addition, ammonia (NH4(+)), as nitrogen sources, accelerated the growth of PRB. The bacterial communities' structure and diversity were significantly affected by electron donors and co-contaminants. Under heterotrophic conditions, both ammonia and nitrate promoted Azospira as the most dominant genera, a fact that might significantly influence the rate of ClO4(-) natural attenuation by degradation. PMID:25382499

  4. Growth dynamics and the evolution of cooperation in microbial populations

    NASA Astrophysics Data System (ADS)

    Cremer, Jonas; Melbinger, Anna; Frey, Erwin

    2012-02-01

    Microbes providing public goods are widespread in nature despite running the risk of being exploited by free-riders. However, the precise ecological factors supporting cooperation are still puzzling. Following recent experiments, we consider the role of population growth and the repetitive fragmentation of populations into new colonies mimicking simple microbial life-cycles. Individual-based modeling reveals that demographic fluctuations, which lead to a large variance in the composition of colonies, promote cooperation. Biased by population dynamics these fluctuations result in two qualitatively distinct regimes of robust cooperation under repetitive fragmentation into groups. First, if the level of cooperation exceeds a threshold, cooperators will take over the whole population. Second, cooperators can also emerge from a single mutant leading to a robust coexistence between cooperators and free-riders. We find frequency and size of population bottlenecks, and growth dynamics to be the major ecological factors determining the regimes and thereby the evolutionary pathway towards cooperation.

  5. Arsenic as an energy source for microbial growth. (Invited)

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.

    2009-12-01

    Arsenic, although known for millenia to be a potent poison, can also constitute the basis for energy metabolism by a number of Bacteria and Archaea. Hence, the oxyanion arsenate [As(V)] can serve as a respiratory electron acceptor for the growth of anaerobes, resulting in the accumulation of arsenite [As(III)]. Conversely, As(III) can serve as an electron donor for the growth of aerobic and anaerobic (e.g., nitrate-respiring) chemoautotrophs, as well as photoautotrophs that grow via anoxygenic photosynthesis. Collectively, these microbes carry out these redox reactions between the +3 and +5 oxidation states that have profound importance for the mobility of As in the environment, and perhaps for the pattern of microbial evolution on Earth. I will focus upon the occurrence of these microbes in extreme environments that are rich in naturally-occurring arsenic.

  6. Microbial growth and macromolecular synthesis in the northwestern Atlantic Ocean

    SciTech Connect

    Cuhel, R.L.; Jannasch, H.W.; Taylor, C.D.

    1983-01-01

    Simultaneous time-course measurements of /sup 35/SO/sub 4//sup 2 -/, /sup 32/PO/sup 43 -/, /sup 15/NH/sub 4//sup +/, and (/sup 14/C)acetate, glucose, and glutamate uptake were made at three stations in the northwestern Atlantic Ocean, using water samples taken from well below the euphotic zone. Marked deviations from linearity were observed in 14 of the 15 cases. At the two most inshore stations uptake of /sup 15/NH/sub 4//sup +/ or incorporation of /sup 35/SO/sub 4//sup 2 -/ into protein was undetectable for 16-30 h, followed by very rapid increases in the rates of activity. The sudden burst of SO/sub 4//sup 2 -/and NH/sub 4//sup +/ uptake was accompanied by a major increase in the incorporation of /sup 32/P into RNA and lipid fractions of the microbial population at a continental slope station. At a station in Sargasso Sea, all substrates were taken up without lag. Extended incubations led to a growth plateau which may be a measure of the total biologically labile organic nutrient supply. In all cases tested, chloramphenicol severely restricted uptake. One of the inshore stations was revisited a year later with similar results. The combined data demonstrate the utility of using inorganic nutrient uptake and subcellular incorporation patterns to measure microbial growth and metabolism and stress the necessity of time-course rather than end-point incubations.

  7. Microbial growth on hydrocarbons: terminal branching inhibits biodegradation.

    PubMed Central

    Schaeffer, T L; Cantwell, S G; Brown, J L; Watt, D S; Fall, R R

    1979-01-01

    A variety of octane-utilizing bacteria and fungi were screened for growth on some terminally branched dimethyloctane derivatives to explore the effects of iso- and anteiso-termini on the biodegradability of such hydrocarbons. Of 27 microbial strains tested, only 9 were found to use any of the branched hydrocarbons tested as a sole carbon source, and then only those hydrocarbons containing at least one iso-terminus were susceptible to degradation. Anteiso-or isopropenyl termini prevented biodegradation. None of the hydrocarbonoclastic yeasts tested was able to utilize branched-hydrocarbon growth sustrates. In the case of pseudomonads containing the OCT plasmid, whole-cell oxidation of n-octane was poorly induced by terminally branched dimethyloctanes. In the presence of a gratuitous inducer of the octane-oxidizing enzymes, the iso-branched 2,7-dimethyloctane was slowly oxidized by whole cells, whereas the anteiso-branched 3,6-dimethyloctane was not oxidized at all. This microbial sampling dramatically illustrated the deleterious effect of alkyl branching, especially anteiso-terminal branching, on the biodegradation of hydrocarbons. PMID:539824

  8. Microbial communities affecting albumen photography heritage: a methodological survey.

    PubMed

    Puškárová, Andrea; Bučková, Mária; Habalová, Božena; Kraková, Lucia; Maková, Alena; Pangallo, Domenico

    2016-01-01

    This study is one of the few investigations which analyze albumen prints, perhaps the most important photographic heritage of the late 19(th) and early 20(th) centuries. The chemical composition of photographic samples was assessed using Fourier-transform infrared spectroscopy and X-ray fluorescence. These two non-invasive techniques revealed the complex nature of albumen prints, which are composed of a mixture of proteins, cellulose and salts. Microbial sampling was performed using cellulose nitrate membranes which also permitted the trapped microflora to be observed with a scanning electron microscope. Microbial analysis was performed using the combination of culture-dependent (cultivation in different media, including one 3% NaCl) and culture-independent (bacterial and fungal cloning and sequencing) approaches. The isolated microorganisms were screened for their lipolytic, proteolytic, cellulolytic, catalase and peroxidase activities. The combination of the culture-dependent and -independent techniques together with enzymatic assays revealed a substantial microbial diversity with several deteriogen microorganisms from the genera Bacillus, Kocuria, Streptomyces and Geobacillus and the fungal strains Acrostalagmus luteoalbus, Bjerkandera adusta, Pleurotus pulmonarius and Trichothecium roseum. PMID:26864429

  9. Microbial communities affecting albumen photography heritage: a methodological survey

    PubMed Central

    Puškárová, Andrea; Bučková, Mária; Habalová, Božena; Kraková, Lucia; Maková, Alena; Pangallo, Domenico

    2016-01-01

    This study is one of the few investigations which analyze albumen prints, perhaps the most important photographic heritage of the late 19th and early 20th centuries. The chemical composition of photographic samples was assessed using Fourier-transform infrared spectroscopy and X-ray fluorescence. These two non-invasive techniques revealed the complex nature of albumen prints, which are composed of a mixture of proteins, cellulose and salts. Microbial sampling was performed using cellulose nitrate membranes which also permitted the trapped microflora to be observed with a scanning electron microscope. Microbial analysis was performed using the combination of culture-dependent (cultivation in different media, including one 3% NaCl) and culture-independent (bacterial and fungal cloning and sequencing) approaches. The isolated microorganisms were screened for their lipolytic, proteolytic, cellulolytic, catalase and peroxidase activities. The combination of the culture-dependent and -independent techniques together with enzymatic assays revealed a substantial microbial diversity with several deteriogen microorganisms from the genera Bacillus, Kocuria, Streptomyces and Geobacillus and the fungal strains Acrostalagmus luteoalbus, Bjerkandera adusta, Pleurotus pulmonarius and Trichothecium roseum. PMID:26864429

  10. Temperature affects microbial abundance, activity and interactions in anaerobic digestion.

    PubMed

    Lin, Qiang; De Vrieze, Jo; Li, Jiabao; Li, Xiangzhen

    2016-06-01

    Temperature is a major factor determining the performance of the anaerobic digestion process. The microbial abundance, activity and interactional networks were investigated under a temperature gradient from 25°C to 55°C through amplicon sequencing, using 16S ribosomal RNA and 16S rRNA gene-based approaches. Comparative analysis of past accumulative elements presented by 16S rRNA gene-based analysis, and the in-situ conditions presented by 16S rRNA-based analysis, provided new insights concerning the identification of microbial functional roles and interactions. The daily methane production and total biogas production increased with temperature up to 50°C, but decreased at 55°C. Increased methanogenesis and hydrolysis at 50°C were main factors causing higher methane production which was also closely related with more well-defined methanogenic and/or related modules with comprehensive interactions and increased functional orderliness referred to more microorganisms participating in interactions. This research demonstrated the importance of evaluating functional roles and interactions of microbial community. PMID:26970926

  11. Microbial communities affecting albumen photography heritage: a methodological survey

    NASA Astrophysics Data System (ADS)

    Puškárová, Andrea; Bučková, Mária; Habalová, Božena; Kraková, Lucia; Maková, Alena; Pangallo, Domenico

    2016-02-01

    This study is one of the few investigations which analyze albumen prints, perhaps the most important photographic heritage of the late 19th and early 20th centuries. The chemical composition of photographic samples was assessed using Fourier-transform infrared spectroscopy and X-ray fluorescence. These two non-invasive techniques revealed the complex nature of albumen prints, which are composed of a mixture of proteins, cellulose and salts. Microbial sampling was performed using cellulose nitrate membranes which also permitted the trapped microflora to be observed with a scanning electron microscope. Microbial analysis was performed using the combination of culture-dependent (cultivation in different media, including one 3% NaCl) and culture-independent (bacterial and fungal cloning and sequencing) approaches. The isolated microorganisms were screened for their lipolytic, proteolytic, cellulolytic, catalase and peroxidase activities. The combination of the culture-dependent and -independent techniques together with enzymatic assays revealed a substantial microbial diversity with several deteriogen microorganisms from the genera Bacillus, Kocuria, Streptomyces and Geobacillus and the fungal strains Acrostalagmus luteoalbus, Bjerkandera adusta, Pleurotus pulmonarius and Trichothecium roseum.

  12. Rhizosphere microbial community composition affects cadmium and zinc uptake by the metal-hyperaccumulating plant Arabidopsis halleri.

    PubMed

    Muehe, E Marie; Weigold, Pascal; Adaktylou, Irini J; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas; Behrens, Sebastian

    2015-03-01

    The remediation of metal-contaminated soils by phytoextraction depends on plant growth and plant metal accessibility. Soil microorganisms can affect the accumulation of metals by plants either by directly or indirectly stimulating plant growth and activity or by (im)mobilizing and/or complexing metals. Understanding the intricate interplay of metal-accumulating plants with their rhizosphere microbiome is an important step toward the application and optimization of phytoremediation. We compared the effects of a "native" and a strongly disturbed (gamma-irradiated) soil microbial communities on cadmium and zinc accumulation by the plant Arabidopsis halleri in soil microcosm experiments. A. halleri accumulated 100% more cadmium and 15% more zinc when grown on the untreated than on the gamma-irradiated soil. Gamma irradiation affected neither plant growth nor the 1 M HCl-extractable metal content of the soil. However, it strongly altered the soil microbial community composition and overall cell numbers. Pyrosequencing of 16S rRNA gene amplicons of DNA extracted from rhizosphere samples of A. halleri identified microbial taxa (Lysobacter, Streptomyces, Agromyces, Nitrospira, "Candidatus Chloracidobacterium") of higher relative sequence abundance in the rhizospheres of A. halleri plants grown on untreated than on gamma-irradiated soil, leading to hypotheses on their potential effect on plant metal uptake. However, further experimental evidence is required, and wherefore we discuss different mechanisms of interaction of A. halleri with its rhizosphere microbiome that might have directly or indirectly affected plant metal accumulation. Deciphering the complex interactions between A. halleri and individual microbial taxa will help to further develop soil metal phytoextraction as an efficient and sustainable remediation strategy. PMID:25595759

  13. Rhizosphere Microbial Community Composition Affects Cadmium and Zinc Uptake by the Metal-Hyperaccumulating Plant Arabidopsis halleri

    PubMed Central

    Muehe, E. Marie; Weigold, Pascal; Adaktylou, Irini J.; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas

    2015-01-01

    The remediation of metal-contaminated soils by phytoextraction depends on plant growth and plant metal accessibility. Soil microorganisms can affect the accumulation of metals by plants either by directly or indirectly stimulating plant growth and activity or by (im)mobilizing and/or complexing metals. Understanding the intricate interplay of metal-accumulating plants with their rhizosphere microbiome is an important step toward the application and optimization of phytoremediation. We compared the effects of a “native” and a strongly disturbed (gamma-irradiated) soil microbial communities on cadmium and zinc accumulation by the plant Arabidopsis halleri in soil microcosm experiments. A. halleri accumulated 100% more cadmium and 15% more zinc when grown on the untreated than on the gamma-irradiated soil. Gamma irradiation affected neither plant growth nor the 1 M HCl-extractable metal content of the soil. However, it strongly altered the soil microbial community composition and overall cell numbers. Pyrosequencing of 16S rRNA gene amplicons of DNA extracted from rhizosphere samples of A. halleri identified microbial taxa (Lysobacter, Streptomyces, Agromyces, Nitrospira, “Candidatus Chloracidobacterium”) of higher relative sequence abundance in the rhizospheres of A. halleri plants grown on untreated than on gamma-irradiated soil, leading to hypotheses on their potential effect on plant metal uptake. However, further experimental evidence is required, and wherefore we discuss different mechanisms of interaction of A. halleri with its rhizosphere microbiome that might have directly or indirectly affected plant metal accumulation. Deciphering the complex interactions between A. halleri and individual microbial taxa will help to further develop soil metal phytoextraction as an efficient and sustainable remediation strategy. PMID:25595759

  14. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumaffected microbial growth rates directly (N limitation) and indirectly (changing the quantity of fine roots). So, 50% decrease in N fertilization caused the overall increase or decrease of microbial growth rates depending on plant species. The μ-value increase was lower for microorganisms growing on yeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were

  15. Impact of Microbial Growth on Subsurface Perfluoroalkyl Acid Transport

    NASA Astrophysics Data System (ADS)

    Weathers, T. S.; Higgins, C. P.; Sharp, J.

    2014-12-01

    The fate and transport of poly and perfluoroalkyl substances (PFASs) in the presence of active microbial communities has not been widely investigated. These emerging contaminants are commonly utilized in aqueous film-forming foams (AFFF) and have often been detected in groundwater. This study explores the transport of a suite of perfluorocarboxylic acids and perfluoroalkylsulfonates, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in microbially active settings. Single point organic carbon normalized sorption coefficients derived by exposing inactive cellular material to PFASs result in more than an order of magnitude increase in sorption compared to soil organic carbon sorption coefficients found in literature. For example, the sorption coefficients for PFOS are 4.05±0.07 L/kg and 2.80±0.08 L/kg for cellular organic carbon and soil organic carbon respectively. This increase in sorption, coupled with enhanced extracellular polymeric substance production observed during growth of a common hydrocarbon degrading soil microbe exposed to source-level concentrations of PFASs (10 mg/L of 11 analytes, 110 mg/L total) may result in PFAS retardation in situ. To address the upscaling of this phenomenon, flow-through columns packed with low-organic carbon sediment and biostimulated with 10 mg/L glucose were exposed to PFAS concentrations from 15 μg/L to 10 mg/L of each 11 analytes. Breakthrough and tailing of each analyte was measured and modeled with Hydrus-1D to explore sorption coefficients over time for microbially active columns.

  16. Detecting Microbial Growth and Metabolism in Geologic Media with Complex Conductivity Measurements

    NASA Astrophysics Data System (ADS)

    Davis, C. A.; Atekwana, E. A.; Slater, L. D.; Bottrell, P. M.; Chasten, L. E.; Heidenreich, J. D.

    2006-05-01

    Complex conductivity measurements between 0.1-1000 Hz were obtained from biostimulated sand-packed (coarse and mixed fine and medium grain) columns to investigate microbial growth, biofilm formation, and microbial metabolism on the electrical properties of porous media. Microbial growth and metabolism was verified by direct microbial counts, pH changes, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the coarse grain columns occurred concurrently with peaks in the microbial cell concentrations. The magnitude of the imaginary conductivity response in the mixed fine and medium grain columns, however, was low compared to the coarse grain sand columns, consistent with lower microbial cell concentrations. It is possible that the pore size in the mixed fine and medium grain sand restricted bacteria cell division, inhibiting microbial growth, and thus the smaller magnitude imaginary conductivity response. The biostimulated columns for both grain sizes displayed similar trends and showed an increase in the real (electrolytic) conductivity and decrease in pH over time. Dynamic changes in the imaginary conductivity arises from the growth and attachment of microbial cells and biofilms to surfaces, whereas, changes in the real conductivity arises from the release of byproducts (ionic species) of microbial metabolism. We conclude that complex conductivity techniques are feasible sensors for detecting microbial growth (imaginary conductivity measurements) and metabolism (real conductivity measurements) with implications for bioremediation and astrobiology studies.

  17. Teaching the Microbial Growth Curve Concept Using Microalgal Cultures and Flow Cytometry

    ERIC Educational Resources Information Center

    Forget, Nathalie; Belzile, Claude; Rioux, Pierre; Nozais, Christian

    2010-01-01

    The microbial growth curve is widely studied within microbiology classes and bacteria are usually the microbial model used. Here, we describe a novel laboratory protocol involving flow cytometry to assess the growth dynamics of the unicellular microalgae "Isochrysis galbana." The algal model represents an appropriate alternative to bacteria…

  18. Inhibition of microbial growth on air cathodes of single chamber microbial fuel cells by incorporating enrofloxacin into the catalyst layer.

    PubMed

    Liu, Weifeng; Cheng, Shaoan; Sun, Dan; Huang, Haobin; Chen, Jie; Cen, Kefa

    2015-10-15

    The inevitable growth of aerobic bacteria on the surface of air cathodes is an important factor reducing the performance stability of air cathode single-chamber membrane-free microbial fuel cells (MFCs). Thus searching for effective methods to inhibit the cathodic microbial growth is critical for the practical application of MFCs. In this study, enrofloxacin (ENR), a broad spectrum fluoroquinolone antibiotic, was incorporated into the catalyst layer of activated carbon air cathodes (ACACs) to inhibit the cathodic microbial growth. The biomass content on ACACs was substantially reduced by 60.2% with ENR treatment after 91 days of MFCs operation. As a result of the inhibited microbial growth, the oxygen reduction catalytic performance of the ENR treated ACACs was much stable compared to the fast performance decline of the untreated control. Consequently, a quite stable electricity production was obtained for the MFCs with the ENR treated ACACs, in contrast with a 22.5% decrease in maximum power density of the MFCs with the untreated cathode. ENR treatment of ACACs showed minimal effects on the anode performance. These results indicate that incorporating antibiotics into ACACs should be a simple and effective strategy to inhibit the microbial growth and improve the long-term stability of the performance of air cathode and the electricity production of MFCs. PMID:25957076

  19. Land use type significantly affects microbial gene transcription in soil.

    PubMed

    Nacke, Heiko; Fischer, Christiane; Thürmer, Andrea; Meinicke, Peter; Daniel, Rolf

    2014-05-01

    Soil microorganisms play an essential role in sustaining biogeochemical processes and cycling of nutrients across different land use types. To gain insights into microbial gene transcription in forest and grassland soil, we isolated mRNA from 32 sampling sites. After sequencing of generated complementary DNA (cDNA), a total of 5,824,229 sequences could be further analyzed. We were able to assign nonribosomal cDNA sequences to all three domains of life. A dominance of bacterial sequences, which were affiliated to 25 different phyla, was found. Bacterial groups capable of aromatic compound degradation such as Phenylobacterium and Burkholderia were detected in significantly higher relative abundance in forest soil than in grassland soil. Accordingly, KEGG pathway categories related to degradation of aromatic ring-containing molecules (e.g., benzoate degradation) were identified in high abundance within forest soil-derived metatranscriptomic datasets. The impact of land use type forest on community composition and activity is evidently to a high degree caused by the presence of wood breakdown products. Correspondingly, bacterial groups known to be involved in lignin degradation and containing ligninolytic genes such as Burkholderia, Bradyrhizobium, and Azospirillum exhibited increased transcriptional activity in forest soil. Higher solar radiation in grassland presumably induced increased transcription of photosynthesis-related genes within this land use type. This is in accordance with high abundance of photosynthetic organisms and plant-infecting viruses in grassland. PMID:24553913

  20. Plant extracts affect in vitro rumen microbial fermentation.

    PubMed

    Busquet, M; Calsamiglia, S; Ferret, A; Kamel, C

    2006-02-01

    Different doses of 12 plant extracts and 6 secondary plant metabolites were incubated for 24 h in diluted ruminal fluid with a 50:50 forage:concentrate diet. Treatments were: control (no additive), plant extracts (anise oil, cade oil, capsicum oil, cinnamon oil, clove bud oil, dill oil, fenugreek, garlic oil, ginger oil, oregano oil, tea tree oil, and yucca), and secondary plant metabolites (anethol, benzyl salicylate, carvacrol, carvone, cinnamaldehyde, and eugenol). Each treatment was supplied at 3, 30, 300, and 3,000 mg/L of culture fluid. At 3,000 mg/L, most treatments decreased total volatile fatty acid concentration, but cade oil, capsicum oil, dill oil, fenugreek, ginger oil, and yucca had no effect. Different doses of anethol, anise oil, carvone, and tea tree oil decreased the proportion of acetate and propionate, which suggests that these compounds may not be nutritionally beneficial to dairy cattle. Garlic oil (300 and 3,000 mg/L) and benzyl salicylate (300 and 3,000 mg/L) reduced acetate and increased propionate and butyrate proportions, suggesting that methane production was inhibited. At 3,000 mg/L, capsicum oil, carvacrol, carvone, cinnamaldehyde, cinnamon oil, clove bud oil, eugenol, fenugreek, and oregano oil resulted in a 30 to 50% reduction in ammonia N concentration. Careful selection and combination of these extracts may allow the manipulation of rumen microbial fermentation. PMID:16428643

  1. Water management history affects GHG kinetics and microbial communities composition of an Italian rice paddy

    NASA Astrophysics Data System (ADS)

    Lagomarsino, Alessandra; Agnelli, Allessandroelio; Pastorelli, Roberta; Pallara, Grazia; Rasse, Daniel; Silvennoinen, Hanna

    2015-04-01

    The water management system of cultivated soils is one of the most important factors affecting the respective magnitudes of CH4 and N2O emissions. We hypothesized an effect of past management on soil microbial communities and greenhouse gas (GHG) production potential The objective of this study were to i) assess the influence of water management history on GHG production potential and microbial community structure, ii) relate GHGs fluxes to the microbial communities involved in CH4 and N2O production inhabiting the different soils. Moreover, the influence of different soil conditioning procedures on GHG potential fluxes was determined. To reach this aim, four soils with different history of water management were compared, using dried and sieved, pre-incubated and fresh soils. Soil conditioning procedures strongly affected GHG emissions potential: drying and sieving determined the highest emission rates and the largest differences among soil types, probably through the release of labile substrates. Conversely, soil pre-incubation tended to homogenize and level out the differences among soils. Microbial communities composition drove GHG emissions potential and was affected by past management. The water management history strongly affected microbial communities structure and the specific microbial pattern of each soil was strictly linked to the gas (CH4 or N2O) emitted. Aerobic soil stimulated N2O peaks, given a possible major contribution of coupled nitrification/denitrification process. As expected, CH4 was lower in aerobic soil, which showed a less abundant archeal community. This work added evidences to support the hypothesis of an adaptation of microbial communities to past land management that reflected in the potential GHG fluxes.

  2. Microbial Functional Potential and Community Composition in Permafrost-Affected Soils of the NW Canadian Arctic

    PubMed Central

    Frank-Fahle, Béatrice A.; Yergeau, Étienne; Greer, Charles W.; Lantuit, Hugues; Wagner, Dirk

    2014-01-01

    Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic. PMID:24416279

  3. Microbial community composition as affected by dryland cropping systems and tillage in a semiarid sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated microbial communities of soil (0-10 cm) as affected by dryland cropping systems under different tillage practices after 5 years. The soil is an Olton sandy loam (Fine, mixed, superactive, thermic Aridic Paleustolls) with an average of 16.4% clay, 67.6% sand and 0.65 g kg-1 of O...

  4. A Thermodynamically-Based Model For Predicting Microbial Growth And Community Composition Coupled To System Geochemistry

    NASA Astrophysics Data System (ADS)

    Istok, J. D.

    2007-12-01

    We present an approach that couples thermodynamic descriptions for microbial growth and geochemical reactions to provide quantitative predictions for the effects of substrate addition or other enviornmental perturbations on microbial community composition. A synthetic microbial community is defined as a collection of defined microbial groups; each with a growth equation derived from bioenergetic principles. The growth equations and standard-state free energy yields are appended to a thermodynamic database for geochemical reactions and the combined equations are solved simultaneously to predict coupled changes in microbial biomass, community composition, and system geochemistry. This approach, with a single set of thermodynamic parameters (one for each growth equation), was used to predict the results of laboratory and field experiments at three geochemically diverse research sites. Predicted effects of ethanol or acetate addition on radionuclide and heavy metal solubility, major ion geochemistry, mineralogy, microbial biomass and community composition were in general agreement with experimental observations although the available experimental data precluded rigorous model testing. Model simulations provide insight into the long-standing difficulty in transferring experimental results from the laboratory to the field and from one site to the next, especially if the form, concentration, or delivery of growth substrate is varied from one experiment to the next. Although originally developed for use in better understanding bioimmobilization of radionuclides and heavy metals via reductive precipitation, the modeling approach is potentially useful for exploring the coupling of microbial growth and geochemical reactions in a variety of basic and applied biotechnology research settings.

  5. Soil microbial biomass and root growth in Bt and non-Bt cotton

    NASA Astrophysics Data System (ADS)

    Tan, D. K. Y.; Broughton, K.; Knox, O. G.; Hulugalle, N. R.

    2012-04-01

    The introduction of transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.) has had a substantial impact on pest management in the cotton industry. While there has been substantial research done on the impact of Bt on the above-ground parts of the cotton plant, less is known about the effect of Bt genes on below ground growth of cotton and soil microbial biomass. The aim of this research was to test the hypothesis that Bt [Sicot 80 BRF (Bollgard II Roundup Ready Flex®)] and non-Bt [Sicot 80 RRF (Roundup Ready Flex®)] transgenic cotton varieties differ in root growth and root turnover, carbon indices and microbial biomass. A field experiment was conducted in Narrabri, north-western NSW. The experimental layout was a randomised block design and used minirhizotron and core break and root washing methods to measure cotton root growth and turnover during the 2008/09 season. Root growth in the surface 0-0.1 m of the soil was measured using the core break and root washing methods, and that in the 0.1 to 1 m depth was measured with a minirhizotron and an I-CAP image capture system. These measurements were used to calculate root length per unit area, root carbon added to the soil through intra-seasonal root death, carbon in roots remaining at the end of the season and root carbon potentially added to the soil. Microbial biomass was also measured using the ninhydrin reactive N method. Root length densities and length per unit area of non-Bt cotton were greater than Bt cotton. There were no differences in root turnover between Bt and non-Bt cotton at 0-1 m soil depth, indicating that soil organic carbon stocks may not be affected by cotton variety. Cotton variety did not have an effect on soil microbial biomass. The results indicate that while there are differences in root morphology between Bt and non-Bt cotton, these do not change the carbon turnover dynamics in the soil.

  6. Reduced Soil Tillage Affects the Concentration, Production and Stabilization of Microbial Biomass

    NASA Astrophysics Data System (ADS)

    van Groenigen, K.; Jones, M.

    2008-12-01

    Soil microbial communities dominated by fungi have been associated with reduced N losses and increased soil aggregation. Moreover, fungal residues have been found to degrade slower than bacterial residues. For these reasons, fungi-dominated communities may be more conducive to ecosystem C storage. In agricultural systems, a shift towards a fungal decomposition pathway might help to regain some of the soil C that was lost due to cultivation. However, measurements on standing microbial biomass alone do not fully reveal fungal and bacterial contributions to SOM dynamics. Therefore, we compared the effect of reduced and conventional tillage on both the growth and concentration of fungal and bacterial biomass, by using leucine and acetate incorporation techniques and epifluorescence microscopy. We also measured the concentration of fungal and bacterial residues, by quantifying amino sugars glucosamine, galactosamine and muramic acid. Soil samples were collected at two different depths from spring barley field plots that were under conventional vs. reduced tillage management for 7.5 growing seasons. Reduced tillage strongly increased both fungal and bacterial biomass in the top soil layer. However, microbial growth rates only showed small responses, suggesting a slower turnover of microbial biomass under reduced tillage. Across soil depths and tillage treatments, total amino sugar contents ranged between 440 and 560 mg C per kilo soil. Fungal derived amino sugars increased under reduced tillage, whereas bacterial residues remained unaffected. These results suggest that reduced tillage enhances the fungal contribution to SOM dynamics both by stimulating fungal growth and stabilization of fungal biomass.

  7. How Population Growth Affects Linkage Disequilibrium

    PubMed Central

    Rogers, Alan R.

    2014-01-01

    The “LD curve” relates the linkage disequilibrium (LD) between pairs of nucleotide sites to the distance that separates them along the chromosome. The shape of this curve reflects natural selection, admixture between populations, and the history of population size. This article derives new results about the last of these effects. When a population expands in size, the LD curve grows steeper, and this effect is especially pronounced following a bottleneck in population size. When a population shrinks, the LD curve rises but remains relatively flat. As LD converges toward a new equilibrium, its time path may not be monotonic. Following an episode of growth, for example, it declines to a low value before rising toward the new equilibrium. These changes happen at different rates for different LD statistics. They are especially slow for estimates of σd2, which therefore allow inferences about ancient population history. For the human population of Europe, these results suggest a history of population growth. PMID:24907258

  8. Soil degradation and amendment effects on soil properties, microbial communities, and plant growth

    NASA Astrophysics Data System (ADS)

    Gebhardt, M.; Fehmi, J. S.; Rasmussen, C.; Gallery, R. E.

    2015-12-01

    Human activities that disrupt soil properties are fundamentally changing ecosystems. Soil degradation, caused by anthropogenic disturbance can decrease microbial abundance and activity, leading to changes in nutrient availability, soil organic matter, and plant establishment. The addition of amendments to disturbed soils have the potential ameliorate these negative consequences. We studied the effects of soil degradation, via an autoclave heat shock method, and the addition of amendments (biochar and woodchips) on microbial activity, soil carbon and nitrogen availability, microbial biomass carbon and nitrogen content, and plant growth of ten plant species native to the semi-arid southwestern US. Relative to non-degraded soils, microbial activity, measured via extracellular enzyme assays, was significantly lower for all seven substrates assayed. These soils also had significantly lower amounts of carbon assimilated into microbial biomass but no change in microbial biomass nitrogen. Soil degradation had no effect on plant biomass. Amendments caused changes in microbial activity: biochar-amended soils had significant increases in potential activity with five of the seven substrates measured; woodchip amended soils had significant increases with two. Soil carbon increased with both amendments but this was not reflected in a significant change in microbial biomass carbon. Biochar-amended soils had increases in soil nitrogen availability but neither amendment caused changes in microbial biomass nitrogen. Biochar amendments had no significant effect on above- or belowground plant biomass while woodchips significantly decreased aboveground plant biomass. Results show that soil degradation decreases microbial activity and changes nutrient dynamics, but these are not reflected in changes in plant growth. Amendments provide nutrient sources and change soil pore space, which cause microbial activities to fluctuate and may, in the case of woodchips, increase plant drought

  9. MICROBIALLY MEDIATED GROWTH SUPPRESSION AND DEATH OF SALMONELLA IN COMPOSTED SEWAGE SLUDGE

    EPA Science Inventory

    The role of compost microflora in the suppression of salmonella regrowth in composted sewage sludge was investigated. Microbial inhibition studies of salmonella growth were conducted on nutrient agar, in composts that had been subjected to different temperatures in compost piles,...

  10. Microbial changes and growth of Listeria monocytogenes during chilled storage of brined shrimp (Pandalus borealis).

    PubMed

    Mejlholm, Ole; Kjeldgaard, Jette; Modberg, Anne; Vest, Mette Bohn; Bøknaes, Niels; Koort, Joanna; Björkroth, Johanna; Dalgaard, Paw

    2008-06-10

    Thirteen storage trials and ten challenge tests were carried out to examine microbial changes, spoilage and the potential growth of Listeria monocytogenes in brined shrimp (Pandalus borealis). Shrimp in brine as well as brined and drained shrimp in modified atmosphere packaging (MAP) were produced and studied. Different recipes were used to study the effect of preserving parameters (organic acids, pH and NaCl) on growth of microorganisms and shelf life at 7-8 degrees C or 12 degrees C. Particularly, brines with different concentrations of (i) benzoic, citric and sorbic acids or (ii) acetic, citric and lactic acids were studied. Furthermore, the effect of adding diacetate to brined shrimp was evaluated. A single batch of cooked and peeled shrimp was used to study both industrially and manually processed brined shrimp with respect to the effect of process hygiene on microbial changes and the shelf life of products. Concentrations of microorganisms on newly produced brined shrimp from an industrial scale processing line were 1.0-2.3 log (CFU g(-1)) higher than comparable concentrations in manually processed samples. This resulted in a substantially shorter shelf life and a more diverse spoilage microflora of the industrially processed brined shrimp. In addition, shelf life of brined shrimp was affected by the types and concentrations of organic acids and by the storage temperature as expected. The effect of MAP was less pronounced. Eighty-two isolates from the spoilage microflora of brined shrimp were identified and they included 53 lactic acid bacteria, 6 coagulase negative Staphylococcus spp., 18 Pseudomonas fluorescens and 5 yeast isolates. After storage at 7 degrees C, P. fluorescens, Enterococcus-like isolates, E. malodoratus, Carnobacterium maltaromaticum, coagulase negative Staphylococcus spp. and Lactobacillus sakei constituted the dominating microflora of shrimp in brines that contained benzoic, citric and sorbic acids as preservatives. L. sakei dominated the

  11. Linking geology and microbiology: inactive pockmarks affect sediment microbial community structure.

    PubMed

    Haverkamp, Thomas H A; Hammer, Øyvind; Jakobsen, Kjetill S

    2014-01-01

    Pockmarks are geological features that are found on the bottom of lakes and oceans all over the globe. Some are active, seeping oil or methane, while others are inactive. Active pockmarks are well studied since they harbor specialized microbial communities that proliferate on the seeping compounds. Such communities are not found in inactive pockmarks. Interestingly, inactive pockmarks are known to have different macrofaunal communities compared to the surrounding sediments. It is undetermined what the microbial composition of inactive pockmarks is and if it shows a similar pattern as the macrofauna. The Norwegian Oslofjord contains many inactive pockmarks and they are well suited to study the influence of these geological features on the microbial community in the sediment. Here we present a detailed analysis of the microbial communities found in three inactive pockmarks and two control samples at two core depth intervals. The communities were analyzed using high-throughput amplicon sequencing of the 16S rRNA V3 region. Microbial communities of surface pockmark sediments were indistinguishable from communities found in the surrounding seabed. In contrast, pockmark communities at 40 cm sediment depth had a significantly different community structure from normal sediments at the same depth. Statistical analysis of chemical variables indicated significant differences in the concentrations of total carbon and non-particulate organic carbon between 40 cm pockmarks and reference sample sediments. We discuss these results in comparison with the taxonomic classification of the OTUs identified in our samples. Our results indicate that microbial communities at the sediment surface are affected by the water column, while the deeper (40 cm) sediment communities are affected by local conditions within the sediment. PMID:24475066

  12. Linking Geology and Microbiology: Inactive Pockmarks Affect Sediment Microbial Community Structure

    PubMed Central

    Haverkamp, Thomas H. A.; Hammer, Øyvind; Jakobsen, Kjetill S.

    2014-01-01

    Pockmarks are geological features that are found on the bottom of lakes and oceans all over the globe. Some are active, seeping oil or methane, while others are inactive. Active pockmarks are well studied since they harbor specialized microbial communities that proliferate on the seeping compounds. Such communities are not found in inactive pockmarks. Interestingly, inactive pockmarks are known to have different macrofaunal communities compared to the surrounding sediments. It is undetermined what the microbial composition of inactive pockmarks is and if it shows a similar pattern as the macrofauna. The Norwegian Oslofjord contains many inactive pockmarks and they are well suited to study the influence of these geological features on the microbial community in the sediment. Here we present a detailed analysis of the microbial communities found in three inactive pockmarks and two control samples at two core depth intervals. The communities were analyzed using high-throughput amplicon sequencing of the 16S rRNA V3 region. Microbial communities of surface pockmark sediments were indistinguishable from communities found in the surrounding seabed. In contrast, pockmark communities at 40 cm sediment depth had a significantly different community structure from normal sediments at the same depth. Statistical analysis of chemical variables indicated significant differences in the concentrations of total carbon and non-particulate organic carbon between 40 cm pockmarks and reference sample sediments. We discuss these results in comparison with the taxonomic classification of the OTUs identified in our samples. Our results indicate that microbial communities at the sediment surface are affected by the water column, while the deeper (40 cm) sediment communities are affected by local conditions within the sediment. PMID:24475066

  13. Microbial growth associated with granular activated carbon in a pilot water treatment facility.

    PubMed Central

    Wilcox, D P; Chang, E; Dickson, K L; Johansson, K R

    1983-01-01

    The microbial dynamics associated with granular activated carbon (GAC) in a pilot water treatment plant were investigated over a period of 16 months. Microbial populations were monitored in the influent and effluent waters and on the GAC particles by means of total plate counts and ATP assays. Microbial populations between the influent and effluent waters of the GAC columns generally increased, indicating microbial growth. The dominant genera of microorganisms isolated from interstitial waters and GAC particles were Achromobacter, Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Corynebacterium, Micrococcus, Microcyclus, Paracoccus, and Pseudomonas. Coliform bacteria were found in small numbers in the effluents from some of the GAC columns in the later months of the study. Oxidation of influent waters with ozone and maintenance of aerobic conditions on the GAC columns failed to appreciably enhance the microbial growth on GAC. PMID:6625567

  14. Quantitative assessment of in situ microbial communities affecting nuclear waste disposal

    SciTech Connect

    White, D.C. |

    1996-05-01

    Microbes in the environments surrounding nuclear waste depositories pose several questions regarding the protection of the surrounding communities. microbes can facilitate microbially influenced corrosion (MIC), mobilize and facilitate the transport of nuclides as well as produce gaseous emissions which can compromise containment. We have developed an analysis of the extant microbiota that is independent of quantitative recovery and subsequent growth, based on signature biomarkers analysis (SBA).

  15. Inhibition of microbial growth by carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Olivi, Massimiliano; Zanni, Elena; de Bellis, Giovanni; Talora, Claudio; Sarto, Maria Sabrina; Palleschi, Claudio; Flahaut, Emmanuel; Monthioux, Marc; Rapino, Stefania; Uccelletti, Daniela; Fiorito, Silvana

    2013-09-01

    In the last years carbon nanotubes have attracted increasing attention for their potential applications in the biomedical field as diagnostic and therapeutic nano tools. Here we investigate the antimicrobial activity of different fully characterized carbon nanotube types (single walled, double walled and multi walled) on representative pathogen species: Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the opportunistic fungus Candida albicans. Our results show that all the carbon nanotube types possess a highly significant antimicrobial capacity, even though they have a colony forming unit capacity and induction of oxidative stress in all the microbial species to a different extent. Moreover, scanning electron microscopy analysis revealed that the microbial cells were wrapped or entrapped by carbon nanotube networks. Our data taken together suggest that the reduced capacity of microbial cells to forming colonies and their oxidative response could be related to the cellular stress induced by the interactions of pathogens with the CNT network.

  16. Main factors controlling microbial community structure, growth and activity after reclamation of a tailing pond with aided phytostabilization

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Acosta, José A.; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2015-04-01

    Reclamation on bare tailing ponds has the potential to represent soil genesis in Technosols favoring the understanding of the changes of microbial communities and function. In this study we used phytostabilization aided with calcium carbonate and pig slurry/manure to reclaim an acidic bare tailing pond with the aim of investigating the effect of amending and different species on microbial community structure and function. We sampled after two years of amending and planting: unamended tailing soil (UTS), non-rhizospheric amended tailing soil (ATS), rhizospheric soil from four species, and non-rhizospheric native forest soil (NS), which acted as reference. The application of amendments increased pH up to neutrality, organic carbon (Corg), C/N and aggregate stability, while decreased salinity and heavy metals availability. No effect of rhizosphere was observed on physicochemical properties, metals immobilization and microbial community structure and function. To account for confounding effects due to soil organic matter, microbial properties were expressed per Corg. The high increments in pH and Corg have been the main factors driving changes in microbial community structure and function. Bacterial biomass was higher in UTS, without significant differences among the rest of soils. Fungal biomass followed the trend UTS < ATS = rhizospheric soils < NS. Bacterial growth increased and fungal growth decreased with increasing pH, despite the high availability of metals at low pH. Enzyme activities were lower in UTS, being β-glucosidase and β-glucosaminidase activities highly correlated with bacterial growth. Microbial activities were not correlated with the exchangeable fraction of heavy metals, indicating that microbial function is not strongly affected by these metals, likely due to the efficiency of the reclamation procedure to reduce metals toxicity. Changes in microbial community composition were largely explained by changes in pH, heavy metals availability and Corg

  17. Effect of growth conditions on microbial activity and iron-sulfide production by Desulfovibrio vulgaris.

    PubMed

    Zhou, Chen; Vannela, Raveender; Hayes, Kim F; Rittmann, Bruce E

    2014-05-15

    Sulfate-reducing bacteria (SRB) can produce iron sulfide (FeS) solids with mineralogical characteristics that may be beneficial for a variety of biogeochemical applications, such as long-term immobilization of uranium. In this study, the growth and metabolism of Desulfovibrio vulgaris, one of the best-studied SRB species, were comprehensively monitored in batch studies, and the biogenic FeS solids were characterized by X-ray diffraction. Controlling the pH by varying the initial pH, the iron-to-sulfate ratio, or the electron donor - affected the growth of D. vulgaris and strongly influenced the formation and growth of FeS solids. In particular, lower pH (from initial conditions or a decrease caused by less sulfate reduction, FeS precipitation, or using pyruvate as the electron donor) produced larger-sized mackinawite (Fe1+xS). Greater accumulation of free sulfide, from more sulfate reduction by D. vulgaris, also led to larger-sized mackinawite and particularly stimulated mackinawite transformation to greigite (Fe3S4) when the free sulfide concentration was 29.3mM. Furthermore, sufficient free Fe(2+) led to the additional formation of vivianite [Fe3(PO4)2·8(H2O)]. Thus, microbially relevant conditions (initial pH, choice of electron donor, and excess or deficiency of sulfide) are tools to generate biogenic FeS solids of different characteristics. PMID:24675611

  18. Effect of silver nanoparticles on growth performance, metabolism and microbial profile of broiler chickens.

    PubMed

    Pineda, Lane; Chwalibog, Andrè; Sawosz, Ewa; Lauridsen, Charlotte; Engberg, Ricarda; Elnif, Jan; Hotowy, Anna; Sawosz, Filip; Gao, Yuhong; Ali, Abdalla; Moghaddam, Heshmat Sepehri

    2012-10-01

    This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, respectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0.03) was increased, but N excretion and efficiency of utilisation was not affected. The populations of bacteria in the intestinal samples were not affected by AgNano supplementation. The concentration of immunoglobulin (IgG) in the blood plasma of broilers supplemented with AgNano decreased at day 36 (p = 0.012). The results demonstrated that AgNano affects N utilisation and plasma IgG concentration; however, it does not influence the microbial populations in the digestive tract, the energy metabolism and growth performance of chickens. PMID:22889095

  19. Comparison of Primary Models to Predict Microbial Growth by the Plate Count and Absorbance Methods

    PubMed Central

    Pla, María-Leonor; Oltra, Sandra; Esteban, María-Dolores; Andreu, Santiago; Palop, Alfredo

    2015-01-01

    The selection of a primary model to describe microbial growth in predictive food microbiology often appears to be subjective. The objective of this research was to check the performance of different mathematical models in predicting growth parameters, both by absorbance and plate count methods. For this purpose, growth curves of three different microorganisms (Bacillus cereus, Listeria monocytogenes, and Escherichia coli) grown under the same conditions, but with different initial concentrations each, were analysed. When measuring the microbial growth of each microorganism by optical density, almost all models provided quite high goodness of fit (r2 > 0.93) for all growth curves. The growth rate remained approximately constant for all growth curves of each microorganism, when considering one growth model, but differences were found among models. Three-phase linear model provided the lowest variation for growth rate values for all three microorganisms. Baranyi model gave a variation marginally higher, despite a much better overall fitting. When measuring the microbial growth by plate count, similar results were obtained. These results provide insight into predictive microbiology and will help food microbiologists and researchers to choose the proper primary growth predictive model. PMID:26539483

  20. Comparison of Primary Models to Predict Microbial Growth by the Plate Count and Absorbance Methods.

    PubMed

    Pla, María-Leonor; Oltra, Sandra; Esteban, María-Dolores; Andreu, Santiago; Palop, Alfredo

    2015-01-01

    The selection of a primary model to describe microbial growth in predictive food microbiology often appears to be subjective. The objective of this research was to check the performance of different mathematical models in predicting growth parameters, both by absorbance and plate count methods. For this purpose, growth curves of three different microorganisms (Bacillus cereus, Listeria monocytogenes, and Escherichia coli) grown under the same conditions, but with different initial concentrations each, were analysed. When measuring the microbial growth of each microorganism by optical density, almost all models provided quite high goodness of fit (r(2) > 0.93) for all growth curves. The growth rate remained approximately constant for all growth curves of each microorganism, when considering one growth model, but differences were found among models. Three-phase linear model provided the lowest variation for growth rate values for all three microorganisms. Baranyi model gave a variation marginally higher, despite a much better overall fitting. When measuring the microbial growth by plate count, similar results were obtained. These results provide insight into predictive microbiology and will help food microbiologists and researchers to choose the proper primary growth predictive model. PMID:26539483

  1. Microbial Growth, Water Flow, and Solute Transport in Unsaturated Porous Media

    NASA Astrophysics Data System (ADS)

    Yarwood, R. R.; Rockhold, M. L.; Niemet, M. R.; Bottomley, P. J.; Selker, J. S.

    2004-05-01

    We present an investigation that studied interactions between microbial growth, water flow, and solute transport in variably saturated porous media. The experimental system provided for continuous, noninvasive observation of microbial activity, while simultaneously monitoring water content and solute flow paths in a two-dimensional porous matrix. The spatial and temporal development of microbial colonization by a Pseudomonas fluorescens bacterium was monitored by induction of a bioluminescent phenotype. A model was developed that allowed quantification of population density from bioluminescence measurements. Liquid saturation was quantified from the transmission of light through the system, and solute flow paths were determined with a dye tracer. Dramatic changes in microbial colonization were observed, including upward migration against flow. This migration was particularly interesting because it cannot be explained by passive transport. Bacterial growth and accumulation significantly impacted the hydrologic properties of the media, including apparent desaturation within the colonized region, diversion of flow around the colonized region, and lowering of the capillary fringe height.

  2. Microbial biofilm growth on irradiated, spent nuclear fuel cladding

    NASA Astrophysics Data System (ADS)

    Bruhn, D. F.; Frank, S. M.; Roberto, F. F.; Pinhero, P. J.; Johnson, S. G.

    2009-02-01

    A fundamental criticism regarding the potential for microbial influenced corrosion in spent nuclear fuel cladding or storage containers concerns whether the required microorganisms can, in fact, survive radiation fields inherent in these materials. This study was performed to unequivocally answer this critique by addressing the potential for biofilm formation, the precursor to microbial-influenced corrosion, in radiation fields representative of spent nuclear fuel storage environments. This study involved the formation of a microbial biofilm on irradiated spent nuclear fuel cladding within a hot cell environment. This was accomplished by introducing 22 species of bacteria, in nutrient-rich media, to test vessels containing irradiated cladding sections and that was then surrounded by radioactive source material. The overall dose rate exceeded 2 Gy/h gamma/beta radiation with the total dose received by some of the bacteria reaching 5 × 10 3 Gy. This study provides evidence for the formation of biofilms on spent-fuel materials, and the implication of microbial influenced corrosion in the storage and permanent deposition of spent nuclear fuel in repository environments.

  3. Microbial Biofilm Growth on Irradiated, Spent Nuclear Fuel Cladding

    SciTech Connect

    S.M. Frank

    2009-02-01

    A fundamental criticism regarding the potential for microbial influenced corrosion in spent nuclear fuel cladding or storage containers concerns whether the required microorganisms can, in fact, survive radiation fields inherent in these materials. This study was performed to unequivocally answer this critique by addressing the potential for biofilm formation, the precursor to microbial-influenced corrosion, in radiation fields representative of spent nuclear fuel storage environments. This study involved the formation of a microbial biofilm on irradiated spent nuclear fuel cladding within a hot cell environment. This was accomplished by introducing 22 species of bacteria, in nutrient-rich media, to test vessels containing irradiated cladding sections and that was then surrounded by radioactive source material. The overall dose rate exceeded 2 Gy/h gamma/beta radiation with the total dose received by some of the bacteria reaching 5 × 103 Gy. This study provides evidence for the formation of biofilms on spent-fuel materials, and the implication of microbial influenced corrosion in the storage and permanent deposition of spent nuclear fuel in repository environments.

  4. Increasing concentrations of phenol progressively affect anaerobic digestion of cellulose and associated microbial communities.

    PubMed

    Chapleur, Olivier; Madigou, Céline; Civade, Raphaël; Rodolphe, Yohan; Mazéas, Laurent; Bouchez, Théodore

    2016-02-01

    Performance stability is a key issue when managing anaerobic digesters. However it can be affected by external disturbances caused by micropollutants. In this study the influence of phenol on the methanization of cellulose was evaluated through batch toxicity assays. Special attention was given to the dynamics of microbial communities by means of automated ribosomal intergenic spacer analysis. We observed that, as phenol concentrations increased, the different steps of anaerobic cellulose digestion were unevenly and progressively affected, methanogenesis being the most sensitive: specific methanogenic activity was half-inhibited at 1.40 g/L of phenol, whereas hydrolysis of cellulose and its fermentation to VFA were observed at up to 2.00 g/L. Depending on the level of phenol, microbial communities resisted either through physiological or structural adaptation. Thus, performances at 0.50 g/L were maintained in spite of the microbial community's shift. However, the communities' ability to adapt was limited and performances decreased drastically beyond 2.00 g/L of phenol. PMID:26614490

  5. Variation in honey bee gut microbial diversity affected by ontogenetic stage, age and geographic location.

    PubMed

    Hroncova, Zuzana; Havlik, Jaroslav; Killer, Jiri; Doskocil, Ivo; Tyl, Jan; Kamler, Martin; Titera, Dalibor; Hakl, Josef; Mrazek, Jakub; Bunesova, Vera; Rada, Vojtech

    2015-01-01

    Social honey bees, Apis mellifera, host a set of distinct microbiota, which is similar across the continents and various honey bee species. Some of these bacteria, such as lactobacilli, have been linked to immunity and defence against pathogens. Pathogen defence is crucial, particularly in larval stages, as many pathogens affect the brood. However, information on larval microbiota is conflicting. Seven developmental stages and drones were sampled from 3 colonies at each of the 4 geographic locations of A. mellifera carnica, and the samples were maintained separately for analysis. We analysed the variation and abundance of important bacterial groups and taxa in the collected bees. Major bacterial groups were evaluated over the entire life of honey bee individuals, where digestive tracts of same aged bees were sampled in the course of time. The results showed that the microbial tract of 6-day-old 5th instar larvae were nearly equally rich in total microbial counts per total digestive tract weight as foraging bees, showing a high percentage of various lactobacilli (Firmicutes) and Gilliamella apicola (Gammaproteobacteria 1). However, during pupation, microbial counts were significantly reduced but recovered quickly by 6 days post-emergence. Between emergence and day 6, imago reached the highest counts of Firmicutes and Gammaproteobacteria, which then gradually declined with bee age. Redundancy analysis conducted using denaturing gradient gel electrophoresis identified bacterial species that were characteristic of each developmental stage. The results suggest that 3-day 4th instar larvae contain low microbial counts that increase 2-fold by day 6 and then decrease during pupation. Microbial succession of the imago begins soon after emergence. We found that bacterial counts do not show only yearly cycles within a colony, but vary on the individual level. Sampling and pooling adult bees or 6th day larvae may lead to high errors and variability, as both of these stages may

  6. Variation in Honey Bee Gut Microbial Diversity Affected by Ontogenetic Stage, Age and Geographic Location

    PubMed Central

    Hroncova, Zuzana; Havlik, Jaroslav; Killer, Jiri; Doskocil, Ivo; Tyl, Jan; Kamler, Martin; Titera, Dalibor; Hakl, Josef; Mrazek, Jakub; Bunesova, Vera; Rada, Vojtech

    2015-01-01

    Social honey bees, Apis mellifera, host a set of distinct microbiota, which is similar across the continents and various honey bee species. Some of these bacteria, such as lactobacilli, have been linked to immunity and defence against pathogens. Pathogen defence is crucial, particularly in larval stages, as many pathogens affect the brood. However, information on larval microbiota is conflicting. Seven developmental stages and drones were sampled from 3 colonies at each of the 4 geographic locations of A. mellifera carnica, and the samples were maintained separately for analysis. We analysed the variation and abundance of important bacterial groups and taxa in the collected bees. Major bacterial groups were evaluated over the entire life of honey bee individuals, where digestive tracts of same aged bees were sampled in the course of time. The results showed that the microbial tract of 6-day-old 5th instar larvae were nearly equally rich in total microbial counts per total digestive tract weight as foraging bees, showing a high percentage of various lactobacilli (Firmicutes) and Gilliamella apicola (Gammaproteobacteria 1). However, during pupation, microbial counts were significantly reduced but recovered quickly by 6 days post-emergence. Between emergence and day 6, imago reached the highest counts of Firmicutes and Gammaproteobacteria, which then gradually declined with bee age. Redundancy analysis conducted using denaturing gradient gel electrophoresis identified bacterial species that were characteristic of each developmental stage. The results suggest that 3-day 4th instar larvae contain low microbial counts that increase 2-fold by day 6 and then decrease during pupation. Microbial succession of the imago begins soon after emergence. We found that bacterial counts do not show only yearly cycles within a colony, but vary on the individual level. Sampling and pooling adult bees or 6th day larvae may lead to high errors and variability, as both of these stages may

  7. Fly ash addition affects microbial biomass and carbon mineralization in agricultural soils.

    PubMed

    Nayak, A K; Kumar, Anjani; Raja, R; Rao, K S; Mohanty, Sangita; Shahid, Mohammad; Tripathy, Rahul; Panda, B B; Bhattacharyya, P

    2014-02-01

    The microbial biomass carbon (MBC) and carbon mineralization of fly ash (FA) amended soil at (0 %, 1.25 %, 2.5 %, 5 %, 10 % and 20 % FA; v/v) was investigated under laboratory conditions for 120 days at 60 % soil water-holding capacity and 25 ± 1°C temperature. The results demonstrated that soil respiration and microbial activities were not suppressed up to 2.5 % FA amendment and these activities decreased significantly at 10 % and 20 % FA treatment with respect to control. Application of 10 % and 20 % FA treated soils showed a decreasing trend of soil MBC with time; and the decrease was significant throughout the period of incubation. The study concluded that application of FA up to 2.5 % can thus be safely used without affecting the soil biological activity and thereby improve nutrient cycling in agricultural soils. PMID:24362819

  8. Determination of Microbial Growth by Protein Assay in an Air-Cathode Single Chamber Microbial Fuel Cell.

    PubMed

    Li, Na; Kakarla, Ramesh; Moon, Jung Mi; Min, Booki

    2015-07-01

    Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/g- COD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-COD-substrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation. PMID:25674807

  9. Prediction of microbial growth in mixed culture with a competition model.

    PubMed

    Fujikawa, Hiroshi; Sakha, Mohammad Z

    2014-01-01

    Prediction of microbial growth in mixed culture was studied with a competition model that we had developed recently. The model, which is composed of the new logistic model and the Lotka-Volterra model, is shown to successfully describe the microbial growth of two species in mixed culture using Staphylococcus aureus, Escherichia coli, and Salmonella. With the parameter values of the model obtained from the experimental data on monoculture and mixed culture with two species, it then succeeded in predicting the simultaneous growth of the three species in mixed culture inoculated with various cell concentrations. To our knowledge, it is the first time for a prediction model for multiple (three) microbial species to be reported. The model, which is not built on any premise for specific microorganisms, may become a basic competition model for microorganisms in food and food materials. PMID:24975413

  10. Modeling Microbial Growth Dynamics, Patterns, and Coexistence on Partially Saturated Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Long, T.; Or, D.

    2005-12-01

    A new modeling tool was developed to study the impact of variations in matric potential on aquatic pathways and substrate diffusion, and on microbial growth and movement on unsaturated rough surfaces. The modeling domain is composed of prescribed distributions of conical pits (sites) connected by prismatic channels (bonds) representing rough surfaces of soils or rocks. The well-defined geometry facilitates exact description of aqueous phase distribution within the roughness for a given matric potential. Microbial growth within the resulting highly variable diffusion network architectures (vary with matric potential) and interactions with nutrient diffusion patterns are simulated by coupling Reaction-Diffusion Method (RDM) and the Active Walker Method (AWM). Simulation results show direct impact of wetness conditions (matric potential values) on microbial growth rates and expansion patters for the same surface roughness. In addition to modification of mean diffusion rates for drier or wetter conditions, the network connectivity may induce significant changes in spatial patters of microbial growth. Impact of these changes on coexistence of two competing microbial species will be discussed.

  11. Growth and element flux at fine taxonomic resolution in natural microbial communities

    NASA Astrophysics Data System (ADS)

    Hungate, Bruce; Mau, Rebecca; Schwartz, Egbert; Caporaso, J. Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J.; Liu, Cindy M.; McHugh, Theresa; Marks, Jane C.; Morrissey, Ember; Price, Lance B.

    2015-04-01

    Microorganisms are the engines of global biogeochemical cycles, driving half of all photosynthesis and nearly all decomposition. Yet, quantifying the rates at which uncultured microbial taxa grow and transform elements in intact and highly diverse natural communities in the environment remains among the most pressing challenges in microbial ecology today. Here, we show how shifts in the density of DNA caused by stable isotope incorporation can be used to estimate the growth rates of individual bacterial taxa in intact soil communities. We found that the distribution of growth rates followed the familiar lognormal distribution observed for the abundances, biomasses, and traits of many organisms. Growth rates of most bacterial taxa increased in response to glucose amendment, though the increase in growth observed for many taxa was larger than could be explained by direct utilization of the added glucose for growth, illustrating that glucose addition indirectly stimulated the utilization of other substrates. Variation in growth rates and phylogenetic distances were quantitatively related, connecting evolutionary history and biogeochemical function in intact soil microbial communities. Our approach has the potential to identify biogeochemically significant taxa in the microbial community and quantify their contributions to element transformations and ecosystem processes.

  12. Carbon tetrachloride degradation: Effect of microbial growth substrate and vitamin B{sub 12} content

    SciTech Connect

    Zou, S.; Stensel, H.D.; Ferguson, J.F.

    2000-05-01

    Microbial degradation kinetics of carbon tetrachloride (CT) under reducing conditions were investigated for different cultures, fed with 1,2-propanediol, dextrose, propionalde-hyde, or acetate and nitrate, in the anaerobic step of an anaerobic/aerobic operation sequence. Methanogenesis was inhibited due to the aerobic step. CT biodegradation rates followed first-order kinetics with respect to CT concentration and biomass and were not affected by the presence of growth substrate. CT degradation rates increased linearly with higher intracellular vitamin B{sub 12} content. The culture fed 1,2-propanediol had the highest vitamin B{sub 12} content, which was 3.8, 4.7, and 16 times that of the propionaldehyde-,dextrose-, and acetate-fed cultures, respectively, and its first-order degradation rate constant was 2.8, 4.5, 6.0 times that for those cultures, respectively. No CT degradation occurred with culture liquid, suggesting that intracellular factors were responsible for CT degradation. The propanediol culture was able to sustain a constant CT degradation rate for a 16-day test period without substrate addition. Compared to a propanediol-fed culture grown only under anaerobic conditions, the propanediol culture grown under the sequential anaerobic/aerobic condition resulted in more biomass growth and a greater CT degradation rate per unit of propanediol fed, although its CT degradation rate per unit of biomass was lower.

  13. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities.

    PubMed

    Liu, Feng; Ying, Guang-Guo; Tao, Ran; Zhao, Jian-Liang; Yang, Ji-Feng; Zhao, Lan-Feng

    2009-05-01

    The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. PMID:19157661

  14. Zinc oxide nanoparticles cause inhibition of microbial denitrification by affecting transcriptional regulation and enzyme activity.

    PubMed

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Liu, Kun; Li, Mu; Yin, Daqiang

    2014-12-01

    Over the past few decades, human activities have accelerated the rates and extents of water eutrophication and global warming through increasing delivery of biologically available nitrogen such as nitrate and large emissions of anthropogenic greenhouse gases. In particular, nitrous oxide (N2O) is one of the most important greenhouse gases, because it has a 300-fold higher global warming potential than carbon dioxide. Microbial denitrification is a major pathway responsible for nitrate removal, and also a dominant source of N2O emissions from terrestrial or aquatic environments. However, whether the release of zinc oxide nanoparticles (ZnO NPs) into the environment affects microbial denitrification is largely unknown. Here we show that the presence of ZnO NPs lead to great increases in nitrate delivery (9.8-fold higher) and N2O emissions (350- and 174-fold higher in the gas and liquid phases, respectively). Our data further reveal that ZnO NPs significantly change the transcriptional regulations of glycolysis and polyhydroxybutyrate synthesis, which causes the decrease in reducing powers available for the reduction of nitrate and N2O. Moreover, ZnO NPs substantially inhibit the gene expressions and catalytic activities of key denitrifying enzymes. These negative effects of ZnO NPs on microbial denitrification finally cause lower nitrate removal and higher N2O emissions, which is likely to exacerbate water eutrophication and global warming. PMID:25384038

  15. Seasonal Variability May Affect Microbial Decomposers and Leaf Decomposition More Than Warming in Streams.

    PubMed

    Duarte, Sofia; Cássio, Fernanda; Ferreira, Verónica; Canhoto, Cristina; Pascoal, Cláudia

    2016-08-01

    Ongoing climate change is expected to affect the diversity and activity of aquatic microbes, which play a key role in plant litter decomposition in forest streams. We used a before-after control-impact (BACI) design to study the effects of warming on a forest stream reach. The stream reach was divided by a longitudinal barrier, and during 1 year (ambient year) both stream halves were at ambient temperature, while in the second year (warmed year) the temperature in one stream half was increased by ca. 3 °C above ambient temperature (experimental half). Fine-mesh bags containing oak (Quercus robur L.) leaves were immersed in both stream halves for up to 60 days in spring and autumn of the ambient and warmed years. We assessed leaf-associated microbial diversity by denaturing gradient gel electrophoresis and identification of fungal conidial morphotypes and microbial activity by quantifying leaf mass loss and productivity of fungi and bacteria. In the ambient year, no differences were found in leaf decomposition rates and microbial productivities either between seasons or stream halves. In the warmed year, phosphorus concentration in the stream water, leaf decomposition rates, and productivity of bacteria were higher in spring than in autumn. They did not differ between stream halves, except for leaf decomposition, which was higher in the experimental half in spring. Fungal and bacterial communities differed between seasons in both years. Seasonal changes in stream water variables had a greater impact on the activity and diversity of microbial decomposers than a warming regime simulating a predicted global warming scenario. PMID:27193000

  16. Metals other than uranium affected microbial community composition in a historical uranium-mining site.

    PubMed

    Sitte, Jana; Löffler, Sylvia; Burkhardt, Eva-Maria; Goldfarb, Katherine C; Büchel, Georg; Hazen, Terry C; Küsel, Kirsten

    2015-12-01

    To understand the links between the long-term impact of uranium and other metals on microbial community composition, ground- and surface water-influenced soils varying greatly in uranium and metal concentrations were investigated at the former uranium-mining district in Ronneburg, Germany. A soil-based 16S PhyloChip approach revealed 2358 bacterial and 35 archaeal operational taxonomic units (OTU) within diverse phylogenetic groups with higher OTU numbers than at other uranium-contaminated sites, e.g., at Oak Ridge. Iron- and sulfate-reducing bacteria (FeRB and SRB), which have the potential to attenuate uranium and other metals by the enzymatic and/or abiotic reduction of metal ions, were found at all sites. Although soil concentrations of solid-phase uranium were high, ranging from 5 to 1569 μg·g (dry weight) soil(-1), redundancy analysis (RDA) and forward selection indicated that neither total nor bio-available uranium concentrations contributed significantly to the observed OTU distribution. Instead, microbial community composition appeared to be influenced more by redox potential. Bacterial communities were also influenced by bio-available manganese and total cobalt and cadmium concentrations. Bio-available cadmium impacted FeRB distribution while bio-available manganese and copper as well as solid-phase zinc concentrations in the soil affected SRB composition. Archaeal communities were influenced by the bio-available lead as well as total zinc and cobalt concentrations. These results suggest that (i) microbial richness was not impacted by heavy metals and radionuclides and that (ii) redox potential and secondary metal contaminants had the strongest effect on microbial community composition, as opposed to uranium, the primary source of contamination. PMID:26122566

  17. Land-use and soil depth affect resource and microbial stoichiometry in a tropical mountain rainforest region of southern Ecuador.

    PubMed

    Tischer, Alexander; Potthast, Karin; Hamer, Ute

    2014-05-01

    Global change phenomena, such as forest disturbance and land-use change, significantly affect elemental balances as well as the structure and function of terrestrial ecosystems. However, the importance of shifts in soil nutrient stoichiometry for the regulation of belowground biota and soil food webs have not been intensively studied for tropical ecosystems. In the present account, we examine the effects of land-use change and soil depth on soil and microbial stoichiometry along a land-use sequence (natural forest, pastures of different ages, secondary succession) in the tropical mountain rainforest region of southern Ecuador. Furthermore, we analyzed (PLFA-method) whether shifts in the microbial community structure were related to alterations in soil and microbial stoichiometry. Soil and microbial stoichiometry were affected by both land-use change and soil depth. After forest disturbance, significant decreases of soil C:N:P ratios at the pastures were followed by increases during secondary succession. Microbial C:N ratios varied slightly in response to land-use change, whereas no fixed microbial C:P and N:P ratios were observed. Shifts in microbial community composition were associated with soil and microbial stoichiometry. Strong positive relationships between PLFA-markers 18:2n6,9c (saprotrophic fungi) and 20:4 (animals) and negative associations between 20:4 and microbial N:P point to land-use change affecting the structure of soil food webs. Significant deviations from global soil and microbial C:N:P ratios indicated a major force of land-use change to alter stoichiometric relationships and to structure biological systems. Our results support the idea that soil biotic communities are stoichiometrically flexible in order to adapt to alterations in resource stoichiometry. PMID:24532178

  18. Optimising Microbial Growth with a Bench-Top Bioreactor

    ERIC Educational Resources Information Center

    Baker, A. M. R.; Borin, S. L.; Chooi, K. P.; Huang, S. S.; Newgas, A. J. S.; Sodagar, D.; Ziegler, C. A.; Chan, G. H. T.; Walsh, K. A. P.

    2006-01-01

    The effects of impeller size, agitation and aeration on the rate of yeast growth were investigated using bench-top bioreactors. This exercise, carried out over a six-month period, served as an effective demonstration of the importance of different operating parameters on cell growth and provided a means of determining the optimisation conditions…

  19. Microbial H2 cycling does not affect δ2H values of ground water

    USGS Publications Warehouse

    Landmeyer, J.E.; Chapelle, F.H.; Bradley, P.M.

    2000-01-01

    Stable hydrogen-isotope values of ground water (δ2H) and dissolved hydrogen concentrations (H(2(aq)) were quantified in a petroleum-hydrocarbon contaminated aquifer to determine whether the production/consumption of H2 by subsurface microorganisms affects ground water &delta2H values. The range of &delta2H observed in monitoring wells sampled (-27.8 ‰c to -15.5 ‰c) was best explained, however, by seasonal differences in recharge temperature as indicated using ground water δ18O values, rather than isotopic exchange reactions involving the microbial cycling of H2 during anaerobic petroleum-hydrocarbon biodegradation. The absence of a measurable hydrogen-isotope exchange between microbially cycled H2 and ground water reflects the fact that the amount of H2 available from the anaerobic decomposition of petroleum hydrocarbons is small relative to the amount of hydrogen present in water, even though milligram per liter concentrations of readily biodegradable contaminants are present at the study site. Additionally, isotopic fractionation calculations indicate that in order for H2 cycling processes to affect δ2H values of ground water, relatively high concentrations of H2 (>0.080 M) would have to be maintained, considerably higher than the 0.2 to 26 nM present at this site and characteristic of anaerobic conditions in general. These observations suggest that the conventional approach of using δ2H and δ18O values to determine recharge history is appropriate even for those ground water systems characterized by anaerobic conditions and extensive microbial H2 cycling.

  20. [Evaluation of microbial growth on single-use vitrectomy probes reprocessed in healthcare practice].

    PubMed

    Pinto, Flávia Morais Gomes; Araújo, Valéria Garcia Lopes; Souza, Rafael Queiroz de; Goveia, Vânia Regina; Missali, Carmen Castilho; Luz, Reginaldo Adalberto de; Graziano, Kazuko Uchikawa

    2012-06-01

    The aim of this study was to evaluate the microbial growth on single-use vitrectomy probes reprocessed in healthcare practice. We investigated nine vitrectomy probes that had been reused and reprocessed using different methods. The samples were sectioned, individually, in portions of 3.5 cm, totaling 979 sampling units (extensions, connectors and vitrectomy cutters), which were inoculated in culture medium and incubated at 37º C for 14 days. The results showed microbial growth on 57 (5.8%) sample units, 25 of which had been sterilized using ethylene oxide, 16 by hydrogen peroxide plasma, and 16 by low-temperature steam and formaldehyde. Seventeen microbial species were identified. The most prevalent were: Micrococcus spp., coagulase-negative Staphylococcus, Pseudomonas spp., and Bacillus subtilis. The reuse of single-use vitrectomy probes was shown to be unsafe, therefore this practice is not recommended. PMID:22773479

  1. Hydrocarbon contamination affects deep-sea benthic oxygen uptake and microbial community composition

    NASA Astrophysics Data System (ADS)

    Main, C. E.; Ruhl, H. A.; Jones, D. O. B.; Yool, A.; Thornton, B.; Mayor, D. J.

    2015-06-01

    Accidental oil well blowouts have the potential to introduce large quantities of hydrocarbons into the deep sea and disperse toxic contaminants to midwater and seafloor areas over ocean-basin scales. Our ability to assess the environmental impacts of these events is currently impaired by our limited understanding of how resident communities are affected. This study examined how two treatment levels of a water accommodated fraction of crude oil affected the oxygen consumption rate of a natural, deep-sea benthic community. We also investigated the resident microbial community's response to hydrocarbon contamination through quantification of phospholipid fatty acids (PLFAs) and their stable carbon isotope (δ13C) values. Sediment community oxygen consumption rates increased significantly in response to increasing levels of contamination in the overlying water of oil-treated microcosms, and bacterial biomass decreased significantly in the presence of oil. Multivariate ordination of PLFA compositional (mol%) data showed that the structure of the microbial community changed in response to hydrocarbon contamination. However, treatment effects on the δ13C values of individual PLFAs were not statistically significant. Our data demonstrate that deep-sea benthic microbes respond to hydrocarbon exposure within 36 h.

  2. Evaluation of indirect impedance for measuring microbial growth in complex food matrices.

    PubMed

    Johnson, N; Chang, Z; Bravo Almeida, C; Michel, M; Iversen, C; Callanan, M

    2014-09-01

    The suitability of indirect impedance to accurately measure microbial growth in real food matrices was investigated. A variety of semi-solid and liquid food products were inoculated with Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Lactobacillus plantarum, Pseudomonas aeruginosa, Escherichia coli, Salmonella enteriditis, Candida tropicalis or Zygosaccharomyces rouxii and CO2 production was monitored using a conductimetric (Don Whitely R.A.B.I.T.) system. The majority (80%) of food and microbe combinations produced a detectable growth signal. The linearity of conductance responses in selected food products was investigated and a good correlation (R(2) ≥ 0.84) was observed between inoculum levels and times to detection. Specific growth rate estimations from the data were sufficiently accurate for predictive modeling in some cases. This initial evaluation of the suitability of indirect impedance to generate microbial growth data in complex food matrices indicates significant potential for the technology as an alternative to plating methods. PMID:24929710

  3. Hot water treatment reduces microbial growth and improves quality of packaged fresh-cut tables grapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Packaged fresh-cut table grape (Vitis vinifera L.) has emerged as a popular snack food because it offers freshness, nutrition, and convenience. However, tissue injury sustained during stem removal, and the openings created after stem removal make grapes susceptible to microbial growth, product deca...

  4. Effect of temperature on microbial growth rate - thermodynamic analysis, the arrhenius and eyring-polanyi connection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this work is to develop a new thermodynamic mathematical model for evaluating the effect of temperature on the rate of microbial growth. The new mathematical model is derived by combining the Arrhenius equation and the Eyring-Polanyi transition theory. The new model, suitable for ...

  5. Influence of different buffers (HEPES/MOPS) on keratinocyte cell viability and microbial growth.

    PubMed

    Dias, Kássia de Carvalho; Barbugli, Paula Aboud; Vergani, Carlos Eduardo

    2016-06-01

    This study assessed the effect of the buffers 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) on keratinocyte cell viability and microbial growth. It was observed that RPMI buffered with HEPES, supplemented with l-glutamine and sodium bicarbonate, can be used as a more suitable medium to promote co-culture. PMID:27060444

  6. Dynamical Allocation of Cellular Resources as an Optimal Control Problem: Novel Insights into Microbial Growth Strategies

    PubMed Central

    Giordano, Nils; Mairet, Francis; Gouzé, Jean-Luc

    2016-01-01

    Microbial physiology exhibits growth laws that relate the macromolecular composition of the cell to the growth rate. Recent work has shown that these empirical regularities can be derived from coarse-grained models of resource allocation. While these studies focus on steady-state growth, such conditions are rarely found in natural habitats, where microorganisms are continually challenged by environmental fluctuations. The aim of this paper is to extend the study of microbial growth strategies to dynamical environments, using a self-replicator model. We formulate dynamical growth maximization as an optimal control problem that can be solved using Pontryagin’s Maximum Principle. We compare this theoretical gold standard with different possible implementations of growth control in bacterial cells. We find that simple control strategies enabling growth-rate maximization at steady state are suboptimal for transitions from one growth regime to another, for example when shifting bacterial cells to a medium supporting a higher growth rate. A near-optimal control strategy in dynamical conditions is shown to require information on several, rather than a single physiological variable. Interestingly, this strategy has structural analogies with the regulation of ribosomal protein synthesis by ppGpp in the enterobacterium Escherichia coli. It involves sensing a mismatch between precursor and ribosome concentrations, as well as the adjustment of ribosome synthesis in a switch-like manner. Our results show how the capability of regulatory systems to integrate information about several physiological variables is critical for optimizing growth in a changing environment. PMID:26958858

  7. Drought induced changes of plant belowground carbon allocation affect soil microbial community function in a subalpine meadow

    NASA Astrophysics Data System (ADS)

    Fuchslueger, L.; Bahn, M.; Fritz, K.; Hasibeder, R.; Richter, A.

    2012-12-01

    There is growing evidence that climate extremes may affect ecosystem carbon dynamics more strongly than gradual changes in temperatures or precipitation. Climate projections suggest more frequent heat waves accompanied by extreme drought periods in many parts of Europe, including the Alps. Drought is considered to decrease plant C uptake and turnover, which may in turn decrease belowground C allocation and potentially has significant consequences for microbial community composition and functioning. However, information on effects of drought on C dynamics at the plant-soil interface in real ecosystems is still scarce. Our study aimed at understanding how summer drought affects soil microbial community composition and the uptake of recently assimilated plant C by different microbial groups in grassland. We hypothesized that under drought 1) the microbial community shifts, fungi being less affected than bacteria, 2) plants decrease belowground C allocation, which further reduces C transfer to soil microbes and 3) the combined effects of belowground C allocation, reduced soil C transport due to reduced soil moisture and shift in microbial communities cause an accumulation of extractable organic C in the soil. Our study was conducted as part of a rain-exclusion experiment in a subalpine meadow in the Austrian Central Alps. After eight weeks of rain exclusion we pulse labelled drought and control plots with 13CO2 and traced C in plant biomass, extractable organic C (EOC) and soil microbial communities using phospholipid fatty acids (PLFA). Drought induced a shift of the microbial community composition: gram-positive bacteria became more dominant, whereas gram-negative bacteria were not affected by drought. Also the relative abundance of fungal biomass was not affected by drought. While total microbial biomass (as estimated by total microbial PLFA content) increased during drought, less 13C was taken up. This reduction was pronounced for bacterial biomarkers. It reflects

  8. Spaceflight and age affect tibial epiphyseal growth plate histomorphometry

    NASA Technical Reports Server (NTRS)

    Montufar-Solis, Dina; Duke, Pauline J.; Durnova, G.

    1992-01-01

    Growth plate histomorphometry of rats flown aboard the Soviet biosatellite Cosmos 2044, a 14-day spaceflight, was compared with that of control groups. In growth plates of flight animals, there was a significant increase in cell number per column and height of the proliferative zone and a reduction in height and cell number in the hypertrophy/calcification zone. No significant differences were found in matrix organization at the ultrastructural level of flight animals, indicating that although spacefligfht continues to affect bone growth of 15-wk-old rats, extracellular matrix is not altered in the same manner as seen previously in younger animals. All groups showed growth plate characteristics attributed to aging: lack of calcification zone, reduced hypertrophy zone, and unraveling of collagen fibrils. Tail-suspended controls did not differ from other controls in any of the parameters measured. The results suggest that growth plates of older rats are less responsive to unloading by spaceflight or suspension than those of younger rats and provide new evidence about the modifying effect of spaceflight on the growth plate.

  9. Plant growth and soil microbial community structure of legumes and grasses grown in monoculture or mixture.

    PubMed

    Chen, Meimei; Chen, Baodong; Marschner, Petra

    2008-01-01

    A greenhouse pot experiment was conducted to investigate the influence of soil moisture content on plant growth and the rhizosphere microbial community structure of four plant species (white clover, alfalfa, sudan grass, tall fescue), grown individually or in a mixture. The soil moisture content was adjusted to 55% or 80% water holding capacity (WHC). The results indicated that the total plant biomass of one pot was lower at 55% WHC. At a given soil moisture, the total plant biomass of white clover and tall fescue in the mixture was lower than that in a monoculture, indicating their poor competitiveness. For leguminous plants, the decrease in soil moisture reduced the total microbial biomass, bacterial biomass, fungal biomass, and fungal/bacterial ratio in soil as assessed by the phospholipid fatty acid analysis, whereas, lower soil moisture increased those parameters in the tall fescue. The microbial biomass in the soil with legumes was higher than that in the soil with grasses and the two plant groups differed in soil microbial community composition. At high soil moisture content, microbial communities of the plant mixture were similar to those of the legume monoculture, and the existence of legumes in the mixture enhanced the bacterial and fungal biomass in the soil compared to the grasses grown in the monoculture, indicating that legumes played a dominant role in the soil microbial community changes in the plant mixture. PMID:19143348

  10. Microbial growth and sensory quality of dried potato slices irradiated by electrons

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Song, Hyeon-Jeong; Song, Kyung-Bin

    2011-06-01

    Electron beam irradiation was applied to secure the microbial safety of dried purple sweet potato. After purple sweet potato slices had been dehydrated with 20% (w/w) maltodextrin solution, the samples were irradiated at doses 2, 4, 6, 8, and 10 kGy and then stored at 20 °C for 60 days. Microbiological data indicated that the populations of total aerobic bacteria and of yeast and molds significantly decreased with increase in irradiation dosage. Specifically, microbial load was reduced by about three log cycles at 6 kGy compared to those of the control. Based on the color measurement of the potato slices, electron beam irradiation treatment did not affect the color quality. Sensory evaluation results also showed that electron beam irradiation did not affect overall sensory scores during storage. These results suggest that electron beam irradiation could be useful for improving microbial safety without impairing the quality of the potato slices during storage.

  11. {sup 210}Pb atmospheric flux and growth rates of a microbial mat from the northwestern Mediterranean Sea (Ebro River Delta)

    SciTech Connect

    Sanchez-Cabeza, J.A.; Masque, P.; Martinez-Alonso, M.; Mir, J.; Esteve, I.

    1999-11-01

    Environmental archives are needed to study the variability of natural systems and the impact of man on them. Microbial mats, modern homologues of stromatolites, can be found in extreme environments such as the Ebro River Delta and were studied as potential environmental archives of atmospheric deposition. {sup 210}Pb, a radiotracer widely used in geochronology studies, was used both to determine the growth rates of a microbial mat from this environment and to estimate the {sup 210}Pb atmospheric flux in the northwestern Mediterranean Sea. The {sup 210}Pb profile showed the presence of three distinct peaks related to low growth-rate periods. This variability indicted the sensitivity of the system to external forcing. The annual atmospheric flux of {sup 210}Pb was 81.2 {+-} 1.4 B1 m{sup {minus}2}yr{sup {minus}1}, which is similar to other values found in the literature. The age profile showed two layers of differing growth rates, being 0.99 {+-} 0.10 mm yr{sup {minus}1} from the surface down to 10 mm depth. The accumulated mass profile showed a change at about 9 mm depth, corresponding to year 1983 {+-} 1. It is noteworthy that this is coincident with a strong El Nino Southern Oscillation event during 1982--1983, which has been shown to affect other ecosystems, including some in the Mediterranean area.

  12. DMPP-added nitrogen fertilizer affects soil N2O emission and microbial activity in Southern Italy

    NASA Astrophysics Data System (ADS)

    Vitale, Luca; De Marco, Anna; Maglione, Giuseppe; Polimeno, Franca; Di Tommasi, Paul; Magliulo, Vincenzo

    2014-05-01

    plots, whereas an opposite trend for basal respiration was observed, thus evidencing a stressful condition for nitrifying microbial population. After 57 and 71 DAS, when fertilizer was applied as 30 kg N ha-1, the microbial biomass was similar between C and DMPP plots, whereas basal respiration resulted statistically lower in DMPP plots than C plots. During these periods, average DMPP N2O fluxes were also comparable or lower. In conclusion, our data evidence a stressful condition for soil microbes and in particular for nitrifiers when a higher DMPP quantity is supplied. On the contrary, when lower quantities of DMPP-added fertilizers are supplied (e.s. 30 kg N ha-1) effectiveness of DMPP in reducing soil N2O emission is guaranteed by reducing the nitrifiers activity without negatively affecting their growth.

  13. Analysis of factors affecting the accuracy, reproducibility, and interpretation of microbial community carbon source utilization patterns

    USGS Publications Warehouse

    Haack, S.K.; Garchow, H.; Klug, M.J.; Forney, L.J.

    1995-01-01

    We determined factors that affect responses of bacterial isolates and model bacterial communities to the 95 carbon substrates in Biolog microliter plates. For isolates and communities of three to six bacterial strains, substrate oxidation rates were typically nonlinear and were delayed by dilution of the inoculum. When inoculum density was controlled, patterns of positive and negative responses exhibited by microbial communities to each of the carbon sources were reproducible. Rates and extents of substrate oxidation by the communities were also reproducible but were not simply the sum of those exhibited by community members when tested separately. Replicates of the same model community clustered when analyzed by principal- components analysis (PCA), and model communities with different compositions were clearly separated un the first PCA axis, which accounted for >60% of the dataset variation. PCA discrimination among different model communities depended on the extent to which specific substrates were oxidized. However, the substrates interpreted by PCA to be most significant in distinguishing the communities changed with reading time, reflecting the nonlinearity of substrate oxidation rates. Although whole-community substrate utilization profiles were reproducible signatures for a given community, the extent of oxidation of specific substrates and the numbers or activities of microorganisms using those substrates in a given community were not correlated. Replicate soil samples varied significantly in the rate and extent of oxidation of seven tested substrates, suggesting microscale heterogeneity in composition of the soil microbial community.

  14. Water level changes affect carbon turnover and microbial community composition in lake sediments

    PubMed Central

    Weise, Lukas; Ulrich, Andreas; Moreano, Matilde; Gessler, Arthur; E. Kayler, Zachary; Steger, Kristin; Zeller, Bernd; Rudolph, Kristin; Knezevic-Jaric, Jelena; Premke, Katrin

    2016-01-01

    Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-desiccation cycles) on carbon turnover. 13C-labelled particulate organic carbon was used to trace and estimate carbon uptake into bacterial biomass (via phospholipid fatty acids) and respiration. Microbial community changes were monitored by combining DNA- and RNA-based real-time PCR quantification and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA. The shifting hydrological regimes in the sediment primarily caused two linked microbial effects: changes in the use of available organic carbon and community composition changes. Drying sediments yielded the highest CO2 emission rates, whereas hydrological shifts increased the uptake of allochthonous organic carbon for respiration. T-RFLP patterns demonstrated that only the most extreme hydrological changes induced a significant shift in the active and total bacterial communities. As current scenarios of climate change predict an increase of drought events, frequent variations of the hydrological regimes of many lake littoral zones in central Europe are anticipated. Based on the results of our study, this phenomenon may increase the intensity and amplitude in rates of allochthonous organic carbon uptake and CO2 emissions. PMID:26902802

  15. Water level changes affect carbon turnover and microbial community composition in lake sediments.

    PubMed

    Weise, Lukas; Ulrich, Andreas; Moreano, Matilde; Gessler, Arthur; Kayler, Zachary E; Steger, Kristin; Zeller, Bernd; Rudolph, Kristin; Knezevic-Jaric, Jelena; Premke, Katrin

    2016-05-01

    Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-desiccation cycles) on carbon turnover. (13)C-labelled particulate organic carbon was used to trace and estimate carbon uptake into bacterial biomass (via phospholipid fatty acids) and respiration. Microbial community changes were monitored by combining DNA- and RNA-based real-time PCR quantification and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA. The shifting hydrological regimes in the sediment primarily caused two linked microbial effects: changes in the use of available organic carbon and community composition changes. Drying sediments yielded the highest CO2 emission rates, whereas hydrological shifts increased the uptake of allochthonous organic carbon for respiration. T-RFLP patterns demonstrated that only the most extreme hydrological changes induced a significant shift in the active and total bacterial communities. As current scenarios of climate change predict an increase of drought events, frequent variations of the hydrological regimes of many lake littoral zones in central Europe are anticipated. Based on the results of our study, this phenomenon may increase the intensity and amplitude in rates of allochthonous organic carbon uptake and CO2 emissions. PMID:26902802

  16. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics

    PubMed Central

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-01-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring–summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus–host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus–host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems. PMID:26296067

  17. Lysozyme affects the microbial catabolism of free arginine in raw-milk hard cheeses.

    PubMed

    D'Incecco, P; Gatti, M; Hogenboom, J A; Bottari, B; Rosi, V; Neviani, E; Pellegrino, L

    2016-08-01

    Lysozyme (LZ) is used in several cheese varieties to prevent late blowing which results from fermentation of lactate by Clostridium tyrobutyricum. Side effects of LZ on lactic acid bacteria population and free amino acid pattern were studied in 16 raw-milk hard cheeses produced in eight parallel cheese makings conducted at four different dairies using the same milk with (LZ+) or without (LZ-) addition of LZ. The LZ-cheeses were characterized by higher numbers of cultivable microbial population and lower amount of DNA arising from lysed bacterial cells with respect to LZ + cheeses. At both 9 and 16 months of ripening, Lactobacillus delbrueckii and Lactobacillus fermentum proved to be the species mostly affected by LZ. The total content of free amino acids indicated the proteolysis extent to be characteristic of the dairy, regardless to the presence of LZ. In contrast, the relative patterns showed the microbial degradation of arginine to be promoted in LZ + cheeses. The data demonstrated that the arginine-deiminase pathway was only partially adopted since citrulline represented the main product and only trace levels of ornithine were found. Differences in arginine degradation were considered for starter and non-starter lactic acid bacteria, at different cheese ripening stages. PMID:27052697

  18. Early infancy microbial and metabolic alterations affect risk of childhood asthma.

    PubMed

    Arrieta, Marie-Claire; Stiemsma, Leah T; Dimitriu, Pedro A; Thorson, Lisa; Russell, Shannon; Yurist-Doutsch, Sophie; Kuzeljevic, Boris; Gold, Matthew J; Britton, Heidi M; Lefebvre, Diana L; Subbarao, Padmaja; Mandhane, Piush; Becker, Allan; McNagny, Kelly M; Sears, Malcolm R; Kollmann, Tobias; Mohn, William W; Turvey, Stuart E; Finlay, B Brett

    2015-09-30

    Asthma is the most prevalent pediatric chronic disease and affects more than 300 million people worldwide. Recent evidence in mice has identified a "critical window" early in life where gut microbial changes (dysbiosis) are most influential in experimental asthma. However, current research has yet to establish whether these changes precede or are involved in human asthma. We compared the gut microbiota of 319 subjects enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) Study, and show that infants at risk of asthma exhibited transient gut microbial dysbiosis during the first 100 days of life. The relative abundance of the bacterial genera Lachnospira, Veillonella, Faecalibacterium, and Rothia was significantly decreased in children at risk of asthma. This reduction in bacterial taxa was accompanied by reduced levels of fecal acetate and dysregulation of enterohepatic metabolites. Inoculation of germ-free mice with these four bacterial taxa ameliorated airway inflammation in their adult progeny, demonstrating a causal role of these bacterial taxa in averting asthma development. These results enhance the potential for future microbe-based diagnostics and therapies, potentially in the form of probiotics, to prevent the development of asthma and other related allergic diseases in children. PMID:26424567

  19. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics.

    PubMed

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-02-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring-summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus-host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus-host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems. PMID:26296067

  20. Numerical solution of a microbial growth model applied to dynamic environments.

    PubMed

    Zhu, Si; Chen, Guibing

    2015-05-01

    The Baranyi and Roberts model is one of the most frequently used microbial growth models. It has been successfully applied to numerous studies of various microorganisms in different food products. Under dynamic conditions, the model is implicitly formulated as a set of two coupled differential equations which could be numerically solved using the Runge-Kutta method. In this study, a simplified numerical solution of the coupled differential equations was derived and used to simulate microbial growth under dynamic conditions in Microsoft Excel. As expected, the results obtained were the same as those from solving the coupled differential equations using a MATLAB Solver. In addition, model parameters were accurately identified by fitting the numerical solution to simulated growth curves under dynamic (time-varying) temperature conditions using the Microsoft Excel Solver. PMID:25765150

  1. Impacts of Microbial Growth on the Air Quality of the International Space Station

    NASA Technical Reports Server (NTRS)

    Macatangay, Ariel V.; Bruce, Rebekah J.

    2010-01-01

    An understanding of the various sources of non-methane volatile organic compounds (NMVOCs) is one facet to ensuring the habitability of crewed spacecraft. Even though the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in the atmosphere and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of can be associated to a single source, the majority of these trace contaminants have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic processes of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, microbial growth has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes which, in many ways, are comparable to human metabolism. As such, it can be expected that microbial growth can lead to the release of volatile organic compounds into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented as well as the possible types of volatile organic compounds that can result from such organisms. This will be correlated to the observations provided by ground-based analysis of ISS atmosphere samples

  2. Impacts of Microbial Growth on the Air Quality of the International Space Station

    NASA Technical Reports Server (NTRS)

    Macatangay, Ariel V.; Bruce, Rebekah J.

    2009-01-01

    An understanding of the various sources of non-methane volatile organic compounds (NMVOCs) is one facet to ensuring the habitability of crewed spacecraft. Even though the International Space Station (ISS) atmosphere is relatively well characterized in terms of what is in the atmosphere and approximately how much, linking the majority of these trace contaminants detected to their source is virtually impossible. Albeit a few of can be associated to a single source, the majority of these trace contaminants have their origins from multiple sources. On crewed spacecraft such as ISS, trace contaminants are broadly categorized as either coming from equipment, which includes systems and payloads, or from the metabolic processes of the crew members. Such widely encompassing categories clearly illustrate the difficulty in linking air contaminants to their source(s). It is well known that microbial growth in ISS can flourish if left unchecked. Although processes are in place to limit microbial growth, in reality, microbial growth has pervaded the habitable environment of ISS. This is simply a consequence of having crewed spacecraft, as humans are the largest contributor to the bioload. As with crew members, microbes also have metabolic processes which, in many ways, are comparable to human metabolism. As such, it can be expected that microbial growth can lead to the release of volatile organic compounds into the ISS atmosphere. Given a large enough microbial population, the impact to the air quality of ISS can be potentially large. A survey of the microbiology found in ISS will be presented as well as the possible types of volatile organic compounds that can result from such organisms. This will be correlated to the observations provided by ground-based analysis of ISS atmosphere samples.

  3. Energy balance affected by electrolyte recirculation and operating modes in microbial fuel cells.

    PubMed

    Jacobson, Kyle S; Kelly, Patrick T; He, Zhen

    2015-03-01

    Energy recovery and consumption in a microbial fuel cell (MFC) can be significantly affected by the operating conditions. This study investigated the effects of electrolyte recirculation and operation mode (continuous vs sequence batch reactor) on the energy balance in a tubular MFC. It was found that decreasing the anolyte recirculation also decreased the energy recovery. Because of the open environment of the cathode electrode, the catholyte recirculation consumed 10 to 50 times more energy than the anolyte recirculation, and resulted in negative energy balances despite the reduction of the anolyte recirculation. Reducing the catholyte recirculation to 20% led to a positive energy balance of 0.0288 kWh m(-3). The MFC operated as a sequence batch reactor generated less energy and had a lower energy balance than the one with continuous operation. Those results encourage the further development of MFC technology to achieve neutral or even positive energy output. PMID:25842536

  4. Factors affecting the performance of microbial fuel cells for sulfur pollutants removal.

    PubMed

    Zhao, Feng; Rahunen, Nelli; Varcoe, John R; Roberts, Alexander J; Avignone-Rossa, Claudio; Thumser, Alfred E; Slade, Robert C T

    2009-03-15

    A microbial fuel cell (MFC) has been developed for removal of sulfur-based pollutants and can be used for simultaneous wastewater treatment and electricity generation. This fuel cell uses an activated carbon cloth+carbon fibre veil composite anode, air-breathing dual cathodes and the sulfate-reducing species Desulfovibrio desulfuricans. 1.16gdm(-3) sulfite and 0.97gdm(-3) thiosulfate were removed from the wastewater at 22 degrees C, representing sulfite and thiosulfate removal conversions of 91% and 86%, respectively. The anode potential was controlled by the concentration of sulfide in the compartment. The performance of the cathode assembly was affected by the concentration of protons in the cation-exchanging ionomer with which the electrocatalyst is co-bound at the three-phase (air, catalyst and support) boundary. PMID:19022647

  5. Effect of refrigeration on microbial growth in the Blairex Water Purifier.

    PubMed

    Harris, M G; Meng, K E; Frank, L J; Mamalis, G

    1987-05-01

    The Blairex Water Purifier is designed to make tap water into purified water that can be used to make saline solution for soft contact lens disinfection and rinsing. The micropore filters of eight Purifiers were perforated to allow a controlled contamination by either Pseudomonas aeruginosa or Serratia marcescens. The bacterial growth was evaluated in these altered Blairex Water Purifiers under refrigerated and unrefrigerated conditions. Those Purifiers that were refrigerated showed significantly less bacterial growth than those Purifiers that were kept at room temperature between samplings. Our findings imply that soft contact lens wearers may reduce the level of microbial growth in undamaged Purifiers by refrigerating the Purifiers between uses. PMID:3111265

  6. Comparative analysis of some models of gene regulation in mixed-substrate microbial growth.

    PubMed

    Narang, Atul

    2006-09-21

    Mixed-substrate microbial growth is of fundamental interest in microbiology and bioengineering. Several mathematical models have been developed to account for the genetic regulation of such systems, especially those resulting in diauxic growth. In this work, we compare the dynamics of three such models (Narang, 1998a. The dynamical analogy between microbial growth on mixtures of substrates and population growth of competing species. Biotechnol. Bioeng. 59, 116-121; Thattai and Shraiman, 2003. Metabolic switching in the sugar phosphotransferase system of Escherichia coli. Biophys. J. 85(2), 744-754; Brandt et al., 2004. Modelling microbial adaptation to changing availability of substrates. Water Res. 38, 1004-1013). We show that these models are dynamically similar--the initial motion of the inducible enzymes in all the models is described by the Lotka-Volterra equations for competing species. In particular, the prediction of diauxic growth corresponds to "extinction" of one of the enzymes during the first few hours of growth. The dynamic similarity occurs because in all the models, the inducible enzymes possess properties characteristic of competing species: they are required for their own synthesis, and they inhibit each other. Despite this dynamic similarity, the models vary with respect to the range of dynamics captured. The Brandt et al. model always predicts the diauxic growth pattern, whereas the remaining two models exhibit both diauxic and non-diauxic growth patterns. The models also differ with respect to the mechanisms that generate the mutual inhibition between the enzymes. In the Narang model, mutual inhibition occurs because the enzymes for each substrate enhance the dilution of the enzymes for the other substrate. The Brandt et al. model superimposes upon this dilution effect an additional mechanism of mutual inhibition. In the Thattai and Shraiman model, the mutual inhibition is entirely due to competition for the phosphoryl groups. For quantitative

  7. Bifunctional silver nanoparticle cathode in microbial fuel cells for microbial growth inhibition with comparable oxygen reduction reaction activity.

    PubMed

    An, Junyeong; Jeon, Hongrae; Lee, Jaeyoung; Chang, In Seop

    2011-06-15

    Organic contamination of water bodies in which benthic microbial fuel cells (benthic MFCs) are installed, and organic crossover from the anode to the cathode of membraneless MFCs, is a factor causing oxygen depletion and substrate loss in the cathode due to the growth of heterotrophic aerobic bacteria. This study examines the possible use of silver nanoparticles (AgNPs) as a cathodic catalyst for MFCs suffering from organic contamination and oxygen depletion. Four treated cathodes (AgNPs-coated, Pt/C-coated, Pt/C+AgNPs-coated, and plain graphite cathodes) were prepared and tested under high levels of organics loading. During operation (fed with 50 mM acetate), the AgNPs-coated system showed the highest DO concentration (0.8 mg/L) in the cathode area as well as the highest current (ranging from 0.04 to 0.12 mA). Based on these results, we concluded that (1) the growth of oxygen-consuming heterotrophic microbes could be inhibited by AgNPs, (2) the function of AgNPs as a bacterial growth inhibitor resulted in a greater increase of DO concentration in the cathode than the other tested cathode systems, (3) AgNPs could be applied as a cathode catalyst for oxygen reduction, and as a result (4) the MFC with the AgNPs-coated cathode led to the highest current generation among the tested MFCs. PMID:21585217

  8. Adapting isostatic microbial growth parameters into non-isostatic models for use in dynamic ecosystems

    NASA Astrophysics Data System (ADS)

    Spangler, J.; Schulz, C. J.; Childers, G. W.

    2009-12-01

    Modeling microbial respiration and growth is an important tool for understanding many geochemical systems. The estimation of growth parameters relies on fitting experimental data to a selected model, such as the Monod equation or some variation, most often under batch or continuous culture conditions. While continuous culture conditions can be analogous to some natural environments, it often isn’t the case. More often, microorganisms are subject to fluctuating temperature, substrate concentrations, pH, water activity, and inhibitory compounds, to name a few. Microbial growth estimation under non-isothermal conditions has been possible through use of numerical solutions and has seen use in the field of food microbiology. In this study, numerical solutions were used to extend growth models under more non-isostatic conditions using momentary growth rate estimates. Using a model organism common in wastewater (Paracoccus denitrificans), growth and respiration rate parameters were estimated under varying static conditions (temperature, pH, electron donor/acceptor concentrations) and used to construct a non-isostatic growth model. After construction of the model, additional experiments were conducted to validate the model. These non-isostatic models hold the potential for allowing the prediction of cell biomass and respiration rates under a diverse array of conditions. By not restricting models to constant environmental conditions, the general applicability of the model can be greatly improved.

  9. Green tea yogurt: major phenolic compounds and microbial growth.

    PubMed

    Amirdivani, Shabboo; Baba, Ahmad Salihin Hj

    2015-07-01

    The purpose of this study was to evaluate fermentation of milk in the presence of green tea (Camellia sinensis) with respect to changes in antioxidant activity, phenolic compounds and the growth of lactic acid bacteria. Pasteurized full fat cow's milk and starter culture were incubated at 41 °C in the presence of two different types of green tea extracts. The yogurts formed were refrigerated (4 °C) for further analysis. The total phenolic content was highest (p < 0.05) in air-dried green tea-yogurt (MGT) followed by steam-treated green tea (JGT) and plain yogurts. Four major compounds in MGTY and JGTY were detected. The highest concentration of major phenolic compounds in both samples was related to quercetin-rhamnosylgalactoside and quercetin-3-O-galactosyl-rhamnosyl-glucoside for MGTY and JGTY respectively during first 7 day of storage. Diphenyl picrylhydrazyl and ferric reducing antioxidant power methods showed highest antioxidant capacity in MGTY, JGTY and PY. Streptococcus thermophillus and Lactobacillus spp. were highest in MGTY followed by JGTY and PY. This paper evaluates the implementation of green tea yogurt as a new product with functional properties and valuable component to promote the growth of beneficial yogurt bacteria and prevention of oxidative stress by enhancing the antioxidant activity of yogurt. PMID:26139940

  10. Monitoring of microbial adhesion and biofilm growth using electrochemical impedancemetry.

    PubMed

    Dheilly, A; Linossier, I; Darchen, A; Hadjiev, D; Corbel, C; Alonso, V

    2008-05-01

    Electrochemical impedance spectroscopy was tested to monitor the cell attachment and the biofilm proliferation in order to identify characteristic events induced on the metal surface by Gram-negative (Pseudomonas aeruginosa PAO1) and Gram-positive (Bacillus subtilis) bacteria strains. Electrochemical impedance spectra of AISI 304 electrodes during cell attachment and initial biofilm growth for both strains were obtained. It can be observed that the resistance increases gradually with the culture time and decreases with the biofilm detachment. So, the applicability of electric cell-substrate impedance sensing (ECIS) for studying the attachment and spreading of cells on a metal surface has been demonstrated. The biofilm formation was also characterized by the use of scanning electron microscopy and confocal laser scanning microscopy and COMSTAT image analysis. The electrochemical results roughly agree with the microscope image observations. The ECIS technique used in this study was used for continuous real-time monitoring of the initial bacterial adhesion and the biofilm growth. It provides a simple and non-expensive electrochemical method for in vitro assessment of the presence of biofilms on metal surfaces. PMID:18330564

  11. Macroalgae Decrease Growth and Alter Microbial Community Structure of the Reef-Building Coral, Porites astreoides

    PubMed Central

    Vega Thurber, Rebecca; Burkepile, Deron E.; Correa, Adrienne M. S.; Thurber, Andrew R.; Shantz, Andrew A.; Welsh, Rory; Pritchard, Catharine; Rosales, Stephanie

    2012-01-01

    With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the coral microbiome, which is thought to play an important role in colony health and survival. Together, such changes in benthic macroalgae and in the coral microbiome may result in a feedback mechanism that contributes to additional coral cover loss. To determine if macroalgae alter the coral microbiome, we conducted a field-based experiment in which the coral Porites astreoides was placed in competition with five species of macroalgae. Macroalgal contact increased variance in the coral-associated microbial community, and two algal species significantly altered microbial community composition. All macroalgae caused the disappearance of a γ-proteobacterium previously hypothesized to be an important mutualist of P. astreoides. Macroalgal contact also triggered: 1) increases or 2) decreases in microbial taxa already present in corals, 3) establishment of new taxa to the coral microbiome, and 4) vectoring and growth of microbial taxa from the macroalgae to the coral. Furthermore, macroalgal competition decreased coral growth rates by an average of 36.8%. Overall, this study found that competition between corals and certain species of macroalgae leads to an altered coral microbiome, providing a potential mechanism by which macroalgae-coral interactions reduce coral health and lead to coral loss on impacted reefs. PMID:22957055

  12. Waste Water Derived Electroactive Microbial Biofilms: Growth, Maintenance, and Basic Characterization

    PubMed Central

    Gimkiewicz, Carla; Harnisch, Falk

    2013-01-01

    The growth of anodic electroactive microbial biofilms from waste water inocula in a fed-batch reactor is demonstrated using a three-electrode setup controlled by a potentiostat. Thereby the use of potentiostats allows an exact adjustment of the electrode potential and ensures reproducible microbial culturing conditions. During growth the current production is monitored using chronoamperometry (CA). Based on these data the maximum current density (jmax) and the coulombic efficiency (CE) are discussed as measures for characterization of the bioelectrocatalytic performance. Cyclic voltammetry (CV), a nondestructive, i.e. noninvasive, method, is used to study the extracellular electron transfer (EET) of electroactive bacteria. CV measurements are performed on anodic biofilm electrodes in the presence of the microbial substrate, i.e. turnover conditions, and in the absence of the substrate, i.e. nonturnover conditions, using different scan rates. Subsequently, data analysis is exemplified and fundamental thermodynamic parameters of the microbial EET are derived and explained: peak potential (Ep), peak current density (jp), formal potential (Ef) and peak separation (ΔEp). Additionally the limits of the method and the state-of the art data analysis are addressed. Thereby this video-article shall provide a guide for the basic experimental steps and the fundamental data analysis. PMID:24430581

  13. Thermal effects on microbial composition and microbiologically induced corrosion and mineral precipitation affecting operation of a geothermal plant in a deep saline aquifer.

    PubMed

    Lerm, Stephanie; Westphal, Anke; Miethling-Graff, Rona; Alawi, Mashal; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

    2013-03-01

    The microbial diversity of a deep saline aquifer used for geothermal heat storage in the North German Basin was investigated. Genetic fingerprinting analyses revealed distinct microbial communities in fluids produced from the cold and warm side of the aquifer. Direct cell counting and quantification of 16S rRNA genes and dissimilatory sulfite reductase (dsrA) genes by real-time PCR proved different population sizes in fluids, showing higher abundance of bacteria and sulfate reducing bacteria (SRB) in cold fluids compared with warm fluids. The operation-dependent temperature increase at the warm well probably enhanced organic matter availability, favoring the growth of fermentative bacteria and SRB in the topside facility after the reduction of fluid temperature. In the cold well, SRB predominated and probably accounted for corrosion damage to the submersible well pump and iron sulfide precipitates in the near wellbore area and topside facility filters. This corresponded to lower sulfate content in fluids produced from the cold well as well as higher content of hydrogen gas that was probably released from corrosion, and maybe favored growth of hydrogenotrophic SRB. This study reflects the high influence of microbial populations for geothermal plant operation, because microbiologically induced precipitative and corrosive processes adversely affect plant reliability. PMID:23358731

  14. Using coagulation to restrict microbial re-growth in tap water by phosphate limitation in water treatment.

    PubMed

    Wen, Gang; Ma, Jun; Huang, Ting-Lin; Egli, Thomas

    2014-09-15

    Extensive microbial re-growth in a drinking water distribution system can deteriorate water quality. The limiting factor for microbial re-growth in a tap water produced by a conventional drinking water treatment plant in China was identified by determining the microbial re-growth potential (MRP) by adding different nutrients to stimulate growth of a natural microbial consortium as inoculum and flow-cytometric enumeration. No obvious change of MRP was found in tap water after addition of carbon, whereas, a 1- to 2-fold increase of MRP was observed after addition of phosphate (P). This clearly demonstrated that microbial re-growth in this tap water was limited by P. Most of the re-grown microbial flora (>85%) consisted of high nucleic acid content cells. A subsequent investigation of the MRP in the actual water treatment plant demonstrated that coagulation was the crucial step for decreasing MRP and producing P-limited water. Therefore, a comparison concerning the control of MRP by three different coagulants was conducted. It showed that all the three coagulants efficiently reduced the MRP and shifted the limitation regime from C to P, but the required dose was different. The study shows that it is feasible to restrict microbial re-growth by P limitation using coagulation in water treatment. PMID:25179107

  15. Monitoring microbial growth and activity using spectral induced polarization and low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Keating, Kristina; Revil, Andre

    2015-04-01

    Microbes and microbial activities in the Earth's subsurface play a significant role in shaping subsurface environments and are involved in environmental applications such as remediation of contaminants in groundwater and oil fields biodegradation. Stimulated microbial growth in such applications could cause wide variety of changes of physical/chemical properties in the subsurface. It is critical to monitor and determine the fate and transportation of microorganisms in the subsurface during such applications. Recent geophysical studies demonstrate the potential of two innovative techniques, spectral induced polarization (SIP) and low-field nuclear magnetic resonance (NMR), for monitoring microbial growth and activities in porous media. The SIP measures complex dielectric properties of porous media at low frequencies of exciting electric field, and NMR studies the porous structure of geologic media and characterizes fluids subsurface. In this laboratory study, we examined both SIP and NMR responses from bacterial growth suspension as well as suspension mixed with silica sands. We focus on the direct contribution of microbes to the SIP and NMR signals in the absence of biofilm formation or biomineralization. We used Zymomonas mobilis and Shewanella oneidensis (MR-1) for SIP and NMR measurements, respectively. The SIP measurements were collected over the frequency range of 0.1 - 1 kHz on Z. mobilis growth suspension and suspension saturated sands at different cell densities. SIP data show two distinct peaks in imaginary conductivity spectra, and both imaginary and real conductivities increased as microbial density increased. NMR data were collected using both CPMG pulse sequence and D-T2 mapping to determine the T2-distribution and diffusion properties on S. oneidensis suspension, pellets (live and dead), and suspension mixed with silica sands. NMR data show a decrease in the T2-distribution in S. oneidensis suspension saturated sands as microbial density increase. A

  16. Leaf Associated Microbial Activities in a Stream Affected by Acid Mine Drainage

    NASA Astrophysics Data System (ADS)

    Schlief, Jeanette

    2004-11-01

    Microbial activity was assessed on birch leaves and plastic strips during 140 days of exposure at three sites in an acidic stream of the Lusatian post-mining landscape, Germany. The sites differed in their degrees of ochre deposition and acidification. The aim of the study was (1) to follow the microbial activities during leaf colonization, (2) to compare the effect of different environmental conditions on leaf associated microbial activities, and (3) to test the microbial availability of leaf litter in acidic mining waters. The activity peaked after 49 days and subsequently decreased gradually at all sites. A formation of iron plaques on leaf surfaces influenced associated microbial activity. It seemed that these plaques inhibit the microbial availability of leaf litter and serve as a microbial habitat by itself. (

  17. Microbial maximal specific growth rate as a square-root function of biomass yield and two kinetic parameters.

    PubMed

    Wong, Wilson W; Liao, James C

    2009-11-01

    Understanding how growth rates changes under different perturbations is fundamental to many aspect of microbial physiology. In this work, we experimentally showed that maximal specific growth rate is a square-root function of the biomass yield, the substrate turnover number, and the maximum synthesis rate of the substrate transporter under that condition. We used Escherichia coli cultures in lactose minimal medium as a model system by introducing genetic modifications, in vitro evolution, and ethanol stress to the cell. Deletion of crr affected all three parameters in different directions while deletion of ptsG decreased only the biomass yield. Ethanol stress negatively impacted all three parameters, while anaerobicity decreased biomass yield and transporter synthesis rate. In addition, laboratory evolution increased the growth rate in lactose mostly through enhancing the expression rate of the lac operon. Despite all these changes, the growth rate of the perturbed strain was successfully related to the three parameters by the square-root equation. Thus, this square-root relationship provides insight into how growth rate is altered by different physiological parameters. PMID:19712746

  18. Scaling and optimal synergy: Two principles determining microbial growth in complex media

    NASA Astrophysics Data System (ADS)

    Massucci, Francesco Alessandro; Guimerà, Roger; Nunes Amaral, Luís A.; Sales-Pardo, Marta

    2015-06-01

    High-throughput experimental techniques and bioinformatics tools make it possible to obtain reconstructions of the metabolism of microbial species. Combined with mathematical frameworks such as flux balance analysis, which assumes that nutrients are used so as to maximize growth, these reconstructions enable us to predict microbial growth. Although such predictions are generally accurate, these approaches do not give insights on how different nutrients are used to produce growth, and thus are difficult to generalize to new media or to different organisms. Here, we propose a systems-level phenomenological model of metabolism inspired by the virial expansion. Our model predicts biomass production given the nutrient uptakes and a reduced set of parameters, which can be easily determined experimentally. To validate our model, we test it against in silico simulations and experimental measurements of growth, and find good agreement. From a biological point of view, our model uncovers the impact that individual nutrients and the synergistic interaction between nutrient pairs have on growth, and suggests that we can understand the growth maximization principle as the optimization of nutrient synergies.

  19. Denitrifying Bacterial Communities Affect Current Production and Nitrous Oxide Accumulation in a Microbial Fuel Cell

    PubMed Central

    Vilar-Sanz, Ariadna; Puig, Sebastià; García-Lledó, Arantzazu; Trias, Rosalia; Balaguer, M. Dolors; Colprim, Jesús; Bañeras, Lluís

    2013-01-01

    The biocathodic reduction of nitrate in Microbial Fuel Cells (MFCs) is an alternative to remove nitrogen in low carbon to nitrogen wastewater and relies entirely on microbial activity. In this paper the community composition of denitrifiers in the cathode of a MFC is analysed in relation to added electron acceptors (nitrate and nitrite) and organic matter in the cathode. Nitrate reducers and nitrite reducers were highly affected by the operational conditions and displayed high diversity. The number of retrieved species-level Operational Taxonomic Units (OTUs) for narG, napA, nirS and nirK genes was 11, 10, 31 and 22, respectively. In contrast, nitrous oxide reducers remained virtually unchanged at all conditions. About 90% of the retrieved nosZ sequences grouped in a single OTU with a high similarity with Oligotropha carboxidovorans nosZ gene. nirS-containing denitrifiers were dominant at all conditions and accounted for a significant amount of the total bacterial density. Current production decreased from 15.0 A·m−3 NCC (Net Cathodic Compartment), when nitrate was used as an electron acceptor, to 14.1 A·m−3 NCC in the case of nitrite. Contrarily, nitrous oxide (N2O) accumulation in the MFC was higher when nitrite was used as the main electron acceptor and accounted for 70% of gaseous nitrogen. Relative abundance of nitrite to nitrous oxide reducers, calculated as (qnirS+qnirK)/qnosZ, correlated positively with N2O emissions. Collectively, data indicate that bacteria catalysing the initial denitrification steps in a MFC are highly influenced by main electron acceptors and have a major influence on current production and N2O accumulation. PMID:23717427

  20. Rapid successions affect microbial N-acetyl-glucosamine uptake patterns during a lacustrine spring phytoplankton bloom.

    PubMed

    Eckert, Ester M; Salcher, Michaela M; Posch, Thomas; Eugster, Bettina; Pernthaler, Jakob

    2012-03-01

    The vernal successions of phytoplankton, heterotrophic nanoflagellates (HNF) and viruses in temperate lakes result in alternating dominance of top-down and bottom-up factors on the bacterial community. This may lead to asynchronous blooms of bacteria with different life strategies and affect the channelling of particular components of the dissolved organic matter (DOM) through microbial food webs. We followed the dynamics of several bacterial populations and of other components of the microbial food web throughout the spring phytoplankton bloom period in a pre-alpine lake, and we assessed bacterial uptake patterns of two constituents of the labile DOM pool (N-acetyl-glucosamine [NAG] and leucine). There was a clear genotypic shift within the bacterial assemblage, from fast growing Cytophaga-Flavobacteria (CF) affiliated with Fluviicola and from Betaproteobacteria (BET) of the Limnohabitans cluster to more grazing resistant AcI Actinobacteria (ACT) and to filamentous morphotypes. This was paralleled by successive blooms of viruses and HNF. We also noted the transient rise of other CF (related to Cyclobacteriaceae and Sphingobacteriaceae) that are not detected by fluorescence in situ hybridization with the general CF probe. Both, the average uptake rates of leucine and the fractions of leucine incorporating bacteria were approximately five to sixfold higher than of NAG. However, the composition of the NAG-active community was much more prone to genotypic successions, in particular of bacteria with different life strategies: While 'opportunistically' growing BET and CF dominated NAG uptake in the initial period ruled by bottom-up factors, ACT constituted the major fraction of NAG active cells during the subsequent phase of high predation pressure. This indicates that some ACT could profit from a substrate that might in parts have originated from the grazing of protists on their bacterial competitors. PMID:22082109

  1. Denitrifying bacterial communities affect current production and nitrous oxide accumulation in a microbial fuel cell.

    PubMed

    Vilar-Sanz, Ariadna; Puig, Sebastià; García-Lledó, Arantzazu; Trias, Rosalia; Balaguer, M Dolors; Colprim, Jesús; Bañeras, Lluís

    2013-01-01

    The biocathodic reduction of nitrate in Microbial Fuel Cells (MFCs) is an alternative to remove nitrogen in low carbon to nitrogen wastewater and relies entirely on microbial activity. In this paper the community composition of denitrifiers in the cathode of a MFC is analysed in relation to added electron acceptors (nitrate and nitrite) and organic matter in the cathode. Nitrate reducers and nitrite reducers were highly affected by the operational conditions and displayed high diversity. The number of retrieved species-level Operational Taxonomic Units (OTUs) for narG, napA, nirS and nirK genes was 11, 10, 31 and 22, respectively. In contrast, nitrous oxide reducers remained virtually unchanged at all conditions. About 90% of the retrieved nosZ sequences grouped in a single OTU with a high similarity with Oligotropha carboxidovorans nosZ gene. nirS-containing denitrifiers were dominant at all conditions and accounted for a significant amount of the total bacterial density. Current production decreased from 15.0 A · m(-3) NCC (Net Cathodic Compartment), when nitrate was used as an electron acceptor, to 14.1 A · m(-3) NCC in the case of nitrite. Contrarily, nitrous oxide (N2O) accumulation in the MFC was higher when nitrite was used as the main electron acceptor and accounted for 70% of gaseous nitrogen. Relative abundance of nitrite to nitrous oxide reducers, calculated as (qnirS+qnirK)/qnosZ, correlated positively with N2O emissions. Collectively, data indicate that bacteria catalysing the initial denitrification steps in a MFC are highly influenced by main electron acceptors and have a major influence on current production and N2O accumulation. PMID:23717427

  2. A trait-based framework for predicting when and where microbial adaptation to climate change will affect ecosystem functioning

    USGS Publications Warehouse

    Wallenstein, Matthew D.; Hall, Edward K.

    2012-01-01

    As the earth system changes in response to human activities, a critical objective is to predict how biogeochemical process rates (e.g. nitrification, decomposition) and ecosystem function (e.g. net ecosystem productivity) will change under future conditions. A particular challenge is that the microbial communities that drive many of these processes are capable of adapting to environmental change in ways that alter ecosystem functioning. Despite evidence that microbes can adapt to temperature, precipitation regimes, and redox fluctuations, microbial communities are typically not optimally adapted to their local environment. For example, temperature optima for growth and enzyme activity are often greater than in situ temperatures in their environment. Here we discuss fundamental constraints on microbial adaptation and suggest specific environments where microbial adaptation to climate change (or lack thereof) is most likely to alter ecosystem functioning. Our framework is based on two principal assumptions. First, there are fundamental ecological trade-offs in microbial community traits that occur across environmental gradients (in time and space). These trade-offs result in shifting of microbial function (e.g. ability to take up resources at low temperature) in response to adaptation of another trait (e.g. limiting maintenance respiration at high temperature). Second, the mechanism and level of microbial community adaptation to changing environmental parameters is a function of the potential rate of change in community composition relative to the rate of environmental change. Together, this framework provides a basis for developing testable predictions about how the rate and degree of microbial adaptation to climate change will alter biogeochemical processes in aquatic and terrestrial ecosystems across the planet.

  3. Strength of Rocks Affected by Deformation Enhanced Grain Growth

    NASA Astrophysics Data System (ADS)

    Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

    2005-12-01

    One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

  4. Microbial Communities: Tracing Growth Processes from Antarctic Lakes to Early Earth to Other Planets

    NASA Astrophysics Data System (ADS)

    Sumner, D. Y.

    2014-12-01

    Life in the Universe is dominated by microbes: they are numerically the most abundant cells in our bodies and in Earth's biosphere, and they are the only life that might be present elsewhere in our solar system. Life beyond our solar system could include macroscopic organisms, but everything we understand about the origin of life suggests it must start with microbes. Thus, understanding microbial ecosystems, in the absence of macroscopic organisms, is critical to understanding early life on Earth and life elsewhere in the Universe - if it exists. But what are the general principles of microbial ecology in the absence of predation? What happens when each cell is a chemical factory that can swap among metabolic processes in response to environmental and emergent cues? Geobiologists and astrobiologists are addressing these questions in diverse ways using both Earth's modern biosphere and its fossil record. Modern microbial communities in shallow, ice-covered lakes, Antarctica (Fig.), provide a model for high productivity microbial ecosystems with no to low predation. In these lakes, photosynthetic communities create macroscopic pinnacles and domes, sometime lithified into stromatolites. They provide an ecological, geochemical and morphological model for Precambrian microbial communities in low sedimentation, low current environments. Insights from these communities include new growth processes for ancient mats, especially some that grew prior to the oxidation of Earth's atmosphere. The diversity of biosignatures created in these communities also provides context for models of life under ice elsewhere in our solar system such as paleolakes on Mars and on icy moons. Results from the Mars Science Laboratory (MSL) team document formerly habitable fluvial and lacustrine environments. Lacustrine environments, in particular, are favorable for preserving biosignatures, and continued investigations by MSL will provide a deeper understanding of the duration of habitable

  5. Factors Affecting Growth of Pinus radiata in Chile

    NASA Astrophysics Data System (ADS)

    Alvarez-Munoz, Jose Santos

    The Chilean forestry industry is based on hundreds of thousands of hectares of Pinus radiata plantations that have been established in a variety of soil and climate conditions. This approach has resulted in highly variable plantation productivity even when the best available technology was used. Little information is known about the ecophysiology basis for this variability. We explored the spatial and temporal variation of stand growth in Chile using a network of permanent sample plots from Modelo Nacional de Simulacion de Pino radiata. We hypothesized that the climate would play an important role in the annual variations in productivity. To answer these questions we developed the following projects: (1) Determination of site resource availability from historical data from automatic weather stations (rainfall, temperatures) and a geophysical model for solar irradiation, (2) Determination of peak annual leaf area index (LAI) for selected permanent sample plots using remote sensing technologies, (3) Analysis of soil, climate, canopy and stand factors affecting the Pinus radiata plantation growth and the use efficiency of site resources. For project 1, we estimated solar irradiation using the r.sun , Hargreaves-Samani (HS), and Bristow-Campbell (BC) models and validated model estimates with observations from weather stations. Estimations from a calibrated r.sun model accounted for 94% of the variance (r2=0.94) in monthly mean measured values. The r.sun model performed quite well for a wide range of Chilean conditions when compared with the HS and BC models. Our estimates of global irradiation may be improved with better estimates of cloudiness as they become available. Our model was able to provide spatial estimates of daily, weekly, monthly and yearly solar irradiation. For project 2, we estimated the inter-annual variation of LAI (Leaf Area Index), using remote sensing technologies. We determined LAI using Landsat Thematic Mapper (TM) data covering a 5 year period

  6. Soil microbial activity is affected by Roundup WeatherMax and pesticides applied to cotton (Gossypium hirsutum)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adoption of glyphosate-based weed control systems has led to increased use of the herbicide with continued use of additional pesticides. Combinations of pesticides may affect soil microbial activity differently than pesticides applied alone. Research was conducted to evaluate the influence of glypho...

  7. Extraction of solubles from plant biomass for use as microbial growth stimulant and methods related thereto

    SciTech Connect

    Lau, Ming Woei

    2015-12-08

    A method for producing a microbial growth stimulant (MGS) from a plant biomass is described. In one embodiment, an ammonium hydroxide solution is used to extract a solution of proteins and ammonia from the biomass. Some of the proteins and ammonia are separated from the extracted solution to provide the MGS solution. The removed ammonia can be recycled and the proteins are useful as animal feeds. In one embodiment, the method comprises extracting solubles from pretreated lignocellulosic biomass with a cellulase enzyme-producing growth medium (such T. reesei) in the presence of water and an aqueous extract.

  8. Development of a multi-classification neural network model to determine the microbial growth/no growth interface.

    PubMed

    Fernández-Navarro, Francisco; Valero, Antonio; Hervás-Martínez, César; Gutiérrez, Pedro A; García-Gimeno, Rosa M; Zurera-Cosano, Gonzalo

    2010-07-15

    Boundary models have been recognized as useful tools to predict the ability of microorganisms to grow at limiting conditions. However, at these conditions, microbial behaviour can vary, being difficult to distinguish between growth or no growth. In this paper, the data from the study of Valero et al. [Valero, A., Pérez-Rodríguez, F., Carrasco, E., Fuentes-Alventosa, J.M., García-Gimeno, R.M., Zurera, G., 2009. Modelling the growth boundaries of Staphylococcus aureus: Effect of temperature, pH and water activity. International Journal of Food Microbiology 133 (1-2), 186-194] belonging to growth/no growth conditions of Staphylococcus aureus against temperature, pH and a(w) were divided into three categorical classes: growth (G), growth transition (GT) and no growth (NG). Subsequently, they were modelled by using a Radial Basis Function Neural Network (RBFNN) in order to create a multi-classification model that was able to predict the probability of belonging at one of the three mentioned classes. The model was developed through an over sampling procedure using a memetic algorithm (MA) in order to balance in part the size of the classes and to improve the accuracy of the classifier. The multi-classification model, named Smote Memetic Radial Basis Function (SMRBF) provided a quite good adjustment to data observed, being able to correctly classify the 86.30% of training data and the 82.26% of generalization data for the three observed classes in the best model. Besides, the high number of replicates per condition tested (n=30) produced a smooth transition between growth and no growth. At the most stringent conditions, the probability of belonging to class GT was higher, thus justifying the inclusion of the class in the new model. The SMRBF model presented in this study can be used to better define microbial growth/no growth interface and the variability associated to these conditions so as to apply this knowledge to a food safety in a decision-making process. PMID

  9. Assessment of Heterotrophic Growth Supported by Soluble Microbial Products in Anammox Biofilm using Multidimensional Modeling.

    PubMed

    Liu, Yiwen; Sun, Jing; Peng, Lai; Wang, Dongbo; Dai, Xiaohu; Ni, Bing-Jie

    2016-01-01

    Anaerobic ammonium oxidation (anammox) is known to autotrophically convert ammonium to dinitrogen gas with nitrite as the electron acceptor, but little is known about their released microbial products and how these are relative to heterotrophic growth in anammox system. In this work, we applied a mathematical model to assess the heterotrophic growth supported by three key microbial products produced by bacteria in anammox biofilm (utilization associated products (UAP), biomass associated products (BAP), and decay released substrate). Both One-dimensional and two-dimensional numerical biofilm models were developed to describe the development of anammox biofilm as a function of the multiple bacteria-substrate interactions. Model simulations show that UAP of anammox is the main organic carbon source for heterotrophs. Heterotrophs are mainly dominant at the surface of the anammox biofilm with small fraction inside the biofilm. 1-D model is sufficient to describe the main substrate concentrations/fluxes within the anammox biofilm, while the 2-D model can give a more detailed biomass distribution. The heterotrophic growth on UAP is mainly present at the outside of anammox biofilm, their growth on BAP (HetB) are present throughout the biofilm, while the growth on decay released substrate (HetD) is mainly located in the inner layers of the biofilm. PMID:27273460

  10. Assessment of Heterotrophic Growth Supported by Soluble Microbial Products in Anammox Biofilm using Multidimensional Modeling

    PubMed Central

    Liu, Yiwen; Sun, Jing; Peng, Lai; Wang, Dongbo; Dai, Xiaohu; Ni, Bing-Jie

    2016-01-01

    Anaerobic ammonium oxidation (anammox) is known to autotrophically convert ammonium to dinitrogen gas with nitrite as the electron acceptor, but little is known about their released microbial products and how these are relative to heterotrophic growth in anammox system. In this work, we applied a mathematical model to assess the heterotrophic growth supported by three key microbial products produced by bacteria in anammox biofilm (utilization associated products (UAP), biomass associated products (BAP), and decay released substrate). Both One-dimensional and two-dimensional numerical biofilm models were developed to describe the development of anammox biofilm as a function of the multiple bacteria–substrate interactions. Model simulations show that UAP of anammox is the main organic carbon source for heterotrophs. Heterotrophs are mainly dominant at the surface of the anammox biofilm with small fraction inside the biofilm. 1-D model is sufficient to describe the main substrate concentrations/fluxes within the anammox biofilm, while the 2-D model can give a more detailed biomass distribution. The heterotrophic growth on UAP is mainly present at the outside of anammox biofilm, their growth on BAP (HetB) are present throughout the biofilm, while the growth on decay released substrate (HetD) is mainly located in the inner layers of the biofilm. PMID:27273460

  11. Plant growth in Arabidopsis is assisted by compost soil-derived microbial communities

    PubMed Central

    Carvalhais, Lilia C.; Muzzi, Frederico; Tan, Chin-Hong; Hsien-Choo, Jin; Schenk, Peer M.

    2013-01-01

    Plants in natural and agricultural environments are continuously exposed to a plethora of diverse microorganisms resulting in microbial colonization of roots and the rhizosphere. This process is believed to be accompanied by an intricate network of ongoing simultaneous interactions. In this study, we examined Arabidopsis thaliana roots and shoots in the presence or absence of whole microbial communities extracted from compost soil. The results show a clear growth promoting effect on Arabidopsis shoots in the presence of soil microbes compared to plants grown in microbe-free soil under otherwise identical conditions. Element analyses showed that iron uptake was facilitated by these mixed microbial communities which also led to transcriptional downregulation of genes required for iron transport. In addition, soil microbial communities suppressed the expression of marker genes involved in nitrogen uptake, oxidative stress/redox signaling, and salicylic acid (SA)-mediated plant defense while upregulating jasmonate (JA) signaling, cell wall organization/biosynthesis and photosynthesis. Multi-species analyses such as simultaneous transcriptional profiling of plants and their interacting microorganisms (metatranscriptomics) coupled to metagenomics may further increase our understanding of the intricate networks underlying plant-microbe interactions. PMID:23847639

  12. Plant growth in Arabidopsis is assisted by compost soil-derived microbial communities.

    PubMed

    Carvalhais, Lilia C; Muzzi, Frederico; Tan, Chin-Hong; Hsien-Choo, Jin; Schenk, Peer M

    2013-01-01

    Plants in natural and agricultural environments are continuously exposed to a plethora of diverse microorganisms resulting in microbial colonization of roots and the rhizosphere. This process is believed to be accompanied by an intricate network of ongoing simultaneous interactions. In this study, we examined Arabidopsis thaliana roots and shoots in the presence or absence of whole microbial communities extracted from compost soil. The results show a clear growth promoting effect on Arabidopsis shoots in the presence of soil microbes compared to plants grown in microbe-free soil under otherwise identical conditions. Element analyses showed that iron uptake was facilitated by these mixed microbial communities which also led to transcriptional downregulation of genes required for iron transport. In addition, soil microbial communities suppressed the expression of marker genes involved in nitrogen uptake, oxidative stress/redox signaling, and salicylic acid (SA)-mediated plant defense while upregulating jasmonate (JA) signaling, cell wall organization/biosynthesis and photosynthesis. Multi-species analyses such as simultaneous transcriptional profiling of plants and their interacting microorganisms (metatranscriptomics) coupled to metagenomics may further increase our understanding of the intricate networks underlying plant-microbe interactions. PMID:23847639

  13. Microbial composition in a deep saline aquifer in the North German Basin -microbiologically induced corrosion and mineral precipitation affecting geothermal plant operation and the effects of plant downtime

    NASA Astrophysics Data System (ADS)

    Lerm, Stephanie; Westphal, Anke; Miethling-Graff, Rona; Alawi, Mashal; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

    2013-04-01

    The microbial composition in fluids of a deep saline geothermal used aquifer in the North German Basin was characterized over a period of five years. The genetic fingerprinting techniques PCR-SSCP and PCR-DGGE revealed distinct microbial communities in fluids produced from the cold and warm side of the aquifer. Direct cell counting and quantification of 16S rRNA genes and dissimilatory sulfite reductase (dsrA) genes by real-time PCR proved different population sizes in fluids, showing higher abundance of Bacteria and sulfate reducing bacteria (SRB) in cold fluids compared to warm fluids. Predominating SRB in the cold well probably accounted for corrosion damage to the submersible well pump, and iron sulfide precipitates in the near wellbore area and topside facility filters. This corresponded to a lower sulfate content in fluids produced from the cold well as well as higher content of hydrogen gas that was probably released from corrosion, and maybe favoured growth of hydrogenotrophic SRB. Plant downtime significantly influenced the microbial biocenosis in fluids. Samples taken after plant restart gave indications about the processes occurring downhole during those phases. High DNA concentrations in fluids at the beginning of the restart process with a decreasing trend over time indicated a higher abundance of microbes during plant downtime compared to regular plant operation. It is likely that a gradual drop in temperature as well as stagnant conditions favoured the growth of microbes and maturation of biofilms at the casing and in pores of the reservoir rock in the near wellbore area. Furthermore, it became obvious that the microorganisms were more associated to particles then free-living. This study reflects the high influence of microbial populations for geothermal plant operation, because microbiologically induced precipitative and corrosive processes adversely affect plant reliability. Those processes may favourably occur during plant downtime due to enhanced

  14. Do plastic particles affect microalgal photosynthesis and growth?

    PubMed

    Sjollema, Sascha B; Redondo-Hasselerharm, Paula; Leslie, Heather A; Kraak, Michiel H S; Vethaak, A Dick

    2016-01-01

    The unbridled increase in plastic pollution of the world's oceans raises concerns about potential effects these materials may have on microalgae, which are primary producers at the basis of the food chain and a major global source of oxygen. Our current understanding about the potential modes and mechanisms of toxic action that plastic particles exert on microalgae is extremely limited. How effects might vary with particle size and the physico-chemical properties of the specific plastic material in question are equally unelucidated, but may hold clues to how toxicity, if observed, is exerted. In this study we selected polystyrene particles, both negatively charged and uncharged, and three different sizes (0.05, 0.5 and 6μm) for testing the effects of size and material properties. Microalgae were exposed to different polystyrene particle sizes and surface charges for 72h. Effects on microalgal photosynthesis and growth were determined by pulse amplitude modulation fluorometry and flow cytometry, respectively. None of the treatments tested in these experiments had an effect on microalgal photosynthesis. Microalgal growth was negatively affected (up to 45%) by uncharged polystyrene particles, but only at high concentrations (250mg/L). Additionally, these adverse effects were demonstrated to increase with decreasing particle size. PMID:26675372

  15. Artificial Polychromatic Light Affects Growth and Physiology in Chicks

    PubMed Central

    Yang, Bo; Yu, Yonghua

    2014-01-01

    Despite the overwhelming use of artificial light on captive animals, its effect on those animals has rarely been studied experimentally. Housing animals in controlled light conditions is useful for assessing the effects of light. The chicken is one of the best-studied animals in artificial light experiments, and here, we evaluate the effect of polychromatic light with various green and blue components on the growth and physiology in chicks. The results indicate that green-blue dual light has two side-effects on chick body mass, depending on the various green to blue ratios. Green-blue dual light with depleted and medium blue component decreased body mass, whereas enriched blue component promoted body mass in chicks compared with monochromatic green- or blue spectra-treated chicks. Moreover, progressive changes in the green to blue ratios of green-blue dual light could give rise to consistent progressive changes in body mass, as suggested by polychromatic light with higher blue component resulting in higher body mass. Correlation analysis confirmed that food intake was positively correlated with final body mass in chicks (R2 = 0.7664, P = 0.0001), suggesting that increased food intake contributed to the increased body mass in chicks exposed to higher blue component. We also found that chicks exposed to higher blue component exhibited higher blood glucose levels. Furthermore, the glucose level was positively related to the final body mass (R2 = 0.6406, P = 0.0001) and food intake (R2 = 0.784, P = 0.0001). These results demonstrate that spectral composition plays a crucial role in affecting growth and physiology in chicks. Moreover, consistent changes in spectral components might cause the synchronous response of growth and physiology. PMID:25469877

  16. Family Poverty Affects the Rate of Human Infant Brain Growth

    PubMed Central

    Hanson, Jamie L.; Hair, Nicole; Shen, Dinggang G.; Shi, Feng; Gilmore, John H.; Wolfe, Barbara L.; Pollak, Seth D.

    2013-01-01

    Living in poverty places children at very high risk for problems across a variety of domains, including schooling, behavioral regulation, and health. Aspects of cognitive functioning, such as information processing, may underlie these kinds of problems. How might poverty affect the brain functions underlying these cognitive processes? Here, we address this question by observing and analyzing repeated measures of brain development of young children between five months and four years of age from economically diverse backgrounds (n = 77). In doing so, we have the opportunity to observe changes in brain growth as children begin to experience the effects of poverty. These children underwent MRI scanning, with subjects completing between 1 and 7 scans longitudinally. Two hundred and three MRI scans were divided into different tissue types using a novel image processing algorithm specifically designed to analyze brain data from young infants. Total gray, white, and cerebral (summation of total gray and white matter) volumes were examined along with volumes of the frontal, parietal, temporal, and occipital lobes. Infants from low-income families had lower volumes of gray matter, tissue critical for processing of information and execution of actions. These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes. In addition, differences in brain growth were found to vary with socioeconomic status (SES), with children from lower-income households having slower trajectories of growth during infancy and early childhood. Volumetric differences were associated with the emergence of disruptive behavioral problems. PMID:24349025

  17. Family poverty affects the rate of human infant brain growth.

    PubMed

    Hanson, Jamie L; Hair, Nicole; Shen, Dinggang G; Shi, Feng; Gilmore, John H; Wolfe, Barbara L; Pollak, Seth D

    2013-01-01

    Living in poverty places children at very high risk for problems across a variety of domains, including schooling, behavioral regulation, and health. Aspects of cognitive functioning, such as information processing, may underlie these kinds of problems. How might poverty affect the brain functions underlying these cognitive processes? Here, we address this question by observing and analyzing repeated measures of brain development of young children between five months and four years of age from economically diverse backgrounds (n = 77). In doing so, we have the opportunity to observe changes in brain growth as children begin to experience the effects of poverty. These children underwent MRI scanning, with subjects completing between 1 and 7 scans longitudinally. Two hundred and three MRI scans were divided into different tissue types using a novel image processing algorithm specifically designed to analyze brain data from young infants. Total gray, white, and cerebral (summation of total gray and white matter) volumes were examined along with volumes of the frontal, parietal, temporal, and occipital lobes. Infants from low-income families had lower volumes of gray matter, tissue critical for processing of information and execution of actions. These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes. In addition, differences in brain growth were found to vary with socioeconomic status (SES), with children from lower-income households having slower trajectories of growth during infancy and early childhood. Volumetric differences were associated with the emergence of disruptive behavioral problems. PMID:24349025

  18. Biohydrogen production in the suspended and attached microbial growth systems from waste pastry hydrolysate.

    PubMed

    Han, Wei; Hu, Yunyi; Li, Shiyi; Li, Feifei; Tang, Junhong

    2016-10-01

    Waste pastry was hydrolyzed by glucoamylase and protease which were obtained from solid state fermentation of Aspergillus awamori and Aspergillus oryzae to produce waste pastry hydrolysate. Then, the effects of hydraulic retention times (HRTs) (4-12h) on hydrogen production rate (HPR) in the suspended microbial growth system (continuous stirred tank reactor, CSTR) and attached microbial growth system (continuous mixed immobilized sludge reactor, CMISR) from waste pastry hydrolysate were investigated. The maximum HPRs of CSTR (201.8mL/(h·L)) and CMISR (255.3mL/(h·L)) were obtained at HRT of 6h and 4h, respectively. The first-order reaction could be used to describe the enzymatic hydrolysis of waste pastry. The carbon content of the waste pastry remained 22.8% in the undigested waste pastry and consumed 77.2% for carbon dioxide and soluble microbial products. To our knowledge, this is the first study which reports biohydrogen production from waste pastry. PMID:27416509

  19. Transient concentrations of NaCl affect the PHA accumulation in mixed microbial culture.

    PubMed

    Palmeiro-Sánchez, T; Fra-Vázquez, A; Rey-Martínez, N; Campos, J L; Mosquera-Corral, A

    2016-04-01

    The present study explores the feasibility of the accumulation of polyhydroxyalkanoates (PHAs) under the presence of transient concentrations of added sodium chloride, by means of a mixed microbial culture (MMC). This culture was enriched on a mixture of volatile fatty acids (VFAs) containing 0.8g Na(+)/L as NaOH. This MMC presented a maximum PHA accumulation capacity of 53wt% with 27Cmol% HV. Accumulation experiments performed with added NaCl at concentrations of 7, 13 and 20g/L shown that this salt provoked a decrease of the biomass PHA production rate, with an IC50 value close to 7gNaCl/L. The accumulated PHA was lower than the corresponding value of the assay without the addition of salt. Furthermore, the composition of the biopolymer, in terms of HB:HV ratio, changed from 2.71 to 6.37Cmol/Cmol, which means a HV decrease between 27 and 14Cmol%. Summarizing, the PHA accumulation by a MMC non-adapted to saline conditions affected the polymer composition and lead to lower production yields and rates than in absence of added NaCl. PMID:26780589

  20. Antibiotic Treatment Affects Intestinal Permeability and Gut Microbial Composition in Wistar Rats Dependent on Antibiotic Class

    PubMed Central

    Tulstrup, Monica Vera-Lise; Christensen, Ellen Gerd; Carvalho, Vera; Linninge, Caroline; Ahrné, Siv; Højberg, Ole; Licht, Tine Rask; Bahl, Martin Iain

    2015-01-01

    Antibiotics are frequently administered orally to treat bacterial infections not necessarily related to the gastrointestinal system. This has adverse effects on the commensal gut microbial community, as it disrupts the intricate balance between specific bacterial groups within this ecosystem, potentially leading to dysbiosis. We hypothesized that modulation of community composition and function induced by antibiotics affects intestinal integrity depending on the antibiotic administered. To address this a total of 60 Wistar rats (housed in pairs with 6 cages per group) were dosed by oral gavage with either amoxicillin (AMX), cefotaxime (CTX), vancomycin (VAN), metronidazole (MTZ), or water (CON) daily for 10–11 days. Bacterial composition, alpha diversity and caecum short chain fatty acid levels were significantly affected by AMX, CTX and VAN, and varied among antibiotic treatments. A general decrease in diversity and an increase in the relative abundance of Proteobacteria was observed for all three antibiotics. Additionally, the relative abundance of Bifidobacteriaceae was increased in the CTX group and both Lactobacillaceae and Verrucomicrobiaceae were increased in the VAN group compared to the CON group. No changes in microbiota composition or function were observed following MTZ treatment. Intestinal permeability to 4 kDa FITC-dextran decreased after CTX and VAN treatment and increased following MTZ treatment. Plasma haptoglobin levels were increased by both AMX and CTX but no changes in expression of host tight junction genes were found in any treatment group. A strong correlation between the level of caecal succinate, the relative abundance of Clostridiaceae 1 family in the caecum, and the level of acute phase protein haptoglobin in blood plasma was observed. In conclusion, antibiotic-induced changes in microbiota may be linked to alterations in intestinal permeability, although the specific interactions remain to be elucidated as changes in permeability did

  1. Microbial response following straw application in a soil affected by a wildfire

    NASA Astrophysics Data System (ADS)

    Barreiro, Ana; Lombao, Alba; Díaz-Raviña, Montserrat; Martin, Angela; Fontúrbel, Maria Teresa; Vega, Jose Antonio; Fernández, Cristina; Carballas, Tarsy

    2015-04-01

    Mulching treatment is often recommended to reduce post-fire erosion and sediments yields but information concerning their effects on soil microorganisms is scarce. In the present investigation the evolution of several parameters related with the mass and activity of soil microorganisms was examined in a hillslope shrubland located in Saviñao (Lugo, NW Spain) and susceptible to suffer post-fire erosion (38% slope). In this area, affected by a medium-high severity wildfire in September 2012, different treatments with wheat straw applied to the burnt soil in mulch strips (800 and 1000 kg ha-1) were established by quadruplicate (10 m x 40 m plots) and compared with the corresponding burnt untreated control. Soil samples were collected from the A horizon (0-2.5 cm depth) at different sampling times over one year after the wildfire and different soil biochemical properties (microbial biomass C, soil respiration, bacterial activity, -glucosidase, urease and phosphatase activities) were analyzed. The results showed large variation among the four field replicates of the same treatment (spatial variability), which makes difficult to evaluate the effect of mulch treatment. The evolution of the different biochemical properties in the post-fire stabilization treatments with the wheat straw applied in mulch strips were mainly related to the time passed after the fire (short- and medium- term changes in soil physical and chemical properties induced by both fire and climatic conditions) rather than to the straw mulching effects; in addition, a different temporal pattern was observed depending on the variable considered. The results pointed out the usefulness of examining intra-annual natural variability (spatial variation, seasonal fluctuations) when different indices of mass and activity of microorganisms were used as monitoring tools in soil ecosystems affected by fire. Acknowledgements. A. Barreiro and A. Lombao are recipients of FPU grants from Spanish Ministry of

  2. Microbial water quality in streams as affected by high flow events

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bottom sediments in surface water sources were shown to serve as reservoirs of pathogen and indicator microorganisms. Resuspension of these sediments during the high flow events strongly modifies microbial quality of recreation and irrigation waters. Therefore, changes in microbial water quality are...

  3. Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

    NASA Astrophysics Data System (ADS)

    Patil, Rajendra; Gholap, Haribhau; Warule, Sambhaji; Banpurkar, Arun; Kulkarni, Gauri; Gade, Wasudeo

    2015-01-01

    The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications.

  4. Development and evaluation of formulations of microbial biotransformed extract of tobacco leaves for hair growth potential

    PubMed Central

    Murkute, Ashlesh V.; Sahu, Mahesh S.; Mali, Prashant Y.; Rangari, Vinod D.

    2010-01-01

    Background: Extensive researches are going on to explore the effective and safe drug for their hair growth. Tobacco leaves are traditionally known to potentiate hair growth promotion. Therefore, the aim of present study was to formulate and evaluate the microbial biotransformed extract of tobacco leaves for hair growth potential in male albino wister rats. Materials and Methods: The extract of was prepared by microbial biotransformation of tobacco leaves in cow urine for 28 days. The herbal formulations (lotion) were formulated by general method using o/w type base in various rations or concentrations such as 10%, 20% and 30% of extract. These lotions were applied on shaved skin area of rats for 30 days once in a day and hair length, serum total protein, and total testosterone were measured. Results: Our formulations show increase in hair growth and serum total protein at concentration dependent manner with effect to standard and control groups. Serum total testosterone decreases according to a concentration dependent manner. Conclusion: Further, series of investigations are, however, necessary to remain exploration, which includes their structural elucidation, characterization, clinical safety, reliability and molecular mechanism involved in this pharmacological activity. PMID:21589756

  5. Chemical diversity of microbial volatiles and their potential for plant growth and productivity

    PubMed Central

    Kanchiswamy, Chidananda Nagamangala; Malnoy, Mickael; Maffei, Massimo E.

    2015-01-01

    Microbial volatile organic compounds (MVOCs) are produced by a wide array of microorganisms ranging from bacteria to fungi. A growing body of evidence indicates that MVOCs are ecofriendly and can be exploited as a cost-effective sustainable strategy for use in agricultural practice as agents that enhance plant growth, productivity, and disease resistance. As naturally occurring chemicals, MVOCs have potential as possible alternatives to harmful pesticides, fungicides, and bactericides as well as genetic modification. Recent studies performed under open field conditions demonstrate that efficiently adopting MVOCs may contribute to sustainable crop protection and production. We review here the chemical diversity of MVOCs by describing microbial–plants and microbial–microbial interactions. Furthermore, we discuss MVOCs role in inducing phenotypic plant responses and their potential physiological effects on crops. Finally, we analyze potential and actual limitations for MVOC use and deployment in field conditions as a sustainable strategy for improving productivity and reducing pesticide use. PMID:25821453

  6. Cultural management of microbial community structure to enhance growth of apple in replant soils.

    PubMed

    Mazzola, Mark; Granatstein, David M; Elfving, Don C; Mullinix, Kent; Gu, Yu-Huan

    2002-12-01

    ABSTRACT Apple replant disease typically is managed through pre-plant application of broad-spectrum soil fumigants including methyl bromide. The impending loss or restricted use of soil fumigants and the needs of an expanding organic tree fruit industry necessitate the development of alternative control measures. The microbial community resident in a wheat field soil was shown to suppress components of the microbial complex that incites apple replant disease. Pseudomonas putida was the primary fluorescent pseudomonad recovered from suppressive soil, whereas Pseudomonas fluorescens bv. III was dominant in a conducive soil; the latter developed within 3 years of orchard establishment at the same site. In greenhouse studies, cultivation of wheat in replant orchard soils prior to planting apple suppressed disease development. Disease suppression was induced in a wheat cultivar-specific manner. Wheat cultivars that enhanced apple seedling growth altered the dominant fluorescent pseudo-monad from Pseudomonas fluorescens bv. III to Pseudomonas putida. The microbial community resident in replant orchard soils after growing wheat also was suppressive to an introduced isolate of Rhizoctonia solani anastomosis group 5, which causes root rot of apple. Incorporation of high glucosinolate containing rapeseed ('Dwarf Essex') meal also enhanced growth of apple in replant soils through suppression of Rhizoc-tonia spp., Cylindrocarpon spp., and Pratylenchus penetrans. Integration of these methods will require knowledge of the impact of the biofumigant component on the wheat-induced disease-suppressive microbial community. Implementation of these control strategies for management of apple replant disease awaits confirmation from ongoing field validation trials. PMID:18943894

  7. Biomechanical ordering and buckling due to microbial growth confined at oil-water interfaces

    NASA Astrophysics Data System (ADS)

    Juarez, Gabriel; Stocker, Roman

    2015-11-01

    Bacteria are unicellular organisms that often exist as densely populated, surface-associated communities. Bacteria are also environmental colloids and spontaneously attach and self-assemble at liquid-liquid interfaces. Here, we present results on the growth dynamics of individual rod-shaped bacteria confined to finite oil-water interfaces of varying curvature. Through experiments using microfluidic chambers and time-lapse microscopy, we study the formation of macroscopic structures observed as adsorbed bacteria grow, divide, and self-assemble in a nematic phase due to biomechanical interactions. The continued growth at the interface leads to a jammed monolayer of cells, which then causes the interface to buckle and undergo large deformations including wrinkling and tubulation. These observations highlight the interplay between physical environment, such as confinement and interface curvature, and active biological processes, such as growth, at the scale of individual agents and shape our understanding of macroscale processes such as microbial degradation of oil in the ocean.

  8. Biological soil crusts: a microenvironment characterized by complex microbial interrelations affected by the presence of the exopolysaccharidic matrix.

    NASA Astrophysics Data System (ADS)

    De Philippis, Roberto

    2015-04-01

    Biological Soil Crusts (BSCs) are complex microbial communities, commonly found in arid and semiarid areas of the world. The capability of the microorganisms residing in BSCs to withstand the harsh environmental conditions typical of these habitats, namely drought and high solar irradiation, is related with the presence of a matrix constituted by microbial-produced extracellular polysaccharides (EPSs), which also accomplish for a wide array of key ecological roles. EPSs represent a huge carbon source directly available to heterotrophic organisms, affect soil characteristics, water regimes, and establish complex interactions with plants. The induction of BSCs on degraded soils is considered a feasible approach to amend and maintain land fertility, as it was reported in a number of recent studies. It was recently shown that BSC induction is beneficial in enhancing SOC (Soil Organic Carbon) and in increasing the abundance of phototrophic organisms and vegetation cover. This lecture will describe the results of a study showing that cyanobacterial-EPS resulted advantageous to the growth and metabolism of seedlings of Caragana korshinskii, a desert sub-shrub widely diffused in the area under study, also contributing a defensive effect against the damaging effects of reactive oxygen species (ROS), generated under UV-irradiation, salt stress and desiccation. A study aimed at investigating the possible correlation between the chemical composition and the macromolecular features of the EPS matrix of induced BSCs of different age, collected in the hyper-arid plateau of Hobq desert, Inner Mongolia, China, will be also presented. The results of this study showed that the characteristics of the EPS of the matrix of the investigated IBSCs cannot be put only in relation with the age of the crusts and the activity of phototrophic microorganisms but, more properly, it has to be taken into account the biotic interactions ongoing between EPS producers (cyanobacteria, green microalgae

  9. Development of a competition model for microbial growth in mixed culture.

    PubMed

    Fujikawa, Hiroshi; Munakata, Kanako; Sakha, Mohammad Z

    2014-01-01

    A novel competition model for describing bacterial growth in mixed culture was developed in this study. Several model candidates were made with our logistic growth model that precisely describes the growth of a monoculture of bacteria. These candidates were then evaluated for the usefulness in describing growth of two competing species in mixed culture using Staphylococcus aureus, Escherichia coli, and Salmonella. Bacterial cells of two species grew at initial doses of 10(3), 10(4), and 10(5) CFU/g at 28ºC. Among the candidates, a model where the Lotka-Volterra model, a general competition model in ecology, was incorporated as a new term in our growth model was the best for describing all types of growth of two competitors in mixed culture. Moreover, the values for the competition coefficient in the model were stable at various combinations of the initial populations of the species. The Baranyi model could also successfully describe the above types of growth in mixed culture when it was coupled with the Gimenez and Dalgaard model. However, the values for the competition coefficients in the competition model varied with the conditions. The present study suggested that our model could be a basic model for describing microbial competition. PMID:24975409

  10. Impact of microbial growth on water flow and solute transport in unsaturated porous media

    SciTech Connect

    Yarwood, R. R.; Rockhold, M. L.; Niemet, M. R.; Selker, John S.; Bottomley, Peter J.

    2006-10-05

    A novel analytical method was developed that permitted real-time, noninvasive measurements of microbial growth and associated changes in hydrodynamic properties in porous media under unsaturated flowing conditions. Salicylate-induced, lux gene-based bioluminescence was used to quantify the temporal and spatial development of colonization over a seven day time course. Water contents were determined daily by measuring light transmission through the system. Hydraulic flow paths were determined daily by pulsing a bromophenol blue dye solution through the colonized region of the sand. Bacterial growth and accumulation had a significant impact on the hydraulic properties of the porous media. Microbial colonization caused localized drying within the colonized zone, with decreases in saturation approaching 50% of antecedent values, and a 25% lowering of the capillary fringe height. Flow was retarded within the colonized zone and diverted around it. The apparent solute velocity through the colonized region was reduced from 0.41 cm min 1 (R2 = 0.99) to 0.25 cm min 1 (R2 = 0.99) by the sixth day of the experiment, associated with maximum population densities that would occupy about 7% of the available pore space within the colonized region. Changes in the extent of colonization occurred over the course of the experiment, including upward migration against flow. The distribution of cells was not determined by water flow alone, but rather by a dynamic interaction between water flow and microbial growth. This experimental system provides rich data sets for the testing of conceptualizations expressed through numerical modeling.

  11. Arabinoxylan‐oligosaccharides (AXOS) affect the protein/carbohydrate fermentation balance and microbial population dynamics of the Simulator of Human Intestinal Microbial Ecosystem

    PubMed Central

    Sanchez, J. I.; Marzorati, M.; Grootaert, C.; Baran, M.; Van Craeyveld, V.; Courtin, C. M.; Broekaert, W. F.; Delcour, J. A.; Verstraete, W.; Van de Wiele, T.

    2009-01-01

    Summary Arabinoxylan‐oligosaccharides (AXOS) are a recently newly discovered class of candidate prebiotics as – depending on their structure – they are fermented in different regions of gastrointestinal tract. This can have an impact on the protein/carbohydrate fermentation balance in the large intestine and, thus, affect the generation of potentially toxic metabolites in the colon originating from proteolytic activity. In this study, we screened different AXOS preparations for their impact on the in vitro intestinal fermentation activity and microbial community structure. Short‐term fermentation experiments with AXOS with an average degree of polymerization (avDP) of 29 allowed part of the oligosaccharides to reach the distal colon, and decreased the concentration of proteolytic markers, whereas AXOS with lower avDP were primarily fermented in the proximal colon. Additionally, prolonged supplementation of AXOS with avDP 29 to the Simulator of Human Intestinal Microbial Ecosystem (SHIME) reactor decreased levels of the toxic proteolytic markers phenol and p‐cresol in the two distal colon compartments and increased concentrations of beneficial short‐chain fatty acids (SCFA) in all colon vessels (25–48%). Denaturant gradient gel electrophoresis (DGGE) analysis indicated that AXOS supplementation only slightly modified the total microbial community, implying that the observed effects on fermentation markers are mainly caused by changes in fermentation activity. Finally, specific quantitative PCR (qPCR) analysis showed that AXOS supplementation significantly increased the amount of health‐promoting lactobacilli as well as of Bacteroides–Prevotella and Clostridium coccoides–Eubacterium rectale groups. These data allow concluding that AXOS are promising candidates to modulate the microbial metabolism in the distal colon. PMID:21261885

  12. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    DOE PAGESBeta

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2016-08-15

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions inmore » a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Lastly, simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.« less

  13. Genetic Diversity Affects the Daily Transcriptional Oscillations of Marine Microbial Populations

    PubMed Central

    Shilova, Irina N.; Robidart, Julie C.; DeLong, Edward F.; Zehr, Jonathan P.

    2016-01-01

    Marine microbial communities are genetically diverse but have robust synchronized daily transcriptional patterns at the genus level that are similar across a wide variety of oceanic regions. We developed a microarray-inspired gene-centric approach to resolve transcription of closely-related but distinct strains/ecotypes in high-throughput sequence data. Applying this approach to the existing metatranscriptomics datasets collected from two different oceanic regions, we found unique and variable patterns of transcription by individual taxa within the abundant picocyanobacteria Prochlorococcus and Synechococcus, the alpha Proteobacterium Pelagibacter and the eukaryotic picophytoplankton Ostreococcus. The results demonstrate that marine microbial taxa respond differentially to variability in space and time in the ocean. These intra-genus individual transcriptional patterns underlie whole microbial community responses, and the approach developed here facilitates deeper insights into microbial population dynamics. PMID:26751368

  14. Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

    PubMed Central

    Kovárová-Kovar, Karin; Egli, Thomas

    1998-01-01

    Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter−1 to ca. 30 μg liter−1. The data suggest that a dilemma exists, namely, that either “intrinsic” KS (under substrate-controlled conditions in chemostat culture) or μmax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture

  15. A thermodynamically-based model for predicting microbial growth and community composition coupled to system geochemistry: Application to uranium bioreduction

    NASA Astrophysics Data System (ADS)

    Istok, J. D.; Park, M.; Michalsen, M.; Spain, A. M.; Krumholz, L. R.; Liu, C.; McKinley, J.; Long, P.; Roden, E.; Peacock, A. D.; Baldwin, B.

    2010-03-01

    'Bioimmobilization' of redox-sensitive heavy metals and radionuclides is being investigated as a way to remediate contaminated groundwater and sediments. In one approach, growth-limiting substrates are added to the subsurface to stimulate the activity of targeted groups of indigenous microorganisms and create conditions favorable for the microbially-mediated reductive precipitation ('bioreduction') of targeted contaminants. We present a theoretical framework for modeling this process that modifies conventional geochemical reaction path modeling to include thermodynamic descriptions for microbial growth and may be called biogeochemical reaction path modeling. In this approach, the actual microbial community is represented by a synthetic microbial community consisting of a collection of microbial groups; each with a unique growth equation that couples a specific pair of energy yielding redox reactions. The growth equations and their computed standard-state free energy yields are appended to the thermodynamic database used in conventional geochemical reaction path modeling, providing a direct coupling between chemical species participating in both microbial growth and geochemical reactions. To compute the biogeochemical reaction paths, growth substrates are reacted incrementally with the defined geochemical environment and the coupled equations are solved simultaneously to predict reaction paths that display changing microbial biomass, community composition (i.e. the fraction of total biomass in each microbial group), and the aqueous and mineral composition of the system, including aqueous speciation and oxidation state of the targeted contaminants. The approach, with growth equations derived from the literature using well-known bioenergetics principles, was used to predict the results of a laboratory microcosm experiment and an in situ field experiment that investigated the bioreduction of uranium. Predicted effects of ethanol or acetate addition on uranium

  16. A thermodynamically-based model for predicting microbial growth and community composition coupled to system geochemistry: Application to uranium bioreduction

    SciTech Connect

    Istok, Jonathan D.; Park, Melora M.; Michalsen, Mandy M.; Spain, A. M.; Krumholz, Lee R.; Liu, Chongxuan; McKinley, James P.; Long, Philip E.; Roden, Eric E.; Peacock, Aaron D.; Baldwin, Brett R.

    2010-04-01

    ‘Bioimmobilization’ of redox-sensitive heavy metals and radionuclides is being investigated as a way to remediate contaminated groundwater and sediments. In one approach, growth-limiting substrates are added to the subsurface to stimulate the activity of targeted groups of indigenous microorganisms and create conditions favorable for the microbially-mediated reductive precipitation (‘bioreduction’) of targeted contaminants. We present a theoretical framework for modeling this process that modifies conventional geochemical reaction path modeling to include thermodynamic descriptions for microbial growth and may be called biogeochemical reaction path modeling. In this approach, the actual microbial community is represented by a synthetic microbial community consisting of a collection of microbial groups; each with a unique growth equation that couples a specific pair of energy yielding redox reactions. The growth equations and their computed standard-state free energy yields are appended to the thermodynamic databasse used in conventional geochemical reaction path modeling, providing a direct coupling between chemical species participating in both microbial growth and geochemical reactions. To compute the biogeochemical reaction paths, growth substrates are added incrementally to a defined geochemical environment and the coupled equations are solved simultaneously to predict microbial biomass, community composition (i.e. the fraction of total biomass in each microbial group), and the aqueous and mineral composition of the system, including aqueous speciation and oxidation state of the targeted contaminants. The approach, with growth equations derived from the literature using well known bioenergetics principles, was used to predict the results of a laboratory microcosm experiment and an in situ field experiment that investigated the bioreduction of uranium. Predicted effects of ethanol or acetate addition on uranium concentration and speciation, major ion

  17. Activity and growth of microbial populations in pressurized deep-sea sediment and animal gut samples.

    PubMed

    Tabor, P S; Deming, J W; Ohwada, K; Colwell, R R

    1982-08-01

    Benthic animals and sediment samples were collected at deep-sea stations in the northwest (3,600-m depth) and southeast (4,300- and 5200-m depths) Atlantic Ocean. Utilization rates of [14C]glutamate (0.67 to 0.74 nmol) in sediment suspensions incubated at in situ temperatures and pressures (3 to 5 degrees C and 360, 430, or 520 atmospheres) were relatively slow, ranging from 0.09 to 0.39 nmol g-1 day-1, whereas rates for pressurized samples of gut suspensions varied widely, ranging from no detectable activity to a rapid rate of 986 nmol g-1 day-1. Gut flora from a holothurian specimen and a fish demonstrated rapid, barophilic substrate utilization, based on relative rates calculated for pressurized samples and samples held at 1 atm (101.325 kPa). Substrate utilization by microbial populations in several sediment samples was not inhibited by in situ pressure. Deep-sea pressures did not restrict growth, measured as doubling time, of culturable bacteria present in a northwest Atlantic sediment sample and in a gut suspension prepared from an abyssal scavenging amphipod. From the results of this study, it was concluded that microbial populations in benthic environments can demonstrate significant metabolic activity under deep-ocean conditions of temperature and pressure. Furthermore, rates of microbial activity in the guts of benthic macrofauna are potentially more rapid than in surrounding deep-sea sediments. PMID:6127054

  18. Activity and growth of microbial populations in pressurized deep-sea sediment and animal gut samples.

    PubMed Central

    Tabor, P S; Deming, J W; Ohwada, K; Colwell, R R

    1982-01-01

    Benthic animals and sediment samples were collected at deep-sea stations in the northwest (3,600-m depth) and southeast (4,300- and 5200-m depths) Atlantic Ocean. Utilization rates of [14C]glutamate (0.67 to 0.74 nmol) in sediment suspensions incubated at in situ temperatures and pressures (3 to 5 degrees C and 360, 430, or 520 atmospheres) were relatively slow, ranging from 0.09 to 0.39 nmol g-1 day-1, whereas rates for pressurized samples of gut suspensions varied widely, ranging from no detectable activity to a rapid rate of 986 nmol g-1 day-1. Gut flora from a holothurian specimen and a fish demonstrated rapid, barophilic substrate utilization, based on relative rates calculated for pressurized samples and samples held at 1 atm (101.325 kPa). Substrate utilization by microbial populations in several sediment samples was not inhibited by in situ pressure. Deep-sea pressures did not restrict growth, measured as doubling time, of culturable bacteria present in a northwest Atlantic sediment sample and in a gut suspension prepared from an abyssal scavenging amphipod. From the results of this study, it was concluded that microbial populations in benthic environments can demonstrate significant metabolic activity under deep-ocean conditions of temperature and pressure. Furthermore, rates of microbial activity in the guts of benthic macrofauna are potentially more rapid than in surrounding deep-sea sediments. PMID:6127054

  19. A Bayesian approach to analyzing phenotype microarray data enables estimation of microbial growth parameters.

    PubMed

    Gerstgrasser, Matthias; Nicholls, Sarah; Stout, Michael; Smart, Katherine; Powell, Chris; Kypraios, Theodore; Stekel, Dov

    2016-06-01

    Biolog phenotype microarrays (PMs) enable simultaneous, high throughput analysis of cell cultures in different environments. The output is high-density time-course data showing redox curves (approximating growth) for each experimental condition. The software provided with the Omnilog incubator/reader summarizes each time-course as a single datum, so most of the information is not used. However, the time courses can be extremely varied and often contain detailed qualitative (shape of curve) and quantitative (values of parameters) information. We present a novel, Bayesian approach to estimating parameters from Phenotype Microarray data, fitting growth models using Markov Chain Monte Carlo (MCMC) methods to enable high throughput estimation of important information, including length of lag phase, maximal "growth" rate and maximum output. We find that the Baranyi model for microbial growth is useful for fitting Biolog data. Moreover, we introduce a new growth model that allows for diauxic growth with a lag phase, which is particularly useful where Phenotype Microarrays have been applied to cells grown in complex mixtures of substrates, for example in industrial or biotechnological applications, such as worts in brewing. Our approach provides more useful information from Biolog data than existing, competing methods, and allows for valuable comparisons between data series and across different models. PMID:26762475

  20. Carbon stabilization and microbial growth in acidic mine soils after addition of different amendments for soil reclamation

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Acosta, Jose; Ángeles Muñoz, María; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2016-04-01

    The extreme soil conditions in metalliferous mine soils have a negative influence on soil biological activity and therefore on soil carbon estabilization. Therefore, amendments are used to increase organic carbon content and activate microbial communities. In order to elucidate some of the factors controlling soil organic carbon stabilization in reclaimed acidic mine soils and its interrelationship with microbial growth and community structure, we performed an incubation experiment with four amendments: pig slurry (PS), pig manure (PM) and biochar (BC), applied with and without marble waste (MW; CaCO3). Results showed that PM and BC (alone or together with MW) contributed to an important increment in recalcitrant organic C, C/N ratio and aggregate stability. Bacterial and fungal growths were highly dependent on pH and labile organic C. PS supported the highest microbial growth; applied alone it stimulated fungal growth, and applied with MW it stimulated bacterial growth. BC promoted the lowest microbial growth, especially for fungi, with no significant increase in fungal biomass. MW+BC increased bacterial growth up to values similar to PM and MW+PM, suggesting that part of the biochar was degraded, at least in short-term mainly by bacteria rather than fungi. PM, MW+PS and MW+PM supported the highest microbial biomass and a similar community structure, related with the presence of high organic C and high pH, with immobilization of metals and increased soil quality. BC contributed to improved soil structure, increased recalcitrant organic C, and decreased metal mobility, with low stimulation of microbial growth.

  1. Turnover of microbial lipids in the deep biosphere and growth of benthic archaeal populations

    NASA Astrophysics Data System (ADS)

    Xie, Sitan; Lipp, Julius S.; Wegener, Gunter; Ferdelman, Timothy G.; Hinrichs, Kai-Uwe

    2013-04-01

    Deep subseafloor sediments host a microbial biosphere with unknown impact on global biogeochemical cycles. This study tests previous evidence based on microbial intact polar lipids (IPLs) as proxies of live biomass, suggesting that Archaea dominate the marine sedimentary biosphere. We devised a sensitive radiotracer assay to measure the decay rate of ([14C]glucosyl)-diphytanylglyceroldiether (GlcDGD) as an analog of archaeal IPLs in continental margin sediments. The degradation kinetics were incorporated in model simulations that constrained the fossil fraction of subseafloor IPLs and rates of archaeal turnover. Simulating the top 1 km in a generic continental margin sediment column, we estimated degradation rate constants of GlcDGD being one to two orders of magnitude lower than those of bacterial IPLs, with half-lives of GlcDGD increasing with depth to 310 ky. Given estimated microbial community turnover times of 1.6-73 ky in sediments deeper than 1 m, 50-96% of archaeal IPLs represent fossil signals. Consequently, previous lipid-based estimates of global subseafloor biomass probably are too high, and the widely observed dominance of archaeal IPLs does not rule out a deep biosphere dominated by Bacteria. Reverse modeling of existing concentration profiles suggest that archaeal IPL synthesis rates decline from around 1,000 pgṡmL-1 sedimentṡy-1 at the surface to 0.2 pgṡmL-1ṡy-1 at 1 km depth, equivalent to production of 7 × 105 to 140 archaeal cellsṡmL-1 sedimentṡy-1, respectively. These constraints on microbial growth are an important step toward understanding the relationship between the deep biosphere and the carbon cycle.

  2. Turnover of microbial lipids in the deep biosphere and growth of benthic archaeal populations

    PubMed Central

    Xie, Sitan; Lipp, Julius S.; Wegener, Gunter; Ferdelman, Timothy G.; Hinrichs, Kai-Uwe

    2013-01-01

    Deep subseafloor sediments host a microbial biosphere with unknown impact on global biogeochemical cycles. This study tests previous evidence based on microbial intact polar lipids (IPLs) as proxies of live biomass, suggesting that Archaea dominate the marine sedimentary biosphere. We devised a sensitive radiotracer assay to measure the decay rate of ([14C]glucosyl)-diphytanylglyceroldiether (GlcDGD) as an analog of archaeal IPLs in continental margin sediments. The degradation kinetics were incorporated in model simulations that constrained the fossil fraction of subseafloor IPLs and rates of archaeal turnover. Simulating the top 1 km in a generic continental margin sediment column, we estimated degradation rate constants of GlcDGD being one to two orders of magnitude lower than those of bacterial IPLs, with half-lives of GlcDGD increasing with depth to 310 ky. Given estimated microbial community turnover times of 1.6–73 ky in sediments deeper than 1 m, 50–96% of archaeal IPLs represent fossil signals. Consequently, previous lipid-based estimates of global subseafloor biomass probably are too high, and the widely observed dominance of archaeal IPLs does not rule out a deep biosphere dominated by Bacteria. Reverse modeling of existing concentration profiles suggest that archaeal IPL synthesis rates decline from around 1,000 pg⋅mL−1 sediment⋅y−1 at the surface to 0.2 pg⋅mL−1⋅y−1 at 1 km depth, equivalent to production of 7 × 105 to 140 archaeal cells⋅mL−1 sediment⋅y−1, respectively. These constraints on microbial growth are an important step toward understanding the relationship between the deep biosphere and the carbon cycle. PMID:23530229

  3. Site- and horizon-specific patterns of microbial community structure and enzyme activities in permafrost-affected soils of Greenland

    PubMed Central

    Gittel, Antje; Bárta, Jiří; Kohoutová, Iva; Schnecker, Jörg; Wild, Birgit; Čapek, Petr; Kaiser, Christina; Torsvik, Vigdis L.; Richter, Andreas; Schleper, Christa; Urich, Tim

    2014-01-01

    Permafrost-affected soils in the Northern latitudes store huge amounts of organic carbon (OC) that is prone to microbial degradation and subsequent release of greenhouse gasses to the atmosphere. In Greenland, the consequences of permafrost thaw have only recently been addressed, and predictions on its impact on the carbon budget are thus still highly uncertain. However, the fate of OC is not only determined by abiotic factors, but closely tied to microbial activity. We investigated eight soil profiles in northeast Greenland comprising two sites with typical tundra vegetation and one wet fen site. We assessed microbial community structure and diversity (SSU rRNA gene tag sequencing, quantification of bacteria, archaea and fungi), and measured hydrolytic and oxidative enzyme activities. Sampling site and thus abiotic factors had a significant impact on microbial community structure, diversity and activity, the wet fen site exhibiting higher potential enzyme activities and presumably being a hot spot for anaerobic degradation processes such as fermentation and methanogenesis. Lowest fungal to bacterial ratios were found in topsoils that had been relocated by cryoturbation (“buried topsoils”), resulting from a decrease in fungal abundance compared to recent (“unburied”) topsoils. Actinobacteria (in particular Intrasporangiaceae) accounted for a major fraction of the microbial community in buried topsoils, but were only of minor abundance in all other soil horizons. It was indicated that the distribution pattern of Actinobacteria and a variety of other bacterial classes was related to the activity of phenol oxidases and peroxidases supporting the hypothesis that bacteria might resume the role of fungi in oxidative enzyme production and degradation of phenolic and other complex substrates in these soils. Our study sheds light on the highly diverse, but poorly-studied communities in permafrost-affected soils in Greenland and their role in OC degradation. PMID

  4. Site- and horizon-specific patterns of microbial community structure and enzyme activities in permafrost-affected soils of Greenland.

    PubMed

    Gittel, Antje; Bárta, Jiří; Kohoutová, Iva; Schnecker, Jörg; Wild, Birgit; Capek, Petr; Kaiser, Christina; Torsvik, Vigdis L; Richter, Andreas; Schleper, Christa; Urich, Tim

    2014-01-01

    Permafrost-affected soils in the Northern latitudes store huge amounts of organic carbon (OC) that is prone to microbial degradation and subsequent release of greenhouse gasses to the atmosphere. In Greenland, the consequences of permafrost thaw have only recently been addressed, and predictions on its impact on the carbon budget are thus still highly uncertain. However, the fate of OC is not only determined by abiotic factors, but closely tied to microbial activity. We investigated eight soil profiles in northeast Greenland comprising two sites with typical tundra vegetation and one wet fen site. We assessed microbial community structure and diversity (SSU rRNA gene tag sequencing, quantification of bacteria, archaea and fungi), and measured hydrolytic and oxidative enzyme activities. Sampling site and thus abiotic factors had a significant impact on microbial community structure, diversity and activity, the wet fen site exhibiting higher potential enzyme activities and presumably being a hot spot for anaerobic degradation processes such as fermentation and methanogenesis. Lowest fungal to bacterial ratios were found in topsoils that had been relocated by cryoturbation ("buried topsoils"), resulting from a decrease in fungal abundance compared to recent ("unburied") topsoils. Actinobacteria (in particular Intrasporangiaceae) accounted for a major fraction of the microbial community in buried topsoils, but were only of minor abundance in all other soil horizons. It was indicated that the distribution pattern of Actinobacteria and a variety of other bacterial classes was related to the activity of phenol oxidases and peroxidases supporting the hypothesis that bacteria might resume the role of fungi in oxidative enzyme production and degradation of phenolic and other complex substrates in these soils. Our study sheds light on the highly diverse, but poorly-studied communities in permafrost-affected soils in Greenland and their role in OC degradation. PMID:25360132

  5. [Carbon source metabolic diversity of soil microbial community under different climate types in the area affected by Wenchuan earthquake].

    PubMed

    Zhang, Guang-Shuai; Lin, Yong-Ming; Ma, Rui-Feng; Deng, Hao-Jun; Du, Kun; Wu, Cheng-Zhen; Hong, Wei

    2015-02-01

    The MS8.0 Wenchuan earthquake in 2008 led to huge damage to land covers in northwest Sichuan, one of the critical fragile eco-regions in China which can be divided into Semi-arid dry hot climate zone (SDHC) and Subtropical humid monsoon climate zone (SHMC). Using the method of Bilog-ECO-microplate technique, this paper aimed to determine the functional diversity of soil microbial community in the earthquake-affected areas which can be divided into undamaged area (U), recover area (R) and damaged area without recovery (D) under different climate types, in order to provide scientific basis for ecological recovery. The results indicated that the average-well-color-development (AWCD) in undamaged area and recovery area showed SDHC > SHMC, which was contrary to the AWCD in the damaged area without recovery. The AWCD of damaged area without recovery was the lowest in both climate zones. The number of carbon source utilization types of soil microbial in SHMC zone was significantly higher than that in SDHC zone. The carbon source utilization types in both climate zones presented a trend of recover area > undamaged area > damaged area without recovery. The carbon source metabolic diversity characteristic of soil microbial community was significantly different in different climate zones. The diversity index and evenness index both showed a ranking of undamaged area > recover area > damaged area without recovery. In addition, the recovery area had the highest richness index. The soil microbial carbon sources metabolism characteristic was affected by soil nutrient, aboveground vegetation biomass and vegetation coverage to some extent. In conclusion, earthquake and its secondary disasters influenced the carbon source metabolic diversity characteristic of soil microbial community mainly through the change of aboveground vegetation and soil environmental factors. PMID:26031097

  6. Does Training Affect Growth? Answers to Common Questions.

    ERIC Educational Resources Information Center

    Daly, Robin M.; Bass, Shona; Caine, Dennis; Howe, Warren

    2002-01-01

    Adolescent athletes may be at risk of restricted growth and delayed maturation when combining intense training with insufficient energy intake. Because catch-up growth commonly occurs with reduced training, final adult stature is generally not compromised. However, in athletes with long-term, clinically delayed maturation, catch-up growth may be…

  7. Using growth-based methods to determine direct effects of salinity on soil microbial communities

    NASA Astrophysics Data System (ADS)

    Rath, Kristin; Rousk, Johannes

    2015-04-01

    Soil salinization is a widespread agricultural problem and increasing salt concentrations in soils have been found to be correlated with decreased microbial activity. A central challenge in microbial ecology is to link environmental factors, such as salinity, to responses in the soil microbial community. That is, it can be difficult to distinguish direct from indirect effects. In order to determine direct salinity effects on the community we employed the ecotoxicological concept of Pollution-Induced Community Tolerance (PICT). This concept is built on the assumption that if salinity had an ecologically relevant effect on the community, it should have selected for more tolerant species and strains, resulting in an overall higher community tolerance to salt in communities from saline soils. Growth-based measures, such as the 3H-leucine incorporation into bacterial protein , provide sensitive tools to estimate community tolerance. They can also provide high temporal resolution in tracking changes in tolerance over time. In our study we used growth-based methods to investigate: i) at what levels of salt exposure and over which time scales salt tolerance can be induced in a non-saline soil, and (ii) if communities from high salinity sites have higher tolerance to salt exposure along natural salinity gradients. In the first part of the study, we exposed a non-saline soil to a range of salinities and monitored the development of community tolerance over time. We found that community tolerance to intermediate salinities up to around 30 mg NaCl per g soil can be induced at relatively short time scales of a few days, providing evidence that microbial communities can adapt rapidly to changes in environmental conditions. In the second part of the study we used soil samples originating from natural salinity gradients encompassing a wide range of salinity levels, with electrical conductivities ranging from 0.1 dS/m to >10 dS/m. We assessed community tolerance to salt by

  8. Microbial Community Analysis of a Coastal Salt Marsh Affected by the Deepwater Horizon Oil Spill

    PubMed Central

    Beazley, Melanie J.; Martinez, Robert J.; Rajan, Suja; Powell, Jessica; Piceno, Yvette M.; Tom, Lauren M.; Andersen, Gary L.; Hazen, Terry C.; Van Nostrand, Joy D.; Zhou, Jizhong; Mortazavi, Behzad; Sobecky, Patricia A.

    2012-01-01

    Coastal salt marshes are highly sensitive wetland ecosystems that can sustain long-term impacts from anthropogenic events such as oil spills. In this study, we examined the microbial communities of a Gulf of Mexico coastal salt marsh during and after the influx of petroleum hydrocarbons following the Deepwater Horizon oil spill. Total hydrocarbon concentrations in salt marsh sediments were highest in June and July 2010 and decreased in September 2010. Coupled PhyloChip and GeoChip microarray analyses demonstrated that the microbial community structure and function of the extant salt marsh hydrocarbon-degrading microbial populations changed significantly during the study. The relative richness and abundance of phyla containing previously described hydrocarbon-degrading bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased in hydrocarbon-contaminated sediments and then decreased once hydrocarbons were below detection. Firmicutes, however, continued to increase in relative richness and abundance after hydrocarbon concentrations were below detection. Functional genes involved in hydrocarbon degradation were enriched in hydrocarbon-contaminated sediments then declined significantly (p<0.05) once hydrocarbon concentrations decreased. A greater decrease in hydrocarbon concentrations among marsh grass sediments compared to inlet sediments (lacking marsh grass) suggests that the marsh rhizosphere microbial communities could also be contributing to hydrocarbon degradation. The results of this study provide a comprehensive view of microbial community structural and functional dynamics within perturbed salt marsh ecosystems. PMID:22815990

  9. MediaDB: A Database of Microbial Growth Conditions in Defined Media

    PubMed Central

    Richards, Matthew A.; Cassen, Victor; Heavner, Benjamin D.; Ajami, Nassim E.; Herrmann, Andrea; Simeonidis, Evangelos; Price, Nathan D.

    2014-01-01

    Isolating pure microbial cultures and cultivating them in the laboratory on defined media is used to more fully characterize the metabolism and physiology of organisms. However, identifying an appropriate growth medium for a novel isolate remains a challenging task. Even organisms with sequenced and annotated genomes can be difficult to grow, despite our ability to build genome-scale metabolic networks that connect genomic data with metabolic function. The scientific literature is scattered with information about defined growth media used successfully for cultivating a wide variety of organisms, but to date there exists no centralized repository to inform efforts to cultivate less characterized organisms by bridging the gap between genomic data and compound composition for growth media. Here we present MediaDB, a manually curated database of defined media that have been used for cultivating organisms with sequenced genomes, with an emphasis on organisms with metabolic network models. The database is accessible online, can be queried by keyword searches or downloaded in its entirety, and can generate exportable individual media formulation files. The data assembled in MediaDB facilitate comparative studies of organism growth media, serve as a starting point for formulating novel growth media, and contribute to formulating media for in silico investigation of metabolic networks. MediaDB is freely available for public use at https://mediadb.systemsbiology.net. PMID:25098325

  10. Factors affecting microbial 2,4,6-trinitrotoluene mineralization in contaminated soil

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    1995-01-01

    The influence of selected environmental factors on microbial TNT mineralization in soils collected from a TNT-contaminated site at Weldon Spring, MO, was examined using uniformly ring-labeled [14C]TNT. Microbial TNT mineralization was significantly inhibited by the addition of cellobiose and syringate. This response suggests that the indigenous microorganisms are capable of metabolizing TNT but preferentially utilize less recalcitrant substrates when available. The observed inhibition of TNT mineralization by TNT concentrations higher than 100 ??mol/kg of soil and by dry soil conditions suggests that toxic inhibition of microbial activity at high TNT concentrations and the periodic drying of these soils have contributed to the long-term persistence of TNT at Weldon Spring. In comparison to aerobic microcosms, mineralization was inhibited in anaerobic microcosms and in microcosms with a headspace of air amended with oxygen, suggesting that a mosaic of aerobic and anaerobic conditions may optimize TNT degradation at this site.

  11. Microbial Functional Diversity, Biomass and Activity as Affected by Soil Surface Mulching in a Semiarid Farmland

    PubMed Central

    Shen, Yufang; Chen, Yingying; Li, Shiqing

    2016-01-01

    Mulching is widely used to increase crop yield in semiarid regions in northwestern China, but little is known about the effect of different mulching systems on the microbial properties of the soil, which play an important role in agroecosystemic functioning and nutrient cycling. Based on a 4-year spring maize (Zea mays L.) field experiment at Changwu Agricultural and Ecological Experimental Station, Shaanxi, we evaluated the responses of soil microbial activity and crop to various management systems. The treatments were NMC (no mulching with inorganic N fertilizer), GMC (gravel mulching with inorganic N fertilizer), FMC (plastic-film mulching with inorganic N fertilizer) and FMO (plastic-film mulching with inorganic N fertilizer and organic manure addition). The results showed that the FMO soil had the highest contents of microbial biomass carbon and nitrogen, dehydrogenase activity, microbial activity and Shannon diversity index. The relative use of carbohydrates and amino acids by microbes was highest in the FMO soil, whereas the relative use of polymers, phenolic compounds and amines was highest in the soil in the NMC soil. Compared with the NMC, an increased but no significant trend of biomass production and nitrogen accumulation was observed under the GMC treatment. The FMC and FMO led a greater increase in biomass production than GMC and NMC. Compare with the NMC treatment, FMC increased grain yield, maize biomass and nitrogen accumulation by 62.2, 62.9 and 86.2%, but no significant difference was found between the FMO and FMC treatments. Some soil biological properties, i.e. microbial biomass carbon, microbial biomass nitrogen, being sensitive to the mulching and organic fertilizer, were significant correlated with yield and nitrogen availability. Film mulching over gravel mulching can serve as an effective measure for crop production and nutrient cycling, and plus organic fertilization additions may thus have improvements in the biological quality of the

  12. Microbial Functional Diversity, Biomass and Activity as Affected by Soil Surface Mulching in a Semiarid Farmland.

    PubMed

    Shen, Yufang; Chen, Yingying; Li, Shiqing

    2016-01-01

    Mulching is widely used to increase crop yield in semiarid regions in northwestern China, but little is known about the effect of different mulching systems on the microbial properties of the soil, which play an important role in agroecosystemic functioning and nutrient cycling. Based on a 4-year spring maize (Zea mays L.) field experiment at Changwu Agricultural and Ecological Experimental Station, Shaanxi, we evaluated the responses of soil microbial activity and crop to various management systems. The treatments were NMC (no mulching with inorganic N fertilizer), GMC (gravel mulching with inorganic N fertilizer), FMC (plastic-film mulching with inorganic N fertilizer) and FMO (plastic-film mulching with inorganic N fertilizer and organic manure addition). The results showed that the FMO soil had the highest contents of microbial biomass carbon and nitrogen, dehydrogenase activity, microbial activity and Shannon diversity index. The relative use of carbohydrates and amino acids by microbes was highest in the FMO soil, whereas the relative use of polymers, phenolic compounds and amines was highest in the soil in the NMC soil. Compared with the NMC, an increased but no significant trend of biomass production and nitrogen accumulation was observed under the GMC treatment. The FMC and FMO led a greater increase in biomass production than GMC and NMC. Compare with the NMC treatment, FMC increased grain yield, maize biomass and nitrogen accumulation by 62.2, 62.9 and 86.2%, but no significant difference was found between the FMO and FMC treatments. Some soil biological properties, i.e. microbial biomass carbon, microbial biomass nitrogen, being sensitive to the mulching and organic fertilizer, were significant correlated with yield and nitrogen availability. Film mulching over gravel mulching can serve as an effective measure for crop production and nutrient cycling, and plus organic fertilization additions may thus have improvements in the biological quality of the

  13. STRUCTURE AND FUNCTION OF SUBSURFACE MICROBIAL COMMUNITIES AFFECTING RADIONUCLIDE TRANSPORT AND BIOIMMOBILIZATION

    SciTech Connect

    Joel E. Kostka; Lee Kerkhof; Kuk-Jeong Chin; Martin Keller; Joseph W. Stucki

    2011-06-15

    to science all show high sequence identity to sequences retrieved from ORFRC subsurface. (2) Based on physiological and phylogenetic characterization, two new species of subsurface bacteria were described: the metal-reducer Geobacter daltonii, and the denitrifier Rhodanobacter denitrificans. (3) Strains isolated from the ORFRC show that Rhodanobacter species are well adapted to the contaminated subsurface. Strains 2APBS1 and 116-2 grow at high salt (3% NaCl), low pH (3.5) and tolerate high concentrations of nitrate (400mM) and nitrite (100mM). Strain 2APBS1 was demonstrated to grow at in situ acidic pHs down to 2.5. (4) R. denitrificans strain 2APBS1 is the first described Rhodanobacter species shown to denitrify. Nitrate is almost entirely converted to N2O, which may account for the large accumulation of N2O in the ORFRC subsurface. (5) G. daltonii, isolated from uranium- and hydrocarbon-contaminated subsurface sediments of the ORFRC, is the first organism from the subsurface clade of the genus Geobacter that is capable of growth on aromatic hydrocarbons. (6) High quality draft genome sequences and a complete eco-physiological description are completed for R. denitrificans strain 2APBS1 and G. daltonii strain FRC-32. (7) Given their demonstrated relevance to DOE remediation efforts and the availability of detailed genotypic/phenotypic characterization, Rhodanobacter denitrificans strain 2APBS1 and Geobacter daltonii strain FRC-32 represent ideal model organisms to provide a predictive understanding of subsurface microbial activity through metabolic modeling. Tasks II and III-Diversity and distribution of active anaerobes and Mechanisms linking electron transport and the fate of radionuclides: (1) Our study showed that members of genus Rhodanobacter and Geobacter are abundant and active in the uranium and nitrate contaminated subsurface. In the contaminant source zone of the Oak Ridge site, Rhodanobacter spp. are the predominant, active organisms detected (comprising

  14. Microbial Community-Level Physiological Profiles (CLPP) and herbicide mineralization potential in groundwater affected by agricultural land use

    NASA Astrophysics Data System (ADS)

    Janniche, Gry Sander; Spliid, Henrik; Albrechtsen, Hans-Jørgen

    2012-10-01

    Diffuse groundwater pollution from agricultural land use may impact the microbial groundwater community, which was investigated as Community-Level Physiological Profiles (CLPP) using EcoPlate™. Water was sampled from seven piezometers and a spring in a small agricultural catchment with diffuse herbicide and nitrate pollution. Based on the Shannon-Wiener and Simpson's diversity indices the diversity in the microbial communities was high. The response from the EcoPlates™ showed which substrates support groundwater bacteria, and all 31 carbon sources were utilized by organisms from at least one water sample. However, only nine carbon sources were utilized by all water samples: D-Mannitol, N-acetyl-D-glucosamine, putrescine, D-galacturonic acid, itaconic acid, 4-hydroxy benzoic acid, tween 40, tween 80, and L-asparagine. In all water samples the microorganisms preferred D-mannitol, D-galacturonic acid, tween 40, and 4-hydroxy benzoic acid as substrates, whereas none preferred 2-hydroxy benzoic acid, α-D-lactose, D,L-α-glycerol phosphate, α-ketobutyric acid, L-threonine and glycyl-L-glutamic acid. Principal Component Analysis of the CLPP's clustered the most agriculturally affected groundwater samples, indicating that the agricultural land use affects the groundwater microbial communities. Furthermore, the ability to mineralize atrazine and isoproturon, which have been used in the catchment, was also associated with this cluster.

  15. Kinetics of microbial growth and biodegradation of methanol and toluene in biofilters and an analysis of the energetic indicators.

    PubMed

    Avalos Ramirez, Antonio; Bénard, Sandrine; Giroir-Fendler, Anne; Jones, J Peter; Heitz, Michèle

    2008-11-25

    The kinetics of microbial growth and the biodegradation of methanol and toluene in (a) biofilters (BFs), and (b) biotrickling filters (BTFs), packed with inert materials, has been studied and analyzed. The specific growth rate, mu, for the treatment of methanol was 0.037h(-1) for a wide range of operating conditions. In the BF, mu was found to be a function of the methanol and toluene concentrations in the biofilm. In the BF used for treating methanol, mu was found to be affected by (1) the nitrogen concentration present in the nutrient solution, and (2) the kind of packing material employed. The kinetics of the methanol and toluene biodegradations were also analyzed using "mixed order" models. A Michaelis-Menten model type provided a good fit for the elimination capacity (EC) of the BTF treating methanol, while a Haldane model type provided a good fit to the EC of the BF treating methanol and toluene. The carbon dioxide production rate was related to the packed bed temperature and the content of the volatile solids within the biofilm. For the BF, the ratio of temperature/carbon dioxide production rate (PCO(2)) was 0.024 degrees C per unit of PCO(2), and for the BTF it was 0.15 degrees C per unit of PCO(2). PMID:18778740

  16. Evolution of cooperation in microbial biofilms - A stochastic model for the growth and survival of bacterial mats

    NASA Astrophysics Data System (ADS)

    Knebel, Johannes; Cremer, Jonas; Melbinger, Anna; Frey, Erwin

    2012-02-01

    Cooperative behavior is essential for microbial biofilms. The structure and composition of a biofilm change over time and thereby influence the evolution of cooperation within the system. In turn, the level of cooperation affects the growth dynamics of the biofilm. Here, we investigate this coupling for an experimentally well-defined situation in which mutants of the Pseudomonas fluorescens strain form a mat at the liquid-air interface by the production of an extra-cellular matrix [1]. We model the occurrence of cooperation in this bacterial population by taking into account the formation of the mat. The presence of cooperators enhances the growth of the mat, but at the same time cheaters can infiltrate the population and put the viability of the mat at risk. We find that the survival time of the mat crucially depends on its initial dynamics which is subject to demographic fluctuations [2]. More generally, our work provides conceptual insights into the requirements and mechanisms for the evolution of cooperation.[1] P. Rainey et al., Nature 425, 72 (2003).[2] A. Melbinger et al., PRL 105, 178101 (2010).

  17. Organizational Career Growth, Affective Occupational Commitment and Turnover Intentions

    ERIC Educational Resources Information Center

    Weng, Qingxiong; McElroy, James C.

    2012-01-01

    Survey data, collected from the People's Republic of China, were used to test Weng's (2010) four facet model of career growth and to examine its effect on occupational commitment and turnover intentions. Weng conceptualized career growth as consisting of four factors: career goal progress, professional ability development, promotion speed, and…

  18. Arid soil microbial enzymatic activity profile as affected by geographical location and soil degradation status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluating soil health is critical for any successful remediation effort. Arid lands, with their minimal carbon and water contents, low nutritional status and restricted, seasonal microbial activity pose specific challenges to soil health restoration and by extension, restoration of ecosystem repr...

  19. Yeast culture supplement during nursing and transport affects immunity and intestinal microbial ecology of weanling pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weaning and transport stress can have a negative impact on the piglet's immune system and intestinal microbiota. The objective of this study was to determine the influence of a yeast product on innate immunity and microbial ecology of the gastrointestinal tract following stress of weaning and trans...

  20. Factors Limiting Microbial Growth and Activity at a Proposed High-Level Nuclear Repository, Yucca Mountain, Nevada

    PubMed Central

    Kieft, T. L.; Kovacik, W. P.; Ringelberg, D. B.; White, D. C.; Haldeman, D. L.; Amy, P. S.; Hersman, L. E.

    1997-01-01

    As part of the characterization of Yucca Mountain, Nev., as a potential repository for high-level nuclear waste, volcanic tuff was analyzed for microbial abundance and activity. Tuff was collected aseptically from nine sites along a tunnel in Yucca Mountain. Microbial abundance was generally low: direct microscopic cell counts were near detection limits at all sites (3.2 x 10(sup4) to 2.0 x 10(sup5) cells g(sup-1) [dry weight]); plate counts of aerobic heterotrophs ranged from 1.0 x 10(sup1) to 3.2 x 10(sup3) CFU g(sup-1) (dry weight). Phospholipid fatty acid concentrations (0.1 to 3.7 pmol g(sup-1)) also indicated low microbial biomasses; diglyceride fatty acid concentrations, indicative of dead cells, were in a similar range (0.2 to 2.3 pmol g(sup-1)). Potential microbial activity was quantified as (sup14)CO(inf2) production in microcosms containing radiolabeled substrates (glucose, acetate, and glutamic acid); amendments with water and nutrient solutions (N and P) were used to test factors potentially limiting this activity. Similarly, the potential for microbial growth and the factors limiting growth were determined by performing plate counts before and after incubating volcanic tuff samples for 24 h under various conditions: ambient moisture, water-amended, and amended with various nutrient solutions (N, P, and organic C). A high potential for microbial activity was demonstrated by high rates of substrate mineralization (as much as 70% of added organic C in 3 weeks). Water was the major limiting factor to growth and microbial activity, while amendments with N and P resulted in little further stimulation. Organic C amendments stimulated growth more than water alone. PMID:16535670

  1. Impact of metabolism and growth phase on the hydrogen isotopic composition of microbial fatty acids

    PubMed Central

    Heinzelmann, Sandra M.; Villanueva, Laura; Sinke-Schoen, Danielle; Sinninghe Damsté, Jaap S.; Schouten, Stefan; van der Meer, Marcel T. J.

    2015-01-01

    Microorganisms are involved in all elemental cycles and therefore it is important to study their metabolism in the natural environment. A recent technique to investigate this is the hydrogen isotopic composition of microbial fatty acids, i.e., heterotrophic microorganisms produce fatty acids enriched in deuterium (D) while photoautotrophic and chemoautotrophic microorganisms produce fatty acids depleted in D compared to the water in the culture medium (growth water). However, the impact of factors other than metabolism have not been investigated. Here, we evaluate the impact of growth phase compared to metabolism on the hydrogen isotopic composition of fatty acids of different environmentally relevant microorganisms with heterotrophic, photoautotrophic and chemoautotrophic metabolisms. Fatty acids produced by heterotrophs are enriched in D compared to growth water with εlipid/water between 82 and 359‰ when grown on glucose or acetate, respectively. Photoautotrophs (εlipid/water between −149 and −264‰) and chemoautotrophs (εlipid/water between −217 and −275‰) produce fatty acids depleted in D. Fatty acids become, in general, enriched by between 4 and 46‰ with growth phase which is minor compared to the influence of metabolisms. Therefore, the D/H ratio of fatty acids is a promising tool to investigate community metabolisms in nature. PMID:26005437

  2. CO2 gradient affects on deep subsurface microbial ecology during carbon sequestration

    NASA Astrophysics Data System (ADS)

    Gulliver, D.; Gregory, K.

    2011-12-01

    Geological carbon sequestration is likely to be part of a comprehensive strategy to minimize the release of greenhouse gasses into the atmosphere. Reservoir storage capacities and long-term security of these deposits will be dependent on the trapping mechanisms and mineral transformation in the deep subsurface. Therefore, a critical need exists to understand the evolution of microbial populations that may influence the biogeochemistry in the reservoirs. As the CO2 front moves through the storage aquifer, microbial communities may preside in residual brine left behind in cracks, dead flow zones, and upstream to the front; this brine will have a gradient of dissolved CO2 in which microbial interaction may behave differently, depending on the distance from the CO2 front. The evolution of microbial ecology along this CO2 gradient was investigated using fluid-slurry samples obtained from the prospective carbon sequestration site, the Arbuckle saline aquifer at the Wellington oil field, KS. The native species of these samples were investigated with a series of batch reactors under constant temperature of 40 °C, constant total pressure of 2,000 psi, and varying CO2 partial pressures of 0 psi, 20 psi, 200 psi, and 2,000 psi. After 1 day, 7 days, and 56 days of exposure in the batch reactors, fluid samples were centrifuged and the resulting pellet was biologically analyzed. Clone libraries and quantitative PCR determined that the bacterial diversity and population of the native microbial community was dependant on both the duration of exposure and the CO2 partial pressure. For example, the microbial community of 0 psi CO2 and 20 psi CO2 was predominantly related to the families halomonadaceae and marinilabiaceae while at 2,000 psi CO2 the community was predominantly in the family psychromonadaceae. The population size at 2,000 psi CO2 was also found to decrease by 3 orders of magnitude after only 7 days of CO2 exposure. Although these experiments were relatively short

  3. Understanding the performance of sulfate reducing bacteria based packed bed reactor by growth kinetics study and microbial profiling.

    PubMed

    Dev, Subhabrata; Roy, Shantonu; Bhattacharya, Jayanta

    2016-07-15

    A novel marine waste extract (MWE) as alternative nitrogen source was explored for the growth of sulfate reducing bacteria (SRB). Variation of sulfate and nitrogen (MWE) showed that SRB growth follows an uncompetitive inhibition model. The maximum specific growth rates (μmax) of 0.085 and 0.124 h(-1) and inhibition constants (Ki) of 56 and 4.6 g/L were observed under optimized sulfate and MWE concentrations, respectively. The kinetic data shows that MWE improves the microbial growth by 27%. The packed bed bioreactor (PBR) under optimized sulfate and MWE regime showed sulfate removal efficiency of 62-66% and metals removal efficiency of 66-75% on using mine wastewater. The microbial community analysis using DGGE showed dominance of SRB (87-89%). The study indicated the optimum dosing of sulfate and cheap organic nitrogen to promote the growth of SRB over other bacteria. PMID:27085153

  4. Increased plant productivity and decreased microbial respiratory C loss by plant growth-promoting rhizobacteria under elevated CO2

    NASA Astrophysics Data System (ADS)

    Nie, Ming; Bell, Colin; Wallenstein, Matthew D.; Pendall, Elise

    2015-03-01

    Increased plant productivity and decreased microbial respiratory C loss can potentially mitigate increasing atmospheric CO2, but we currently lack effective means to achieve these goals. Soil microbes may play critical roles in mediating plant productivity and soil C/N dynamics under future climate scenarios of elevated CO2 (eCO2) through optimizing functioning of the root-soil interface. By using a labeling technique with 13C and 15N, we examined the effects of plant growth-promoting Pseudomonas fluorescens on C and N cycling in the rhizosphere of a common grass species under eCO2. These microbial inoculants were shown to increase plant productivity. Although strong competition for N between the plant and soil microbes was observed, the plant can increase its capacity to store more biomass C per unit of N under P. fluorescens addition. Unlike eCO2 effects, P. fluorescens inoculants did not change mass-specific microbial respiration and accelerate soil decomposition related to N cycling, suggesting these microbial inoculants mitigated positive feedbacks of soil microbial decomposition to eCO2. The potential to mitigate climate change by optimizing soil microbial functioning by plant growth-promoting Pseudomonas fluorescens is a prospect for ecosystem management.

  5. Increased plant productivity and decreased microbial respiratory C loss by plant growth-promoting rhizobacteria under elevated CO2

    PubMed Central

    Nie, Ming; Bell, Colin; Wallenstein, Matthew D.; Pendall, Elise

    2015-01-01

    Increased plant productivity and decreased microbial respiratory C loss can potentially mitigate increasing atmospheric CO2, but we currently lack effective means to achieve these goals. Soil microbes may play critical roles in mediating plant productivity and soil C/N dynamics under future climate scenarios of elevated CO2 (eCO2) through optimizing functioning of the root-soil interface. By using a labeling technique with 13C and 15N, we examined the effects of plant growth-promoting Pseudomonas fluorescens on C and N cycling in the rhizosphere of a common grass species under eCO2. These microbial inoculants were shown to increase plant productivity. Although strong competition for N between the plant and soil microbes was observed, the plant can increase its capacity to store more biomass C per unit of N under P. fluorescens addition. Unlike eCO2 effects, P. fluorescens inoculants did not change mass-specific microbial respiration and accelerate soil decomposition related to N cycling, suggesting these microbial inoculants mitigated positive feedbacks of soil microbial decomposition to eCO2. The potential to mitigate climate change by optimizing soil microbial functioning by plant growth-promoting Pseudomonas fluorescens is a prospect for ecosystem management. PMID:25784647

  6. Elemental Economy: microbial strategies for optimizing growth in the face of nutrient limitation

    PubMed Central

    Merchant, Sabeeha S.; Helmann, John D.

    2014-01-01

    Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility at fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Despite their prodigious capacity for molecular transformations, microorganisms are powerless in the face of the immutability of the elements. Limitations for specific elements, either fleeting or persisting over eons, have left an indelible trace on microbial genomes, physiology, and their very atomic composition. We here review the impact of elemental limitation on microbes, with a focus on selected genetic model systems and representative microbes from the ocean ecosystem. Evolutionary adaptations that enhance growth in the face of persistent or recurrent elemental limitations are evident from genome and proteome analyses. These range from the extreme (such as dispensing with a requirement for a hard to obtain element) to the extremely subtle (changes in protein amino acid sequences that slightly, but significantly, reduce cellular carbon, nitrogen, or sulfur demand). One near universal adaptation is the development of sophisticated acclimation programs by which cells adjust their chemical composition in response to a changing environment. When specific elements become limiting, acclimation typically begins with an increased commitment to acquisition and a concomitant mobilization of stored resources. If elemental limitation persists, the cell implements austerity measures including elemental-sparing and elemental-recycling. Insights into these fundamental cellular properties have emerged from studies at many different levels; including ecology, biological oceanography, biogeochemistry, molecular genetics, genomics, and microbial physiology. Here, we present a synthesis of these diverse studies and attempt to discern some overarching themes. PMID:22633059

  7. Slower Economic Growth Affects the 1995 Labor Market.

    ERIC Educational Resources Information Center

    Gardner, Jennifer M.; Hayghe, Howard V.

    1996-01-01

    Shows how job growth slowed dramatically in 1995, but the unemployment rate remained little changed. Discusses trends in nonfarm payroll employment by industry and changes in employment status of people in various demographic and occupational groups. (Author)

  8. Growth performance and intestinal microbial populations of growing pigs fed diets containing sucrose thermal oligosaccharide caramel.

    PubMed

    Orban, J I; Patterson, J A; Adeola, O; Sutton, A L; Richards, G N

    1997-01-01

    Four experiments were conducted to determine growth performance and changes in intestinal microbial populations of growing pigs fed diets containing sucrose thermal oligosaccharide caramel (STOC). Ninety-six barrows and 96 gilts were group-fed experimental nursery diets for 32 d after weaning in both Exp. 1 and 2. For each experiment, pigs were divided into four groups of 48 pigs and were fed either control, antibiotic (Apramycin sulfate, 34 mg/kg), 1% STOC, or 2% STOC diets for 32 d after weaning. Each diet was replicated six times with eight pigs per replication. Pigs were either orally gavaged (Exp 1) with water of STOC (2 g per pig) or pigs were creep-fed (Exp 2) either a control diet or a 2% STOC diet for 5 d before weaning (33 d). At the end of Exp 1 and 2, cecal material was collected for enumeration of total aerobes, total anaerobes, coliforms, lactobacilli, and bifidobacteria. Gilts (96 per experiment) used in Exp. 3 and 4 were weaned at 26 d and fed experimental nursery diets for 32 d. They were fed either a control or 1% STOC diet and were otherwise treated as previously described. There were no significant effects of STOC or antibiotic on ADG, ADFI, feed efficiency, or cecal microbial populations in pigs in this study. Feeding diets containing either antibiotic of STOC did not improve animal performance or change intestinal bacterial populations in the present study. PMID:9027562

  9. Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources.

    PubMed

    Kai, Fuu Ming; Tyler, Stanley C; Randerson, James T; Blake, Donald R

    2011-08-11

    Atmospheric methane (CH(4)) increased through much of the twentieth century, but this trend gradually weakened until a stable state was temporarily reached around the turn of the millennium, after which levels increased once more. The reasons for the slowdown are incompletely understood, with past work identifying changes in fossil fuel, wetland and agricultural sources and hydroxyl (OH) sinks as important causal factors. Here we show that the late-twentieth-century changes in the CH(4) growth rates are best explained by reduced microbial sources in the Northern Hemisphere. Our results, based on synchronous time series of atmospheric CH(4) mixing and (13)C/(12)C ratios and a two-box atmospheric model, indicate that the evolution of the mixing ratio requires no significant change in Southern Hemisphere sources between 1984 and 2005. Observed changes in the interhemispheric difference of (13)C effectively exclude reduced fossil fuel emissions as the primary cause of the slowdown. The (13)C observations are consistent with long-term reductions in agricultural emissions or another microbial source within the Northern Hemisphere. Approximately half (51 ± 18%) of the decrease in Northern Hemisphere CH(4) emissions can be explained by reduced emissions from rice agriculture in Asia over the past three decades associated with increases in fertilizer application and reductions in water use. PMID:21833086

  10. Prospecting cold deserts of north western Himalayas for microbial diversity and plant growth promoting attributes.

    PubMed

    Yadav, Ajar Nath; Sachan, Shashwati Ghosh; Verma, Priyanka; Saxena, Anil Kumar

    2015-06-01

    Microbial communities in different samples collected from cold deserts of north western Himalayas, India, were analyzed using 16S rRNA gene sequencing and phospholipid fatty acids (PLFA) analysis. A total of 232 bacterial isolates were characterized employing 16S rDNA-Amplified Ribosomal DNA Restriction Analysis with the three restriction endonucleases Alu I, Msp I and Hae III, which led to formation of 29-54 groups for the different sites, adding up to169 groups. 16S rRNA gene based phylogenetic analysis, revealed that 82 distinct species of 31 different genera, belonged to four phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. PLFA profiling was performed for concerned samples which gave an estimate of microbial communities without cultivating the microorganisms. PLFA analysis led to characterization of diverse group of microbes in different samples such as gram-negative, gram-positive bacteria, actinomycetes, cyanobacteria, anaerobic bacteria, sulphate reducing bacteria and fungi. The representative strains were screened for their plant growth promoting attributes, which included production of ammonia, HCN, gibberellic acid, IAA and siderophore; solubilization of phosphorus and activity of ACC deaminase. In vitro antifungal activity assay was performed against Rhizoctonia solani and Macrophomina phaseolina. Cold adapted microorganisms may serve as inoculants for crops growing under cold climatic conditions. To our knowledge, this is the first report for the presence of Arthrobacter nicotianae, Brevundimonas terrae, Paenibacillus tylopili and Pseudomonas cedrina in cold deserts and exhibit multifunctional PGP attributes at low temperatures. PMID:25575970

  11. Spatial pattern formation of microbes at the soil microscale affect soil C and N turnover in an individual-based microbial community model

    NASA Astrophysics Data System (ADS)

    Kaiser, Christina; Evans, Sarah; Dieckmann, Ulf; Widder, Stefanie

    2016-04-01

    At the μm-scale, soil is a highly structured and complex environment, both in physical as well as in biological terms, characterized by non-linear interactions between microbes, substrates and minerals. As known from mathematics and theoretical ecology, spatial structure significantly affects the system's behaviour by enabling synergistic dynamics, facilitating diversity, and leading to emergent phenomena such as self-organisation and self-regulation. Such phenomena, however, are rarely considered when investigating mechanisms of microbial soil organic matter turnover. Soil organic matter is the largest terrestrial reservoir for organic carbon (C) and nitrogen (N) and plays a pivotal role in global biogeochemical cycles. Still, the underlying mechanisms of microbial soil organic matter buildup and turnover remain elusive. We explored mechanisms of microbial soil organic matter turnover using an individual-based, stoichiometrically and spatially explicit computer model, which simulates the microbial de-composer system at the soil microscale (i.e. on a grid of 100 x 100 soil microsites). Soil organic matter dynamics in our model emerge as the result of interactions among individual microbes with certain functional traits (f.e. enzyme production rates, growth rates, cell stoichiometry) at the microscale. By degrading complex substrates, and releasing labile substances microbes in our model continusly shape their environment, which in turn feeds back to spatiotemporal dynamics of the microbial community. In order to test the effect of microbial functional traits and organic matter input rate on soil organic matter turnover and C and N storage, we ran the model into steady state using continuous inputs of fresh organic material. Surprisingly, certain parameter settings that induce resource limitation of microbes lead to regular spatial pattern formation (f.e. moving spiral waves) of microbes and substrate at the μm-scale at steady-state. The occurrence of these

  12. Cry1Ac Transgenic Sugarcane Does Not Affect the Diversity of Microbial Communities and Has No Significant Effect on Enzyme Activities in Rhizosphere Soil within One Crop Season

    PubMed Central

    Zhou, Dinggang; Xu, Liping; Gao, Shiwu; Guo, Jinlong; Luo, Jun; You, Qian; Que, Youxiong

    2016-01-01

    Cry1Ac transgenic sugarcane provides a promising way to control stem-borer pests. Biosafety assessment of soil ecosystem for cry1Ac transgenic sugarcane is urgently needed because of the important role of soil microorganisms in nutrient transformations and element cycling, however little is known. This study aimed to explore the potential impact of cry1Ac transgenic sugarcane on rhizosphere soil enzyme activities and microbial community diversity, and also to investigate whether the gene flow occurs through horizontal gene transfer. We found no horizontal gene flow from cry1Ac sugarcane to soil. No significant difference in the population of culturable microorganisms between the non-GM and cry1Ac transgenic sugarcane was observed, and there were no significant interactions between the sugarcane lines and the growth stages. A relatively consistent trend at community-level, represented by the functional diversity index, was found between the cry1Ac sugarcane and the non-transgenic lines. Most soil samples showed no significant difference in the activities of four soil enzymes: urease, protease, sucrose, and acid phosphate monoester between the non-transgenic and cry1Ac sugarcane lines. We conclude, based on one crop season, that the cry1Ac sugarcane lines may not affect the microbial community structure and functional diversity of the rhizosphere soil and have few negative effects on soil enzymes. PMID:27014291

  13. Coupling Microbial Growth with Nanoparticles: A Universal Strategy To Produce Functional Fungal Hyphae Macrospheres.

    PubMed

    Zhu, Wen-Kun; Cong, Huai-Ping; Guan, Qing-Fang; Yao, Wei-Tang; Liang, Hai-Wei; Wang, Wei; Yu, Shu-Hong

    2016-05-25

    Macroscale assembly of nanoscale building blocks is an intriguing way to translate the unique characteristics of individual nanoparticles into macroscopic materials. However, the lack of the efficient universal assembly strategy seriously hinders the possibility of macroscale architectures in practical applications. Herein, we develop a general, environment-friendly, and scalable microbial growth method for the construction of macroscopic composite assemblies with excellent mechanical strength by in situ integrating various types of nanoparticles into fungal hyphae (FH) macrospheres. Notably, the size of the FH-based composite spheres and the loading amount of the nanoparticles with different dimensions can be well tuned by controlling the cultivation time and the dosage of nanoparticles, respectively. Interestingly, bifunctional FH-based core-shell macrospheres can also be achieved by programmed assembling two different kinds of nanoparticles in the cultivation process. The produced multifunctional FH-based composite spheres exhibit wide potential applications in magnetic actuation, photothermal therapy, and contaminant adsorption, etc. PMID:27148809

  14. Well constructions with inhibited microbial growth and methods of antimicrobial treatment in wells

    DOEpatents

    Lee, Brady D.; Dooley, Kirk J.

    2004-11-02

    The invention includes methods of inhibiting microbial growth in a well. A packing material containing a mixture of a first material and an antimicrobial agent is provided to at least partially fill a well bore. One or more access tubes are provided in an annular space around a casing within the well bore. The access tubes have a first terminal opening located at or above a ground surface and have a length that extends from the first terminal opening at least part of the depth of the well bore. The access tubes have a second terminal opening located within the well bore. An antimicrobial material is supplied into the well bore through the first terminal opening of the access tubes. The invention also includes well constructs.

  15. Volatile organic compounds associated with microbial growth in automobile air conditioning systems.

    PubMed

    Rose, L J; Simmons, R B; Crow, S A; Ahearn, D G

    2000-09-01

    Volatile organic compounds from Penicillium viridicatum and Methylobacterium mesophilicum growing on laboratory media and on component materials of automobile air conditioners were analyzed with gas chromatography and mass spectrometry. P. viridicatum produced compounds such as 4-methyl thiazole, terpenes and alcohols, whereas M. mesophilicum produced dimethyl disulfide, dimethyl trisulfide, and chlorophenol with growth on laboratory media. In comparison with laboratory media, fewer volatiles were detected from colonized foam insulation materials. Biofilms of M. mesophilicum on aluminum evaporator components produced mainly dimethyl disulfide. These biofilms, after inoculation with P. viridicatum, produced offensive smelling alcohols and esters such as 2-methyl propanol, 3-penten-2-ol, and the ethyl ester of butanoic acid. The moisture and substrates innate to the automobile air conditioning systems provided an environment suitable for microbial biofilm development and odor production. Reduction of retained moisture in the air conditioning system coupled with use of less susceptible or antimicrobial substrates are advised for remediation of the noxious odors. PMID:10915209

  16. The mechanism of ethanol treatment on inhibiting lettuce enzymatic browning and microbial growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tissue browning of fresh-cut lettuce greatly affects its quality and consumers’ appreciation. This study investigated the effects of ethanol treatment on enzymatic browning and natural microflora growth of lettuce stem discs. After treated with 20% ethanol for 2 min and then drained by a spinner, le...

  17. Next-Generation Pyrosequencing Analysis of Microbial Biofilm Communities on Granular Activated Carbon in Treatment of Oil Sands Process-Affected Water

    PubMed Central

    Islam, M. Shahinoor; Zhang, Yanyan; McPhedran, Kerry N.

    2015-01-01

    The development of biodegradation treatment processes for oil sands process-affected water (OSPW) has been progressing in recent years with the promising potential of biofilm reactors. Previously, the granular activated carbon (GAC) biofilm process was successfully employed for treatment of a large variety of recalcitrant organic compounds in domestic and industrial wastewaters. In this study, GAC biofilm microbial development and degradation efficiency were investigated for OSPW treatment by monitoring the biofilm growth on the GAC surface in raw and ozonated OSPW in batch bioreactors. The GAC biofilm community was characterized using a next-generation 16S rRNA gene pyrosequencing technique that revealed that the phylum Proteobacteria was dominant in both OSPW and biofilms, with further in-depth analysis showing higher abundances of Alpha- and Gammaproteobacteria sequences. Interestingly, many known polyaromatic hydrocarbon degraders, namely, Burkholderiales, Pseudomonadales, Bdellovibrionales, and Sphingomonadales, were observed in the GAC biofilm. Ozonation decreased the microbial diversity in planktonic OSPW but increased the microbial diversity in the GAC biofilms. Quantitative real-time PCR revealed similar bacterial gene copy numbers (>109 gene copies/g of GAC) for both raw and ozonated OSPW GAC biofilms. The observed rates of removal of naphthenic acids (NAs) over the 2-day experiments for the GAC biofilm treatments of raw and ozonated OSPW were 31% and 66%, respectively. Overall, a relatively low ozone dose (30 mg of O3/liter utilized) combined with GAC biofilm treatment significantly increased NA removal rates. The treatment of OSPW in bioreactors using GAC biofilms is a promising technology for the reduction of recalcitrant OSPW organic compounds. PMID:25841014

  18. Next-generation pyrosequencing analysis of microbial biofilm communities on granular activated carbon in treatment of oil sands process-affected water.

    PubMed

    Islam, M Shahinoor; Zhang, Yanyan; McPhedran, Kerry N; Liu, Yang; Gamal El-Din, Mohamed

    2015-06-15

    The development of biodegradation treatment processes for oil sands process-affected water (OSPW) has been progressing in recent years with the promising potential of biofilm reactors. Previously, the granular activated carbon (GAC) biofilm process was successfully employed for treatment of a large variety of recalcitrant organic compounds in domestic and industrial wastewaters. In this study, GAC biofilm microbial development and degradation efficiency were investigated for OSPW treatment by monitoring the biofilm growth on the GAC surface in raw and ozonated OSPW in batch bioreactors. The GAC biofilm community was characterized using a next-generation 16S rRNA gene pyrosequencing technique that revealed that the phylum Proteobacteria was dominant in both OSPW and biofilms, with further in-depth analysis showing higher abundances of Alpha- and Gammaproteobacteria sequences. Interestingly, many known polyaromatic hydrocarbon degraders, namely, Burkholderiales, Pseudomonadales, Bdellovibrionales, and Sphingomonadales, were observed in the GAC biofilm. Ozonation decreased the microbial diversity in planktonic OSPW but increased the microbial diversity in the GAC biofilms. Quantitative real-time PCR revealed similar bacterial gene copy numbers (>10(9) gene copies/g of GAC) for both raw and ozonated OSPW GAC biofilms. The observed rates of removal of naphthenic acids (NAs) over the 2-day experiments for the GAC biofilm treatments of raw and ozonated OSPW were 31% and 66%, respectively. Overall, a relatively low ozone dose (30 mg of O3/liter utilized) combined with GAC biofilm treatment significantly increased NA removal rates. The treatment of OSPW in bioreactors using GAC biofilms is a promising technology for the reduction of recalcitrant OSPW organic compounds. PMID:25841014

  19. The soil microbial community composition and soil microbial carbon uptake are more affected by soil type than by different vegetation types (C3 and C4 plants) and seasonal changes

    NASA Astrophysics Data System (ADS)

    Griselle Mellado Vazquez, Perla; Lange, Markus; Gleixner, Gerd

    2016-04-01

    This study investigates the influence of different vegetation types (C3 and C4 plants), soil type and seasonal changes on the soil microbial biomass, soil microbial community composition and soil microbial carbon (C) uptake. We collected soil samples in winter (non-growing season) and summer (growing season) in 2012 from an experimental site cropping C3 and C4 plants for 6 years on two different soil types (sandy and clayey). The amount of phospholipid fatty acids (PLFAs) and their compound-specific δ13C values were used to determined microbial biomass and the flow of C from plants to soil microorganisms, respectively. Higher microbial biomass was found in the growing season. The microbial community composition was mainly explained by soil type. Higher amounts of SOC were driving the predominance of G+ bacteria, actinobacteria and cyclic G- bacteria in sandy soils, whereas root biomass was significantly related to the increased proportions of G- bacteria in clayey soils. Plant-derived C in G- bacteria increased significantly in clayey soils in the growing season. This increase was positively and significantly driven by root biomass. Moreover, changes in plant-derived C among microbial groups pointed to specific capabilities of different microbial groups to decompose distinct sources of C. We concluded that soil texture and favorable growth conditions driven by rhizosphere interactions are the most important factors controlling the soil microbial community. Our results demonstrate that a change of C3 plants vs. C4 plants has only a minor effect on the soil microbial community. Thus, such experiments are well suited to investigate soil organic matter dynamics as they allow to trace the C flow from plants into the soil microbial community without changing the community abundance and composition.

  20. Effects of electron beam irradiation on the microbial growth and quality of beef jerky during storage

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Chun, Ho-Hyun; Song, Hyeon-Jeong; Song, Kyung-Bin

    2010-11-01

    Electron beam irradiation was applied to improve the microbial safety of beef jerky during storage. Beef jerky samples were irradiated at doses of 1, 3, 5, and 10 kGy and stored at 20 °C for 60 d. Microbiological data indicated that the populations of total aerobic bacteria significantly decreased with increasing irradiation dosage. In particular, the populations of total aerobic bacteria were significantly decreased by 1.76 log CFU/g at 10 kJ/m 2, compared to the control. Color measurements showed reduced Hunter L and a values of beef jerky for all the treatments during storage, and the Hunter L, a, and b values of beef jerky were not significantly different among the treatments. Sensory evaluation results also showed that electron beam irradiation did not affect sensory scores in overall during storage. Therefore, the results suggest that electron beam irradiation could be useful in improving the microbial safety without impairing the quality of beef jerky during storage.

  1. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Wheeler, R. M.; Sager, J. C.; Knott, W. M.

    1990-01-01

    The development of the tubular membrane plant growth unit for the delivery of water and nutrients to roots in microgravity has recently focused on measuring the effects of changes in physical variables controlling solution availability to the plants. Significant effects of membrane pore size and the negative pressure used to contain the solution were demonstrated. Generally, wheat grew better in units with a larger pore size but equal negative pressure and in units with the same pore size but less negative pressure. Lettuce also exhibited better plant growth at less negative pressure.

  2. Fecal Microbial Diversity in Pre-Weaned Dairy Calves as Described by Pyrosequencing of Metagenomic 16S rDNA. Associations of Faecalibacterium Species with Health and Growth

    PubMed Central

    Oikonomou, Georgios; Teixeira, Andre Gustavo Vieira; Foditsch, Carla; Bicalho, Marcela Lucas; Machado, Vinicius Silva; Bicalho, Rodrigo Carvalho

    2013-01-01

    In this study, we use barcoded pyrosequencing of the 16S rRNA gene to characterize the fecal microbiota of neonatal calves and identify possible relationships of certain microbiota profiles with health and weight gain. Fecal samples were obtained weekly from 61 calves from birth until weaning (seventh week of the calves' life). Firmicutes was the most prevalent phylum, with a prevalence ranging from 63.84% to 81.90%, followed by Bacteroidetes (8.36% to 23.93%), Proteobacteria (3.72% to 9.75%), Fusobacteria (0.76% to 5.67%), and Actinobacteria (1.02% to 2.35%). Chao1 index gradually increased from the first to the seventh postnatal week. Chao1 index was lower during the third, fourth, and fifth week of life in calves that suffered from pneumonia and were treated with antibiotics. Diarrhea incidence during the first four weeks of the calves' life was also associated with a reduction of microbial diversity during the third week of life. Increased fecal microbial diversity after the second week of life was associated with higher weight gain. Using discriminant analysis we were able to show differences in the microbiota profiles between different weeks of life, between high and low weight gain groups of calves, and between calves affected and not affected with diarrhea during the first four weeks life. The prevalence of Faecalibacterium spp. in the first week of life was associated with weight gain and the incidence of diarrhea, with higher prevalence being associated with higher weight gain and less diarrhea. Representative sequences from Faecalibacterium spp. were closely affiliated to Faecalibacterium prausnitzii. Results presented here provide new information regarding the intestinal microbiota of neonatal calves and its association with health and growth. Fecal microbial diversity was associated with calf age, disease status and growth rates. Results suggesting a possible beneficial effect of Faecalibacterium spp. on health and growth are promising. PMID:23646192

  3. Adenoma-linked barrier defects and microbial products drive IL-23/IL-17-mediated tumour growth

    PubMed Central

    Grivennikov, Sergei I.; Wang, Kepeng; Mucida, Daniel; Stewart, C. Andrew; Schnabl, Bernd; Jauch, Dominik; Taniguchi, Koji; Yu, Guann-Yi; Osterreicher, Christoph H.; Hung, Kenneth E.; Datz, Christian; Feng, Ying; Fearon, Eric R.; Oukka, Mohamed; Tessarollo, Lino; Coppola, Vincenzo; Yarovinsky, Felix; Cheroutre, Hilde; Eckmann, Lars; Trinchieri, Giorgio; Karin, Michael

    2013-01-01

    Approximately 2% of colorectal cancer is linked to pre-existing inflammation known as colitis-associated cancer, but most develops in patients without underlying inflammatory bowel disease. Colorectal cancer often follows a genetic pathway whereby loss of the adenomatous polyposis coli (APC) tumour suppressor and activation of β-catenin are followed by mutations in K-Ras, PIK3CA and TP53, as the tumour emerges and progresses1,2. Curiously, however, ‘inflammatory signature’ genes characteristic of colitis-associated cancer are also upregulated in colorectal cancer3,4. Further, like most solid tumours, colorectal cancer exhibits immune/inflammatory infiltrates5, referred to as ‘tumour elicited inflammation’6. Although infiltrating CD4+ TH1 cells and CD8+ cytotoxic T cells constitute a positive prognostic sign in colorectal cancer7,8, myeloid cells and T-helper interleukin (IL)-17-producing (TH17) cells promote tumorigenesis5,6, and a ‘TH17 expression signature’ in stage I/II colorectal cancer is associated with a drastic decrease in disease-free survival9. Despite its pathogenic importance, the mechanisms responsible for the appearance of tumour-elicited inflammation are poorly understood. Many epithelial cancers develop proximally to microbial communities, which are physically separated from immune cells by an epithelial barrier10. We investigated mechanisms responsible for tumour-elicited inflammation in a mouse model of colorectal tumorigenesis, which, like human colorectal cancer, exhibits upregulation of IL-23 and IL-17. Here we show that IL-23 signalling promotes tumour growth and progression, and development of a tumoural IL-17 response. IL-23 is mainly produced by tumour-associated myeloid cells that are likely to be activated by microbial products, which penetrate the tumours but not adjacent tissue. Both early and late colorectal neoplasms exhibit defective expression of several barrier proteins. We propose that barrier deterioration induced by

  4. Dissolved oxygen concentration affects hybrid striped bass growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in ponds at night during the growing season is important because fish growth and yield are greater in ponds with higher nightly DO concentrations. Three studies were conducted to quantify performance traits and metabolic responses of hybrid striped b...

  5. Seed Production Affects Maternal Growth and Senescence in Arabidopsis.

    PubMed

    Wuest, Samuel Elias; Philipp, Matthias Anton; Guthörl, Daniela; Schmid, Bernhard; Grossniklaus, Ueli

    2016-05-01

    Correlative control (influence of one organ over another organ) of seeds over maternal growth is one of the most obvious phenotypic expressions of the trade-off between growth and reproduction. However, the underlying molecular mechanisms are largely unknown. Here, we characterize the physiological and molecular effects of correlative inhibition by seeds on Arabidopsis (Arabidopsis thaliana) inflorescences, i.e. global proliferative arrest (GPA) during which all maternal growth ceases upon the production of a given number of seeds. We observed transcriptional responses to growth- and branching-inhibitory hormones, and low mitotic activity in meristems upon GPA, but found that meristems retain their identity and proliferative potential. In shoot tissues, we detected the induction of stress- and senescence-related gene expression upon fruit production and GPA, and a drop in chlorophyll levels, suggestive of altered source-sink relationships between vegetative shoot and reproductive tissues. Levels of shoot reactive oxygen species, however, strongly decreased upon GPA, a phenomenon that is associated with bud dormancy in some perennials. Indeed, gene expression changes in arrested apical inflorescences after fruit removal resembled changes observed in axillary buds following release from apical dominance. This suggests that GPA represents a form of bud dormancy, and that dominance is gradually transferred from growing inflorescences to maturing seeds, allowing offspring control over maternal resources, simultaneously restricting offspring number. This would provide a mechanistic explanation for the constraint between offspring quality and quantity. PMID:27009281

  6. Reducing microbial growth and improving quality of fresh-cut table grapes using a mild heat treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Packaged fresh-cut table grapes (Vitis vinifera L.) have emerged as a popular snack food because they offer freshness, nutrition, and convenience. However, tissue injury sustained during stem removal, and the openings created after stem removal make the grapes susceptible to microbial growth, produ...

  7. BIODEGRADATION DURING CONTAMINANT TRANSPORT IN POROUS MEDIA. 4. IMPACT OF MICROBIAL LAG AND BACTERIAL CELL GROWTH. (R825415)

    EPA Science Inventory

    Abstract

    Miscible-displacement experiments were conducted to examine the impact of microbial lag and bacterial cell growth on the transport of salicylate, a model hydrocarbon compound. The impacts of these processes were examined separately, as well as jointly, to dete...

  8. Effects of Direct-Fed Microbials on Growth Performance, Gut Morphometry, and Immune Characteristics in Broiler Chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to compare growth performance, gut morphometry, and parameters of local and systemic immunity in broiler chickens fed for 22 consecutive days with a diet supplemented with one of eight Bacillus spp. as a direct-fed microbial (DFM), a commercial product incorporating three DF...

  9. Effects of direct-fed microbials on growth performance, gut morphometry, and immune characteristics in broiler chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to compare growth performance, gut morphometry, and parameters of local and systemic immunity in broiler chickens fed for 22 consecutive days with a diet supplemented with one of eight Bacillus spp. as a direct-fed microbial (DFM), a commercial product incorporating three DF...

  10. Biogeochemistry of Stinking Springs, Utah. Part II: Microbial Diversity and Photo- and Chemo-Autotrophic Growth Rates in a Layered Microbial Mat

    NASA Astrophysics Data System (ADS)

    Monteverde, D.; Metzger, J. G.; Bournod, C.; Kelly, H.; Johnson, H.; Sessions, A. L.; Osburn, M.; Shapiro, R. S.; Rideout, J.; Johnston, D. T.; Stevenson, B.; Stamps, B. W.; Vuono, D.; Hanselmann, K.; Spear, J. R.

    2013-12-01

    Layered microbial mats have garnered attention for their high phylogenetic diversity and exploitation of geochemical gradients often on the mm scale. However, despite their novelty and implications for early life diversification, little is known about layered microbial mat growth rates or the interdependence of the microbial communities within the system. Stinking Springs, a warm, sulfidic, saline spring northeast of the Great Salt Lake, serves as our test-site to investigate some of these questions. Stinking Springs undergoes downstream changes in pH (6.59-8.14), sulfide (527μM - below detection), sulfate (13-600μM), TCO2 (7.77-3.71mM), and temperature (40-21°C) along its ~150m flow path. The first 10m of discharge is channelized, beyond that, the spring supports a 10 to 40mm-thick layered microbial mat covering ~40% of the total spring runoff area. The mat was divided into four texturally-distinct layers which were each analyzed for 16S rRNA, lipid abundance, and bicarbonate and acetate uptake rates in addition to standard microscopy analyses. 16S rRNA analyses confirmed high taxa diversity within each layer, which varied significantly in taxa makeup such that no single phylum dominated the abundance (>33%) in more than one mat layer. The taxonomic diversity tended to increase with mat depth, a similar finding to other studies on layered microbial mats. A mat sampling transect across 16 meters showed that layer taxonomic diversity was conserved horizontally for all four mat layers, which implies mat depth has a larger control on diversity than physical or chemical parameters. Microscopy indicated the presence of diatoms in all layers which was confirmed by lipid abundance of sterols and long-branch fatty acid methyl esters. Incubation experiments were conducted in light and dark conditions over 24 hours with separate 13C-tagged bicarbonate and acetate additions. Heterotrophic growth rates (acetate uptake; 0.03-0.65%/day) were higher than autotrophic growth

  11. Phasic temperature change patterns affect growth and tuberization in potatoes

    SciTech Connect

    Cao, W.; Tibbitts, T.W. . Dept. of Horticulture)

    1994-07-01

    This study determined the response of potato (Solanum tuberosum L., cv. Norland) plants to various patterns of air temperature changes over different growth periods. In each of two experiments under controlled environments, eight treatments of temperature changes were carried out in two growth rooms maintained at 17 and 22 C and a constant vapor pressure deficit of 0.60 kPa and 14-hour photoperiod. Plants were grown for 63 days after transplanting of tissue culture plantlets in 20-liter pots containing peat-vermiculite mix. Temperature changes were imposed on days 21 and 42, which were essentially at the beginning of tuber initiation and tuber enlargement, respectively, for this cultivar. Plants were moved between two temperature rooms to obtain eight temperature change patterns: 17-17-17, 17-17-22, 17-22-17, 22-17-17, 17-22-22, 22-17-22, 22-22-17, and 22-22-22C over three 21-day growth periods. At harvest on day 63, total plant dry weight was higher for the treatments beginning with 22 C than for those beginning with 17C, with highest biomass obtained at 22-22-17 and 22-17-17C. Shoot dry weight increased with temperature increased from 17-17-17 to 22-22-22C during the three growth periods. Tuber dry weight was highest with 22-17-17C, and lowest with 17-17-22 and 17-22-22C. With 22-17-17C, both dry weights of stolons and roots were lowest. Total tuber number and number of small tubers were highest with 17-17-17 and 17-17-22C, and lowest with 17-22-22 and 22-22-22C, whereas number of medium tubers was highest with 22-17-22C, and number of large tubers was highest with 22-17-17C. This study indicates that tuber development of potatoes is optimized with a phasic pattern of high temperature during early growth and low temperature during later growth.

  12. Soil moisture variations affect short-term plant-microbial competition for ammonium, glycine, and glutamate

    PubMed Central

    Månsson, Katarina F; Olsson, Magnus O; Falkengren-Grerup, Ursula; Bengtsson, Göran

    2014-01-01

    We tested whether the presence of plant roots would impair the uptake of ammonium (), glycine, and glutamate by microorganisms in a deciduous forest soil exposed to constant or variable moisture in a short-term (24-h) experiment. The uptake of 15NH4 and dual labeled amino acids by the grass Festuca gigantea L. and soil microorganisms was determined in planted and unplanted soils maintained at 60% WHC (water holding capacity) or subject to drying and rewetting. The experiment used a design by which competition was tested in soils that were primed by plant roots to the same extent in the planted and unplanted treatments. Festuca gigantea had no effect on microbial N uptake in the constant moist soil, but its presence doubled the microbial uptake in the dried and rewetted soil compared with the constant moist. The drying and rewetting reduced by half or more the uptake by F. gigantea, despite more than 60% increase in the soil concentration of . At the same time, the amino acid and -N became equally valued in the plant uptake, suggesting that plants used amino acids to compensate for the lower acquisition. Our results demonstrate the flexibility in plant-microbial use of different N sources in response to soil moisture fluctuations and emphasize the importance of including transient soil conditions in experiments on resource competition between plants and soil microorganisms. Competition between plants and microorganisms for N is demonstrated by a combination of removal of one of the potential competitors, the plant, and subsequent observations of the uptake of N in the organisms in soils that differ only in the physical presence and absence of the plant during a short assay. Those conditions are necessary to unequivocally test for competition. PMID:24772283

  13. Feedbacks between flow, sediment motion and microbial growth on sand bars initiate and shape elongated stromatolite mounds

    NASA Astrophysics Data System (ADS)

    Mariotti, G.; Perron, J. T.; Bosak, T.

    2014-07-01

    Elongated stromatolites are often used as indicators of current direction and shoreline orientation, especially in paleoenvironmental reconstructions. However, mechanisms that create shore-parallel, m-scale elongated stromatolite mounds in carbonate sand are not well understood. We propose that this geometry is initiated by microbial growth on the parts of sand bars that experience low wave-induced bed shear stresses. We test this idea by growing microbial mats on carbonate sand bars in a laboratory wave tank. Cyanobacterial mats grow on the bar runnels, where sediment motion is negligible, but are absent from the bar ridges, where the waves generate migrating ripples. When microbially-promoted lithification reinforces and preserves this initial pattern, elongated stromatolites should initiate in the runnels of sand bars, with long wavelengths (5-100 m) and small width-to-wavelength ratios (∼0.3). These dimensions are consistent with modern shore-parallel stromatolites in Hamelin Pool, Western Australia, and with patterns of microbial colonization in other sandy sediments. This model of elongated stromatolite mounds can inform paleoenvironmental reconstructions by clarifying and quantifying feedbacks among waves, sediment transport and microbial growth.

  14. Organic Matter Loading Affects Lodgepole Pine Seedling Growth

    NASA Astrophysics Data System (ADS)

    Wei, Xiaohua; Li, Qinglin; Waterhouse, M. J.; Armleder, H. M.

    2012-06-01

    Organic matter plays important roles in returning nutrients to the soil, maintaining forest productivity and creating habitats in forest ecosystems. Forest biomass is in increasing demand for energy production, and organic matter has been considered as a potential supply. Thus, an important management question is how much organic matter should be retained after forest harvesting to maintain forest productivity. To address this question, an experimental trial was established in 1996 to evaluate the responses of lodgepole pine seedling growth to organic matter loading treatments. Four organic matter loading treatments were randomly assigned to each of four homogeneous pine sites: removal of all organic matter on the forest floor, organic matter loading quantity similar to whole-tree-harvesting residuals left on site, organic matter loading quantity similar to stem-only-harvesting residuals, and organic matter loading quantity more similar to what would be found in disease- or insect-killed stands. Our 10-year data showed that height and diameter had 29 and 35 % increase, respectively, comparing the treatment with the most organic matter loading to the treatment with the least organic matter loading. The positive response of seedling growth to organic matter loading may be associated with nutrients and/or microclimate change caused by organic matter, and requires further study. The dynamic response of seedling growth to organic matter loading treatments highlights the importance of long-term studies. Implications of those results on organic matter management are discussed in the context of forest productivity sustainability.

  15. Growth in body size affects rotational performance in women's gymnastics.

    PubMed

    Ackland, Timothy; Elliott, Bruce; Richards, Joanne

    2003-07-01

    National and state representative female gymnasts (n = 37), aged initially between 10 and 12 years, completed a mixed longitudinal study over 3.3 years, to investigate the effect of body size on gymnastic performance. Subjects were tested at four-monthly intervals on a battery of measures including structural growth, strength and gymnastic performance. The group were divided into 'high growers' and 'low growers' based on height (> 18 cm or < 14 cm/37 months, respectively) and body mass (> 15 kg or < 12 kg/37 months, respectively) for comparative purposes. Development of gymnastic performance was assessed through generic skills (front and back rotations, a twisting jump and a V-sit action) and a vertical jump for maximum height. The results show that the smaller gymnast, with a high strength to mass ratio, has greater potential for performing skills involving whole-body rotations. Larger gymnasts, while able to produce more power and greater angular momentum, could not match the performance of the smaller ones. The magnitude of growth experienced by the gymnast over this period has a varying effect on performance. While some activities were greatly influenced by rapid increases in whole-body moment of inertia (e.g. back rotation), performance on others like the front rotation and vertical jump, appeared partly immune to the physical and mechanical changes associated with growth. PMID:14737925

  16. Growth and aggressiveness factors affecting Monilinia spp. survival peaches.

    PubMed

    Villarino, M; Melgarejo, P; De Cal, A

    2016-06-16

    Brown rot of stone fruit is caused by three species of Monilinia, Monilinia laxa, M. fructigena, and M. fructicola. Eleven components of 20 different isolates of each of the three Monilinia species were analyzed to determine distinct aggressiveness and growth characteristics among the three fungi. M. fructicola showed the greatest lesion diameter, and the lowest incubation and latency period on fruit postharvest, however isolates of M. fructigena exhibited less aggressiveness components. Five growth characteristics of M. fructicola could be used to distinguish M. fructicola from the other two species. The dendrogram generated from only the presence of sclerotia and lesion length on infected fruit separated the 60 isolates into two clusters (r=0.93). One cluster was composed of the M. laxa and M. fructigena isolates and the other cluster comprised the M. fructicola isolates. However, the dendrogram generated based on the presence of stromata and sclerotia in the same colony of the three species when they were grown on potato dextrose agar, and the lesion diameter on fruit infected with each species separated the 60 isolates into three clusters (r=0.81). Each cluster comprised the isolates of each of three Monilinia spp. We discussed the effect of M. fructicola growth and aggressiveness differences on the displacement of M. laxa and M. fructigena by M. fructicola recorded in Spanish peach orchards and their effect on brown rot at postharvest. PMID:27043383

  17. Growth and aggressiveness factors affecting Monilinia spp. survival peaches.

    PubMed

    Villarino, M; Melgarejo, P; De Cal, A

    2016-05-01

    Brown rot of stone fruit is caused by three species of Monilinia, Monilinia laxa, M. fructigena, and M. fructicola. Eleven components of 20 different isolates of each of the three Monilinia species were analysed to determine distinct aggressiveness and growth characteristics among the three fungi. M. fructicola showed the greatest lesion diameter, and the lowest incubation and latency period on fruit postharvest, however isolates of M. fructigena exhibited less aggressiveness components. Five growth characteristics of M. fructicola could be used to distinguish M. fructicola from the other two species. The dendrogram generated from only the presence of sclerotia and lesion length on infected fruit separated the 60 isolates into two clusters (r=0.93). One cluster was composed of the M. laxa and M. fructigena isolates and the other cluster comprised the M. fructicola isolates. However, the dendrogram generated based on the presence of stromata and sclerotia in the same colony of the three species when they were grown on potato dextrose agar, and the lesion diameter on fruit infected with each species separated the 60 isolates into three clusters (r=0.81). Each cluster comprised the isolates of each of three Monilinia spp. We discussed the effect of M. fructicola growth and aggressiveness differences on the displacement of M. laxa and M. fructigena by M. fructicola recorded in Spanish peach orchards and their effect on brown rot at postharvest. PMID:26918325

  18. Comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and Rusitec fermenters. I. Digestibility, fermentation parameters, and microbial growth.

    PubMed

    Martínez, M E; Ranilla, M J; Tejido, M L; Ramos, S; Carro, M D

    2010-08-01

    Four ruminally and duodenally cannulated sheep and 8 Rusitec fermenters were used to determine the effects of forage to concentrate (F:C) ratio and type of forage in the diet on ruminal fermentation and microbial protein synthesis. The purpose of the study was to assess how closely fermenters can mimic the dietary differences found in vivo. The 4 experimental diets contained F:C ratios of 70:30 or 30:70 with either alfalfa hay or grass hay as the forage. Microbial growth was determined in both systems using (15)N as a microbial marker. Rusitec fermenters detected differences between diets similar to those observed in sheep by changing F:C ratio on pH; neutral detergent fiber digestibility; total volatile fatty acid concentrations; molar proportions of acetate, propionate, butyrate, isovalerate, and caproate; and amylase activity. In contrast, Rusitec fermenters did not reproduce the dietary differences found in sheep for NH(3)-N and lactate concentrations, dry matter (DM) digestibility, proportions of isobutyrate and valerate, carboxymethylcellulase and xylanase activities, and microbial growth and its efficiency. Regarding the effect of the type of forage in the diet, Rusitec fermenters detected differences between diets similar to those found in sheep for most determined parameters, with the exception of pH, DM digestibility, butyrate proportion, and carboxymethylcellulase activity. Minimum pH and maximal volatile fatty acid concentrations were reached at 2h and at 6 to 8h postfeeding in sheep and fermenters, respectively, indicating that feed fermentation was slower in fermenters compared with that in sheep. There were differences between systems in the magnitude of most determined parameters. In general, fermenters showed lower lactate concentrations, neutral detergent fiber digestibility, acetate:propionate ratios, and enzymatic activities. On the contrary, fermenters showed greater NH(3)-N concentrations, DM digestibility, and proportions of propionate

  19. Stabilising metal(loid)s in soil with iron and aluminium-based products: microbial, biochemical and plant growth impact.

    PubMed

    Garau, Giovanni; Silvetti, Margherita; Castaldi, Paola; Mele, Elena; Deiana, Pietrino; Deiana, Salvatore

    2014-06-15

    Four iron and aluminium-based products, including red mud (RM), hematite (Fe2O3), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg(-1)), Cd (18 mg kg(-1)), Cu (264 mg kg(-1)), Pb (710 mg kg(-1)), Zn (522 mg kg(-1))]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and β-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered. PMID:24685456

  20. Microbial diversity affects self-organization of the soil–microbe system with consequences for function

    PubMed Central

    Crawford, John W.; Deacon, Lewis; Grinev, Dmitri; Harris, James A.; Ritz, Karl; Singh, Brajesh K.; Young, Iain

    2012-01-01

    Soils are complex ecosystems and the pore-scale physical structure regulates key processes that support terrestrial life. These include maintaining an appropriate mixture of air and water in soil, nutrient cycling and carbon sequestration. There is evidence that this structure is not random, although the organizing mechanism is not known. Using X-ray microtomography and controlled microcosms, we provide evidence that organization of pore-scale structure arises spontaneously out of the interaction between microbial activity, particle aggregation and resource flows in soil. A simple computational model shows that these interactions give rise to self-organization involving both physical particles and microbes that gives soil unique material properties. The consequence of self-organization for the functioning of soil is determined using lattice Boltzmann simulation of fluid flow through the observed structures, and predicts that the resultant micro-structural changes can significantly increase hydraulic conductivity. Manipulation of the diversity of the microbial community reveals a link between the measured change in micro-porosity and the ratio of fungal to bacterial biomass. We suggest that this behaviour may play an important role in the way that soil responds to management and climatic change, but that this capacity for self-organization has limits. PMID:22158839

  1. Biogas digestates affect crop P uptake and soil microbial community composition.

    PubMed

    Hupfauf, Sebastian; Bachmann, Silvia; Fernández-Delgado Juárez, Marina; Insam, Heribert; Eichler-Löbermann, Bettina

    2016-01-15

    Fermentation residues from biogas production are known as valuable organic fertilisers. This study deals with the effect of cattle slurry, co-digested cattle slurry, co-digested energy crops and mineral fertilisers on the activity and composition of soil microbiota. Furthermore, the effect of solid-liquid separation as a common pre-treatment of digestate was tested. The fertilising effects were analysed in an 8-week pot experiment on loamy sand using two crops, Amaranthus cruentus and Sorghum bicolor. Amaranth, as a crop with significantly higher P uptake, triggered stress for occurring soil microbes and thereby caused a reduction of microbial biomass C in the soil. Irrespective of the crop, microbial basal respiration and metabolic quotient were higher with the digestates than with the untreated slurry or the mineral treatments. Community level physiological profiles with MicroResp showed considerable differences among the treatments, with particularly strong effects of solid-liquid separation. Similar results were also found on a structural level (PCR-DGGE). Alkaline phosphatase gene analyses revealed high sensitivity to different fertilisation regimes. PMID:26410342

  2. Experimental factors affecting PCR-based estimates of microbial species richness and evenness

    SciTech Connect

    Engelbrektson, Anna; Kunin, Victor; Wrighton, Kelly C.; Zvenigorodsky, Natasha; Chen, Feng; Ochman, Howard; Hugenholtz, Philip

    2009-12-01

    Pyrosequencing of 16S rRNA gene amplicons for microbial community profiling can, for equivalent costs, yield greater than two orders of magnitude more sensitivity than traditional PCR-cloning and Sanger sequencing. With this increased sensitivity and the ability to analyze multiple samples in parallel, it has become possible to evaluate several technical aspects of PCRbased community structure profiling methods. We tested the effect of amplicon length and primer pair on estimates of species richness number of species and evenness relative abundance of species by assessing the potentially tractable microbial community residing in the termite hindgut. Two regions of the 16S rRNA gene were sequenced from one of two common priming sites, spanning the V1-V2 or V8 regions, using amplicons ranging n length from 352 to 1443 bp. Our results demonstrate that both amplicon length and primer pair markedly influence estimates of richness and evenness. However, estimates of species evenness are consistent among different primer pairs targeting the same region. These results highlight the importance of experimental methodology when comparing diversity estimates across communities.

  3. Influence of packaging conditions on natural microbial population growth of endive.

    PubMed

    Charles, Florence; Rugani, Nathalie; Gontard, Nathalie

    2005-05-01

    The influence of three packaging conditions, i.e., unmodified atmosphere packaging (UAP), passive modified atmosphere packaging (MAP), and active MAP, on the natural microbial population growth of endive was investigated at 20 degrees C. For UAP, endive was placed in macroperforated oriented polypropylene pouches that maintained gas composition close to that of air (21 kPa O2 and 0 kPa CO2) but also limited superficial product dehydration. For MAP, endive was placed in low-density polyethylene pouches that induced a 3 kPa O2 and 5 kPa CO2 equilibrium atmosphere composition. Steady state was reached after 25 h of storage with an oxygen absorbing packet (active MAP) compared with 100 h without the packet (passive MAP) and was maintained for 200 h. After 312 h of storage, both active and passive MAP reduced total aerobic mesophile, yeast, and mold population growth compared with endive in UAP. Active MAP accelerated and improved the inhibition of Pseudomonas spp. and Enterobacteriaceae, respectively, probably because of the rapid O2 depletion during the transition period. A shift in the Enterobacteriaceae subpopulation from Rhanella aquatilis to Enterobacter agglomerans was observed for both passive and active MAP. PMID:15895736

  4. Real-time optical monitoring of microbial growth using optimal combination of light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Kobayashi, Ken-ichi; Yamada, Takeshi; Hiraishi, Akira; Nakauchi, Shigeki

    2012-12-01

    We developed a real-time optical monitoring system consisting of a monochrome complementary metal-oxide semiconductor (CMOS) camera and two light-emitting diodes (LEDs) with a constant temperature incubator for the rapid detection of microbial growth on solid media. As a target organism, we used Alicyclobacillus acidocaldarius, which is an acidophilic thermophilic endospore-forming bacterium able to survive in pasteurization processes and grow in acidic drink products such as apple juice. This bacterium was cultured on agar medium with a redox dye applied to improve detection sensitivity. On the basis of spectroscopic properties of the colony, medium, and LEDs, an optimal combination of two LED illuminations was selected to maximize the contrast between the colony and medium areas. We measured A. acidocaldarius and Escherichia coli at two different dilution levels using these two LEDs. From the results of time-course changes in the number of detected pixels in the detection images, a similar growth rate was estimated amongst the same species of microbes, regardless of the dilution level. This system has the ability to detect a colony of approximately 26 μm in diameter in a detection image, and it can be interpreted that the size corresponds to less than 20 μm diameter in visual inspection.

  5. The effect of Triphala and Chlorhexidine mouthwash on dental plaque, gingival inflammation, and microbial growth

    PubMed Central

    Bajaj, Neeti; Tandon, Shobha

    2011-01-01

    The objective of this study was to ascertain the effects of a mouthwash prepared with Triphala on dental plaque, gingival inflammation, and microbial growth and compare it with commercially available Chlorhexidine mouthwash. This study was conducted after ethics committee approval and written consent from guardians (and assent from the children) were obtained. A total of 1431 students in the age group 8–12 years, belonging to classes fourth to seventh, were the subjects for this study. The Knowledge, Attitude and Practice (KAP) of the subjects was determined using a questionnaire. The students were divided into three groups namely, Group I (n = 457) using Triphala mouthwash (0.6%), Group II (n = 440) using Chlorhexidine mouthwash (0.1%) (positive control), and Group III (n = 412) using distilled water (negative control). The assessment was carried out on the basis of plaque scores, gingival scores, and the microbiological analysis (Streptococcus and lactobacilli counts). Statistical analysis for plaque and gingival scores was conducted using the paired sample t-test (for intragroup) and the Tukey's test (for intergroup conducted along with analysis of variance test). For the Streptococcus mutans and Lactobacillus counts, Wilcoxon and Mann–Whitney test were applied for intragroup and intergroup comparison, respectively. All the tests were carried out using the SPSS software. Both the Group I and Group II showed progressive decrease in plaque scores from baseline to the end of 9 months; however, for Group III increase in plaque scores from the baseline to the end of 9 months was noted. Both Group I and Group II showed similar effect on gingival health. There was inhibitory effect on microbial counts except Lactobacillus where Triphala had shown better results than Chlorhexidine. It was concluded that there was no significant difference between the Triphala and the Chlorhexidine mouthwash. PMID:21897640

  6. Dietary Nisin Modulates the Gastrointestinal Microbial Ecology and Enhances Growth Performance of the Broiler Chickens

    PubMed Central

    Józefiak, Damian; Kierończyk, Bartosz; Juśkiewicz, Jerzy; Zduńczyk, Zenon; Rawski, Mateusz; Długosz, Jakub; Sip, Anna; Højberg, Ole

    2013-01-01

    Due to antimicrobial properties, nisin is one of the most commonly used and investigated bacteriocins for food preservation. Surprisingly, nisin has had limited use in animal feed as well as there are only few reports on its influence on microbial ecology of the gastrointestinal tract (GIT). The present study therefore aimed at investigating effects of dietary nisin on broiler chicken GIT microbial ecology and performance in comparison to salinomycin, the widely used ionophore coccidiostat. In total, 720 one-day-old male Ross 308 chicks were randomly distributed to six experimental groups. The positive control (PC) diet was supplemented with salinomycin (60 mg/kg). The nisin (NI) diets were supplemented with increasing levels (100, 300, 900 and 2700 IU nisin/g, respectively) of the bacteriocin. The negative control (NC) diet contained no additives. At slaughter (35 days of age), activity of specific bacterial enzymes (α- and β-glucosidases, α-galactosidases and β-glucuronidase) in crop, ileum and caeca were significantly higher (P<0.05) in the NC group, and nisin supplementation decreased the enzyme activities to levels observed for the PC group. A similar inhibitory influence on bacterial activity was reflected in the levels of short-chain fatty acids (SCFA) and putrefactive SCFA (PSCFA) in digesta from crop and ileum; no effect was observed in caeca. Counts of Bacteroides and Enterobacteriacae in ileum digesta were significantly (P<0.001) decreased by nisin and salinomycin, but no effects were observed on the counts of Clostridium perfringens, Lactobacillus/Enterococcus and total bacteria. Like salinomycin, nisin supplementation improved broiler growth performance in a dose-dependent manner; compared to the NC group, the body weight gain of the NI900 and NI2700 groups was improved by 4.7 and 8.7%, respectively. Our findings suggest that dietary nisin exerts a mode of action similar to salinomycin and could be considered as a dietary supplement for broiler

  7. Dietary nisin modulates the gastrointestinal microbial ecology and enhances growth performance of the broiler chickens.

    PubMed

    Józefiak, Damian; Kierończyk, Bartosz; Juśkiewicz, Jerzy; Zduńczyk, Zenon; Rawski, Mateusz; Długosz, Jakub; Sip, Anna; Højberg, Ole

    2013-01-01

    Due to antimicrobial properties, nisin is one of the most commonly used and investigated bacteriocins for food preservation. Surprisingly, nisin has had limited use in animal feed as well as there are only few reports on its influence on microbial ecology of the gastrointestinal tract (GIT). The present study therefore aimed at investigating effects of dietary nisin on broiler chicken GIT microbial ecology and performance in comparison to salinomycin, the widely used ionophore coccidiostat. In total, 720 one-day-old male Ross 308 chicks were randomly distributed to six experimental groups. The positive control (PC) diet was supplemented with salinomycin (60 mg/kg). The nisin (NI) diets were supplemented with increasing levels (100, 300, 900 and 2700 IU nisin/g, respectively) of the bacteriocin. The negative control (NC) diet contained no additives. At slaughter (35 days of age), activity of specific bacterial enzymes (α- and β-glucosidases, α-galactosidases and β-glucuronidase) in crop, ileum and caeca were significantly higher (P<0.05) in the NC group, and nisin supplementation decreased the enzyme activities to levels observed for the PC group. A similar inhibitory influence on bacterial activity was reflected in the levels of short-chain fatty acids (SCFA) and putrefactive SCFA (PSCFA) in digesta from crop and ileum; no effect was observed in caeca. Counts of Bacteroides and Enterobacteriacae in ileum digesta were significantly (P<0.001) decreased by nisin and salinomycin, but no effects were observed on the counts of Clostridium perfringens, Lactobacillus/Enterococcus and total bacteria. Like salinomycin, nisin supplementation improved broiler growth performance in a dose-dependent manner; compared to the NC group, the body weight gain of the NI₉₀₀ and NI₂₇₀₀ groups was improved by 4.7 and 8.7%, respectively. Our findings suggest that dietary nisin exerts a mode of action similar to salinomycin and could be considered as a dietary supplement

  8. The effect of Triphala and Chlorhexidine mouthwash on dental plaque, gingival inflammation, and microbial growth.

    PubMed

    Bajaj, Neeti; Tandon, Shobha

    2011-01-01

    The objective of this study was to ascertain the effects of a mouthwash prepared with Triphala on dental plaque, gingival inflammation, and microbial growth and compare it with commercially available Chlorhexidine mouthwash. This study was conducted after ethics committee approval and written consent from guardians (and assent from the children) were obtained. A total of 1431 students in the age group 8-12 years, belonging to classes fourth to seventh, were the subjects for this study. The Knowledge, Attitude and Practice (KAP) of the subjects was determined using a questionnaire. The students were divided into three groups namely, Group I (n = 457) using Triphala mouthwash (0.6%), Group II (n = 440) using Chlorhexidine mouthwash (0.1%) (positive control), and Group III (n = 412) using distilled water (negative control). The assessment was carried out on the basis of plaque scores, gingival scores, and the microbiological analysis (Streptococcus and lactobacilli counts). Statistical analysis for plaque and gingival scores was conducted using the paired sample t-test (for intragroup) and the Tukey's test (for intergroup conducted along with analysis of variance test). For the Streptococcus mutans and Lactobacillus counts, Wilcoxon and Mann-Whitney test were applied for intragroup and intergroup comparison, respectively. All the tests were carried out using the SPSS software. Both the Group I and Group II showed progressive decrease in plaque scores from baseline to the end of 9 months; however, for Group III increase in plaque scores from the baseline to the end of 9 months was noted. Both Group I and Group II showed similar effect on gingival health. There was inhibitory effect on microbial counts except Lactobacillus where Triphala had shown better results than Chlorhexidine. It was concluded that there was no significant difference between the Triphala and the Chlorhexidine mouthwash. PMID:21897640

  9. Mexican propolis flavonoids affect photosynthesis and seedling growth.

    PubMed

    King-Díaz, Beatriz; Granados-Pineda, Jessica; Bah, Mustapha; Rivero-Cruz, J Fausto; Lotina-Hennsen, Blas

    2015-10-01

    As a continuous effort to find new natural products with potential herbicide activity, flavonoids acacetin (1), chrysin (2) and 4',7-dimethylnarangenin (3) were isolated from a propolis sample collected in the rural area of Mexico City and their effects on the photosynthesis light reactions and on the growth of Lolium perenne, Echinochloa crus-galli and Physalis ixocarpa seedlings were investigated. Acacetin (1) acted as an uncoupler by enhancing the electron transport under basal and phosphorylating conditions and the Mg(2+)-ATPase. Chrysin (2) at low concentrations behaved as an uncoupler and at concentrations up to 100 μM its behavior was as a Hill reaction inhibitor. Finally, 4',7-dimethylnarangenin (3) in a concentration-dependent manner behaved as a Hill reaction inhibitor. Flavonoids 2 and 3 inhibited the uncoupled photosystem II reaction measured from water to 2,5-dichloro-1,4-benzoquinone (DCBQ), and they did not inhibit the uncoupled partial reactions measured from water to sodium silicomolybdate (SiMo) and from diphenylcarbazide (DPC) to diclorophenol indophenol (DCPIP). These results indicated that chrysin and 4',7-dimethylnarangenin inhibited the acceptor side of PS II. The results were corroborated with fluorescence of chlorophyll a measurements. Flavonoids also showed activity on the growth of seedlings of Lolium perenne and Echinochloa crus-galli. PMID:26318278

  10. Increased nitrogen deposition did not affect the composition and turnover of plant and microbial biomarkers in forest soil density fractions

    NASA Astrophysics Data System (ADS)

    Griepentrog, Marco; Bodé, Samuel; Boeckx, Pascal; Hagedorn, Frank; Wiesenberg, Guido L. B.; Schmidt, Michael W. I.

    2013-04-01

    Increased atmospheric nitrogen (N) deposition and elevated CO2 concentrations affect many forests and their ecosystem functions, including organic matter cycling in soils, the largest carbon pool of terrestrial ecosystems. However, it is still not clear how, and what the underlying mechanisms are. Specific molecules of plant and microbial origin (biomarkers) might respond differently to N deposition, depending on their internal N content. Microbial cell-wall-constituents with high-N content like amino sugars are reliable biomarkers to distinguish between fungal- and bacterial-derived organic residues. Individual lipids are plant-specific biomarkers that lack N in their molecular structure. Here, we tested the effects of elevated CO2 and increased N deposition on the dynamics of plant and microbial biomarkers by studying their composition and turnover in forest soil density fractions. Furthermore, we tested the hypothesis that these biomarkers respond differently to increased N deposition, depending on their internal N content. We used soil samples from a 4-year elevated CO2 and N deposition experiment in model forest ecosystems (open-top chambers), that were fumigated with ambient and 13C-depleted CO2 and treated with two levels of 15N-labeled fertilizer. Bulk soil was separated into free light fraction, occluded light fraction and heavy fraction by density fractionation and ultrasonic dispersion. The heavy fraction was further particle-size fractionated with 20 μm as a cut-off. We determined carbon and N concentrations and their isotopic compositions (δ13C, δ15N) within bulk soil and density fractions. Therein, we extracted and quantified individual amino sugars and lipids and conducted compound-specific stable-isotope-analysis using GC- and LC-IRMS. Results show that amino sugars were mainly stabilized in association with soil minerals. Especially bacterial amino sugars were preferentially associated with soil minerals, exemplified by a consistent decrease

  11. Formaldehyde exposure affects growth and metabolism of common bean

    SciTech Connect

    Mutters, R.G.; Madore, M. ); Bytnerowicz, A. )

    1993-01-01

    Recent state and federal directives have slated a substantial increase in the use of methanol as an alternative to gasoline in both fleet and private vehicles in the coming decade. The incomplete combustion of methanol produces formaldehyde vapor, and catalytic converter technology that completely oxidizes formaldehyde has yet to be developed. The approach of this study was to use a range of methanol concentrations encompassing levels currently found or that may occur in the future in the ambient air of some heavily polluted areas to test the potential phytotoxicity of formaldehyde. The study had the following objectives: (1) design and build a formaldehyde vapor generator with sufficient capacity for long-term plant fumigations; (2) determine growth response of common bean to formaldehyde; (3) evaluate physiological and biochemical changes of bean plants associated with formaldehyde exposures. 20 refs., 2 figs., 2 tabs.

  12. Evaluation of normalized energy recovery (NER) in microbial fuel cells affected by reactor dimensions and substrates.

    PubMed

    Xiao, Li; Ge, Zheng; Kelly, Patrick; Zhang, Fei; He, Zhen

    2014-04-01

    The objective of this study is to provide an initial evaluation of normalized energy recovery (NER - a new parameter for presenting energy performance) in microbial fuel cells (MFCs) through investigation of the effects of reactor dimensions and anode substrates. Although the larger-size MFCs generally have lower maximum power densities, their maximum NER is comparable to that of the smaller MFCs at the same anolyte flow rate. The mixed messages obtained from the MFC size tests suggest that MFCs can be further scaled up without decreasing energy recovery under certain conditions. The low-strength substrates seem to be more suitable for MFC treatment of wastewater, in terms of both energy recovery and organic removal. However, because the MFCs could not achieve the maximum NER and the maximum organic removal efficiency at the same time, one must determine a major goal for MFCs treating wastewater between energy recovery and contaminant removal. PMID:24534787

  13. Compositional Changes and Baking Performance of Rye Dough As Affected by Microbial Transglutaminase and Xylanase.

    PubMed

    Grossmann, Isabel; Döring, Clemens; Jekle, Mario; Becker, Thomas; Koehler, Peter

    2016-07-20

    Doughs supplemented with endoxylanase (XYL) and varying amounts of microbial transglutaminase (TG) were analyzed by sequential protein extraction, quantitation of protein fractions and protein types, and determination of water-extractable arabinoxylans. With increasing TG activity, the concentration of prolamins and glutelins decreased and increased, respectively, and the prolamin-to-glutelin ratio strongly declined. The overall amount of extractable protein decreased with increasing TG level showing that cross-linking by TG provided high-molecular-weight protein aggregates. The decrease of the high-molecular-weight arabinoxylan fraction and the concurrent increase of the medium-molecular-weight fraction confirmed the degradation of arabinoxylans by XYL. However, XYL addition did not lead to significant improved cross-linking of rye proteins by TG. Volume and crumb hardness measurements of bread showed increased protein connectivity induced by XYL and TG. Significant positive effects on the final bread quality were especially obtained by XYL addition. PMID:27349134

  14. Does the essential oil of Lippia sidoides Cham. (pepper-rosmarin) affect its endophytic microbial community?

    PubMed Central

    2013-01-01

    Background Lippia sidoides Cham., also known as pepper-rosmarin, produces an essential oil in its leaves that is currently used by the pharmaceutical, perfumery and cosmetic industries for its antimicrobial and aromatic properties. Because of the antimicrobial compounds (mainly thymol and carvacrol) found in the essential oil, we believe that the endophytic microorganisms found in L. sidoides are selected to live in different parts of the plant. Results In this study, the endophytic microbial communities from the stems and leaves of four L. sidoides genotypes were determined using cultivation-dependent and cultivation-independent approaches. In total, 145 endophytic bacterial strains were isolated and further grouped using either ERIC-PCR or BOX-PCR, resulting in 76 groups composed of different genera predominantly belonging to the Gammaproteobacteria. The endophytic microbial diversity was also analyzed by PCR-DGGE using 16S rRNA-based universal and group-specific primers for total bacteria, Alphaproteobacteria, Betaproteobacteria and Actinobacteria and 18S rRNA-based primers for fungi. PCR-DGGE profile analysis and principal component analysis showed that the total bacteria, Alphaproteobacteria, Betaproteobacteria and fungi were influenced not only by the location within the plant (leaf vs. stem) but also by the presence of the main components of the L. sidoides essential oil (thymol and/or carvacrol) in the leaves. However, the same could not be observed within the Actinobacteria. Conclusion The data presented here are the first step to begin shedding light on the impact of the essential oil in the endophytic microorganisms in pepper-rosmarin. PMID:23387945

  15. An investigation of the sensitivity of low-field nuclear magnetic resonance to microbial growth and activity

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Keating, K.

    2014-12-01

    Microbes and microbial processes play a significant role in shaping subsurface environments and are involved in applications ranging from microbially enhanced oil recovery to soil and groundwater contaminant remediation. Stimulated microbial growth in such applications could cause wide variety of changes of physical/chemical properties in the subsurface; however, due to the complexity of subsurface systems,it is difficult to monitor the growth of microbes and microbial activity in porous media. The focus of this research is to determine if low-field nuclear magnetic resonance (NMR), a method used in well logging to characterize fluids in hydrocarbon reservoirs or water in aquifers, can be used to directly detect the presence and the growth of microbes in geologic media. In this laboratory study, low-field NMR (2 MHz) relaxation measurements were collected on microbial suspensions with measured densities (i.e. biomasses), microbial pellets (live and dead), and inoculated silica. We focus on the direct contribution of microbes to the NMR signals in the absence of biomineralization. Shewanella oneidensis (MR-1), a facultative metal reducer known to play an important role in subsurface environments, were used as a model organism and were inoculated under aerobic condition. Data were collected using a CPMG pulse sequence, which was to determine the T2-distribution, and using a gradient spin-echo (PGSE) plus CPMG pulse sequence, which was used to encode diffusion properties and determine the effective diffusion-spin-spin relaxation correlation (D-T2) plot. Our data show no obvious change in the T2-distribution as S. oneidensis density varied in suspension, but show a clear distinction in the T2-distribution and D-T2 plots between live and dead cell pellets. A decrease in the T2-distribution is observed in the inoculated sand column. These results will provide a basis for understanding the effect of microbes within geologic media on low-field NMR measurements. This

  16. Growth of ponderosa pine seedlings as affected by air pollution

    NASA Astrophysics Data System (ADS)

    Momen, B.; Anderson, P. D.; Houpis, J. L. J.; Helms, J. A.

    The effect of air pollution on seedling survival and competitive ability is important to natural and artificial regeneration of forest trees. Although biochemical and physiological processes are sensitive indicators of pollution stress, the cumulative effects of air pollutants on seedling vigor and competitive ability may be assessed directly from whole-plant growth characteristics such as diameter, height, and photosynthetic area. A few studies that have examined intraspecific variation in seedling response to air pollution indicate that genotypic differences are important in assessing potential effects of air pollution on forest regeneration. Here, we studied the effects of acid rain (no-rain, pH 5.1 rain, pH 3.0 rain) and ozone (filtered, ambient, twice-ambient) in the field on height, diameter, volume, the height:diameter ratio, maximum needle length, and time to reach maximum needle length in seedlings of three families of ponderosa pine ( Pinus ponderosa Dougl. ex Laws). Seedling diameter, height, volume, and height:diameter ratio related significantly to their pre-treatment values. Twice-ambient ozone decreased seedling diameter compared with ozone-filtered air. A significant family-by-ozone interaction was detected for seedling height, as the height of only one of the three families was decreased by twice-ambient ozone compared with the ambient level. Seedling diameter was larger and the height:diameter ratio was smaller under pH 3.0 rain compared to either the no-rain or the pH 5.1-rain treatment. This suggests greater seedling vigor, perhaps due to a foliar fertilization effect of the pH 3.0 rain.

  17. Deep-water microbialites of the Mesoproterozoic Dismal Lakes Group: microbial growth, lithification, and implications for coniform stromatolites.

    PubMed

    Bartley, J K; Kah, L C; Frank, T D; Lyons, T W

    2015-01-01

    Offshore facies of the Mesoproterozoic Sulky Formation, Dismal Lakes Group, arctic Canada, preserve microbialites with unusual morphology. These microbialites grew in water depths greater than several tens of meters and correlate with high-relief conical stromatolites of the more proximal September Lake reef complex. The gross morphology of these microbial facies consists of ridge-like vertical supports draped by concave-upward, subhorizontal elements, resulting in tent-shaped cuspate microbialites with substantial primary void space. Morphological and petrographic analyses suggest a model wherein penecontemporaneous upward growth of ridge elements and development of subhorizontal draping elements initially resulted in a buoyantly supported, unlithified microbial form. Lithification began via precipitation within organic elements during microbialite growth. Mineralization either stabilized or facilitated collapse of initially neutrally buoyant microbialite forms. Microbial structures and breccias were then further stabilized by precipitation of marine herringbone cement. During late-stage diagenesis, remaining void space was occluded by ferroan dolomite cement. Cuspate microbialites are most similar to those found in offshore facies of Neoarchean carbonate platforms and to unlithified, buoyantly supported microbial mats in modern ice-covered Antarctic lakes. We suggest that such unusual microbialite morphologies are a product of the interaction between motile and non-motile communities under nutrient-limiting conditions, followed by early lithification, which served to preserve the resultant microbial form. The presence of marine herringbone cement, commonly associated with high dissolved inorganic carbon (DIC), low O2 conditions, also suggests growth in association with reducing environments at or near the seafloor or in conjunction with a geochemical interface. Predominance of coniform stromatolite forms in the Proterozoic--across a variety of depositional

  18. Biofilm feeding: Microbial colonization of food promotes the growth of a detritivorous arthropod.

    PubMed

    Horváthová, Terézia; Babik, Wiesław; Bauchinger, Ulf

    2016-01-01

    Feeding on plant material is common among animals, but how different animals overcome the dietary deficiencies imposed by this feeding strategy is not well understood. Microorganisms are generally considered to play a vital role in the nutritional ecology of plant feeding animals. Commonly microbes living inside animal bodies are considered more important, but recent studies suggest external microbes significantly shape plant-feeding strategies in invertebrates. Here we investigate how external microbes that typically form biofilm on primary plant material affect growth rates in a terrestrial isopod species Porcellio scaber. We experimentally manipulated the amount of biofilm on three different primary diet sources and quantified growth and survival of individuals that fed on food with either a small or large amount of biofilm. In addition, we tested how dietary manipulation shapes the composition of bacterial communities in the gut. The presence of visible biofilm significantly affected the growth of isopods: individuals that fed on the primary diet source with a large amount of biofilm gained more mass than individuals feeding on a diet with marginal biofilm. Diet also significantly affected the bacterial gut community. The primary diet source mainly determined the taxonomic composition of the bacterial community in the isopod gut, whereas the amount of biofilm affected the relative abundance of bacterial taxa. Our study suggests that terrestrial isopods may cope with low-quality plant matter by feeding on biofilm, with decomposition of plant material by organisms outside of the feeding organism (here a terrestrial isopod) probably playing a major role. Future investigations may be directed towards the primary diet source, plant matter, and the secondary diet source, biofilm, and should assess if both components are indeed uptaken in detritivorous species. PMID:27110187

  19. Biofilm feeding: Microbial colonization of food promotes the growth of a detritivorous arthropod

    PubMed Central

    Horváthová, Terézia; Babik, Wiesław; Bauchinger, Ulf

    2016-01-01

    Abstract Feeding on plant material is common among animals, but how different animals overcome the dietary deficiencies imposed by this feeding strategy is not well understood. Microorganisms are generally considered to play a vital role in the nutritional ecology of plant feeding animals. Commonly microbes living inside animal bodies are considered more important, but recent studies suggest external microbes significantly shape plant-feeding strategies in invertebrates. Here we investigate how external microbes that typically form biofilm on primary plant material affect growth rates in a terrestrial isopod species Porcellio scaber. We experimentally manipulated the amount of biofilm on three different primary diet sources and quantified growth and survival of individuals that fed on food with either a small or large amount of biofilm. In addition, we tested how dietary manipulation shapes the composition of bacterial communities in the gut. The presence of visible biofilm significantly affected the growth of isopods: individuals that fed on the primary diet source with a large amount of biofilm gained more mass than individuals feeding on a diet with marginal biofilm. Diet also significantly affected the bacterial gut community. The primary diet source mainly determined the taxonomic composition of the bacterial community in the isopod gut, whereas the amount of biofilm affected the relative abundance of bacterial taxa. Our study suggests that terrestrial isopods may cope with low-quality plant matter by feeding on biofilm, with decomposition of plant material by organisms outside of the feeding organism (here a terrestrial isopod) probably playing a major role. Future investigations may be directed towards the primary diet source, plant matter, and the secondary diet source, biofilm, and should assess if both components are indeed uptaken in detritivorous species. PMID:27110187

  20. Key design factors affecting microbial community composition and pathogenic organism removal in horizontal subsurface flow constructed wetlands.

    PubMed

    Morató, Jordi; Codony, Francesc; Sánchez, Olga; Pérez, Leonardo Martín; García, Joan; Mas, Jordi

    2014-05-15

    Constructed wetlands constitute an interesting option for wastewater reuse since high concentrations of contaminants and pathogenic microorganisms can be removed with these natural treatment systems. In this work, the role of key design factors which could affect microbial removal and wetland performance, such as granular media, water depth and season effect was evaluated in a pilot system consisting of eight parallel horizontal subsurface flow (HSSF) constructed wetlands treating urban wastewater from Les Franqueses del Vallès (Barcelona, Spain). Gravel biofilm as well as influent and effluent water samples of these systems were taken in order to detect the presence of bacterial indicators such as total coliforms (TC), Escherichia coli, fecal enterococci (FE), Clostridium perfringens, and other microbial groups such as Pseudomonas and Aeromonas. The overall microbial inactivation ratio ranged between 1.4 and 2.9 log-units for heterotrophic plate counts (HPC), from 1.2 to 2.2 log units for total coliforms (TC) and from 1.4 to 2.3 log units for E. coli. The presence of fine granulometry strongly influenced the removal of all the bacterial groups analyzed. This effect was significant for TC (p=0.009), E. coli (p=0.004), and FE (p=0.012). Shallow HSSF constructed wetlands were more effective for removing Clostridium spores (p=0.039), and were also more efficient for removing TC (p=0.011) and E. coli (p=0.013) when fine granulometry was used. On the other hand, changes in the total bacterial community from gravel biofilm were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of polymerase chain reaction (PCR)-amplified fragments of the 16S rRNA gene recovered from DGGE bands. Cluster analysis of the DGGE banding pattern from the different wetlands showed that microbial assemblages separated according to water depth, and sequences of different phylogenetic groups, such as Alpha, Beta and Delta-Proteobacteria, Nitrospirae, Bacteroidetes

  1. Alteration of proteoglycan sulfation affects bone growth and remodeling

    PubMed Central

    Gualeni, Benedetta; de Vernejoul, Marie-Christine; Marty-Morieux, Caroline; De Leonardis, Fabio; Franchi, Marco; Monti, Luca; Forlino, Antonella; Houillier, Pascal; Rossi, Antonio; Geoffroy, Valerie

    2013-01-01

    Diastrophic dysplasia (DTD) is a chondrodysplasia caused by mutations in the SLC26A2 gene, leading to reduced intracellular sulfate pool in chondrocytes, osteoblasts and fibroblasts. Hence, proteoglycans are undersulfated in the cartilage and bone of DTD patients. To characterize the bone phenotype of this skeletal dysplasia we used the Slc26a2 knock-in mouse (dtd mouse), that was previously validated as an animal model of DTD in humans. X-rays, bone densitometry, static and dynamic histomorphometry, and in vitro studies revealed a primary bone defect in the dtd mouse model. We showed in vivo that this primary bone defect in dtd mice is due to decreased bone accrual associated with a decreased trabecular and periosteal appositional rate at the cell level in one month-old mice. Although the osteoclast number evaluated by histomorphometry was not different in dtd compared to wild-type mice, urine analysis of deoxypyridinoline cross-links and serum levels of type I collagen C-terminal telopeptides showed a higher resorption rate in dtd mice compared to wild-type littermates. Electron microscopy studies showed that collagen fibrils in bone were thinner and less organized in dtd compared to wild-type mice. These data suggest that the low bone mass observed in mutant mice could possibly be linked to the different bone matrix compositions/organizations in dtd mice triggering changes in osteoblast and osteoclast activities. Overall, these results suggest that proteoglycan undersulfation not only affects the properties of hyaline cartilage, but can also lead to unbalanced bone modeling and remodeling activities, demonstrating the importance of proteoglycan sulfation in bone homeostasis. PMID:23369989

  2. Prevention of Acid Mine Drainage Through Complexation of Ferric Iron by Soluble Microbial Growth Products

    NASA Astrophysics Data System (ADS)

    Pandey, S.; Yacob, T. W.; Silverstein, J.; Rajaram, H.; Minchow, K.; Basta, J.

    2011-12-01

    Acid mine drainage (AMD) is a widespread environmental problem with deleterious impacts on water quality in streams and watersheds. AMD is generated largely by the oxidation of metal sulfides (i.e. pyrite) by ferric iron. This abiotic reaction is catalyzed by conversion of ferrous to ferric iron by iron and sulfur oxidizing microorganisms. Biostimulation is currently being investigated as an attempt to inhibit the oxidation of pyrite and growth of iron oxidizing bacteria through addition of organic carbon. This may stimulate growth of indigenous communities of acidophilic heterotrophic bacteria to compete for oxygen. The goal of this research is to investigate a secondary mechanism associated with carbon addition: complexation of free Fe(III) by soluble microbial growth products (SMPs) produced by microorganisms growing in waste rock. Exploratory research at the laboratory scale examined the effect of soluble microbial products (SMPs) on the kinetics of oxidation of pure pyrite during shaker flask experiments. The results confirmed a decrease in the rate of pyrite oxidation that was dependent upon the concentration of SMPs in solution. We are using these data to verify results from a pyrite oxidation model that accounts for SMPs. This reactor model involves differential-algebraic equations incorporating total component mass balances and mass action laws for equilibrium reactions. Species concentrations determined in each time step are applied to abiotic pyrite oxidation rate expressions from the literature to determine the evolution of total component concentrations. The model was embedded in a parameter estimation algorithm to determine the reactive surface area of pyrite in an abiotic control experiment, yielding an optimized value of 0.0037 m2. The optimized model exhibited similar behavior to the experiment for this case; the root mean squared of residuals for Fe(III) was calculated to be 7.58 x 10-4 M, which is several orders of magnitude less than the actual

  3. Microbial colonization affects the efficiency of photovoltaic panels in a tropical environment.

    PubMed

    Shirakawa, Marcia A; Zilles, Roberto; Mocelin, Andre; Gaylarde, Christine C; Gorbushina, Anna; Heidrich, Gabriele; Giudice, Mauro C; Del Negro, Gilda M B; John, Vanderley M

    2015-07-01

    Sub-aerial biofilm (SAB) development on solar panels was studied in São Paulo. After 6, 12 and 18 months' exposure, photovoltaic panels were covered by increasing proportions of organic matter (42%, 53% and 58%, respectively). Fungi were an important component of these biofilms; very few phototrophs were found. Major microorganisms detected were melanised meristematic ascomycetes and pigmented bacterial genera Arthrobacter and Tetracoccus. While diverse algae, cyanobacteria and bacteria were identified in biofilms at 6 and 12 months, diversity at a later stage was reduced to that typical for SAB: the only fungal group detected in 18 month biofilm was the meristematic Dothideomycetes and the only phototrophs Ulothrix and Chlorella. Photovoltaic modules showed significant power reductions after 6, 12 (both 7%) and 18 (11%) months. The lack of difference in power reduction between 6 and 12 months reflects the dual nature of soiling, which can result from the deposition of particulates as well as from SAB fouling. Although 12-month old SAB demonstrated an almost 10-fold increase in fungal colonization and a higher organic content, the larger non-microbial particles (above 10 μm), which were important for efficiency reduction of lightly-biofilmed panels, were removed by high rainfall just before the 12-month sampling. PMID:25909440

  4. By passing microbial resistance: xylitol controls microorganisms growth by means of its anti-adherence property.

    PubMed

    Ferreira, Aline S; Silva-Paes-Leme, Annelisa F; Raposo, Nádia R B; da Silva, Sílvio S

    2015-01-01

    Xylitol is an important polyalcohol suitable for use in odontological, medical and pharmaceutical products and as an additive in food. The first studies on the efficacy of xylitol in the control and treatment of infections started in the late 1970s and it is still applied for this purpose, with safety and very little contribution to resistance. Xylitol seems to act against microorganisms exerting an anti-adherence effect. Some research studies have demonstrated its action against Gram-positive and Gram-negative bacteria and yeasts. However, a clear explanation of how xylitol is effective has not been completely established yet. Some evidence shows that xylitol acts on gene expression, down-regulating the ones which are involved in the microorganisms' virulence, such as capsule formation. Another possible clarification is that xylitol blocks lectin-like receptors. The most important aspect is that, over time, xylitol bypasses microbial resistance and succeeds in controlling infection, either alone or combined with another compound. In this review, the effect of xylitol in inhibiting the growth of a different microorganism is described, focusing on studies in which such an anti-adherent property was highlighted. This is the first mini-review to describe xylitol as an anti-adherent compound and take into consideration how it exerts such action. PMID:25483720

  5. Microbial growth and quorum sensing antagonist activities of herbal plants extracts.

    PubMed

    Al-Hussaini, Reema; Mahasneh, Adel M

    2009-01-01

    Antimicrobial and antiquorum sensing (AQS) activities of fourteen ethanolic extracts of different parts of eight plants were screened against four Gram-positive, five Gram-negative bacteria and four fungi. Depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. Among the Grampositive bacteria tested, for example, activities of Laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against Bacillus subtilis up to a 25 mm one against methicillin resistant Staphylococcus aureus. Staphylococcus aureus and Aspergillus fumigatus were the most susceptible among bacteria and fungi tested towards other plant parts. Of interest is the tangible antifungal activity of a Tecoma capensis flower extract, which is reported for the first time. However, minimum inhibitory concentrations (MIC's) for both bacteria and fungi were relatively high (0.5-3.0 mg). As for antiquorum sensing activity against Chromobacterium violaceum, superior activity (>17 mm QS inhibition) was associated with Sonchus oleraceus and Laurus nobilis extracts and weak to good activity (8-17 mm) was recorded for other plants. In conclusion, results indicate the potential of these plant extracts in treating microbial infections through cell growth inhibition or quorum sensing antagonism, which is reported for the first time, thus validating their medicinal use. PMID:19783935

  6. Macroscopic models for predicting changes in saturated porous media properties caused by microbial growth

    SciTech Connect

    Clement, T.P.; Hooker, B.S.; Skeen, R.S.

    1996-09-01

    Analytical equations are developed to model changes in porosity, specific surface area, and permeability caused by biomass accumulation in porous media. The proposed equations do not assume any specific pattern for microbial growth but instead are based on macroscopic estimates of average biomass concentrations. For porous media with a pore-size distribution index value ({lambda}) equal to 3, the macroscopic model predictions of porosity, specific surface area, and permeability changes are in exact agreement with biofilm-model predictions. At other values of {lambda} between 2 and 5, simulated porosity profiles are identical and relative specific surface area and permeability profiles show minor deviations. In comparison to biofilm-based models, the macroscopic models are relatively simple to implement and are computationally more efficient. Simulations of biologically reactive flow in a one-dimensional column show that the macroscopic and biofilm approach based transport codes predict almost identical porosity and permeability profiles. The macroscopic models are simple and useful tools for estimating changes in various porous media properties during bioremediation of contaminated aquifers.

  7. Structural effects of ionic liquids on microalgal growth inhibition and microbial degradation.

    PubMed

    Pham, Thi Phuong Thuy; Cho, Chul-Woong; Yun, Yeoung-Sang

    2016-03-01

    In the present study, we investigated structural effects of various ionic liquids (ILs) on microalgal growth inhibition and microbial biodegradability. For this, we tested pyridinium- and pyrrolidinium-based ILs with various alkyl chain lengths and bromide anion, and compared the toxicological effects with log EC50 values of imidazolium-based IL with the same alkyl chains and anion from literature. Comparing determined EC50 values of cationic moieties with the same alkyl chain length, pyridinium-based ILs were found to be slightly more toxic towards the freshwater green alga, Pseudokirchneriella subcapitata, than a series of pyrrolidinium and imidazolium except to 1-octyl-3-methylimidazolium bromide. Concerning the biodegradation study of 12 ILs using the activated sludge microorganisms, the results showed that the pyridinium derivatives except to 1-propyl-3-methylpyridinium cation were degraded. Whereas in case of imidazolium- and pyrrolidinium-based compounds, only n-hexyl and n-octyl substituted cations were fully degraded but no significant biodegradation was observed for the short chains (three and four alkyl chains). PMID:26330315

  8. Evaluation of americium-241 toxicity influence on the microbial growth of organic wastes

    SciTech Connect

    Takehiro Marumo, Julio; Padua Ferreira, Rafael Vicente de; Keiko Isiki, Vera Lucia; Miyamoto, Hissae; Sayuri Takara, Aline; Kazumi Sakata, Solange; Bellini, Maria Helena; Cardoso Pedroso de Lima, Luis Filipe

    2007-07-01

    Available in abstract form only. Full text of publication follows: Since the licenses for using radioactive sources in radioactive lightning rods were lifted by the Brazilian national nuclear authority, in 1989, the radioactive devices have been replaced by Franklin type and collected as radioactive waste. However, only 20 percent of the estimated total number of installed rods was delivered to Brazilian Nuclear Commission. This situation causes concern, due to, first, the possibility of the rods being disposed as domestic waste, and second, the americium, the most commonly employed radionuclide, is classified as a high-toxicity element. In the present study, Am-241 migration experiments were performed by a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as a common solid waste. Besides the risk evaluation, it is important to know the mechanism of the Am-241 release or retention in waste as well as its influence in the waste decomposition processes. Many factors are involved, but microorganisms present in the waste play an important role in its degradation, which control the physical and chemical processes. The objective of this work was to evaluate the Am-241 influence on the microbial population by counting number of cells in lysimeters leachate. Preliminary results suggest that americium may influence significantly the bacteria growth in organic waste, evidenced by culture under aerobiosis and an-aerobiosis and the antimicrobial resistance test. (authors)

  9. ATP monitoring technology for microbial growth control in potable water systems

    NASA Astrophysics Data System (ADS)

    Whalen, Patrick A.; Whalen, Philip J.; Cairns, James E.

    2006-05-01

    ATP (Adenosine Triphosphate) is the primary energy transfer molecule present in all living biological cells on Earth. ATP cannot be produced or maintained by anything but a living organism, and as such, its measurement is a direct indication of biological activity. The main advantage of ATP as a biological indicator is the speed of the analysis - from collecting the sample to obtaining the result, only minutes are required. The technology to measure ATP is already widely utilized to verify disinfection efficacy in the food industry and is also commonly applied in industrial water processes such as cooling water systems to monitor microbial growth and biocide applications. Research has indicated that ATP measurement technology can also play a key role in such important industries as potable water distribution and biological wastewater treatment. As will be detailed in this paper, LuminUltra Technologies has developed and applied ATP measurement technologies designed for any water type, and as such can provide a method to rapidly and accurately determine the level of biological activity in drinking water supplies. Because of its speed and specificity to biological activity, ATP measurement can play a key role in defending against failing drinking water quality, including those encountered during routine operation and also bioterrorism.

  10. Effect of pretreatments on microbial growth and sensory properties of dry-salted olives.

    PubMed

    Değirmencioğlu, Nurcan; Gürbüz, Ozan; Değirmencioğlu, Ali; Yildiz, Semanur

    2014-09-01

    The effect of various washing solutions (acetic acid, lactic acid, and chlorine dioxide) and NaCl concentrations (2.5, 5.0, and 10.0%) on the stability of dry-salted olives (cultivars Gemlik and Edincik) during storage was studied. Vacuum-packed olives were stored at 4°C for 7 months and monitored for microbiological changes that occurred in the dry-salted olives during the dry-salting process and for their stability during storage. Microbial populations were enumerated using pour plating (for aerobic plate counts) and spread plating (for counts of lactic acid bacteria and yeasts and molds). Aerobic plate counts were <2.5 log CFU/g for olive samples washed in chlorine dioxide at all NaCl concentrations. At 4°C, the population of yeasts and molds increased steadily during the shelf life in Gemlik olive samples washed with all of the solutions, except chlorine dioxide, whereas yeast and mold counts in Edincik olives decreased depending on the increase in salt concentration. Therefore, different combinations of organic acids, NaCl, and vacuum packaging can be successfully used to control the growth of yeasts and molds in these olives. The combination of vacuum sealing (with a 10-ppm chlorine dioxide wash) and storage at 4°C was the most effective approach for controlling the growth of lactic acid bacteria and yeasts and molds. Members of the sensory panel considered saltiness to be appropriate at 2.5 and 5.0% NaCl. Softness and bitterness scores increased with reduced NaCl concentrations, but rancidity and hardness scores increased as NaCl concentration increased. PMID:25198844

  11. Microbial enrichment of a novel growing substrate and its effect on plant growth.

    PubMed

    Trifonova, R; Postma, J; Schilder, M T; van Elsas, J D

    2009-10-01

    The quality of torrefied grass fibers (TGF) as a new potting soil ingredient was tested in a greenhouse experiment. TGF was colonized with previously selected microorganisms. Four colonization treatments were compared: (1) no inoculants, (2) the fungus Coniochaeta ligniaria F/TGF15 alone, (3) the fungus followed by inoculation with two selected bacteria, and (4) the fungus with seven selected bacteria. Cultivation-based and DNA-based methods, i.e., PCR-DGGE and BOX-PCR, were applied to assess the bacterial and fungal communities established in the TGF. Although colonization was not performed under sterile conditions, all inoculated strains were recovered from TGF up to 26 days incubation. Stable fungal and bacterial populations of 10(8) and 10(9) CFU/g TGF, respectively, were reached. As a side effect of the torrefaction process that aimed at the chemical stabilization of grass fibers, potentially phytotoxic compounds were generated. These phytotoxic compounds were cold-extracted from the fibers and analyzed by gas chromatography mass spectrometry. Four of 15 target compounds that had previously been found in the extract of TGF were encountered, namely phenol, 2-methoxyphenol, benzopyran-2-one, and tetrahydro-5,6,7,7a-benzofuranone. The concentration of these compounds decreased significantly during incubation. The colonized TGF was mixed with peat (P) in a range of 100%:0%, 50%:50%, 20%:80%, and 0%:100% TGF/P (w/w), respectively, to assess suitability for plant growth. Germination of tomato seeds was assessed three times, i.e., with inoculated TGF that had been incubated for 12, 21, and 26 days. In these tests, 90-100% of the seeds germinated in 50%:50% and 20%:80% TGF/P, whereas on average only 50% of the seeds germinated in pure TGF. Germination was not improved by the microbial inoculants. However, plant fresh weight as well as leaf area of 28-day-old tomato plants were significantly increased in all treatments where C. ligniaria F/TGF15 was inoculated compared

  12. Will anticipated future climatic conditions affect belowground C utilization? - Insights into the role of microbial functional groups in a temperate heath/grassland.

    NASA Astrophysics Data System (ADS)

    Reinsch, Sabine; Michelsen, Anders; Sárossy, Zsuzsa; Egsgaard, Helge; Kappel Schmidt, Inger; Jakobsen, Iver; Ambus, Per

    2013-04-01

    The global terrestrial soil organic matter stock is the biggest terrestrial carbon pool (1500 Pg C) of which about 4 % is turned over annually. Thus, terrestrial ecosystems have the potential to accelerate or diminish atmospheric climate change effects via belowground carbon processes. We investigated the effect of elevated CO2 (510 ppm), prolonged spring/summer droughts and increased temperature (1 ˚C) on belowground carbon allocation and on the recovery of carbon by the soil microbial community. An in-situ 13C-carbon pulse-labeling experiment was carried out in a temperate heath/grassland (Denmark) in May 2011. Recently assimilated 13C-carbon was traced into roots, soil and microbial biomass 1, 2 and 8 days after pulse-labeling. The importance of the microbial community in C utilization was investigated using 13C enrichment patterns in microbial functional groups on the basis of phospholipid fatty acids (PLFAs) in roots. Gram-negative and gram-positive bacteria were distinguished from the decomposer groups of actinomycetes (belonging to the group of gram-positive bacteria) and saprophytic fungi. Mycorrhizal fungi specific PLFAs were not detected probably due to limited sample size in combination with restricted sensitivity of the used GC-c-IRMS setup. Climate treatments did not affect 13C allocation into roots, soil and microbial biomass carbon and also the total microbial biomass size stayed unchanged as frequently observed. However, climate treatments changed the composition of the microbial community: elevated CO2 significantly reduced the abundance of gram-negative bacteria (17:0cy) but did not affect the abundance of decomposers. Drought favored the bacterial community whereas increased temperatures showed reduced abundance of gram-negative bacteria (19:0cy) and changed the actinomycetes community (10Me16:0, 10Me18:0). However, not only the microbial community composition was affected by the applied climatic conditions, but also the activity of microbial

  13. Bioenergetic Limitations on Slow Microbial Growth in the Subsurface: What is the Burden of Maintenance on the Overall Energy Budget?

    NASA Astrophysics Data System (ADS)

    Smeaton, C. M.; Bajracharya, B. M.; Ridenour, C.; Van Cappellen, P.

    2014-12-01

    In low energy environments such as the subsurface, the minimum energy required to maintain cellular integrity and function (maintenance energy) may represent a significant fraction of the total energy available to microbial communities. However, traditional kinetic and thermodynamic models incorporating key microbial processes are often developed using data collected in nutrient rich growth media. In this study, slow microbial growth in the subsurface was simulated using a flow through bioreactor system in experiments designed to determine the maintenance energy requirement of the model subsurface bacterium Shewanella oneidensis. An existing bioreactor system (Applikon EZ-control®, 2.4 L) was modified to include a biomass retention filtration unit (retentostat) resulting in biomass accumulation over time. An artificial low-nutrient groundwater medium was optimized for slow S. oneidensis growth and was supplied and removed from the reactor at flow rates on the order of 1 mL min-1 with a dilution rate of 0.025 h-1. The retentostat was run under electron donor limited conditions with nitrate, a common groundwater contaminant, supplied at 0.025 mM h-1 and lactate supplied in excess at 0.125 mM h-1. Respiratory ammonification of nitrate by S. oneidensis and cell growth was monitored over time (40 days) and compared to parallel incubations in batch reactors. Initial rates of ammonification were similar in the bioreactor and batch reactors, however, optical density and ATP measurements showed slow yet increasing microbial growth over time (generation time = 17 days) in the retentostat. In contrast, cells in the batch reactors did not grow significantly and died within 2 weeks of inoculation. A maintenance energy demand was estimated (2.5 kJ C-mol biomass h-1) by fitting the biomass production rates to the van Verseveld equation. The low maintenance energy demand of S. oneidensis as compared to typical maintenance energies reported in the literature (>10 kJ C-mol biomass

  14. Surface Orientation Affects the Direction of Cone Growth by Leptolyngbya sp. Strain C1, a Likely Architect of Coniform Structures Octopus Spring (Yellowstone National Park)

    PubMed Central

    Reyes, Kristina; Gonzalez, Nicolas I.; Stewart, Joshua; Ospino, Frank; Nguyen, Dickie; Cho, David T.; Ghahremani, Nahal; Spear, John R.

    2013-01-01

    Laminated, microbially produced stromatolites within the rock record provide some of the earliest evidence for life on Earth. The chemical, physical, and biological factors that lead to the initiation of these organosedimentary structures and shape their morphology are unclear. Modern coniform structures with morphological features similar to stromatolites are found on the surface of cyanobacterial/microbial mats. They display a vertical element of growth, can have lamination, can be lithified, and observably grow with time. To begin to understand the microbial processes and interactions required for cone formation, we determined the phylogenetic composition of the microbial community of a coniform structure from a cyanobacterial mat at Octopus Spring, Yellowstone National Park, and reconstituted coniform structures in vitro. The 16S rRNA clone library from the coniform structure was dominated by Leptolyngbya sp. Other cyanobacteria and heterotrophic bacteria were present in much lower abundance. The same Leptolyngbya sp. identified in the clone library was also enriched in the laboratory and could produce cones in vitro. When coniform structures were cultivated in the laboratory, the initial incubation conditions were found to influence coniform morphology. In addition, both the angle of illumination and the orientation of the surface affected the angle of cone formation demonstrating how external factors can influence coniform, and likely, stromatolite morphology. PMID:23241986

  15. How do Gradients in Mineralogy and Nutrient Availability Alter Links between Microbial Growth Efficiency and Soil Carbon Storage?

    NASA Astrophysics Data System (ADS)

    Cusack, D. F.; Reed, S.; Wieder, W. R.; Taylor, P.; Cleveland, C. C.; Chadwick, O.; Vitousek, P.

    2013-12-01

    Our understanding of the terrestrial carbon (C) balance depends on understanding how C is (1) partitioned by heterotrophic microbes to biomass vs. respiration (i.e. growth efficiency), and (2) stabilized and stored in soils. Microbial growth efficiency may also strongly influence soil C stabilization if microbial biomass is a dominant source of C to organo-mineral associations. We hypothesized that natural variation in nutrient availability, as well as addition of scarce nutrients, may alter growth efficiency such that soil C storage on mineral surfaces increases without increasing C losses via heterotrophic respiration. We predicted that nutrient poor sites with relatively high reactive mineral availability (i.e. not C-saturated) have the largest potential to store new microbial biomass C. To test our hypothesis we used a microbial radionuclide-labeling technique combined with long- and short-term nutrient additions to follow C through soils that vary in mineral composition and background nutrient availability. We collected mineral soils (0-10 cm depth) from 8 Hawaiian sites that provided maximum variation in nutrient availability, reactive mineral content, and background soil C. Soils were sieved, pooled by site, and homogenized prior to a laboratory addition of radio (14C)-labeled sucrose, including nitrogen (N) and/or phosphorus (P) additions in full factorial design. We followed the 14C into microbial biomass growth, into soil mineral fractions, and into 14C-respiration (CO2) over 24 hours. We say effects of laboratory fertilization and ecosystem conditions on microbial growth efficiency and C losses via CO2. Across the 8 diverse soils, the full addition of 14C-sucrose+NP increased cumulative loss of 14C-CO2 relative to addition of 14C-sucrose alone (p<0.05), with the effect becoming more pronounced over the course of the experiment. Addition of 14C-sucrose with one additional nutrient (N or P) did not increase 14C-CO2 across the 8 soils relative to 14C

  16. Rumen microorganisms, methane production, and microbial protein synthesis affected by mangosteen peel powder supplement in lactating dairy cows.

    PubMed

    Polyorach, Sineenart; Wanapat, Metha; Cherdthong, Anusorn; Kang, Sungchhang

    2016-03-01

    Four crossbred dairy cows (50 % Holstein-Friesian × 50 % Thai native), 404 ± 50.0 kg of body weight (4 years old) and 90 ± 5 day in milk with daily milk production of 9 ± 2.0 kg/day, were randomly assigned according to a 4 × 4 Latin square design to study the effect of mangosteen (Garcinia mangostana) peel powder (MSP) supplementation on rumen microorganisms, methane production, and microbial protein synthesis fed concentrate containing yeast fermented cassava chip protein (YEFECAP). The treatments were different levels of MSP supplementation at 0, 100, 200, and 300 g/head/day. Rice straw was used as a roughage source fed ad libitum, and concentrate containing YEFECAP at 200 g/kg concentrate was offered corresponding to concentrate-to-milk-yield ratio at 1:2. A quantitative real-time PCR approach was used to determine the population densities of ruminal microorganisms. The results revealed that supplementation of MSP did not affect on Fibrobactor succinogenes, Ruminococcus flavefaciens, and Ruminococcus albus (P > 0.05). However, total bacteria was linearly increased (P < 0.01) while methanogens and protozoal population were linearly decreased (P < 0.01) with increasing level of MSP supplementation. Increasing level of MSP supplement could decrease rumen methane production from 27.5 to 23.7 mmol/100 ml(3). Furthermore, cows that received MSP at 300 g/head/day had the highest microbial crude protein and efficiency of rumen microbial N synthesis (416.8 g/day and 16.2 g/kg organic matter truly digested in the rumen (OMDR), respectively). In conclusion, supplementation of MSP at 300 g/head/day with YEFECAP as a protein source in the concentrate mixture revealed an enhancement of rumen fermentation and methane reduction in lactating dairy cows. PMID:26885988

  17. Rumen microbial and fermentation characteristics are affected differently by bacterial probiotic supplementation during induced lactic and subacute acidosis in sheep

    PubMed Central

    2012-01-01

    Background Ruminal disbiosis induced by feeding is the cause of ruminal acidosis, a digestive disorder prevalent in high-producing ruminants. Because probiotic microorganisms can modulate the gastrointestinal microbiota, propionibacteria- and lactobacilli-based probiotics were tested for their effectiveness in preventing different forms of acidosis. Results Lactic acidosis, butyric and propionic subacute ruminal acidosis (SARA) were induced by feed chalenges in three groups of four wethers intraruminally dosed with wheat, corn or beet pulp. In each group, wethers were either not supplemented (C) or supplemented with Propionibacterium P63 alone (P) or combined with L. plantarum (Lp + P) or L. rhamnosus (Lr + P). Compared with C, all the probiotics stimulated lactobacilli proliferation, which reached up to 25% of total bacteria during wheat-induced lactic acidosis. This induced a large increase in lactate concentration, which decreased ruminal pH. During the corn-induced butyric SARA, Lp + P decreased Prevotella spp. proportion with a concomitant decrease in microbial amylase activity and total volatile fatty acids concentration, and an increase in xylanase activity and pH. Relative to the beet pulp-induced propionic SARA, P and Lr + P improved ruminal pH without affecting the microbial or fermentation characteristics. Regardless of acidosis type, denaturing gradient gel electrophoresis revealed that probiotic supplementations modified the bacterial community structure. Conclusion This work showed that the effectiveness of the bacterial probiotics tested depended on the acidosis type. Although these probiotics were ineffective in lactic acidosis because of a deeply disturbed rumen microbiota, some of the probiotics tested may be useful to minimize the occurrence of butyric and propionic SARA in sheep. However, their modes of action need to be further investigated. PMID:22812531

  18. Effects of feeding corn silage inoculated with microbial additives on the ruminal fermentation, microbial protein yield, and growth performance of lambs.

    PubMed

    Basso, F C; Adesogan, A T; Lara, E C; Rabelo, C H S; Berchielli, T T; Teixeira, I A M A; Siqueira, G R; Reis, R A

    2014-12-01

    This study aimed to examine the effects of feeding corn silage inoculated without or with either Lactobacillus buchneri (LB) alone or a combination of LB and Lactobacillus plantarum (LBLP) on the apparent digestibility, ruminal fermentation, microbial protein synthesis, and growth performance of lambs. Thirty Santa Inês×Dorper crossbred intact males lambs weighing 20.4±3.8 kg were blocked by weight into 10 groups. Lambs in each group were randomly assigned to 1 of the following 3 dietary treatments: untreated (Control), LB, and LBLP silage. Lambs were fed experimental diets for 61 d. The apparent digestibility was indirectly estimated from indigestible NDF measured on d 57 to 59. Spot urine samples were collected from all animals on d 59 to estimate microbial protein synthesis. Lambs were slaughtered for carcass evaluation on d 61 when they weighed 32.4±5.2 kg. Six additional ruminally cannulated Santa Inês×Dorper crossbred wethers weighing 40.5±1.8 kg were used to examine dietary effects on ruminal fermentation. Average daily gain was increased when lambs were fed LBLP silage (P<0.05) but not LB silage. The LBLP silage had the highest (P<0.05) lactic acid concentration and both inoculated silages had greater acetic acid concentrations than the Control silage (P<0.05). Inoculation of corn silage increased intakes of DM, OM, CP, NDF, total carbohydrate (CHO), and GE by the lambs but decreased digestibility of DM, OM, CP, total and nonstructural carbohydrates, and concentration of GE and ME. (P<0.05). Nevertheless, lambs fed inoculated silages had greater microbial N supply than those on the Control treatment (P<0.05). The acetate to propionate ratio was lower in ruminal fluid of wethers in LBLP treatment than LB and Control treatment (P<0.05) and ruminal pH tended to be greater in LB lambs than in LBLP and Control wethers (P<0.10). Finally, the inoculation with both bacteria combined enhanced the silage fermentation. The intakes of DM, OM, CP, NDF, and GE

  19. Colony-live —a high-throughput method for measuring microbial colony growth kinetics— reveals diverse growth effects of gene knockouts in Escherichia coli

    PubMed Central

    2014-01-01

    Background Precise quantitative growth measurements and detection of small growth changes in high-throughput manner is essential for fundamental studies of bacterial cell. However, an inherent tradeoff for measurement quality in high-throughput methods sacrifices some measurement quality. A key challenge has been how to enhance measurement quality without sacrificing throughput. Results We developed a new high-throughput measurement system, termed Colony-live. Here we show that Colony-live provides accurate measurement of three growth values (lag time of growth (LTG), maximum growth rate (MGR), and saturation point growth (SPG)) by visualizing colony growth over time. By using a new normalization method for colony growth, Colony-live gives more precise and accurate growth values than the conventional method. We demonstrated the utility of Colony-live by measuring growth values for the entire Keio collection of Escherichia coli single-gene knockout mutants. By using Colony-live, we were able to identify subtle growth defects of single-gene knockout mutants that were undetectable by the conventional method quantified by fixed time-point camera imaging. Further, Colony-live can reveal genes that influence the length of the lag-phase and the saturation point of growth. Conclusions Measurement quality is critical to achieving the resolution required to identify unique phenotypes among a diverse range of phenotypes. Sharing high-quality genome-wide datasets should benefit many researchers who are interested in specific gene functions or the architecture of cellular systems. Our Colony-live system provides a new powerful tool to accelerate accumulation of knowledge of microbial growth phenotypes. PMID:24964927

  20. Calf and disease factors affecting growth in female Holstein calves in Florida, USA.

    PubMed

    Donovan, G A; Dohoo, I R; Montgomery, D M; Bennett, F L

    1998-01-01

    A prospective cohort study was undertaken to determine calf-level factors that affect performance (growth) between birth and 14 months of age in a convenience sample of approximately 3300 female Holstein calves born in 1991 on two large Florida dairy farms. Data collected on each calf at birth included farm of origin, birth date, weight, height at the pelvis, and serum total protein (a measure of colostral immunoglobulin absorption). Birth season was dichotomized into summer and winter using meteorological data collected by University of Florida Agricultural Research Stations. Data collected at approximately 6 and 14 months of age included age, weight, height at the pelvis, and height at the withers. Growth in weight and stature (height) was calculated for each growth period; growth period 1 (GP1) = birth to 6 months, and growth period 2 (GP2) = 6 to 14 months. Health data collected included data of initial treatment and number of treatments for the diseases diarrhea, omphalitis, septicemia, pneumonia and keratoconjunctivitis. After adjusting for disease occurrence, passive transfer of colostral immunoglobulins had no significant effect on body weight gain or pelvic height growth. Season of birth and occurrence of diarrhea, septicemia and respiratory disease were significant variables decreasing heifer growth (height and weight) in GP1. These variables plus farm, birth weight and exact age when '6 month' data were collected explained 20% and 31% of the variation in body weight gain and pelvic height growth, respectively, in GP1. The number of days treated for pneumonia before 6 months of age significantly decreased average daily weight gain in GP2 (P < 0.025), but did not affect stature growth. Treatment for pneumonia after 6 months of age did not significantly affect weight or height gain after age 6 months. Neither omphalitis nor keratoconjunctivitis explained variability in growth in either of the growth periods. PMID:9500160

  1. Validation of a predictive model coupling gas transfer and microbial growth in fresh food packed under modified atmosphere.

    PubMed

    Guillard, V; Couvert, O; Stahl, V; Hanin, A; Denis, C; Huchet, V; Chaix, E; Loriot, C; Vincelot, T; Thuault, D

    2016-09-01

    Predicting microbial safety of fresh products in modified atmosphere packaging implies to take into account the dynamic of O2, CO2 and N2 exchanges in the system and its effect on microbial growth. In this paper a mechanistic model coupling gas transfer and predictive microbiology was validated using dedicated challenge-tests performed on poultry meat, fresh salmon and processed cheese, inoculated with either Listeria monocytogenes or Pseudomonas fluorescens and packed in commercially used packaging materials (tray + lid films). The model succeeded in predicting the relative variation of O2, CO2 and N2 partial pressure in headspace and the growth of the studied microorganisms without any parameter identification. This work highlighted that the respiration of the targeted microorganism itself and/or that of the naturally present microflora could not be neglected in most of the cases, and could, in the particular case of aerobic microbes contribute to limit the growth by removing all residual O2 in the package. This work also confirmed the low sensitivity of L. monocytogenes toward CO2 while that of P. fluorescens permitted to efficiently prevent its growth by choosing the right combination of packaging gas permeability value and initial % of CO2 initially flushed in the pack. PMID:27217358

  2. Microbial environment affects innate immunity in two closely related earthworm species Eisenia andrei and Eisenia fetida.

    PubMed

    Dvořák, Jiří; Mančíková, Veronika; Pižl, Václav; Elhottová, Dana; Silerová, Marcela; Roubalová, Radka; Skanta, František; Procházková, Petra; Bilej, Martin

    2013-01-01

    Survival of earthworms in the environment depends on their ability to recognize and eliminate potential pathogens. This work is aimed to compare the innate defense mechanisms of two closely related earthworm species, Eisenia andrei and Eisenia fetida, that inhabit substantially different ecological niches. While E. andrei lives in a compost and manure, E. fetida can be found in the litter layer in forests. Therefore, the influence of environment-specific microbiota on the immune response of both species was followed. Firstly, a reliable method to discern between E. andrei and E. fetida based on species-specific primers for cytochrome c oxidase I (COI) and stringent PCR conditions was developed. Secondly, to analyze the immunological profile in both earthworm species, the activity and expression of lysozyme, pattern recognition protein CCF, and antimicrobial proteins with hemolytic function, fetidin and lysenins, have been assessed. Whereas, CCF and lysozyme showed only slight differences in the expression and activity, fetidin/lysenins expression as well as the hemolytic activity was considerably higher in E. andrei as compared to E. fetida. The expression of fetidin/lysenins in E. fetida was not affected upon the challenge with compost microbiota, suggesting more substantial changes in the regulation of the gene expression. Genomic DNA analyses revealed significantly higher level of fetidin/lysenins (determined using universal primer pairs) in E. andrei compared to E. fetida. It can be hypothesized that E. andrei colonizing compost as a new habitat acquired an evolutionary selection advantage resulting in a higher expression of antimicrobial proteins. PMID:24223917

  3. Microbial Environment Affects Innate Immunity in Two Closely Related Earthworm Species Eisenia andrei and Eisenia fetida

    PubMed Central

    Dvořák, Jiří; Mančíková, Veronika; Pižl, Václav; Elhottová, Dana; Šilerová, Marcela; Roubalová, Radka; Škanta, František; Procházková, Petra; Bilej, Martin

    2013-01-01

    Survival of earthworms in the environment depends on their ability to recognize and eliminate potential pathogens. This work is aimed to compare the innate defense mechanisms of two closely related earthworm species, Eisenia andrei and Eisenia fetida, that inhabit substantially different ecological niches. While E. andrei lives in a compost and manure, E. fetida can be found in the litter layer in forests. Therefore, the influence of environment-specific microbiota on the immune response of both species was followed. Firstly, a reliable method to discern between E. andrei and E. fetida based on species-specific primers for cytochrome c oxidase I (COI) and stringent PCR conditions was developed. Secondly, to analyze the immunological profile in both earthworm species, the activity and expression of lysozyme, pattern recognition protein CCF, and antimicrobial proteins with hemolytic function, fetidin and lysenins, have been assessed. Whereas, CCF and lysozyme showed only slight differences in the expression and activity, fetidin/lysenins expression as well as the hemolytic activity was considerably higher in E. andrei as compared to E. fetida. The expression of fetidin/lysenins in E. fetida was not affected upon the challenge with compost microbiota, suggesting more substantial changes in the regulation of the gene expression. Genomic DNA analyses revealed significantly higher level of fetidin/lysenins (determined using universal primer pairs) in E. andrei compared to E. fetida. It can be hypothesized that E. andrei colonizing compost as a new habitat acquired an evolutionary selection advantage resulting in a higher expression of antimicrobial proteins. PMID:24223917

  4. Plant Pathogenic Microbial Communication Affected by Elevated Temperature in Pectobacterium carotovorum subsp. carotovorum.

    PubMed

    Saha, N D; Chaudhary, A; Singh, S D; Singh, D; Walia, S; Das, T K

    2015-11-01

    Gram-negative plant pathogenic bacteria regulate specific gene expression in a population density-dependent manner by sensing level of Acyl-Homoserine Lactone (HSL) molecules which they produce and liberate to the environment, called Quorum Sensing (QS). The production of virulence factors (extracellular enzyme viz. cellulase, pectinase, etc.) in Pectobacterium carotovorum subsp. carotovorum (Pcc) is under strong regulation of QS. The QS signal molecule, N-(3-oxohexanoyl)-L-Homoserine Lactone (OHHL) was found as the central regulatory system for the virulence factor production in Pcc and is also under strict regulation of external environmental temperature. Under seven different incubation temperatures (24, 26, 28, 30, 33, 35, and 37 °C) in laboratory condition, highest amount of OHHL (804 violacein unit) and highest (79 %) Disease Severity Index (DSI) were measured at 33 °C. The OHHL production kinetics showed accumulation of highest concentration of OHHL at late log phase of the growth but diminution in the concentration occurred during stationary phase onwards to death phase. At higher temperature (35 and 37 °C) exposure, OHHL was not at detectable range. The effect of temperature on virulence factor production is the concomitant effect of HSL production and degradation which justifies less disease severity index in cross-inoculated tomato fruits incubated at 35 and 37 °C. The nondetection of the OHHL in the elevated temperature may because of degradation as these signal molecules are quite sensitive and prone to get degraded under different physical factors. This result provides the rationale behind the highest disease severity up to certain elevated temperature and leaves opportunities for investigation on mutation, co-evolution of superior plant pathogen with more stable HSL signals-mediated pathogenesis under global warming context. PMID:26271295

  5. Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes

    PubMed Central

    Telling, Jon; Anesio, Alexandre M.; Tranter, Martyn; Fountain, Andrew G.; Nylen, Thomas; Hawkings, Jon; Singh, Virendra B.; Kaur, Preeti; Musilova, Michaela; Wadham, Jemma L.

    2014-01-01

    The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

  6. Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes.

    PubMed

    Telling, Jon; Anesio, Alexandre M; Tranter, Martyn; Fountain, Andrew G; Nylen, Thomas; Hawkings, Jon; Singh, Virendra B; Kaur, Preeti; Musilova, Michaela; Wadham, Jemma L

    2014-01-01

    The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

  7. Effect of different film packaging on microbial growth in minimally processed cactus pear (Opuntia ficus-indica).

    PubMed

    Palma, A; Mangia, N P; Fadda, A; Barberis, A; Schirra, M; D'Aquino, S

    2013-01-01

    Microorganisms are natural contaminants of fresh produce and minimally processed products, and contamination arises from a number of sources, including the environment, postharvest handling and processing. Fresh-cut products are particularly susceptible to microbial contaminations because of the changes occurring in the tissues during processing. In package gas composition of modified atmosphere packaging (MAP) in combination with low storage temperatures besides reducing physiological activity of packaged produce, can also delay pathogen growth. Present study investigated on the effect of MAPs, achieved with different plastic films, on microbial growth of minimally processed cactus pear (Opuntio ficus-indica) fruit. Five different plastic materials were used for packaging the manually peeled fruit. That is: a) polypropylene film (Termoplast MY 40 micron thickness, O2 transmission rate 300 cc/m2/24h); b) polyethylene film (Bolphane BHE, 11 micron thickness, O2 transmission rate 19000 cc/m2/24h); c) polypropylene laser-perforated films (Mach Packaging) with 8, 16 or 32 100-micron holes. Total aerobic psychrophilic, mesophilic microorganisms, Enterobacteriaceae, yeast, mould populations and in-package CO2, O2 and C2H4 were determined at each storage time. Different final gas compositions, ranging from 7.8 KPa to 17.1 KPa O2, and 12.7 KPa to 2.6 KPa CO2, were achieved with MY and micro perforated films, respectively. Differences were detected in the mesophilic, Enterobacteriaceae and yeast loads, while no difference was detected in psychrophilic microorganisms. At the end of storage, microbial load in fruits sealed with MY film was significantly lower than in those sealed with BHE and micro perforated films. Furthermore, fruits packed with micro-perforated films showed the highest microbial load. This occurrence may in part be related to in-package gas composition and in part to a continuous contamination of microorganisms through micro-holes. PMID:25145227

  8. Postnatal nutritional restriction affects growth and immune function of piglets with intra-uterine growth restriction.

    PubMed

    Hu, Liang; Liu, Yan; Yan, Chuan; Peng, Xie; Xu, Qin; Xuan, Yue; Han, Fei; Tian, Gang; Fang, Zhengfeng; Lin, Yan; Xu, Shengyu; Zhang, Keying; Chen, Daiwen; Wu, De; Che, Lianqiang

    2015-07-14

    Postnatal rapid growth by excess intake of nutrients has been associated with an increased susceptibility to diseases in neonates with intra-uterine growth restricted (IUGR). The aim of the present study was to determine whether postnatal nutritional restriction could improve intestinal development and immune function of neonates with IUGR using piglets as model. A total of twelve pairs of normal-birth weight (NBW) and IUGR piglets (7 d old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake (RNI) by artificially liquid feeding for a period of 21 d. Blood samples and intestinal tissues were collected at necropsy and were analysed for morphology, digestive enzyme activities, immune cells and expression of innate immunity-related genes. The results indicated that both IUGR and postnatal nutritional restriction delayed the growth rate during the sucking period. Irrespective of nutrient intake, piglets with IUGR had a significantly lower villous height and crypt depth in the ileum than the NBW piglets. Moreover, IUGR decreased alkaline phosphatase activity while enhanced lactase activity in the jejunum and mRNA expressions of Toll-like receptor 9 (TLR-9) and DNA methyltransferase 1 (DNMT1) in the ileum of piglets. Irrespective of body weight, RNI significantly decreased the number and/or percentage of peripheral leucocytes, lymphocytes and monocytes of piglets, whereas the percentage of neutrophils and the ratio of CD4+ to CD8+ were increased. Furthermore, RNI markedly enhanced the mRNA expression of TLR-9 and DNMT1, but decreased the expression of NOD2 and TRAF-6 in the ileum of piglets. In summary, postnatal nutritional restriction led to abnormal cellular and innate immune response, as well as delayed the growth and intestinal development of IUGR piglets. PMID:26059215

  9. Relative contributions of mercury bioavailability and microbial growth rate on net methylmercury production by anaerobic mixed cultures†

    PubMed Central

    Kucharzyk, Katarzyna H.; Deshusses, Marc A.; Porter, Kaitlyn A.; Hsu-Kim, Heileen

    2016-01-01

    Monomethylmercury (MeHg) is produced in many aquatic environments by anaerobic microorganisms that take up and methylate inorganic forms of Hg(II). Net methylation of Hg(II) appears to be correlated with factors that affect the activity of the anaerobic microbial community and factors that increase the bioavailability of Hg(II) to these organisms. However, the relative importance of one versus the other is difficult to elucidate even though this information can greatly assist remediation efforts and risk assessments. Here, we investigated the effects of Hg speciation (dissolved Hg and nanoparticulate HgS) and microbial activity on the net production of MeHg using two mixed microbial cultures that were enriched from marine sediments under sulfate reducing conditions. The cultures were amended with dissolved Hg (added as a dissolved nitrate salt) and nanoparticulate HgS, and grown under different carbon substrate concentrations. The results indicated that net mercury methylation was the highest for cultures incubated in the greatest carbon substrate concentration (60 mM) compared to incubations with less carbon (0.6 and 6 mM), regardless of the form of mercury amended. Net MeHg production in cultures exposed to HgS nanoparticles was significantly slower than in cultures exposed to dissolved Hg; however, the difference diminished with slower growing cultures with low carbon addition (0.6 mM). The net Hg methylation rate was found to correlate with sulfate reduction rate in cultures exposed to dissolved Hg, while methylation rate was roughly constant for cultures exposed to nanoparticulate HgS. These results indicated a potential threshold of microbial productivity: below this point net MeHg production was limited by microbial activity, regardless of Hg bioavailability. Above this threshold of productivity, Hg speciation became a contributing factor towards net MeHg production. PMID:26211614

  10. Effect of androgens and glucocorticoids on microbial growth and antimicrobial susceptibility.

    PubMed

    Plotkin, Balbina J; Roose, Robert J; Erikson, Quenby; Viselli, Susan M

    2003-12-01

    The effects of androgens, testosterone and dihydrotestosterone (DHT), of an environmental anti-androgen, 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), and of glucocorticoids, hydrocortisone and dexamethasone, on growth kinetics and antibiotic susceptibility of E. faecalis, E. coli, P. aeurginosa, and S. aureus were measured. For P. aeurginosa, the presence of either DHT or DDE caused at least a fourfold shift in the minimum inhibitory concentration (MIC) of cefepime and tobramycin. DHT and DDE also affected the response of E. faecalis to meropenem and norfloxacin, resulting in a shift from sensitive to intermediate resistance (four-fold increase in MIC). Hydrocortisone (2 microM) induced an increase in the sensitivity of S. aureus to erythromycin, as compared to hormone-free control (from 0.5 to 0.06 microg/mL). The susceptibility pattern of E. coli was unaffected by the hormones tested. These changes in susceptibility to antibiotics were unrelated to alterations in growth kinetics. For all organisms tested, the alterations in MICs occurred only in the presence of hormone, indicative of changes in the phenotype of these stable quality control strains. PMID:14756537

  11. Analysis of matrix effects critical to microbial transport in organic waste-affected soils across laboratory and field scales

    NASA Astrophysics Data System (ADS)

    Unc, Adrian; Goss, Michael J.; Cook, Simon; Li, Xunde; Atwill, Edward R.; Harter, Thomas

    2012-06-01

    Organic waste applications to soil (manure, various wastewaters, and biosolids) are among the most significant sources of bacterial contamination in surface and groundwater. Transport of bacteria through the vadose zone depends on flow path geometry and stability and is mitigated by interaction between soil, soil solution, air-water interfaces, and characteristics of microbial surfaces. After initial entry, the transport through soil depends on continued entrainment of bacteria and resuspension of those retained in the porous structure. We evaluated the retention of bacteria-sized artificial microspheres, varying in diameter and surface charge and applied in different suspending solutions, by a range of sieved soils contained in minicolumns, the transport of hydrophobic bacteria-sized microspheres through undisturbed soil columns as affected by waste type under simulated rainfall, and the field-scale transport of Enterococcus spp. to an unconfined sandy aquifer after the application of liquid manure. Microsphere retention reflected microsphere properties. The soil type and suspending solution affected retention of hydrophilic but not hydrophobic particles. Retention was not necessarily facilitated by manure-microsphere-soil interactions but by manure-soil interactions. Undisturbed column studies confirmed the governing role of waste type on vadose-zone microsphere transport. Filtration theory applied as an integrated analysis of transport across length scales showed that effective collision efficiency depended on the distance of travel. It followed a power law behavior with the power coefficient varying from ˜0.4 over short distances to >0.9 over 1 m (i.e., very little filtration for a finite fraction of biocolloids), consistent with reduced influence of soil solution and biocolloid properties at longer travel distances.

  12. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites

    PubMed Central

    Ko, Kyung-Seok; Ha, Kyoochul; Kong, In Chul

    2015-01-01

    The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co3O4 and TiO2) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co3O4 > NiO > TiO2. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%–92% and 78%–82% of the control (p-value 0.0010) based on ATP content and 78%–95% and 72%–94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement. PMID:26610489

  13. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites.

    PubMed

    Ko, Kyung-Seok; Ha, Kyoochul; Kong, In Chul

    2015-01-01

    The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co₃O₄ and TiO₂) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co₃O₄ > NiO > TiO₂. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%-92% and 78%-82% of the control (p-value 0.0010) based on ATP content and 78%-95% and 72%-94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement. PMID:26610489

  14. Soil type affects Pinus ponderosa var. scopulorum (Pinaceae) seedling growth in simulated drought experiments1

    PubMed Central

    Lindsey, Alexander J.; Kilgore, Jason S.

    2013-01-01

    • Premise of the study: Effects of drought stress and media type interactions on growth of Pinus ponderosa var. scopulorum germinants were investigated. • Methods and Results: Soil properties and growth responses under drought were compared across four growth media types: two native soils (dolomitic limestone and granite), a soil-less industry standard conifer medium, and a custom-mixed conifer medium. After 35 d of growth, the seedlings under drought stress (reduced watering) produced less shoot and root biomass than watered control seedlings. Organic media led to decreased root biomass, but increased root length and shoot biomass relative to the mineral soils. • Conclusions: Media type affected root-to-shoot biomass partitioning of P. ponderosa var. scopulorum, which may influence net photosynthetic rates, growth, and long-term seedling survival. Further work should examine how specific soil properties like bulk density and organic matter influence biomass allocation in greenhouse studies. PMID:25202578

  15. An affective-cognitive processing model of post-traumatic growth.

    PubMed

    Joseph, Stephen; Murphy, David; Regel, Stephen

    2012-01-01

    A topic that has begun to attract interest from clinical psychologists and psychotherapists is post-traumatic growth. First, we provide a general overview of the field, setting out the historical development, main concepts, measurement issues and research findings. Second, we review evidence showing that the relationship between post-traumatic stress and post-traumatic growth is likely curvilinear. Third, a new affective-cognitive processing model of post-traumatic growth will be introduced in which post-traumatic stress is understood to be the engine of post-traumatic growth. Fourth, points of clinical intervention are described showing the ways in which therapists can facilitate post-traumatic growth. PMID:22610981

  16. Methods for Facilitating Microbial Growth on Pulp Mill Waste Streams and Characterization of the Biodegradation Potential of Cultured Microbes

    PubMed Central

    Mathews, Stephanie L.; Ayoub, Ali S.; Pawlak, Joel; Grunden, Amy M.

    2013-01-01

    The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor. PMID:24378616

  17. Methods for facilitating microbial growth on pulp mill waste streams and characterization of the biodegradation potential of cultured microbes.

    PubMed

    Mathews, Stephanie L; Ayoub, Ali S; Pawlak, Joel; Grunden, Amy M

    2013-01-01

    The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor. PMID:24378616

  18. Soil microbial abundance, activity and diversity response in two different altitude-adapted plant communities affected by wildfire in Sierra Nevada National Park (Granada, Spain)

    NASA Astrophysics Data System (ADS)

    Bárcenas-Moreno, Gema; Zavala, Lorena; Jordan, Antonio; Bååth, Erland; Mataix-Beneyto, Jorge

    2013-04-01

    Plant communities can play an important role in fire severity and post-fire ecosystem recovery due to their role as combustible and different plant-soil microorganisms interactions. Possible differences induced by plant and microorganisms response after fire could affect the general ecosystem short and long-term response and its sustainability. The main objective of this work was the evaluation of the effect of wildfire on soil microbial abundance, activity and diversity in two different plant communities associated to different altitudes in Sierra Nevada National Park (Granada, Spain). Samples were collected in two areas located on the Sierra Nevada Mountain between 1700 and 2000 m above sea level which were affected by a large wildfire in 2005. Two samplings were carried out 8 and 20 months after fire and samples were collected in both burned and unburned (control) zones in each plant community area. Area A is located at 1700m and it is formed by Quercus rotundifolia forest while area B is located at 2000 m altitude and is composed of alpine vegetation formed by creeping bearing shrubs. Microbial biomass measured by Fumigation-Extraction method followed the same trend in both areas showing slight and no significant differences between burned and unburned area during the study period while viable and cultivable bacteria abundance were markedly higher in fire affected samples than in the control ones in both samplings. Viable and cultivable filamentous fungi had different behavior depending of plant vegetation community studied showing no differences between burned and unburned area in area A while was significantly higher in burned samples than in the control ones in area B. Microbial activity monitoring with soil microbial respiration appears to had been affected immediately after fire since microbial respiration was lower in burned samples from area A than in unburned one only 8 months after fire and no significant differences were observed between burned and

  19. Disruption of the lower food web in Lake Ontario: Did it affect alewife growth or condition?

    USGS Publications Warehouse

    O'Gorman, R.; Prindle, S.E.; Lantry, J.R.; Lantry, B.F.

    2008-01-01

    From the early 1980s to the late 1990s, a succession of non-native invertebrates colonized Lake Ontario and the suite of consequences caused by their colonization became known as "food web disruption". For example, the native burrowing amphipod Diporeia spp., a key link in the profundal food web, declined to near absence, exotic predaceous cladocerans with long spines proliferated, altering the zooplankton community, and depth distributions of fishes shifted. These changes had the potential to affect growth and condition of planktivorous alewife Alosa pseudoharengus, the most abundant fish in the lake. To determine if food web disruption affected alewife, we used change-point analysis to examine alewife growth and adult alewife condition during 1976-2006 and analysis-of-variance to determine if values between change points differed significantly. There were no change points in growth during the first year of life. Of three change points in growth during the second year of life, one coincided with the shift in springtime distribution of alewife to deeper water but it was not associated with a significant change in growth. After the second year of life, no change points in growth were evident, although growth in the third year of life spiked in those years when Bythotrephes, the largest of the exotic cladocerans, was abundant suggesting that it was a profitable prey item for age-2 fish. We detected two change points in condition of adult alewife in fall, but the first occurred in 1981, well before disruption began. A second change point occurred in 2003, well after disruption began. After the springtime distribution of alewife shifted deeper during 1992-1994, growth in the first two years of life became more variable, and growth in years of life two and older became correlated (P < 0.05). In conclusion, food web disruption had no negative affect on growth and condition of alewife in Lake Ontario although it appears to have resulted in growth in the first two years of

  20. CO2 enrichment at night affects the growth and yield of common beans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Some experiments to determine the crop yield increase expected with rising atmospheric carbon dioxide concentration added carbon dioxide only during the daytime, without tests of whether elevation of carbon dioxide at night affected plant growth. In this experiment, two cultivars of common bean wer...

  1. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  2. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    PubMed Central

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-01-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction. PMID:25008009

  3. Carbonate fabrics in the modern microbialites of Pavilion Lake: two suites of microfabrics that reflect variation in microbial community morphology, growth habit, and lithification.

    PubMed

    Theisen, C Harwood; Sumner, D Y; Mackey, T J; Lim, D S S; Brady, A L; Slater, G F

    2015-07-01

    Modern microbialites in Pavilion Lake, BC, provide an analog for ancient non-stromatolitic microbialites that formed from in situ mineralization. Because Pavilion microbialites are mineralizing under the influence of microbial communities, they provide insights into how biological processes influence microbialite microfabrics and mesostructures. Hemispherical nodules and micrite-microbial crusts are two mesostructures within Pavilion microbialites that are directly associated with photosynthetic communities. Both filamentous cyanobacteria in hemispherical nodules and branching filamentous green algae in micrite-microbial crusts were associated with calcite precipitation at microbialite surfaces and with characteristic microfabrics in the lithified microbialite. Hemispherical nodules formed at microbialite surfaces when calcite precipitated around filamentous cyanobacteria with a radial growth habit. The radial filament pattern was preserved within the microbialite to varying degrees. Some subsurface nodules contained well-defined filaments, whereas others contained only dispersed organic inclusions. Variation in filament preservation is interpreted to reflect differences in timing and amount of carbonate precipitation relative to heterotrophic decay, with more defined filaments reflecting greater lithification prior to degradation than more diffuse filaments. Micrite-microbial crusts produce the second suite of microfabrics and form in association with filamentous green algae oriented perpendicular to the microbialite surface. Some crusts include calcified filaments, whereas others contained voids that reflect the filamentous community in shape, size, and distribution. Pavilion microbialites demonstrate that microfabric variation can reflect differences in lithification processes and microbial metabolisms as well as microbial community morphology and organization. Even when the morphology of individual filaments or cells is not well preserved, the microbial growth

  4. Dental caries affects body weight, growth and quality of life in pre-school children.

    PubMed

    Sheiham, A

    2006-11-25

    The effect of a relatively common chronic disease, severe dental caries, affects young childrens' growth and well-being. Treating dental caries in pre-school children would increase growth rates and the quality of life of millions of children. Severe untreated dental caries is common in pre-school children in many countries. Children with severe caries weighed less than controls, and after treatment of decayed teeth there was more rapid weight gain and improvements in their quality of life. This may be due to dietary intake improving because pain affected the quantity and variety of food eaten, and second, chronic inflammation from caries related pulpitis and abscesses is known to suppress growth through a metabolic pathway and to reduce haemoglobin as a result of depressed erythrocyte production. PMID:17128231

  5. GROWTH MEASUREMENTS OF TERRESTRIAL MICROBIAL SPECIES BY A CONTINUOUS-FLOW TECHNIQUE (JOURNAL VERSION)

    EPA Science Inventory

    A continuous nutrient flow system has been developed to measure microbial activity in soil with various concentrations of added substrate. The system consists of a thin soil layer through which substrate was added continuously over periods up to 4.5 days. Substrate utilization wa...

  6. Characterization of microbial growth on processing equipment by electrochemical impedance spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial activity that leads to the formation of biofilms on process equipment can accelerate corrosion, reduce heat transfer rates, and generally decrease process efficiencies. Additional concerns arise in the food and pharma industries where product quality and safety are a high priority. Followi...

  7. Stable carbon isotope fractionation of six strongly fractionating microorganisms is not affected by growth temperature under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Penger, Jörn; Conrad, Ralf; Blaser, Martin

    2014-09-01

    Temperature is the major driving force for many biological as well as chemical reactions and may impact the fractionation of stable carbon isotopes. Thus, a good correlation between temperature and fractionation is observed in many chemical systems that are controlled by an equilibrium isotope effect. In contrast, biological systems that are usually controlled by a kinetic isotope effect are less well studied with respect to temperature effects and have shown contrasting results. We studied three different biological pathways (methylotrophic methanogenesis, hydrogenotrophic methanogenesis, acetogenesis by the acetyl-CoA pathway) which are characterized by very strong carbon isotope enrichment factors (-50‰ to -83‰). The microorganisms (Methanosarcina barkeri, Methanosarcina acetivorans, Methanolobus zinderi, Methanothermobacter marburgensis, Methanothermobacter thermoautotrophicus, Thermoanaerobacter kivui) exhibiting these pathways were grown at different temperatures ranging between 25 and 68 °C, and the fractionation factors were determined from 13C/12C isotope discrimination during substrate depletion and product formation. Our experiments showed that the fractionation factors were different for the different metabolic pathways but were not much affected by the different growth temperatures. Slight variations were well within the standard errors of replication and regression analysis. Our results showed that temperature had no significant effect on the fractionation of stable carbon isotopes during anaerobic microbial metabolism with relatively strong isotope fractionation.

  8. Modeling and optimization of Newfoundland shrimp waste hydrolysis for microbial growth using response surface methodology and artificial neural networks.

    PubMed

    Zhang, Kedong; Zhang, Baiyu; Chen, Bing; Jing, Liang; Zhu, Zhiwen; Kazemi, Khoshrooz

    2016-08-15

    The hydrolyzed protein derived from seafood waste is regarded as a premium and low-cost nitrogen source for microbial growth. In this study, optimization of enzymatic shrimp waste hydrolyzing process was investigated. The degree of hydrolysis (DH) with four processing variables including enzyme/substrate ratio (E/S), hydrolysis time, initial pH value and temperature, were monitored. The DH values were used for response surface methodology (RSM) optimization through central composite design (CCD) and for training artificial neural network (ANN) to make a process prediction. Results indicated that the optimum levels of variables are: E/S ratio at 1.64%, hydrolysis time at 3.59h, initial pH at 9 and temperature at 52.57°C. Hydrocarbon-degrading bacteria Bacillus subtilis N3-1P was cultivated using different DHs of hydrolysate. The associated growth curves were generated. The research output facilitated effective shrimp waste utilization. PMID:27312986

  9. Slow pyrolysis of poultry litter and pine woody biomass: impact of chars and bio-oils on microbial growth.

    PubMed

    Das, K C; Garcia-Perez, M; Bibens, B; Melear, N

    2008-06-01

    Accidental or prescribed fires in forests and in cultivated fields, as well as primitive charcoal production practices, are responsible for the release of large amounts of gases, char and condensable organic molecules into the environment. This paper describes the impact of condensable organic molecules and chars resulting from the slow pyrolysis of poultry litter, pine chips and pine pellets on the growth of microbial populations in soil and water. The proximate and elemental analyses as well as the content of proteins, cellulose, hemicellulose, lignin, and ash for each of these bio-materials are reported. The yields and some properties of char and condensable liquids are also documented. The behavior of microbial populations in soil and water is followed through respiration studies. It was found that biological activity was highest when aqueous fractions from poultry litter were applied in water. Cumulative oxygen consumption over a 120-h period was highest in the aqueous phases from poultry litter coarse fraction (1.82 mg/g). On average the oxygen consumption when oily fractions from poultry litter were applied represented 44 to 62% of that when aqueous fractions were applied. Pine chip and pine pellet derived liquids and chars produced respiration activity that were an order of magnitude lower than that of poultry litter liquid fractions. These results suggest that the growth observed is due to the effect of protein-derived molecules. PMID:18444073

  10. Efficacy of sodium hypochlorite and acidified sodium chlorite in preventing browning and microbial growth on fresh-cut produce.

    PubMed

    Sun, Shih Hui; Kim, Su Jin; Kwak, Soo Jin; Yoon, Ki Sun

    2012-09-01

    The use of suitable sanitizers can increase the quality of fresh-cut produce and reduce the risk of foodborne illnesses. The objective of this study was to compare the washing effects of 100 mg/L sodium hypochlorite (SH) and 500 mg/L acidified sodium chlorite (ASC) on the prevention of enzymatic browning and the growth of microbial populations, including aerobic plate counts, E. coli, and coliforms, throughout storage at 4°C and 10°C. Fresh-cut zucchini, cucumbers, green bell peppers, and root vegetables such as potatoes, sweet potatoes, carrots, and radishes were used. Compared to SH washing, ASC washing significantly (p<0.05) reduced microbial contamination on the fresh-cut produce and prevented browning of fresh-cut potatoes and sweet potatoes during storage. More effective inhibition of aerobic plate counts and coliforms growth was observed on fresh-cut produce treated with ASC during storage at 10°C. Polyphenol oxidase (PPO) activity of fresh-cut potatoes and sweet potatoes was more effectively inhibited after washing with ASC. The use of 500 mg/L ASC can provide effective antimicrobial and anti-browning treatments of fresh-cut produce, including processed root vegetables. PMID:24471086

  11. Efficacy of Sodium Hypochlorite and Acidified Sodium Chlorite in Preventing Browning and Microbial Growth on Fresh-Cut Produce

    PubMed Central

    Sun, Shih Hui; Kim, Su Jin; Kwak, Soo Jin; Yoon, Ki Sun

    2012-01-01

    The use of suitable sanitizers can increase the quality of fresh-cut produce and reduce the risk of foodborne illnesses. The objective of this study was to compare the washing effects of 100 mg/L sodium hypochlorite (SH) and 500 mg/L acidified sodium chlorite (ASC) on the prevention of enzymatic browning and the growth of microbial populations, including aerobic plate counts, E. coli, and coliforms, throughout storage at 4°C and 10°C. Fresh-cut zucchini, cucumbers, green bell peppers, and root vegetables such as potatoes, sweet potatoes, carrots, and radishes were used. Compared to SH washing, ASC washing significantly (p<0.05) reduced microbial contamination on the fresh-cut produce and prevented browning of fresh-cut potatoes and sweet potatoes during storage. More effective inhibition of aerobic plate counts and coliforms growth was observed on fresh-cut produce treated with ASC during storage at 10°C. Polyphenol oxidase (PPO) activity of fresh-cut potatoes and sweet potatoes was more effectively inhibited after washing with ASC. The use of 500 mg/L ASC can provide effective antimicrobial and anti-browning treatments of fresh-cut produce, including processed root vegetables. PMID:24471086

  12. Range expansions transition from pulled to pushed waves as growth becomes more cooperative in an experimental microbial population.

    PubMed

    Gandhi, Saurabh R; Yurtsev, Eugene Anatoly; Korolev, Kirill S; Gore, Jeff

    2016-06-21

    Range expansions are becoming more frequent due to environmental changes and rare long-distance dispersal, often facilitated by anthropogenic activities. Simple models in theoretical ecology explain many emergent properties of range expansions, such as a constant expansion velocity, in terms of organism-level properties such as growth and dispersal rates. Testing these quantitative predictions in natural populations is difficult because of large environmental variability. Here, we used a controlled microbial model system to study range expansions of populations with and without intraspecific cooperativity. For noncooperative growth, the expansion dynamics were dominated by population growth at the low-density front, which pulled the expansion forward. We found these expansions to be in close quantitative agreement with the classical theory of pulled waves by Fisher [Fisher RA (1937) Ann Eugen 7(4):355-369] and Skellam [Skellam JG (1951) Biometrika 38(1-2):196-218], suitably adapted to our experimental system. However, as cooperativity increased, the expansions transitioned to being pushed, that is, controlled by growth and dispersal in the bulk as well as in the front. Given the prevalence of cooperative growth in nature, understanding the effects of cooperativity is essential to managing invading species and understanding their evolution. PMID:27185918

  13. Range expansions transition from pulled to pushed waves as growth becomes more cooperative in an experimental microbial population

    PubMed Central

    Yurtsev, Eugene Anatoly; Korolev, Kirill S.; Gore, Jeff

    2016-01-01

    Range expansions are becoming more frequent due to environmental changes and rare long-distance dispersal, often facilitated by anthropogenic activities. Simple models in theoretical ecology explain many emergent properties of range expansions, such as a constant expansion velocity, in terms of organism-level properties such as growth and dispersal rates. Testing these quantitative predictions in natural populations is difficult because of large environmental variability. Here, we used a controlled microbial model system to study range expansions of populations with and without intraspecific cooperativity. For noncooperative growth, the expansion dynamics were dominated by population growth at the low-density front, which pulled the expansion forward. We found these expansions to be in close quantitative agreement with the classical theory of pulled waves by Fisher [Fisher RA (1937) Ann Eugen 7(4):355–369] and Skellam [Skellam JG (1951) Biometrika 38(1-2):196–218], suitably adapted to our experimental system. However, as cooperativity increased, the expansions transitioned to being pushed, that is, controlled by growth and dispersal in the bulk as well as in the front. Given the prevalence of cooperative growth in nature, understanding the effects of cooperativity is essential to managing invading species and understanding their evolution. PMID:27185918

  14. Habitat management affects soil chemistry and allochthonous organic inputs mediating microbial structure and exo-enzyme activity in Wadden Sea salt-marsh soils

    NASA Astrophysics Data System (ADS)

    Mueller, Peter; Granse, Dirk; Thi Do, Hai; Weingartner, Magdalena; Nolte, Stefanie; Hoth, Stefan; Jensen, Kai

    2016-04-01

    The Wadden Sea (WS) region is Europe's largest wetland and home to approximately 20% of its salt marsh area. Mainland salt marshes of the WS are anthropogenically influenced systems and have traditionally been used for livestock grazing in wide parts. After foundation of WS National Parks in the late 1980s and early 1990s, artificial drainage has been abandoned; however, livestock grazing is still common in many areas of the National Parks and is under ongoing discussion as a habitat-management practice. While studies so far focused on effects of livestock grazing on biodiversity, little is known about how biogeochemical processes, element cycling, and particularly carbon sequestration are affected. Here, we present data from a recent field study focusing on grazing effects on soil properties, microbial exo-enzyme activity, microbial abundance and structure. Exo-enzyme activity was studied conducting digestive enzyme assays for various enzymes involved in C- and N cycling. Microbial abundance and structure was assessed measuring specific gene abundance of fungi and bacteria using quantitative PCR. Soil compaction induced by grazing led to higher bulk density and decreases in soil redox (∆ >100 mV). Soil pH was significantly lower in grazed parts. Further, the proportion of allochthonous organic matter (marine input) was significantly smaller in grazed vs. ungrazed sites, likely caused by a higher sediment trapping capacity of the taller vegetation in the ungrazed sites. Grazing induced changes in bulk density, pH and redox resulted in reduced activity of enzymes involved in microbial C acquisition; however, there was no grazing effect on enzymes involved in N acquisition. While changes in pH, bulk density or redox did not affect microbial abundance and structure, the relative amount of marine organic matter significantly reduced the relative abundance of fungi (F:B ratio). We conclude that livestock grazing directly affects microbial exo-enzyme activity, thus

  15. Microbial biodiversity in cheese consortia and comparative Listeria growth on surfaces of uncooked pressed cheeses.

    PubMed

    Callon, Cécile; Retureau, Emilie; Didienne, Robert; Montel, Marie-Christine

    2014-03-17

    The study set out to determine how changes in the microbial diversity of a complex antilisterial consortium from the surface of St-Nectaire cheese modify its antilisterial activities. On the basis of the microbial composition of a natural complex consortium named TR15 (Truefood consortium 15), three new consortia of different species and strain compositions were defined: TR15-SC (58 isolates from TR15 collection), TR15-M (pools of isolates from selective counting media) and TR15-BHI (pools of isolates from BHI medium). Their antilisterial activities on the surfaces of uncooked pressed cheese made with pasteurised milk were compared with the activity of complex consortium TR15 and a control cheese inoculated only with starter culture (Streptococcus thermophilus, Lactobacillus delbrueckii). The natural consortium TR15 was the most inhibitory, followed by reconstituted consortium TR15-BHI. The dynamics of the cheese rind microbial flora were monitored by counting on media and by isolate identification using 16S rDNA sequencing and direct 16S rDNA Single Strand Conformation Polymorphism analysis. The combination of these methods showed that rind with natural consortium TR15 had greater microbial diversity and different microbial dynamics than cheese rinds with reconstituted consortia. Cheese rind with the natural consortium showed higher citrate consumption and the highest concentrations of lactic and acetic acids, connected with high levels of lactic acid bacteria such as Carnobacterium maltaromaticum, Vagococcus fluvialis, Enterococcus gilvus, Leuconostoc mesenteroides, Brochothrix thermosphacta and Lactococcus lactis, ripening bacteria such as Arthrobacter nicotianae/arilaitensis, and Gram negative bacteria (Pseudomonas psychrophila and Enterobacter spp.). The highest L. monocytogenes count was on rind with TR15-M and was positively associated with the highest pH value, high succinic and citric acid contents, and the highest levels of Marinilactibacillus

  16. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling

    PubMed Central

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M.; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  17. Controlled Cu nanoparticle growth on wrinkle affecting deposition of large scale graphene

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohsin; Uddin, Md Jasim; Rahman, Muhammad Anisur; Kishi, Naoki; Soga, Tetsuo

    2016-09-01

    For Chemical Vapor Deposition (CVD) grown graphene on Cu substrate, deviation from atomic orientation in crystals may be resulted from diffusion of abnormalities in the form of Cu nanoparticle (NP) formation or defects and affects graphene quality and properties drastically. However, for the uniform graphene deposition, mechanism of nanoparticle formation and its suppression procedure need to be better understood. We report growth of graphene, affected by Cu nanoparticles (NPs) emergence on Cu substrates. In the current study, growth of these nanoparticles has been suppressed by fine tuning of carrier gas by two-fold gas insertion mechanism and hence, quality and uniformity of graphene is significantly improved. It has been also observed that during the deposition by CVD, Cu nanoparticles cluster preferentially on wrinkles or terrace of the Cu surface. Composition of NP is extensively studied and found to be the oxide nanoparticle of Cu. Our result, controlled NP growth affecting deposition of graphene layer would provide useful insight on the growth of uniform and high quality Single layer or bilayer graphene for numerous electronics applications.

  18. Evaluation of Houttuynia cordata and Taraxacum officinale on Growth Performance, Nutrient Digestibility, Blood Characteristics, and Fecal Microbial Shedding in Diet for Weaning Pigs.

    PubMed

    Yan, L; Zhang, Z F; Park, J C; Kim, I H

    2012-10-01

    A total of 144 pigs ((Landrace×Yorkshire)×Duroc] with an average initial BW of 8.45±0.57 kg were used in a 5-wk growth trial. Pigs were randomly allocated to 4 treatments with 9 replications per pen in a randomized complex block design. Dietary treatments included: i) CON (basal diet), ii) ANT (CON+tylosin 1 g/kg), iii) H1 (CON+H. cordata 1 g/kg) and iv) T1 (CON+T. officinale 1 g/kg). In this study, pigs fed the ANT and T1 treatment had a higher (p<0.05) average daily gain (ADG) and gain:feed (G:F) ratio than those fed CON and H1 treatment. Dietary ANT and T1 treatment led to a higher energy digestibility than the CON group. No difference (p>0.05) was observed on the growth performance and apparent total tract digestibility with H1 supplementation compared with the CON treatment. The inclusion of ANT treatment led to a higher (p<0.05) lymphocyte concentration compared with the CON treatment. Dietary supplementation of herbs did not affect (p>0.05) the blood characteristics (white blood cell (WBC), red blood cell (RBC), IgG, lymphocyte). No difference was observed on (p<0.05) fecal microbial shedding (E. coli and lactobacillus) between ANT and CON groups. Treatments H1 and T1 reduced the fecal E. coli concentration compared with the CON treatment, whereas the fecal lactobacillus concentration was not affected by the herb supplementation (p>0.05). In conclusion, the inclusion of T. officinale (1 g/kg) increased growth performance, feed efficiency, energy digestibility similarly to the antibiotic treatment. Dietary supplementation of T. officinale and H. cordata (1 g/kg) reduced the fecal E. coli concentration in weaning pigs. PMID:25049500

  19. Low frequency electromagnetic waves as a supplemental energy source to sustain microbial growth?

    NASA Astrophysics Data System (ADS)

    Gusev, Victor A.; Schulze-Makuch, Dirk

    2005-03-01

    Microbial populations in tetra-distilled water collapsed when cultured in a permalloy chamber shielding the populations from the sun's and earth's electromagnetic field, but thrived when cultured in an ordinary thermostat open to the electromagnetic field. Theoretically, protons in liquid water can be excited at their natural resonance frequencies through Langmuir oscillations and obtain enough kinetic energy to charge the transmembrane potential of a cell. Microbes may be capable of converting this energy into chemical energy to supplement their energy needs.

  20. Dietary marker effects on fecal microbial ecology, fecal VFA, nutrient digestibility coefficients, and growth performance in finishing pigs.

    PubMed

    Kerr, B J; Weber, T E; Ziemer, C J

    2015-05-01

    control diet. In Exp. 2, no effect of dietary marker on pig performance was noted. Overall, the data indicate that the inclusion of Cr2O3, Fe2O3, or TiO2 as digestibility markers have little to no impact on microbial ecology, fecal ammonia or VFA concentrations, nutrient digestibility, or pig growth performance indicating they are suitable for use in digestion studies. PMID:26020314

  1. Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub.

    PubMed

    Milner, Jos M; Varpe, Øystein; van der Wal, René; Hansen, Brage Bremset

    2016-04-01

    Effects of climate change are predicted to be greatest at high latitudes, with more pronounced warming in winter than summer. Extreme mid-winter warm spells and heavy rain-on-snow events are already increasing in frequency in the Arctic, with implications for snow-pack and ground-ice formation. These may in turn affect key components of Arctic ecosystems. However, the fitness consequences of extreme winter weather events for tundra plants are not well understood, especially in the high Arctic. We simulated an extreme mid-winter rain-on-snow event at a field site in high Arctic Svalbard (78°N) by experimentally encasing tundra vegetation in ice. After the subsequent growing season, we measured the effects of icing on growth and fitness indices in the common tundra plant, Arctic bell-heather (Cassiope tetragona). The suitability of this species for retrospective growth analysis enabled us to compare shoot growth in pre and postmanipulation years in icing treatment and control plants, as well as shoot survival and flowering. Plants from icing treatment plots had higher shoot mortality and lower flowering success than controls. At the individual sample level, heavily flowering plants invested less in shoot growth than nonflowering plants, while shoot growth was positively related to the degree of shoot mortality. Therefore, contrary to expectation, undamaged shoots showed enhanced growth in ice treatment plants. This suggests that following damage, aboveground resources were allocated to the few remaining undamaged meristems. The enhanced shoot growth measured in our icing treatment plants has implications for climate studies based on retrospective analyses of Cassiope. As shoot growth in this species responds positively to summer warming, it also highlights a potentially complex interaction between summer and winter conditions. By documenting strong effects of icing on growth and reproduction of a widespread tundra plant, our study contributes to an understanding of

  2. Insulin-like growth factor- I and factors affecting it in thalassemia major

    PubMed Central

    Soliman, Ashraf T.; Sanctis, Vincenzo De; Elalaily, Rania; Yassin, Mohamed

    2015-01-01

    Despite improvement of blood transfusion regimens and iron chelation therapy growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis still occur in good number of thalassemic patients. Decreased IGF-1 secretion occurs in the majority of the thalassemic patients particularly those with growth and pubertal delay. Many factors contribute to this decreased synthesis of IGF-I including disturbed growth hormone (GH) - insulin-like growth factor - I (IGF-I) axis. The possible factors contributing to low IGF-I synthesis in thalassemia and the possible interaction between low IGF-I secretion and the occurrence of these complications is discussed in this mini-review. Improvement of IGF-I secretion in thalassemic patients should be intended to improve linear growth and bone mineral accretion in thalassemic patients. This can be attained through adequate correction of anemia and proper chelation, nutritional supplementation (increasing caloric intake), correction of vitamin D and zinc deficiencies, induction of puberty and correction of hypogonadism at the proper time and treating GH deficiency. This review paper provides a summary of the current state of knowledge regarding IGF-I and factors affecting it in patients with thalassaemia major (TM). Search on PubMed and reference lists of articles with the term ‘IGF-I, GH, growth, thalassemia, thyroxine, anemia, vitamin D, and zinc’ was carried out. A hundred and forty-eight articles were found and used in the write up and the data analyzed was included in this report. PMID:25729686

  3. Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth.

    PubMed

    G T Pereira, Anirene; Utsunomiya, Yuri T; Milanesi, Marco; Torrecilha, Rafaela B P; Carmo, Adriana S; Neves, Haroldo H R; Carvalheiro, Roberto; Ajmone-Marsan, Paolo; Sonstegard, Tad S; Sölkner, Johann; Contreras-Castillo, Carmen J; Garcia, José F

    2016-01-01

    Two complementary methods, namely Multi-Trait Meta-Analysis and Versatile Gene-Based Test for Genome-wide Association Studies (VEGAS), were used to identify putative pleiotropic genes affecting carcass traits in Bos indicus (Nellore) cattle. The genotypic data comprised over 777,000 single-nucleotide polymorphism markers scored in 995 bulls, and the phenotypic data included deregressed breeding values (dEBV) for weight measurements at birth, weaning and yearling, as well visual scores taken at weaning and yearling for carcass finishing precocity, conformation and muscling. Both analyses pointed to the pleomorphic adenoma gene 1 (PLAG1) as a major pleiotropic gene. VEGAS analysis revealed 224 additional candidates. From these, 57 participated, together with PLAG1, in a network involved in the modulation of the function and expression of IGF1 (insulin like growth factor 1), IGF2 (insulin like growth factor 2), GH1 (growth hormone 1), IGF1R (insulin like growth factor 1 receptor) and GHR (growth hormone receptor), suggesting that those pleiotropic genes operate as satellite regulators of the growth pathway. PMID:27410030

  4. Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth

    PubMed Central

    Milanesi, Marco; Torrecilha, Rafaela B. P.; Carmo, Adriana S.; Neves, Haroldo H. R.; Carvalheiro, Roberto; Ajmone-Marsan, Paolo; Sonstegard, Tad S.; Sölkner, Johann; Contreras-Castillo, Carmen J.; Garcia, José F.

    2016-01-01

    Two complementary methods, namely Multi-Trait Meta-Analysis and Versatile Gene-Based Test for Genome-wide Association Studies (VEGAS), were used to identify putative pleiotropic genes affecting carcass traits in Bos indicus (Nellore) cattle. The genotypic data comprised over 777,000 single-nucleotide polymorphism markers scored in 995 bulls, and the phenotypic data included deregressed breeding values (dEBV) for weight measurements at birth, weaning and yearling, as well visual scores taken at weaning and yearling for carcass finishing precocity, conformation and muscling. Both analyses pointed to the pleomorphic adenoma gene 1 (PLAG1) as a major pleiotropic gene. VEGAS analysis revealed 224 additional candidates. From these, 57 participated, together with PLAG1, in a network involved in the modulation of the function and expression of IGF1 (insulin like growth factor 1), IGF2 (insulin like growth factor 2), GH1 (growth hormone 1), IGF1R (insulin like growth factor 1 receptor) and GHR (growth hormone receptor), suggesting that those pleiotropic genes operate as satellite regulators of the growth pathway. PMID:27410030

  5. Microbial stratification in low pH oxic and suboxic macroscopic growths along an acid mine drainage.

    PubMed

    Méndez-García, Celia; Mesa, Victoria; Sprenger, Richard R; Richter, Michael; Diez, María Suárez; Solano, Jennifer; Bargiela, Rafael; Golyshina, Olga V; Manteca, Ángel; Ramos, Juan Luis; Gallego, José R; Llorente, Irene; Martins dos Santos, Vitor A P; Jensen, Ole N; Peláez, Ana I; Sánchez, Jesús; Ferrer, Manuel

    2014-06-01

    Macroscopic growths at geographically separated acid mine drainages (AMDs) exhibit distinct populations. Yet, local heterogeneities are poorly understood. To gain novel mechanistic insights into this, we used OMICs tools to profile microbial populations coexisting in a single pyrite gallery AMD (pH ∼2) in three distinct compartments: two from a stratified streamer (uppermost oxic and lowermost anoxic sediment-attached strata) and one from a submerged anoxic non-stratified mat biofilm. The communities colonising pyrite and those in the mature formations appear to be populated by the greatest diversity of bacteria and archaea (including 'ARMAN' (archaeal Richmond Mine acidophilic nano-organisms)-related), as compared with the known AMD, with ∼44.9% unclassified sequences. We propose that the thick polymeric matrix may provide a safety shield against the prevailing extreme condition and also a massive carbon source, enabling non-typical acidophiles to develop more easily. Only 1 of 39 species were shared, suggesting a high metabolic heterogeneity in local microenvironments, defined by the O2 concentration, spatial location and biofilm architecture. The suboxic mats, compositionally most similar to each other, are more diverse and active for S, CO2, CH4, fatty acid and lipopolysaccharide metabolism. The oxic stratum of the streamer, displaying a higher diversity of the so-called 'ARMAN'-related Euryarchaeota, shows a higher expression level of proteins involved in signal transduction, cell growth and N, H2, Fe, aromatic amino acids, sphingolipid and peptidoglycan metabolism. Our study is the first to highlight profound taxonomic and functional shifts in single AMD formations, as well as new microbial species and the importance of H2 in acidic suboxic macroscopic growths. PMID:24430486

  6. Microbial stratification in low pH oxic and suboxic macroscopic growths along an acid mine drainage

    PubMed Central

    Méndez-García, Celia; Mesa, Victoria; Sprenger, Richard R; Richter, Michael; Diez, María Suárez; Solano, Jennifer; Bargiela, Rafael; Golyshina, Olga V; Manteca, Ángel; Ramos, Juan Luis; Gallego, José R; Llorente, Irene; Martins dos Santos, Vitor AP; Jensen, Ole N; Peláez, Ana I; Sánchez, Jesús; Ferrer, Manuel

    2014-01-01

    Macroscopic growths at geographically separated acid mine drainages (AMDs) exhibit distinct populations. Yet, local heterogeneities are poorly understood. To gain novel mechanistic insights into this, we used OMICs tools to profile microbial populations coexisting in a single pyrite gallery AMD (pH ∼2) in three distinct compartments: two from a stratified streamer (uppermost oxic and lowermost anoxic sediment-attached strata) and one from a submerged anoxic non-stratified mat biofilm. The communities colonising pyrite and those in the mature formations appear to be populated by the greatest diversity of bacteria and archaea (including ‘ARMAN' (archaeal Richmond Mine acidophilic nano-organisms)-related), as compared with the known AMD, with ∼44.9% unclassified sequences. We propose that the thick polymeric matrix may provide a safety shield against the prevailing extreme condition and also a massive carbon source, enabling non-typical acidophiles to develop more easily. Only 1 of 39 species were shared, suggesting a high metabolic heterogeneity in local microenvironments, defined by the O2 concentration, spatial location and biofilm architecture. The suboxic mats, compositionally most similar to each other, are more diverse and active for S, CO2, CH4, fatty acid and lipopolysaccharide metabolism. The oxic stratum of the streamer, displaying a higher diversity of the so-called ‘ARMAN'-related Euryarchaeota, shows a higher expression level of proteins involved in signal transduction, cell growth and N, H2, Fe, aromatic amino acids, sphingolipid and peptidoglycan metabolism. Our study is the first to highlight profound taxonomic and functional shifts in single AMD formations, as well as new microbial species and the importance of H2 in acidic suboxic macroscopic growths. PMID:24430486

  7. Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation.

    PubMed

    Liao, Yingping; Min, Xiaobo; Yang, Zhihui; Chai, Liyuan; Zhang, Shujuan; Wang, Yangyang

    2014-01-01

    Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils. PMID:23784058

  8. Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids; Part I. Effects on growth performance, microbial populations and immune status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pigs (n=88) weaned at 19 ± 2 d of age were used in a 14 d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on immune status, Salmonella infection and shedding, and intestinal microbial populations following a Salmonella Typhimurium challenge. Pigs were ch...

  9. Growth of Bacillus cereus on solid media as affected by agar, sodium chloride, and potassium sorbate.

    PubMed

    Stecchini, M L; Del Torre, M; Donda, S; Maltini, E

    2000-07-01

    The effect of two independent variables: microstructure, as modified by the agar content (1.0, 4.0, 7.0%), and water activity (a(w)), as modified by the NaCl content (0.5, 2.5, 4.5%), in the absence or in the presence of potassium sorbate (0.0; 2,000 ppm) on Bacillus cereus growth on solid media was studied. The time to visible growth (TVG) and the radial growth rate (RGR) of colonies were evaluated. TVG was not affected by microstructure and K-sorbate, although when a(w) was reduced, TVG tended to increase. RGR depended on linear effects of microstructure and a(w) variables and their interaction. When K-sorbate was added to cultural media, RGR was reduced significantly. However, in the presence of K-sorbate, RGR was found to change only when a(w) vas varied. PMID:10914662

  10. Low-strength ultrasonication positively affects methanogenic granules toward higher AD performance: Implications from microbial community shift.

    PubMed

    Cho, Si-Kyung; Kim, Dong-Hoon; Quince, Christopher; Im, Wan-Taek; Oh, Sae-Eun; Shin, Seung Gu

    2016-09-01

    To elucidate the enhanced methane yield from organic wastes, the effects of low-strength ultrasonication on the microbial community structures in upflow anaerobic sludge blanket reactors were for the first time analyzed using pyrosequencing. Interestingly, a more even microbial community was observed in the ultrasonicated granules than in the control, which could compensate for the decreased richness and resulted in comparable (archaea) or even higher (bacteria) diversity. The ultrasonicated granules contained higher levels of δ-Proteobacteria, of which many are reportedly potential syntrophs, as well as methanogenic genera Methanosaeta, Methanotorris, and Methanococcus. The increased presence of syntrophic bacteria with their methanogenic partners was discussed with respect to hydrogen flux; their selective proliferation seems to be responsible for the enhanced anaerobic performance. This study is the first research shedding light on the novel function of low-strength ultrasound shifting the microbial structure towards better biogas production performance, and will facilitate application of low-strength ultrasound to other bioprocesses. PMID:27150761

  11. Dietary microbial phytase exerts mixed effects on the gut health of tilapia: a possible reason for the null effect on growth promotion.

    PubMed

    Hu, Jun; Ran, Chao; He, Suxu; Cao, Yanan; Yao, Bin; Ye, Yuantu; Zhang, Xuezhen; Zhou, Zhigang

    2016-06-01

    The present study evaluated the effects of dietary microbial phytase on the growth and gut health of hybrid tilapia (Oreochromis niloticus ♀×Oreochromis aureus ♂), focusing on the effect on intestinal histology, adhesive microbiota and expression of immune-related cytokine genes. Tilapia were fed either control diet or diet supplemented with microbial phytase (1000 U/kg). Each diet was randomly assigned to four groups of fish reared in cages (3×3×2 m). After 12 weeks of feeding, weight gain and feed conversion ratio of tilapia were not significantly improved by dietary microbial phytase supplementation. However, significantly higher level of P content in the scales, tighter and more regular intestinal mucosa folds were observed in the microbial phytase group and the microvilli density was significantly increased. The adhesive gut bacterial communities were strikingly altered by microbial phytase supplementation (0·41microbial phytase, as indicated by the up-regulated intestinal expressions of the cytokine genes (tnf-α and tgf-β) and hsp70. In addition, the gut microvilli height was significantly decreased in the phytase group. These results indicate that dietary microbial phytase may exert mixed effects on hybrid tilapia, and can guide our future selection of phytases as aquafeed additives - that is, eliminating those that can stimulate intestinal inflammation. PMID:27080419

  12. Gonadotropin ratio affects the in vitro growth of rhesus ovarian preantral follicles.

    PubMed

    Kim, Yoon Young; Yun, Jun-Won; Kim, Jong Min; Park, Chung Gyu; Rosenwaks, Zev; Liu, Hung Ching; Kang, Byeong-Cheol; Ku, Seung-Yup

    2016-04-01

    In vitro follicle growth (IVFG) strategy is critical in the fertility preservation of cancer survivors; however, its optimal protocol needs to be developed using primate models since the availability of human samples is limited. Only a few previous studies have reported the successful IVFG of rhesus monkey ovaries using low-dose follicle-stimulating hormone (FSH) (0.3 or 3 ng/mL) and long-term culture (up to 5 weeks) and it is still uncertain in regard to the optimal culture duration and effective dose of treated gonadotropins applicable to the IVFG of rhesus preantral follicles. Recently, we have reported that the FSH to luteinizing hormone (LH) ratio affects the in vitro growth of murine ovarian follicles. We aimed to investigate whether gonadotropin ratios affect the efficiency of rhesus follicular growth in vitro Ovaries were collected from six necropsied rhesus macaques (4-9 years) and preantral follicles were retrieved and cultured for 14 days using 200 mIU/mL FSH. The characteristics of follicular growth were compared between the FSH:LH=1:1 (n=24) and FSH:LH=2:1 (n=24) groups. High concentration gonadotropin treatment shortened the duration required for in vitro maturation of rhesus preantral follicles. The FSH:LH=2:1 group showed a faster follicular growth and enabled the acquisition of mature oocytes, although the expression of growth differentiation factor (GDF)-9 and anti-Müllerian hormone (AMH) did not differ significantly between the two groups. Taken together, high dose gonadotropin treatment can shorten the duration of IVFG and the gonadotropin ratio is important in the IVFG of rhesus monkey ovaries. PMID:26980777

  13. Gonadotropin ratio affects the in vitro growth of rhesus ovarian preantral follicles

    PubMed Central

    Kim, Yoon Young; Yun, Jun-Won; Kim, Jong Min; Park, Chung Gyu; Rosenwaks, Zev; Liu, Hung Ching; Kang, Byeong-Cheol; Ku, Seung-Yup

    2016-01-01

    In vitro follicle growth (IVFG) strategy is critical in the fertility preservation of cancer survivors; however, its optimal protocol needs to be developed using primate models since the availability of human samples is limited. Only a few previous studies have reported the successful IVFG of rhesus monkey ovaries using low-dose follicle-stimulating hormone (FSH) (0.3 or 3 ng/mL) and long-term culture (up to 5 weeks) and it is still uncertain in regard to the optimal culture duration and effective dose of treated gonadotropins applicable to the IVFG of rhesus preantral follicles. Recently, we have reported that the FSH to luteinizing hormone (LH) ratio affects the in vitro growth of murine ovarian follicles. We aimed to investigate whether gonadotropin ratios affect the efficiency of rhesus follicular growth in vitro. Ovaries were collected from six necropsied rhesus macaques (4–9 years) and preantral follicles were retrieved and cultured for 14 days using 200 mIU/mL FSH. The characteristics of follicular growth were compared between the FSH:LH=1:1 (n=24) and FSH:LH=2:1 (n=24) groups. High concentration gonadotropin treatment shortened the duration required for in vitro maturation of rhesus preantral follicles. The FSH:LH=2:1 group showed a faster follicular growth and enabled the acquisition of mature oocytes, although the expression of growth differentiation factor (GDF)-9 and anti-Müllerian hormone (AMH) did not differ significantly between the two groups. Taken together, high dose gonadotropin treatment can shorten the duration of IVFG and the gonadotropin ratio is important in the IVFG of rhesus monkey ovaries. PMID:26980777

  14. Low frequency electromagnetic waves as a supplemental energy source to sustain microbial growth?

    PubMed

    Gusev, Victor A; Schulze-Makuch, Dirk

    2005-03-01

    Microbial populations in tetra-distilled water collapsed when cultured in a permalloy chamber shielding the populations from the sun's and earth's electromagnetic field, but thrived when cultured in an ordinary thermostat open to the electromagnetic field. Theoretically, protons in liquid water can be excited at their natural resonance frequencies through Langmuir oscillations and obtain enough kinetic energy to charge the transmembrane potential of a cell. Microbes may be capable of converting this energy into chemical energy to supplement their energy needs. PMID:15700175

  15. Biphasic toxicodynamic features of some antimicrobial agents on microbial growth: a dynamic mathematical model and its implications on hormesis

    PubMed Central

    2010-01-01

    Background In the present work, we describe a group of anomalous dose-response (DR) profiles and develop a dynamic model that is able to explain them. Responses were obtained from conventional assays of three antimicrobial agents (nisin, pediocin and phenol) against two microorganisms (Carnobacterium piscicola and Leuconostoc mesenteroides). Results Some of these anomalous profiles show biphasic trends which are usually attributed to hormetic responses. But they can also be explained as the result of the time-course of the response from a microbial population with a bimodal distribution of sensitivity to an effector, and there is evidence suggesting this last origin. In light of interest in the hormetic phenomenology and the possibility of confusing it with other phenomena, especially in the bioassay of complex materials we try to define some criteria which allow us to distinguish between sensu stricto hormesis and biphasic responses due to other causes. Finally, we discuss some problems concerning the metric of the dose in connection with the exposure time, and we make a cautionary suggestion about the use of bacteriocins as antimicrobial agents. Conclusions The mathematical model proposed, which combines the basis of DR theory with microbial growth kinetics, can generate and explain all types of anomalous experimental profiles. These profiles could also be described in a simpler way by means of bisigmoidal equations. Such equations could be successfully used in a microbiology and toxicology context to discriminate between hormesis and other biphasic phenomena. PMID:20723220

  16. TatC-dependent translocation of pyoverdine is responsible for the microbial growth suppression.

    PubMed

    Lee, Yeji; Kim, Yong-Jae; Lee, Jung-Hoon; Yu, Hyung Eun; Lee, Kiho; Jin, Shouguang; Ha, Un-Hwan

    2016-02-01

    Infections are often not caused by a colonization of Pseudomonas aeruginosa alone but by a consortium of other bacteria. Little is known about the impact of P. aeruginosa on the growth of other bacteria upon coinfection. Here, cell-ree culture supernatants obtained from P. aeruginosa suppressed the growth of a number of bacterial strains such as Corynebacterium glutamicum, Bacillus subtilis, Staphylococcus aureus, and Agrobacterium tumefaciens, but had little effect on the growth of Escherichia coli and Salmonella Typhimurium. The growth suppression effect was obvious when P. aeruginosa was cultivated in M9 minimal media, and the suppression was not due to pyocyanin, a well-known antimicrobial toxin secreted by P. aeruginosa. By performing transposon mutagenesis, PA5070 encoding TatC was identified, and the culture supernatant of its mutant did not suppress the growth. HPLC analysis of supernatants showed that pyoverdine was a secondary metabolite present in culture supernatants of the wild-type strain, but not in those of the PA5070 mutant. Supplementation of FeCl2 as a source of iron compromised the growth suppression effect of supernatants and also recovered biofilm formation of S. aureus, indicating that pyoverdine-mediated iron acquisition is responsible for the growth suppression. Thus, this study provides the action of TatC-dependent pyoverdine translocation for the growth suppression of other bacteria, and it might aid understanding of the impact of P. aeruginosa in the complex community of bacterial species upon coinfection. PMID:26832668

  17. Rearing Tenebrio molitor in BLSS: Dietary fiber affects larval growth, development, and respiration characteristics

    NASA Astrophysics Data System (ADS)

    Li, Leyuan; Stasiak, Michael; Li, Liang; Xie, Beizhen; Fu, Yuming; Gidzinski, Danuta; Dixon, Mike; Liu, Hong

    2016-01-01

    Rearing of yellow mealworm (Tenebrio molitor L.) will provide good animal nutrition for astronauts in a bioregenerative life support system. In this study, growth and biomass conversion data of T. molitor larvae were tested for calculating the stoichiometric equation of its growth. Result of a respiratory quotient test proved the validity of the equation. Fiber had the most reduction in mass during T. molitor‧s consumption, and thus it is speculated that fiber is an important factor affecting larval growth of T. molitor. In order to further confirm this hypothesis and find out a proper feed fiber content, T. molitor larvae were fed on diets with 4 levels of fiber. Larval growth, development and respiration in each group were compared and analyzed. Results showed that crude-fiber content of 5% had a significant promoting effect on larvae in early instars, and is beneficial for pupa eclosion. When fed on feed of 5-10% crude-fiber, larvae in later instars reached optimal levels in growth, development and respiration. Therefore, we suggest that crude fiber content in feed can be controlled within 5-10%, and with the consideration of food palatability, a crude fiber of 5% is advisable.

  18. Root cooling strongly affects diel leaf growth dynamics, water and carbohydrate relations in Ricinus communis.

    PubMed

    Poiré, Richard; Schneider, Heike; Thorpe, Michael R; Kuhn, Arnd J; Schurr, Ulrich; Walter, Achim

    2010-03-01

    In laboratory and greenhouse experiments with potted plants, shoots and roots are exposed to temperature regimes throughout a 24 h (diel) cycle that can differ strongly from the regime under which these plants have evolved. In the field, roots are often exposed to lower temperatures than shoots. When the root-zone temperature in Ricinus communis was decreased below a threshold value, leaf growth occurred preferentially at night and was strongly inhibited during the day. Overall, leaf expansion, shoot biomass growth, root elongation and ramification decreased rapidly, carbon fluxes from shoot to root were diminished and carbohydrate contents of both root and shoot increased. Further, transpiration rate was not affected, yet hydrostatic tensions in shoot xylem increased. When root temperature was increased again, xylem tension reduced, leaf growth recovered rapidly, carbon fluxes from shoot to root increased, and carbohydrate pools were depleted. We hypothesize that the decreased uptake of water in cool roots diminishes the growth potential of the entire plant - especially diurnally, when the growing leaf loses water via transpiration. As a consequence, leaf growth and metabolite concentrations can vary enormously, depending on root-zone temperature and its heterogeneity inside pots. PMID:19968824

  19. Shoot Turgor Does Not Limit Shoot Growth of NaCl-Affected Wheat and Barley 1

    PubMed Central

    Termaat, Annie; Passioura, John B.; Munns, Rana

    1985-01-01

    The aim of this work was to test the hypothesis that the reduced growth rate of wheat and barley that results when the roots are exposed to NaCl is due to inadequate turgor in the expanding cells of the leaves. The hypothesis was tested by exposing plants to 100 millimolar NaCl (which reduced their growth rates by about 20%), growing them for 7 to 10 days with their roots in pressure chambers, and applying sufficient pneumatic pressure in the chambers to offset the osmotic pressure of the NaCl, namely, 0.48 megapascals. The results showed that applying the pressure had no sustained effect (relative to unpressurized controls) on growth rates, transpiration rates, or osmotic pressures of the cell sap, in either the fully expanded or currently expanding leaf tissue, of both wheat and barley. The results indicate that the applied pressure correspondingly increased turgor in the shoot although this was not directly measured. We conclude that shoot turgor alone was not regulating the growth of these NaCl-affected plants, and, after discussing other possible influences, argue that a message arising in the roots may be regulating the growth of the shoot. PMID:16664152

  20. Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants).

    PubMed

    Black, V J; Stewart, C A; Roberts, J A; Black, C R

    2007-01-01

    Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production. PMID:17803646

  1. Different types of stainless steel used in equipment in meat plants do not affect the initial microbial transfer, including pathogens, from pork skin

    PubMed Central

    Larivière-Gauthier, Guillaume; Quessy, Sylvain; Fournaise, Sylvain; Letellier, Ann; Fravalo, Philippe

    2015-01-01

    This study describes and measures the impact of different compositions and finishes of stainless steel used in equipment in the meat industry on the transfer of natural flora and selected pathogens from artificially contaminated pork skin. It is known that the adhesion to surfaces of Listeria monocytogenes and Salmonella, 2 pathogens frequently found in contaminated pork meat, depends on the nature and roughness of the surface. Our results show no statistically significant differences in microbial transfer regardless of the types of stainless steel considered, with the highest measured transfer difference being 0.18 log colony-forming units (CFUs)/800 cm2. Moreover, no differences in total microbial community were observed after transfer on the 5 types of stainless steel using single-strand conformation polymorphism (SSCP). It was concluded that the different characteristics of the stainless steel tested did not affect the initial bacterial transfer in this study. PMID:26130860

  2. Temperature Effects on Microbial CH4 and CO2 Production in Permafrost-Affected Soils From the Barrow Environmental Observatory

    NASA Astrophysics Data System (ADS)

    Graham, D. E.; Roy Chowdhury, T.; Zheng, J.; Moon, J. W.; Yang, Z.; Gu, B.; Wullschleger, S. D.

    2015-12-01

    Warmer Arctic temperatures are increasing the annual soil thaw depth and prolonging the thaw season in Alaskan permafrost zones. This change exposes organic matter buried in the soils and permafrost to microbial degradation and mineralization to form CO2 and CH4. The proportion and fluxes of these greenhouse gases released into the atmosphere control the global feedback on warming. To improve representations of these biogeochemical processes in terrestrial ecosystem models we compared soil properties and microbial activities in core samples of polygonal tundra from the Barrow Environmental Observatory. Measurements of soil water potential through the soil column characterized water binding to the organic and mineral components. This suction combines with temperature to control freezing, gas diffusion and microbial activity. The temperature-dependence of CO2 and CH4 production from anoxic soil incubations at -2, +4 or +8 °C identified a significant lag in methanogenesis relative to CO2 production by anaerobic respiration and fermentation. Changes in the abundance of methanogen signature genes during incubations indicate that microbial population shifts caused by thawing and warmer temperatures drive changes in the mixtures of soil carbon degradation products. Comparisons of samples collected across the microtopographic features of ice-wedge polygons address the impacts of water saturation, iron reduction and organic matter content on CH4 production and oxidation. These combined measurements build process understanding that can be applied across scales to constrain key response factors in models that address Arctic soil warming.

  3. Organic matter quantity and source affects microbial community structure and function following volcanic eruption on Kasatochi Island, Alaska.

    PubMed

    Zeglin, Lydia H; Wang, Bronwen; Waythomas, Christopher; Rainey, Frederick; Talbot, Sandra L

    2016-01-01

    In August 2008, Kasatochi volcano erupted and buried a small island in pyroclastic deposits and fine ash; since then, microbes, plants and birds have begun to re-colonize the initially sterile surface. Five years post-eruption, bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) copy numbers and extracellular enzyme activity (EEA) potentials were one to two orders of magnitude greater in pyroclastic materials with organic matter (OM) inputs relative to those without, despite minimal accumulation of OM (< 0.2%C). When normalized by OM levels, post-eruptive surfaces with OM inputs had the highest β-glucosidase, phosphatase, NAGase and cellobiohydrolase activities, and had microbial population sizes approaching those in reference soils. In contrast, the strongest factor determining bacterial community composition was the dominance of plants versus birds as OM input vectors. Although soil pH ranged from 3.9 to 7.0, and %C ranged 100×, differentiation between plant- and bird-associated microbial communities suggested that cell dispersal or nutrient availability are more likely drivers of assembly than pH or OM content. This study exemplifies the complex relationship between microbial cell dispersal, soil geochemistry, and microbial structure and function; and illustrates the potential for soil microbiota to be resilient to disturbance. PMID:26032670

  4. Microbial Transformation of Triadimefon to Triadimenol in Soils: Selective Production Rates of Triadimenol Stereoisomers Affect Exposure and Risk

    EPA Science Inventory

    The microbial transformation of triadimefon, an agricultural fungicide of the 1,2,4-triazole class, was followed at a nominal concentration of 50 μg/mL over 4 months under aerobic conditions in three different soil types. Rates and products of transformation were measured, as wel...

  5. Organic matter quantity and source affects microbial community structure and function following volcanic eruption on Kasatochi Island, Alaska

    USGS Publications Warehouse

    Zeglin, Lydia H.; Wang, Bronwen; Waythomas, Christopher F.; Rainey, Frederick; Talbot, Sandra

    2016-01-01

    In August 2008, Kasatochi volcano erupted and buried a small island in pyroclastic deposits and fine ash; since then, microbes, plants and birds have begun to re-colonize the initially sterile surface. Five years post-eruption, bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) copy numbers and extracellular enzyme activity (EEA) potentials were one to two orders of magnitude greater in pyroclastic materials with organic matter (OM) inputs relative to those without, despite minimal accumulation of OM (< 0.2%C). When normalized by OM levels, post-eruptive surfaces with OM inputs had the highest β-glucosidase, phosphatase, NAGase and cellobiohydrolase activities, and had microbial population sizes approaching those in reference soils. In contrast, the strongest factor determining bacterial community composition was the dominance of plants versus birds as OM input vectors. Although soil pH ranged from 3.9 to 7.0, and %C ranged 100×, differentiation between plant- and bird-associated microbial communities suggested that cell dispersal or nutrient availability are more likely drivers of assembly than pH or OM content. This study exemplifies the complex relationship between microbial cell dispersal, soil geochemistry, and microbial structure and function; and illustrates the potential for soil microbiota to be resilient to disturbance.

  6. Plasmid Transfer of Plasminogen K1-5 Reduces Subcutaneous Hepatoma Growth by Affecting Inflammatory Factors

    PubMed Central

    Koch, Lea A.; Strassburg, Christian P.; Raskopf, Esther

    2014-01-01

    There is evidence that plasminogen K1-5 (PlgK1-5) directly affects tumour cells and inflammation. Therefore, we analysed if PlgK1-5 has immediate effects on hepatoma cells and inflammatory factors in vitro and in vivo. In vitro, effects of plasmid encoding PlgK1-5 (pK1-5) on Hepa129, Hepa1-6, and HuH7 cell viability, apoptosis, and proliferation as well as VEGF and TNF-alpha expression and STAT3-phosphorylation were investigated. In vivo, tumour growth, proliferation, vessel density, and effects on vascular endothelial growth factor (VEGF) and tumour necrosis factor alpha (TNF-alpha) expression were examined following treatment with pK1-5. In vivo, pK1-5 halved cell viability; cell death was increased by up to 15% compared to the corresponding controls. Proliferation was not affected. VEGF, TNF-alpha, and STAT3-phosphorylation were affected following treatment with pK1-5. In vivo, ten days after treatment initiation, pK1-5 reduced subcutaneous tumour growth by 32% and mitosis by up to 77% compared to the controls. Vessel density was reduced by 50%. TNF-alpha levels in tumour and liver tissue were increased, whereas VEGF levels in tumours and livers were reduced after pK1-5 treatment. Taken together, plasmid gene transfer of PlgK1-5 inhibits hepatoma (cell) growth not only by reducing vessel density but also by inducing apoptosis, inhibiting proliferation, and triggering inflammation. PMID:24895598

  7. Spatial heterogeneity of soil biochar content affects soil quality and wheat growth and yield.

    PubMed

    Olmo, Manuel; Lozano, Ana María; Barrón, Vidal; Villar, Rafael

    2016-08-15

    Biochar (BC) is a carbonaceous material obtained by pyrolysis of organic waste materials and has been proposed as a soil management strategy to mitigate global warming and to improve crop productivity. Once BC has been applied to the soil, its imperfect and incomplete mixing with soil during the first few years and the standard agronomic practices (i.e. tillage, sowing) may generate spatial heterogeneity of the BC content in the soil, which may have implications for soil properties and their effects on plant growth. We investigated how, after two agronomic seasons, the spatial heterogeneity of olive-tree prunings BC applied to a vertisol affected soil characteristics and wheat growth and yield. During the second agronomic season and just before wheat germination, we determined the BC content in the soil by an in-situ visual categorization based on the soil darkening, which was strongly correlated to the BC content of the soil and the soil brightness. We found a high spatial heterogeneity in the BC plots, which affected soil characteristics and wheat growth and yield. Patches with high BC content showed reduced soil compaction and increased soil moisture, pH, electrical conductivity, and nutrient availability (P, Ca, K, Mn, Fe, and Zn); consequently, wheat had greater tillering and higher relative growth rate and grain yield. However, if the spatial heterogeneity of the soil BC content had not been taken into account in the data analysis, most of the effects of BC on wheat growth would not have been detected. Our study reveals the importance of taking into account the spatial heterogeneity of the BC content. PMID:27110980

  8. Effects of Resveratrol and Essential Oils on Growth Performance, Immunity, Digestibility and Fecal Microbial Shedding in Challenged Piglets

    PubMed Central

    Ahmed, S. T.; Hossain, M. E.; Kim, G. M.; Hwang, J. A.; Ji, H.; Yang, C. J.

    2013-01-01

    A study was conducted to evaluate the effects of resveratrol and essential oils from medicinal plants on the growth performance, immunity, digestibility, and fecal microbial shedding of weaned piglets. A total of 48 weaned piglets (8 kg initial weight, 28-d-old) were randomly allotted to four dietary treatments with 3 replications of 4 piglets each. The dietary treatments were NC (negative control; basal diet), PC (positive control; basal diet+0.002% apramycin), T1 (basal diet+0.2% resveratrol), and T2 (basal diet+0.0125% essential oil blend). All piglets were orally challenged with 5 ml culture fluid containing 2.3×108 cfu/ml of Escherichia coli KCTC 2571 and 5.9×108 cfu/ml Salmonella enterica serover Typhimurium. The PC group (p<0.05) showed the highest average daily gain (ADG) and average daily feed intake (ADFI) throughout the experimental period, although feed conversion ratio (FCR) was improved in the T1 group (p>0.05). Serum IgG level was increased in the T1 group, whereas TNF-α levels was reduced in the supplemented groups compared to control (p<0.05). The PC diet improved the dry matter (DM) digestibility, whereas PC and T2 diets improved nitrogen (N) digestibility compared to NC and T1 diets (p<0.05). Fecal Salmonella and E. coli counts were reduced in all treatment groups compared to control (p<0.05). Fecal Lactobacillus spp. count was increased in the T2 group compared to others (p<0.05). Dietary treatments had no significant effect on fecal Bacillus spp. count throughout the entire experimental period. Based on these results, resveratrol showed strong potential as antibiotic alternatives for reversing the adverse effects of weaning stress on growth performance, immunity and microbial environment in E. coli and Salmonella-challenged piglets. PMID:25049839

  9. Effect of high oxygen modified atmosphere packaging on microbial growth and sensorial qualities of fresh-cut produce.

    PubMed

    Jacxsens, L; Devlieghere, F; Van der Steen, C; Debevere, J

    2001-12-30

    The application of High Oxygen Atmospheres (HOA) (i.e. > 70% O2) for packaging ready-to-eat vegetables was evaluated as an alternative technique for low O2 Equilibrium Modified Atmosphere (EMA) packaging (3% O2-5% CO2-balance N2) for respiring products. Comparative experiments between both techniques were performed in-vitro and in-vivo. Typical spoilage causing microorganisms (Pseudomonas fluorescens, Candida lambica), the moulds Botrytis cinerea, Aspergillus flavus and the opportunistic psychrotrophic human pathogenic microorganism associated with refrigerated minimally processed vegetables. Aeromonas caviae (HG4), showed a retarded growth during the conducted in-vitro studies at 4 degrees C in 70%, 80% and 95% O2 as examples of HOA compared to the in-vitro experiments in 5% O2 (as example of EMA packaging) and the effect was more pronounced in 95% O2. The effect of the high O2-concentrations on the human pathogen Listeria monocytogenes resulted in an extended lag phase (95% O2). The plant pathogen Erwinia carotovora was increasingly stimulated by increasing high O2-concentrations. During a storage experiment of three types of ready-to-eat vegetables (mushroom slices, grated celeriac and shredded chicory endive), which are sensitive to enzymatic browning and microbial spoilage, the effect of EMA and HOA (95% O2-5% N2) on their quality and shelf life was compared. High O2 atmospheres were found to be particularly effective in inhibiting enzymatic browning of the tested vegetables. Also, the microbial quality was better as a reduction in yeast growth was observed. The HOA can be applied as an alternative for low O2 modified atmospheres for some specific types of ready-to-eat vegetables, sensitive to enzymatic browning and spoilage by yeasts. PMID:11789938

  10. Microbial Growth and Air Pollutants in the Corrosion of Carbonate Rocks: Results from Laboratory and Outdoor Experimental Tests

    NASA Astrophysics Data System (ADS)

    Moroni, B.; Poli, G.; Pitzurra, L.

    2003-04-01

    Microorganisms and atmospheric pollution are primary causes of deterioration of materials exposed to open air. Due to the variety of chemical-mineralogical compositions and textures, stone represents a variegated substrate that interacts with environmental fluids and particulate, and is a selective environment for biological proliferation. Carbonate rocks, in particular, are highly exposed to environmental decay and extremely susceptible to acid attack caused by atmospheric pollutants and metabolic acid production. The aim of this work is to study the combined effect of microbial contamination and atmospheric pollutants in the weathering of carbonate rocks by means of laboratory and outdoor exposure tests. Laboratory experiments performed on carbonate rocks allowed evaluation of the influence of the gas mixture in the chemical modifications of the lithic substrate, and formulation of a kinetic model of sulphation. The obtained results suggest that nucleation alternates with growth as leading processes in the development of sulphation. In particular, nucleation of the reaction products is the leading process in the initial period of sulphation, which is characterized by a marked slowdown of the reaction progress, whereas growth of the products is the leading process in the subsequent period of resumption of sulphation. In situ experiments performed by exposing limestone specimens at two air monitoring stations in Perugia with different degrees of urban air pollution showed high levels of fungal colonization at early times and the presence of weathering products (i.e. gypsum) in the longer term. Results point to a combined effect of microbial colonization and atmospheric pollutants in promoting the weathering of stone through acid attack within the film of water present on the surface of the exposed material, and through the oxidation of metal sulphide particulate pollutant to sulphate. Laboratory tests assaying the extent of fungal colonization and/or chemical

  11. An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures.

    PubMed

    Lee, Jason S; Ray, Richard I; Lowe, Kristine L; Jones-Meehan, Joanne; Little, Brenda J

    2003-04-01

    Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures. PMID:14618716

  12. An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures

    NASA Technical Reports Server (NTRS)

    Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.

    2003-01-01

    Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.

  13. Better to light a candle than curse the darkness: illuminating spatial localization and temporal dynamics of rapid microbial growth in the rhizosphere.

    PubMed

    Herron, Patrick M; Gage, Daniel J; Arango Pinedo, Catalina; Haider, Zane K; Cardon, Zoe G

    2013-01-01

    The rhizosphere is a hotbed of microbial activity in ecosystems, fueled by carbon compounds from plant roots. Basic questions about the location and dynamics of plant-spurred microbial growth in the rhizosphere are difficult to answer with standard, destructive soil assays mixing a multitude of microbe-scale microenvironments in a single, often sieved, sample. Soil microbial biosensors designed with the luxCDABE reporter genes fused to a promoter of interest enable continuous imaging of the microbial perception of (and response to) environmental conditions in soil. We used the common soil bacterium Pseudomonas putida KT2440 as host to plasmid pZKH2 containing a fusion between the strong constitutive promoter nptII and luxCDABE (coding for light-emitting proteins) from Vibrio fischeri. Experiments in liquid media demonstrated that high light production by KT2440/pZKH2 was associated with rapid microbial growth supported by high carbon availability. We applied the biosensors in microcosms filled with non-sterile soil in which corn (Zea mays L.), black poplar (Populus nigra L.), or tomato (Solanum lycopersicum L.) was growing. We detected minimal light production from microbiosensors in the bulk soil, but biosensors reported continuously from around roots for as long as six days. For corn, peaks of luminescence were detected 1-4 and 20-35 mm along the root axis behind growing root tips, with the location of maximum light production moving farther back from the tip as root growth rate increased. For poplar, luminescence around mature roots increased and decreased on a coordinated diel rhythm, but was not bright near root tips. For tomato, luminescence was dynamic, but did not exhibit a diel rhythm, appearing in acropetal waves along roots. KT2440/pZKH2 revealed that root tips are not always the only, or even the dominant, hotspots for rhizosphere microbial growth, and carbon availability is highly variable in space and time around roots. PMID:24032034

  14. Better to light a candle than curse the darkness: illuminating spatial localization and temporal dynamics of rapid microbial growth in the rhizosphere

    PubMed Central

    Herron, Patrick M.; Gage, Daniel J.; Arango Pinedo, Catalina; Haider, Zane K.; Cardon, Zoe G.

    2013-01-01

    The rhizosphere is a hotbed of microbial activity in ecosystems, fueled by carbon compounds from plant roots. Basic questions about the location and dynamics of plant-spurred microbial growth in the rhizosphere are difficult to answer with standard, destructive soil assays mixing a multitude of microbe-scale microenvironments in a single, often sieved, sample. Soil microbial biosensors designed with the luxCDABE reporter genes fused to a promoter of interest enable continuous imaging of the microbial perception of (and response to) environmental conditions in soil. We used the common soil bacterium Pseudomonas putida KT2440 as host to plasmid pZKH2 containing a fusion between the strong constitutive promoter nptII and luxCDABE (coding for light-emitting proteins) from Vibrio fischeri. Experiments in liquid media demonstrated that high light production by KT2440/pZKH2 was associated with rapid microbial growth supported by high carbon availability. We applied the biosensors in microcosms filled with non-sterile soil in which corn (Zea mays L.), black poplar (Populus nigra L.), or tomato (Solanum lycopersicum L.) was growing. We detected minimal light production from microbiosensors in the bulk soil, but biosensors reported continuously from around roots for as long as six days. For corn, peaks of luminescence were detected 1–4 and 20–35 mm along the root axis behind growing root tips, with the location of maximum light production moving farther back from the tip as root growth rate increased. For poplar, luminescence around mature roots increased and decreased on a coordinated diel rhythm, but was not bright near root tips. For tomato, luminescence was dynamic, but did not exhibit a diel rhythm, appearing in acropetal waves along roots. KT2440/pZKH2 revealed that root tips are not always the only, or even the dominant, hotspots for rhizosphere microbial growth, and carbon availability is highly variable in space and time around roots. PMID:24032034

  15. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  16. Factors affecting microbial spoilage and shelf-life of chilled vacuum-packed lamb transported to distant markets: a review.

    PubMed

    Mills, John; Donnison, Andrea; Brightwell, Gale

    2014-09-01

    Vacuum-packaging and stringent control of storage temperatures enable the export of meat to distant markets, supplying a chilled product that can favourably compete with local fresh meats. To save fuel and reduce emissions, the speed of ships travelling to international markets has decreased resulting in requirement for the shelf-life of chilled lamb to be extended beyond the recognised time of 60-70 days. Growth of microorganisms and ability to cause spoilage of vacuum-packed lamb are dependent on many factors, including the type and initial concentration of spoilage bacteria, meat pH, water activity, availability of substrates, oxygen availability and, most importantly, storage time and temperature of the packaged product. This paper reviews the existing knowledge of the spoilage bacteria affecting vacuum-packed lamb, discusses the impact of these bacteria on product quality, shelf-life and spoilage, and concludes that under specified conditions the shelf-life of chilled lamb can be extended to beyond 70 days. PMID:24875594

  17. A lipid-accumulating alga maintains growth in outdoor, alkaliphilic raceway pond with mixed microbial communities

    DOE PAGESBeta

    Bell, Tisza A.S.; Prithiviraj, Bharath; Wahlen, Brad D.; Fields, Matthew W.; Peyton, Brent M.

    2016-01-07

    Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal “crop.” In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (~9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgarismore » and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. As a result, the characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass

  18. A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities

    PubMed Central

    Bell, Tisza A. S.; Prithiviraj, Bharath; Wahlen, Brad D.; Fields, Matthew W.; Peyton, Brent M.

    2016-01-01

    Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal “crop.” In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (∼9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgaris and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. The characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an

  19. A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities.

    PubMed

    Bell, Tisza A S; Prithiviraj, Bharath; Wahlen, Brad D; Fields, Matthew W; Peyton, Brent M

    2015-01-01

    Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal "crop." In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgaris BA050 was previously isolated from Soap Lake, Washington, a system characterized by a high pH (∼9.8). An outdoor raceway pond (200 L) was inoculated with C. vulgaris and monitored for 10 days and then the culture was transferred to a 2,000 L raceway pond and cultivated for an additional 6 days. Community DNA samples were collected over the 16-day period in conjunction with water chemistry analyses and cell counts. Universal primers for the SSU rRNA gene sequences for Eukarya, Bacteria, and Archaea were used for barcoded pyrosequence determination. The environmental parameters that most closely correlated with C. vulgaris abundance were pH and phosphate. Community analyses indicated that the pond system remained dominated by the Chlorella population (93% of eukaryotic sequences), but was also colonized by other microorganisms. Bacterial sequence diversity increased over time while archaeal sequence diversity declined over the same time period. Using SparCC co-occurrence network analysis, a positive correlation was observed between C. vulgaris and Pseudomonas sp. throughout the experiment, which may suggest a symbiotic relationship between the two organisms. The putative relationship coupled with high pH may have contributed to the success of C. vulgaris. The characterization of the microbial community dynamics of an alkaliphilic open pond system provides significant insight into open pond systems that could be used to control photoautotrophic biomass productivity in an open

  20. Influence of mechanical disintegration on the microbial growth of aerobic sludge biomass: A comparative study of ultrasonic and shear gap homogenizers by oxygen uptake measurements.

    PubMed

    Divyalakshmi, P; Murugan, D; Sivarajan, M; Saravanan, P; Lajapathi Rai, C

    2015-11-01

    Wastewater treatment plant incorporates physical, chemical and biological processes to treat and remove the contaminants. The main drawback of conventional activated sludge process is the huge production of excess sludge, which is an unavoidable byproduct. The treatment and disposal of excess sludge costs about 60% of the total operating cost. The ideal way to reduce excess sludge production during wastewater treatment is by preventing biomass formation within the aerobic treatment train rather than post treatment of the generated sludge. In the present investigation two different mechanical devices namely, Ultrasonic and Shear Gap homogenizers have been employed to disintegrate the aerobic biomass. This study is intended to restrict the multiplication of microbial biomass and at the same time degrade the organics present in wastewater by increasing the oxidative capacity of microorganisms. The disintegrability on biomass was determined by biochemical methods. Degree of inactivation provides the information on inability of microorganisms to consume oxygen upon disruption. The soluble COD quantifies the extent of release of intra cellular compounds. The participation of disintegrated microorganism in wastewater treatment process was carried out in two identical respirometeric reactors. The results show that Ultrasonic homogenizer is very effective in the disruption of microorganisms leading to a maximum microbial growth reduction of 27%. On the other hand, Shear gap homogenizer does not favor the sludge growth reduction rather it facilitates the growth. This study also shows that for better microbial growth reduction, floc size reduction alone is not sufficient but also microbial disruption is essential. PMID:25866205

  1. [The effect of soil inoculation with microbial pesticide destructors on plant growth and development].

    PubMed

    Lisina, T O; Garan'kina, N G; Kruglov, Iu V

    2001-01-01

    Soil inoculation with liquid cultures of Bacillus megaterium 501 and Exophiala nigrum A-29 capable of degrading several organophosphorus pesticides accelerated growth and development of experimental plants, formation of their generative organs, and improved their productivity. This was particularly observed under stress plant growth conditions on phytotoxic peach substrates. The microorganisms inoculated can probably degrade phytotoxins present in soils, thereby favoring the plant development. PMID:11443911

  2. A primary screen of the bovine genome for quantitative trait loci affecting carcass and growth traits.

    PubMed

    Stone, R T; Keele, J W; Shackelford, S D; Kappes, S M; Koohmaraie, M

    1999-06-01

    A primary genomic screen for quantitative trait loci (QTL) affecting carcass and growth traits was performed by genotyping 238 microsatellite markers on 185 out of 300 total progeny from a Bos indicus x Bos taurus sire mated to Bos taurus cows. The following traits were analyzed for QTL effects: birth weight (BWT), weaning weight (WW), yearling weight (YW), hot carcass weight (HCW), dressing percentage (DP), fat thickness (FT), marbling score (MAR), longissimus muscle area (LMA), rib bone (RibB), rib fat (RibF), and rib muscle (RibM), and the predicted whole carcass traits, retail product yield (RPYD), fat trim yield (FATYD), bone yield (BOYD), retail product weight (RPWT), fat weight (FATWT), and bone weight (BOWT). Data were analyzed by generating an F-statistic profile computed at 1-cM intervals for each chromosome by the regression of phenotype on the conditional probability of receiving the Brahman allele from the sire. There was compelling evidence for a QTL allele of Brahman origin affecting an increase in RibB and a decrease in DP on chromosome 5 (BTA5). Putative QTL at or just below the threshold for genome-wide significance were as follows: an increase in RPYD and component traits on BTA2 and BTA13, an increase in LMA on BTA14, and an increase in BWT on BTA1. Results provided represent a portion of our efforts to identify and characterize QTL affecting carcass and growth traits. PMID:10375215

  3. Dietary blueberry supplementation affects growth but not vascularization of neural transplants

    PubMed Central

    Willis, Lauren M; Small, Brent J; Bickford, Paula C; Umphlet, Claudia D; Moore, Alfred B; Granholm, Ann-Charlotte E

    2009-01-01

    Transplantation of neural tissue has been attempted as a treatment method for neurodegenerative disorders. Grafted neurons survive to a lesser extent into middle-aged or aged hosts, and survival rates of < 10% of grafted neurons is common. Antioxidant diets, such as blueberry, can exert powerful effects on developing neurons and blood vessels in vitro, but studies are lacking that examine the effects of these diets on transplanted tissues. In this study, we examined the effects of a blueberry diet on survival, growth, and vascularization of fetal hippocampal tissue to the anterior chamber of the eye of young or middle-aged female rats. Previous work from our group showed significant increase in neuronal survival and development with blueberry diet in grafts. However, the effects of antioxidant diet on vascular development in grafts have not been explored previously. The age of the host affected individual vessel morphology in that aged hosts contained grafts with thick, undeveloped walls, and wider lumen. The blood–brain barrier also appeared to be affected by the age of the host. The blueberry diet did not affect vessel morphology or density of vessel-associated protein markers but gave rise to significantly increased growth capacity, cytoarchitecture, and the final size of hippocampal grafts. PMID:18285804

  4. Prediction of competitive microbial growth in mixed culture at dynamic temperature patterns.

    PubMed

    Fujikawa, Hiroshi; Sakha, Mohammad Z

    2014-01-01

    A novel competition model developed with the new logistic model and the Lotka-Volterra model successfully predicted the growth of bacteria in mixed culture using the mesophiles Staphylococcus aureus, Escherichia coli, and Salmonella at a constant temperature in our previous studies. In this study, we further studied the prediction of the growth of those bacteria in mixed culture at dynamic temperatures with various initial populations with the competition model. First, we studied the growth kinetics of the species in a monoculture at various constant temperatures ranging from 16℃ to 32℃. With the analyzed data in the monoculture, we then examined the prediction of bacterial growth in mixed culture with two and three species. The growth of the bacteria in the mixed culture at dynamic temperatures was successfully predicted with the model. The residuals between the observed and predicted populations at the data points were <0.5 log at most points, being 83.3% and 84.2% for the two-species mixture and the three-species mixture, respectively. The present study showed that the model could be applied to the competitive growth in mixed culture at dynamic temperature patterns. PMID:25252643

  5. Response to long-term growth hormone therapy in patients affected by RASopathies and growth hormone deficiency: Patterns of growth, puberty and final height data.

    PubMed

    Tamburrino, Federica; Gibertoni, Dino; Rossi, Cesare; Scarano, Emanuela; Perri, Annamaria; Montanari, Francesca; Fantini, Maria Pia; Pession, Andrea; Tartaglia, Marco; Mazzanti, Laura

    2015-11-01

    RASopathies are developmental disorders caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. Reduced growth is a common feature. Several studies generated data on growth, final height (FH), and height velocity (HV) after growth hormone (GH) treatment in patients with these disorders, particularly in Noonan syndrome, the most common RASopathy. These studies, however, refer to heterogeneous cohorts in terms of molecular information, GH status, age at start and length of therapy, and GH dosage. This work reports growth data in 88 patients affected by RASopathies with molecularly confirmed diagnosis, together with statistics on body proportions, pubertal pattern, and FH in 33, including 16 treated with GH therapy for proven GH deficiency. Thirty-three patients showed GH deficiency after pharmacological tests, and were GH-treated for an average period of 6.8 ± 4.8 years. Before starting therapy, HV was -2.6 ± 1.3 SDS, and mean basal IGF1 levels were -2.0 ± 1.1 SDS. Long-term GH therapy, starting early during childhood, resulted in a positive height response compared with untreated patients (1.3 SDS in terms of height-gain), normalizing FH for Ranke standards but not for general population and Target Height. Pubertal timing negatively affected pubertal growth spurt and FH, with IGF1 standardized score increased from -2.43 to -0.27 SDS. During GH treatment, no significant change in bone age velocity, body proportions, or cardiovascular function was observed. PMID:26227443

  6. Kinetics of grain growth in the weld heat-affected zone of Alloy 718

    SciTech Connect

    Radhakrishnan, B.; Thompson, R.G.

    1993-12-01

    Grain-boundary liquation occurs in the weld heat-affected zone (HAZ) of the Ni-base superalloy 718 at locations where the peak temperatures are greater than about 1,200 C. The evolution of the grain structure at the HAZ locations depends upon the interaction between the grains and the grain-boundary liquid. The evolution of grain structure in the presence of grain-boundary liquid was simulated by subjecting samples to controlled thermal cycles using resistance heating. A measurement of grain size as a function of isothermal hold at two peak temperatures of 1,200 C and 1,227 C indicated that in alloy 718, the kinetics of grain growth depended upon the prior thermal history of the alloy. In the solution-treated alloy, the presence of grain-boundary liquid did not arrest grain growth at either peak temperature. In the homogenized and aged alloy, a grain refinement was observed at the peak temperature of 1,227 C, while an arrest of grain growth was observed at a peak temperature of 1,200 C. Liquid film migration (LFM) and subgrain coalescence, either acting alone or simultaneously, are shown to explain most of the observed microstructural phenomena and the kinetics of grain growth in the alloy.

  7. Kinetics of grain growth in the weld heat-affected zone of alloy 718

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, B.; Thompson, R. G.

    1993-12-01

    Grain-boundary liquation occurs in the weld heat-affected zone (HAZ) of the Ni-base superalloy 718 at locations where the peak temperatures are greater than about 1200 ‡C. The evolution of the grain structure at these HAZ locations depends upon the interaction between the grains and the grain-boundary liquid. The evolution of grain structure in the presence of grain-boundary liquid was simulated by subjecting samples to controlled thermal cycles using resistance heating. A measurement of grain size as a function of isothermal hold at two peak temperatures of 1200 ‡C and 1227 ‡C indicated that in alloy 718, the kinetics of grain growth depended upon the prior thermal history of the alloy. In the solution-treated alloy, the presence of grain-boundary liquid did not arrest grain growth at either peak temperature. In the homogenized and aged alloy, a grain refinement was observed at the peak temperature of 1227 ‡C, while an arrest of grain growth was observed at a peak temperature of 1200‡C. Liquid film migration (LFM) and subgrain coalescence, either acting alone or simultaneously, are shown to explain most of the observed microstructural phenomena and the kinetics of grain growth in the alloy.

  8. Alkyl-methylimidazolium ionic liquids affect the growth and fermentative metabolism of Clostridium sp

    SciTech Connect

    Nancharaiah, Y.V.; Francis, A.

    2011-06-01

    In this study, the effect of ionic liquids, 1-ethyl-3-methylimidazolium acetate [EMIM][Ac], 1-ethyl-3-methylimidazolium diethylphosphate [EMIM][DEP], and 1-methyl-3-methylimidazolium dimethylphosphate [MMIM][DMP] on the growth and glucose fermentation of Clostridium sp. was investigated. Among the three ionic liquids tested, [MMIM][DMP] was found to be least toxic. Growth of Clostridium sp. was not inhibited up to 2.5, 4 and 4 g L{sup -1} of [EMIM][Ac], [EMIM][DEP] and [MMIM][DMP], respectively. [EMIM][Ac] at <2.5 g L{sup -1}, showed hormetic effect and stimulated the growth and fermentation by modulating medium pH. Total organic acid production increased in the presence of 2.5 and 2 g L{sup -1} of [EMIM][Ac] and [MMIM][DMP]. Ionic liquids had no significant influence on alcohol production at <2.5 g L{sup -1}. Total gas production was affected by ILs at {ge}2.5 g L{sup -1} and varied with type of methylimidazolium IL. Overall, the results show that the growth and fermentative metabolism of Clostridium sp. is not impacted by ILs at concentrations below 2.5 g L{sup -1}.

  9. Opioid and nicotine receptors affect growth regulation of human lung cancer cell lines

    SciTech Connect

    Maneckjee, R.; Minna, J.D. Uniformed Services Univ. of the Health Sciences, Bethesda, MD )

    1990-05-01

    Using specific radioactively-labeled ligands, the authors find that lung cancer cell lines of diverse histologic types express multiple, high-affinity membrane receptors for {mu}, {delta}, and {kappa} opioid agonists and for nicotine and {alpha}-bungarotoxin. These receptors are biologically active because cAMP levels decreased in lung cancer cells after opioid and nicotine application. Nicotine at concentrations found in the blood of smokers had no effect on in vitro lung cancer cell growth, whereas {mu}, {delta}, and {kappa} opioid agonists at low concentrations inhibited lung cancer growth in vitro. They also found that lung cancer cells expressed various combinations of immunoreactive opioid peptides ({beta}-endorphin, enkephalin, or dynorphin), suggesting the participation of opioids in a negative autocrine loop or tumor-suppressing system. Due to the almost universal exposure of patients with lung cancer to nicotine, they tested whether nicotine affected the response of lung cancer cell growth to opioids and found that nicotine at concentrations of 100-200 nM partially or totally reversed opioid-induced growth inhibition in 9/14 lung cancer cell lines. These in vitro results for lung cancer cells suggest that opioids could function as part of a tumor suppressor system and that nicotine can function to circumvent this system in the pathogenesis of lung cancer.

  10. Flavonoid accumulation in Arabidopsis repressed in lignin synthesis affects auxin transport and plant growth.

    PubMed

    Besseau, Sébastien; Hoffmann, Laurent; Geoffroy, Pierrette; Lapierre, Catherine; Pollet, Brigitte; Legrand, Michel

    2007-01-01

    In Arabidopsis thaliana, silencing of hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT), a lignin biosynthetic gene, results in a strong reduction of plant growth. We show that, in HCT-silenced plants, lignin synthesis repression leads to the redirection of the metabolic flux into flavonoids through chalcone synthase activity. Several flavonol glycosides and acylated anthocyanin were shown to accumulate in higher amounts in silenced plants. By contrast, sinapoylmalate levels were barely affected, suggesting that the synthesis of that phenylpropanoid compound might be HCT-independent. The growth phenotype of HCT-silenced plants was shown to be controlled by light and to depend on chalcone synthase expression. Histochemical analysis of silenced stem tissues demonstrated altered tracheary elements. The level of plant growth reduction of HCT-deficient plants was correlated with the inhibition of auxin transport. Suppression of flavonoid accumulation by chalcone synthase repression in HCT-deficient plants restored normal auxin transport and wild-type plant growth. By contrast, the lignin structure of the plants simultaneously repressed for HCT and chalcone synthase remained as severely altered as in HCT-silenced plants, with a large predominance of nonmethoxylated H units. These data demonstrate that the reduced size phenotype of HCT-silenced plants is not due to the alteration of lignin synthesis but to flavonoid accumulation. PMID:17237352

  11. ZnO Nanoparticles Affect Bacillus subtilis Cell Growth and Biofilm Formation

    PubMed Central

    Hsueh, Yi-Huang; Ke, Wan-Ju; Hsieh, Chien-Te; Lin, Kuen-Song; Tzou, Dong-Ying; Chiang, Chao-Lung

    2015-01-01

    Zinc oxide nanoparticles (ZnO NPs) are an important antimicrobial additive in many industrial applications. However, mass-produced ZnO NPs are ultimately disposed of in the environment, which can threaten soil-dwelling microorganisms that play important roles in biodegradation, nutrient recycling, plant protection, and ecological balance. This study sought to understand how ZnO NPs affect Bacillus subtilis, a plant-beneficial bacterium ubiquitously found in soil. The impact of ZnO NPs on B. subtilis growth, FtsZ ring formation, cytosolic protein activity, and biofilm formation were assessed, and our results show that B. subtilis growth is inhibited by high concentrations of ZnO NPs (≥ 50 ppm), with cells exhibiting a prolonged lag phase and delayed medial FtsZ ring formation. RedoxSensor and Phag-GFP fluorescence data further show that at ZnO-NP concentrations above 50 ppm, B. subtilis reductase activity, membrane stability, and protein expression all decrease. SDS-PAGE Stains-All staining results and FT-IR data further demonstrate that ZnO NPs negatively affect exopolysaccharide production. Moreover, it was found that B. subtilis biofilm surface structures became smooth under ZnO-NP concentrations of only 5–10 ppm, with concentrations ≤ 25 ppm significantly reducing biofilm formation activity. XANES and EXAFS spectra analysis further confirmed the presence of ZnO in co-cultured B. subtilis cells, which suggests penetration of cell membranes by either ZnO NPs or toxic Zn+ ions from ionized ZnO NPs, the latter of which may be deionized to ZnO within bacterial cells. Together, these results demonstrate that ZnO NPs can affect B. subtilis viability through the inhibition of cell growth, cytosolic protein expression, and biofilm formation, and suggest that future ZnO-NP waste management strategies would do well to mitigate the potential environmental impact engendered by the disposal of these nanoparticles. PMID:26039692

  12. Microbial colonization and growth on metal sulfides and other mineral surfaces

    NASA Technical Reports Server (NTRS)

    Caldwell, D.; Sundquist, A. R.; Lawrence, J.; Doyle, A. P.

    1985-01-01

    To determine whether a bacterial film forms on sulfur minerals in situ, various sulfur containing and other minerals were incubated in Penitencia Creek. The rate of cell growth and attachment within the surface microenvironment of mineral surfaces was also determined. To determine whether surfaces enriched with soluble sulfur substrates (cysteine, glutathione, thioglycolate, sulfite, and thiosulfate) increased the rate of growth or attachment of natural communities, membrane enrichments were incubated. These rates were determined as described by Caldwell et al. (1981, 1983). The growth of Pseudomonas fluorescens, a heterotrophic sulfur oxidizer, was studied in batch cell suspensions and in continuous culture. In batch culture the cells were oxygen limited (growth rate 0.33 per hour under oxygen limitations and 0.52 per hour when vigorously aerated). Growth within the film was glucose limited. Several behavioral phenomena were observed for cells growing within the hydrodynamic boundary layer. Despite a flow of 10 cm per second in the environment, the bacteria were able to move freely in both directions within the hydrodynamic boundary layer.

  13. Microbial growth inhibition by alternating electric fields in mice with Pseudomonas aeruginosa lung infection.

    PubMed

    Giladi, Moshe; Porat, Yaara; Blatt, Alexandra; Shmueli, Esther; Wasserman, Yoram; Kirson, Eilon D; Palti, Yoram

    2010-08-01

    High-frequency, low-intensity electric fields generated by insulated electrodes have previously been shown to inhibit bacterial growth in vitro. In the present study, we tested the effect of these antimicrobial fields (AMFields) on the development of lung infection caused by Pseudomonas aeruginosa in mice. We demonstrate that AMFields (10 MHz) significantly inhibit bacterial growth in vivo, both as a stand-alone treatment and in combination with ceftazidime. In addition, we show that peripheral (skin) heating of about 2 degrees C can contribute to bacterial growth inhibition in the lungs of mice. We suggest that the combination of alternating electric fields, together with the heat produced during their application, may serve as a novel antibacterial treatment modality. PMID:20547811

  14. Ameloblastin, an Extracellular Matrix Protein, Affects Long Bone Growth and Mineralization.

    PubMed

    Lu, Xuanyu; Fukumoto, Satoshi; Yamada, Yoshihiko; Evans, Carla A; Diekwisch, Thomas Gh; Luan, Xianghong

    2016-06-01

    Matrix molecules such as the enamel-related calcium-binding phosphoprotein ameloblastin (AMBN) are expressed in multiple tissues, including teeth, bones, and cartilage. Here we have asked whether AMBN is of functional importance for timely long bone development and, if so, how it exerts its function related to osteogenesis. Adolescent AMBN-deficient mice (AMBN(Δ5-6) ) suffered from a 33% to 38% reduction in femur length and an 8.4% shorter trunk spinal column when compared with WT controls, whereas there was no difference between adult animals. On a cellular level, AMBN truncation resulted in a shortened growth plate and a 41% to 49% reduction in the number of proliferating tibia chondrocytes and osteoblasts. Bone marrow stromal cells (BMSCs) isolated from AMBN mutant mice displayed defects in proliferation and differentiation potential as well as cytoskeleton organization. Osteogenesis-related growth factors, such as insulin-like growth factor 1 (IGF1) and BMP7, were also significantly (46% to 73%) reduced in AMBN-deficient BMSCs. Addition of exogenous AMBN restored cytoskeleton structures in AMBN mutant BMSCs and resulted in a dramatic 400% to 600% increase in BMP2, BMP7, and Col1A expression. Block of RhoA diminished the effect of AMBN on osteogenic growth factor and matrix protein gene expression. Addition of exogenous BMP7 and IGF1 rescued the proliferation and differentiation potential of AMBN-deficient BMSCs. Confirming the effects of AMBN on long bone growth, back-crossing of mutant mice with full-length AMBN overexpressors resulted in a complete rescue of AMBN(Δ5-6) bone defects. Together, these data indicate that AMBN affects extracellular matrix production and cell adhesion properties in the long bone growth plate, resulting in altered cytoskeletal dynamics, increased osteogenesis-related gene expression, as well as osteoblast and chondrocyte proliferation. We propose that AMBN facilitates rapid long bone growth and an important growth spurt during the

  15. Bifunctional quaternary ammonium compounds to inhibit biofilm growth and enhance performance for activated carbon air-cathode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Nan; Liu, Yinan; An, Jingkun; Feng, Cuijuan; Wang, Xin

    2014-12-01

    The slow diffusion of hydroxyl out of the catalyst layer as well as the biofouling on the surface of cathode are two problems affecting power for membrane-less air-cathode microbial fuel cells (MFCs). In order to solve both of them simultaneously, here we simply modify activated carbon air-cathode using a bifunctional quaternary ammonium compound (QAC) by forced evaporation. The maximum power density reaches 1041 ± 12 mW m-2 in an unbuffered medium (0.5 g L-1 NaCl), which is 17% higher than the control, probably due to the accelerated anion transport in the catalyst layer. After 2 months, the protein content reduced by a factor of 26 and the power density increases by 33%, indicating that the QAC modification can effectively inhibit the growth of cathodic biofilm and improve the stability of performance. The addition of NaOH and QAC epoxy have a negative effect on power production due to the clogging of pores in catalyst layer.

  16. High throughput nanostructure-initiator mass spectrometry screening of microbial growth conditions for maximal β-glucosidase production

    PubMed Central

    Cheng, Xiaoliang; Hiras, Jennifer; Deng, Kai; Bowen, Benjamin; Simmons, Blake A.; Adams, Paul D.; Singer, Steven W.; Northen, Trent R.

    2013-01-01

    Production of biofuels via enzymatic hydrolysis of complex plant polysaccharides is a subject of intense global interest. Microbial communities are known to express a wide range of enzymes necessary for the saccharification of lignocellulosic feedstocks and serve as a powerful reservoir for enzyme discovery. However, the growth temperature and conditions that yield high cellulase activity vary widely, and the throughput to identify optimal conditions has been limited by the slow handling and conventional analysis. A rapid method that uses small volumes of isolate culture to resolve specific enzyme activity is needed. In this work, a high throughput nanostructure-initiator mass spectrometry (NIMS)-based approach was developed for screening a thermophilic cellulolytic actinomycete, Thermobispora bispora, for β-glucosidase production under various growth conditions. Media that produced high β-glucosidase activity were found to be I/S + glucose or microcrystalline cellulose (MCC), Medium 84 + rolled oats, and M9TE + MCC at 45°C. Supernatants of cell cultures grown in M9TE + 1% MCC cleaved 2.5 times more substrate at 45°C than at all other temperatures. While T. bispora is reported to grow optimally at 60°C in Medium 84 + rolled oats and M9TE + 1% MCC, approximately 40% more conversion was observed at 45°C. This high throughput NIMS approach may provide an important tool in discovery and characterization of enzymes from environmental microbes for industrial and biofuel applications. PMID:24367356

  17. Beyond Agar: Gel Substrates with Improved Optical Clarity and Drug Efficiency and Reduced Autofluorescence for Microbial Growth Experiments

    PubMed Central

    Jaeger, Philipp A.; McElfresh, Cameron; Wong, Lily R.

    2015-01-01

    Agar, a seaweed extract, has been the standard support matrix for microbial experiments for over a century. Recent developments in high-throughput genetic screens have created a need to reevaluate the suitability of agar for use as colony support, as modern robotic printing systems now routinely spot thousands of colonies within the area of a single microtiter plate. Identifying optimal biophysical, biochemical, and biological properties of the gel support matrix in these extreme experimental conditions is instrumental to achieving the best possible reproducibility and sensitivity. Here we systematically evaluate a range of gelling agents by using the yeast Saccharomyces cerevisiae as a model microbe. We find that carrageenan and Phytagel have superior optical clarity and reduced autofluorescence, crucial for high-resolution imaging and fluorescent reporter screens. Nutrient choice and use of refined Noble agar or pure agarose reduce the effective dose of numerous selective drugs by >50%, potentially enabling large cost savings in genetic screens. Using thousands of mutant yeast strains to compare colony growth between substrates, we found no evidence of significant growth or nutrient biases between gel substrates, indicating that researchers could freely pick and choose the optimal gel for their respective application and experimental condition. PMID:26070672

  18. Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

    PubMed Central

    Sandor, Manette E.; Chazdon, Robin L.

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields. PMID:24454700

  19. Effects of random motility on microbial growth and competition in a flow reactor

    SciTech Connect

    Ballyk, M.; Dung, L.; Jones, D.A.; Smith, H.L.

    1998-11-01

    The authors investigate the effects of random motility on the ability of a microbial population to survive in pure culture and to be a good competitor for scarce nutrient in mixed culture in a flow reactor model consisting of a nonlinear parabolic system of partial differential equations. For pure culture (*a single population), a sharp condition is derived which distinguishes between the two outcomes: (1) washout of the population from the reactor or (2) persistence of the population and the existence of a unique single-population steady state. The simulations suggest that this steady state is globally attracting. For the case of two populations competing for scarce nutrient, they obtain sufficient conditions for the uniform persistence of the two populations, for the existence of a coexistence steady state, and for the ability of one population to competitively exclude a rival. Extensive simulations are reported which suggest that (1) all solutions approach some steady state solution, (2) all possible outcomes exhibited by the classical competitive Lotka-Volterra ODE model can occur in the model, and (3) the outcome of competition between two bacterial strains can depend rather subtly on their respective random motility coefficients.

  20. Single-cell genomics reveal metabolic strategies for microbial growth and survival in an oligotrophic aquifer

    SciTech Connect

    Wilkins, Michael J.; Kennedy, David W.; Castelle, Cindy; Field, Erin; Stepanauskas, Ramunas; Fredrickson, Jim K.; Konopka, Allan

    2014-02-09

    Bacteria from the genus Pedobacter are a major component of microbial assemblages at Hanford Site and have been shown to significantly change in abundance in response to the subsurface intrusion of Columbia River water. Here we employed single cell genomics techniques to shed light on the physiological niche of these microorganisms. Analysis of four Pedobacter single amplified genomes (SAGs) from Hanford Site sediments revealed a chemoheterotrophic lifestyle, with the potential to exist under both aerobic and microaerophilic conditions via expression of both aa3­-type and cbb3-type cytochrome c oxidases. These SAGs encoded a wide-range of both intra-and extra­-cellular carbohydrate-active enzymes, potentially enabling the degradation of recalcitrant substrates such as xylan and chitin, and the utilization of more labile sugars such as mannose and fucose. Coupled to these enzymes, a diversity of transporters and sugar-binding molecules were involved in the uptake of carbon from the extracellular local environment. The SAGs were enriched in TonB-dependent receptors (TBDRs), which play a key role in uptake of substrates resulting from degradation of recalcitrant carbon. CRISPR-Cas mechanisms for resisting viral infections were identified in all SAGs. These data demonstrate the potential mechanisms utilized for persistence by heterotrophic microorganisms in a carbon-limited aquifer, and hint at potential linkages between observed Pedobacter abundance shifts within the 300 Area subsurface and biogeochemical shifts associated with Columbia River water intrusion.

  1. Statistical support for the ATL program. [microbial growth in zero gravity

    NASA Technical Reports Server (NTRS)

    Hinkelmann, K.; Myers, R. H.

    1976-01-01

    Statistical experimental designs are presented for various numbers of organisms and agar solutions pertinent to the experiment, ""colony growth in zero gravity''. Missions lasting 7 and 30 days are considered. For the designs listed, the statistical analysis of the observations obtained on the space shuttle are outlined.

  2. Influence of Partial Denitrification and Mixotrophic Growth of NOB on Microbial Distribution in Aerobic Granular Sludge.

    PubMed

    Winkler, Mari-K H; Le, Quan H; Volcke, Eveline I P

    2015-09-15

    In aerobic granular sludge (AGS), the growth of nitrite oxidizing bacteria (NOB) can be uncoupled from the nitrite supply of ammonia oxidizing bacteria (AOB). Besides, unlike for conventional activated sludge, Nitrobacter was found to be the dominant NOB and not Nitrospira. To explain these experimental observations, two possible pathways have been put forward in literature. The first one involves the availability of additional nitrite from partial denitrification (nitrite-loop) and the second one consists of mixotrophic growth of Nitrobacter in the presence of acetate (ping-pong). In this contribution, mathematical models were set up to assess the possibility of these pathways to explain the reported observations. Simulation results revealed that both pathways influenced the nitrifier distribution in the granules. The nitrite-loop pathway led to an elevated NOB/AOB ratio, while mixotrophic growth of Nitrobacter guaranteed their predominance among the NOB population. Besides, mixotrophic growth of Nitrobacter could lead to NO emission from AGS. An increasing temperature and/or a decreasing oxygen concentration led to an elevated NOB/AOB ratio and increased NO emissions. PMID:26248168

  3. Influence of microbial growth in the redox potential of fermented cucumbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Commonly, pH measurements are used during the production of fermented cucumbers to indirectly monitor growth of lactic acid bacteria (LAB) and acid production. Redox potential (Eh) measurements, which are determined by the flux of electrons in a system, could serve as a more accurate tool to monitor...

  4. Microbial Inoculation Improves Growth of Oil Palm Plants (Elaeis guineensis Jacq.)

    PubMed Central

    Om, Azlin Che; Ghazali, Amir Hamzah Ahmad; Keng, Chan Lai; Ishak, Zamzuri

    2009-01-01

    Introduction of diazotrophic rhizobacteria to oil palm tissues during the in vitro micropropagation process establishes an early associative interaction between the plant cells and bacteria. In the association, the diazotrophs provide the host plants with phytohormones and fixed nitrogen. This study was conducted to observe growth of bacterised tissue cultured oil palm plants under ex vitro conditions after 280 days of growth. Root dry weight, shoot dry weight, root volume, bacterial colonisation, leaf protein and chlorophyll content of the host plants were observed. The results revealed that the inocula successfully colonised roots of the host plants. Plants inoculated with Acetobacter diazotrophicus (R12) had more root dry weight and volume than plants inoculated with Azospirillum brasilense (Sp7). Leaf protein and chlorophyll content were higher in the bacterised plants compared to Control 2 plants (inoculated with killed Sp7). These results suggest that the diazotrophs successfully improved the growth of the host plant (oil palm) and minimised the amount of N fertiliser necessary for growth. PMID:24575180

  5. Structural stability, microbial biomass and community composition of sediments affected by the hydric dynamics of an urban stormwater infiltration basin. Dynamics of physical and microbial characteristics of stormwater sediment.

    PubMed

    Badin, Anne Laure; Monier, Armelle; Volatier, Laurence; Geremia, Roberto A; Delolme, Cécile; Bedell, Jean-Philippe

    2011-05-01

    The sedimentary layer deposited at the surface of stormwater infiltration basins is highly organic and multicontaminated. It undergoes considerable moisture content fluctuations due to the drying and inundation cycles (called hydric dynamics) of these basins. Little is known about the microflora of the sediments and its dynamics; hence, the purpose of this study is to describe the physicochemical and biological characteristics of the sediments at different hydric statuses of the infiltration basin. Sediments were sampled at five time points following rain events and dry periods. They were characterized by physical (aggregation), chemical (nutrients and heavy metals), and biological (total, bacterial and fungal biomasses, and genotypic fingerprints of total bacterial and fungal communities) parameters. Data were processed using statistical analyses which indicated that heavy metal (1,841 μg/g dry weight (DW)) and organic matter (11%) remained stable through time. By contrast, aggregation, nutrient content (NH₄⁺, 53-717 μg/g DW), pH (6.9-7.4), and biological parameters were shown to vary with sediment water content and sediment biomass, and were higher consecutive to stormwater flows into the basin (up to 7 mg C/g DW) than during dry periods (0.6 mg C/g DW). Coinertia analysis revealed that the structure of the bacterial communities is driven by the hydric dynamics of the infiltration basin, although no such trend was found for fungal communities. Hydric dynamics more than rain events appear to be more relevant for explaining variations of aggregation, microbial biomass, and shift in the microbial community composition. We concluded that the hydric dynamics of stormwater infiltration basins greatly affects the structural stability of the sedimentary layer, the biomass of the microbial community living in it and its dynamics. The decrease in aggregation consecutive to rewetting probably enhances access to organic matter (OM), explaining the consecutive release

  6. Microbial growth fluctuating in response to solar-terrestrial activity variations.

    PubMed

    Voychuk, S I; Gromozova, E N

    2012-01-01

    Populations of microorganisms display fluctuations in the variable physiological and biochemical properties during cultivation under constant laboratory conditions. A series of explanations were proposed for this phenomenon, and different factors were studied as possible regulators. It was found that such fluctuations possess cosmic rhythms, but no factor(s) were proposed that could sufficiently explain and predict the magnitude of changes that happened on a daily basis in the long-term experiments. In this study we investigated specific growth rate fluctuations of Saccharomyces cerevisiae yeasts that were marked daily during cultivation under constant conditions. The effects of different solar and terrestrial factors were then analysed. The significant correlation indices were found for growth rate fluctuations against solar wind speed and the number of flares M on the Sun. These two factors determined the cyclic nature of the growth rate fluctuations, and thus its general course of increase or decrease. The effects of several other factors (Flares C number, planetary A index variation, and changes in the atmospheric factors such as temperature and humidity) and their two-way interactions were significant in producing an equation to describe the magnitude of changes of the yeast's growth parameters. The R2 of the equation achieved 91% and adjusted R2 was 78%. It is obvious that temperature and humidity are the factors that cannot directly influence the yeast populations under laboratory conditions and thus we suppose that they only reflect modifications of the really important factor(s) that take place in the Earth's atmosphere. We have concluded that different solar and terrestrial factors are responsible for the fluctuations in the daily kinetic parameters of the yeast growth. PMID:22830199

  7. Effects of drought-affected corn and nonstarch polysaccharide enzyme inclusion on nursery pig growth performance.

    PubMed

    Jones, C K; Frantz, E L; Bingham, A C; Bergstrom, J R; DeRouchey, J M; Patience, J F

    2015-04-01

    The effectiveness of carbohydrase enzymes has been inconsistent in corn-based swine diets; however, the increased substrate of nonstarch polysaccharides in drought-affected corn may provide an economic model for enzyme inclusion, but this has not been evaluated. A total of 360 barrows (PIC 1050 × 337, initially 5.85 kg BW) were used to determine the effects of drought-affected corn inclusion with or without supplementation of commercial carbohydrases on growth performance and nutrient digestibility of nursery pigs. Initially, 34 corn samples were collected to find representatives of normal and drought-affected corn. The lot selected to represent the normal corn had a test weight of 719.4 kg/m3, 15.0% moisture, and 4.2% xylan. The lot selected to represent drought-affected corn had a test weight of 698.8 kg/m3, 14.3% moisture, and 4.7% xylan. After a 10-d acclimation period postweaning, nursery pigs were randomly allotted to 1 of 8 dietary treatments in a completely randomized design. Treatments were arranged in a 2 × 4 factorial with main effects of corn (normal vs. drought affected) and enzyme inclusion (none vs. 100 mg/kg Enzyme A vs. 250 mg/kg Enzyme B vs. 100 mg/kg Enzyme A + 250 mg/kg Enzyme B). Both enzymes were included blends of β-glucanase, cellulose, and xylanase (Enzyme A) or hemicellulase and pectinases (Enzyme B). Pigs were fed treatment diets from d 10 to 35 postweaning in 2 phases. Feed and fecal samples were collected on d 30 postweaning to determine apparent total tract digestibility of nutrients. The nutrient concentrations of normal and drought-affected corn were similar, which resulted in few treatment or main effects differences of corn type or enzyme inclusion. No interactions were observed (P > 0.10) between corn source and enzyme inclusion. Overall (d 10 to 35), treatments had no effect on ADG or ADFI, but enzyme A inclusion tended to improve (P < 0.10; 0.74 vs. 0.69) G:F, which was primarily driven by the improved feed efficiency (0

  8. Water potential affects Coniothyrium minitans growth, germination and parasitism of Sclerotinia sclerotiorum sclerotia.

    PubMed

    Jones, E Eirian; Stewart, Alison; Whipps, John M

    2011-09-01

    Water availability is an important environmental factor which has major effects on fungal activity. The effects of osmotic (KCl amended agar) and matric Polyethylene glycol ((PEG) 8000 amended agar) potentials over the range -0.1 to -5.0MPa on mycelial growth and conidial germination of eight isolates of the sclerotial parasite Coniothyrium minitans was assessed. The influence of soil water potential on the ability of three selected isolates (LU112, LU545, and T5R42i) to parasitise sclerotia of the plant pathogen Sclerotinia sclerotiorum was determined. For all eight C. minitans isolates, decreasing osmotic and matric potentials caused a reduction in mycelial growth and conidial germination. Isolates were more sensitive to decreasing matric potential than osmotic potential. Across the isolates, growth at an osmotic potential of -5.0MPa was 30-70% of the growth seen in the control, whereas less than 20% of the control growth was seen at the corresponding matric potential. Across all isolates no conidial germination was seen at matric potential of -5.0MPa. The C. minitans isolates varied in their sensitivity to decreasing water potentials. Mycelial growth and conidial germination of three isolates (LU112, Conio, and CH1) were more tolerant of low osmotic potential and matric potential with respect to mycelial growth. Isolates T5R42i and LU430 were least tolerant. In contrast, conidial germination of isolates Conio, LU545, and T5R42i were less sensitive to decreasing matric potential. Soil water potential was seen to affect infection and viability of sclerotia by the three C. minitans isolates. Isolate LU545 reduced sclerotial viability over a wider water potential range (-0.01 to -1.5MPa) compared with LU112 (-0.01 to -1.0MPa), with isolate T5R42i being intermediate. Indigenous soil fungi (Trichoderma spp. and Clonostachys rosea) were recovered from sclerotia but did not result in reduction in sclerotial viability. The relevance of these results in relation to

  9. A growth QTL on chicken chromosome 1 affects emotionality and sociality.

    PubMed

    Wirén, Anna; Jensen, Per

    2011-03-01

    Domestication of animals, regardless of species, is often accompanied by simultaneous changes in several physiological and behavioral traits (e.g. growth rate and fearfulness). In this study we compared the social behavior and emotional reactivity, as measured in a battery of behavioral tests, of two groups of chickens selected from a common genetic background, an advanced intercross line between the ancestral red junglefowl ("RJF") and the domesticated White Leghorn layer ("WL"). The birds were selected for homozygosity for alternative alleles at one locus (a microsatellite marker), centrally positioned in a previously identified pleiotropic growth QTL on chromosome 1, closely linked to one major candidate gene (AVPR1a) for certain aspects of social behavior. Birds homozygous for the WL allele ("WL genotype") had a modified pattern of social and emotional reactions than birds homozygous for the RJF allele ("RJF genotype"), shown by different scores in a principal components analysis. These results suggest that the growth QTL affects a number of domestication related behavioral traits, and may have been a primary target of selection during domestication. The QTL contains a multitude of genes, several of which have been linked to social behavior (for example the vasotocin receptor AVPR1a targeted in this experiment). Future studies aimed at making a higher resolution genotypic characterization of the QTL should give more information about which of these genes may be considered the strongest candidates for bringing about the behavioral changes associated with animal domestication. PMID:20596888

  10. Sodic Soil Properties and Sunflower Growth as Affected by Byproducts of Flue Gas Desulfurization

    PubMed Central

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2012-01-01

    The main component of the byproducts of flue gas desulfurization (BFGD) is CaSO4, which can be used to improve sodic soils. The effects of BFGD on sodic soil properties and sunflower growth were studied in a pot experiment. The experiment consisted of eight treatments, at four BFGD rates (0, 7.5, 15 and 22.5 t ha−1) and two leaching levels (750 and 1200 m3 ha−1). The germination rate and yield of the sunflower increased, and the exchangeable sodium percentage (ESP), pH and total dissolved salts (TDS) in the soils decreased after the byproducts were applied. Excessive BFGD also affected sunflower germination and growth, and leaching improved reclamation efficiency. The physical and chemical properties of the reclaimed soils were best when the byproducts were applied at 7.5 t ha−1 and water was supplied at 1200 m3·ha−1. Under these conditions, the soil pH, ESP, and TDS decreased from 9.2, 63.5 and 0.65% to 7.8, 2.8 and 0.06%, and the germination rate and yield per sunflower reached 90% and 36.4 g, respectively. Salinity should be controlled by leaching when sodic soils are reclaimed with BFGD as sunflower growth is very sensitive to salinity during its seedling stage. PMID:23285042

  11. Review of Factors Affecting the Growth and Survival of Follicular Grafts

    PubMed Central

    Parsley, William M; Perez-Meza, David

    2010-01-01

    Great strides have been made in hair restoration over the past 20 years. A better understanding of natural balding and non-balding patterns along with more respect for ageing has helped guide proper hairline design. Additionally, the use of smaller grafts has created a significantly improved natural appearance to the transplanted grafts. Inconsistent growth and survival of follicular grafts, however, has continued to be a problem that has perplexed hair restoration surgeons. This review attempts to explore the stresses affecting grafts during transplantation and some of the complexities involved in graft growth and survival. These authors reviewed the literature to determine the primary scope of aspects influencing growth and survival of follicular grafts. This scope includes patient selection, operating techniques, graft care, storage solutions and additives. The primary focus of the hair restoration surgeons should first be attention to the fundamentals of hair care, hydration, temperature, time out of body and gentle handling. Factors such as advanced storage solutions and additives can be helpful once the fundamentals have been addressed. PMID:21031063

  12. Streptomycin affects the growth and photochemical activity of the alga Chlorella vulgaris.

    PubMed

    Perales-Vela, Hugo Virgilio; García, Roberto Velasco; Gómez-Juárez, Evelyn Alicia; Salcedo-Álvarez, Martha Ofelia; Cañizares-Villanueva, Rosa Olivia

    2016-10-01

    Antibiotics are increasingly being used in human and veterinary medicine, as well as pest control in agriculture. Recently, their emergence in the aquatic environment has become a global concern. The aim of this study was to evaluate the effect of streptomycin on growth and photosynthetic activity of Chlorella vulgaris after 72h exposure. We found that growth, photosynthetic activity and the content of the D1 protein of photosystem II decreased. Analysis of chlorophyll a fluorescence emission shows a reduction in the energy transfer between the antenna complex and reaction center. Also the activity of the oxygen evolution complex and electron flow between QA and QB were significantly reduced; in contrast, we found an increase in the reduction rate of the acceptor side of photosystem I. The foregoing can be attributed to the inhibition of the synthesis of the D1 protein and perhaps other coded chloroplast proteins that are part of the electron transport chain which are essential for the transformation of solar energy in the photosystems. We conclude that micromolar concentrations of streptomycin can affect growth and photosynthetic activity of Chlorella vulgaris. The accumulation of antibiotics in the environment can become an ecological problem for primary producers in the aquatic environment. PMID:27344399

  13. Loss of stromal JUNB does not affect tumor growth and angiogenesis.

    PubMed

    Braun, Jennifer; Strittmatter, Karin; Nübel, Tobias; Komljenovic, Dorde; Sator-Schmitt, Melanie; Bäuerle, Tobias; Angel, Peter; Schorpp-Kistner, Marina

    2014-03-15

    The transcription factor AP-1 subunit JUNB has been shown to play a pivotal role in angiogenesis. It positively controls angiogenesis by regulating Vegfa as well as the transcriptional regulator Cbfb and its target Mmp13. In line with these findings, it has been demonstrated that tumor cell-derived JUNB promotes tumor growth and angiogenesis. In contrast to JUNB's function in tumor cells, the role of host-derived stromal JUNB has not been elucidated so far. Here, we show that ablation of Junb in stromal cells including endothelial cells (ECs), vascular smooth muscle cells (SMCs) and fibroblasts does not affect tumor growth in two different syngeneic mouse models, the B16-F1 melanoma and the Lewis lung carcinoma model. In-depth analyses of the tumors revealed that tumor angiogenesis remains unaffected as assessed by measurements of the microvascular density and relative blood volume in the tumor. Furthermore, we could show that the maturation status of the tumor vasculature, analyzed by the SMC marker expression, α-smooth muscle actin and Desmin, as well as the attachment of pericytes to the endothelium, is not changed upon ablation of Junb. Taken together, these results indicate that the pro-angiogenic functions of stromal JUNB are well compensated with regard to tumor angiogenesis and tumor growth. PMID:24027048

  14. Sodic soil properties and sunflower growth as affected by byproducts of flue gas desulfurization.

    PubMed

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2012-01-01

    The main component of the byproducts of flue gas desulfurization (BFGD) is CaSO(4), which can be used to improve sodic soils. The effects of BFGD on sodic soil properties and sunflower growth were studied in a pot experiment. The experiment consisted of eight treatments, at four BFGD rates (0, 7.5, 15 and 22.5 t ha(-1)) and two leaching levels (750 and 1200 m(3) ha(-1)). The germination rate and yield of the sunflower increased, and the exchangeable sodium percentage (ESP), pH and total dissolved salts (TDS) in the soils decreased after the byproducts were applied. Excessive BFGD also affected sunflower germination and growth, and leaching improved reclamation efficiency. The physical and chemical properties of the reclaimed soils were best when the byproducts were applied at 7.5 t ha(-1) and water was supplied at 1200 m(3)·ha(-1). Under these conditions, the soil pH, ESP, and TDS decreased from 9.2, 63.5 and 0.65% to 7.8, 2.8 and 0.06%, and the germination rate and yield per sunflower reached 90% and 36.4 g, respectively. Salinity should be controlled by leaching when sodic soils are reclaimed with BFGD as sunflower growth is very sensitive to salinity during its seedling stage. PMID:23285042

  15. Does forest fragmentation affect the same way all growth-forms?

    PubMed

    Rodríguez-Loinaz, Gloria; Amezaga, Ibone; Onaindia, Miren

    2012-02-01

    Fragmentation of natural habitats is one of the main causes of the loss of biodiversity. However, all plants do not respond to habitat fragmentation in the same way due to differences in species traits. We studied the effect of patch size and isolation on the biodiversity of vegetation in the mixed-oak forests in the north of the Iberian Peninsula. The aim was to evaluate whether all the growth-forms of vegetation are equally affected by forest fragmentation in order to improve the management strategies to restore this type of vegetation. This study has shown that the effect of the area and spatial isolation of the patches was not the same for the different growth-forms. Fragmentation had a mainly negative effect on the richness and diversity of forest specialist species, especially ferns and herbaceous growth-forms. Moreover, the presence and/or cover of woodland herbaceous species (such as Lamiastrum galeobdolon and Helleborus viridis) and of woodland ferns (namely Asplenium adiantum-nigrum, Asplenium trichomanes, Polystichum setiferum, Dryopteris affinis) were negatively affected by patch size, possibly due to the reduction of habitat quality. These species have been replaced by more generalist species (such as Cardamine pratensis, Cirsium sp., Pulmonaria longifolia or Rumex acetosella) in small patches. Patch isolation had a negative effect on the presence of forest specialist species (namely, L. galeobdolon, Frangula alnus, Hypericum androsaemum, A. adiantum-nigrum and Athyrium filix-femina) and favored colonization by more generalist species such as Cirsium sp., Calluna vulgaris, Erica arborea or Ulex sp. Thus, in this region special attention should be paid to the conservation of forest specialist species, especially ferns and herbs. In conservation policy focused on forest specialist species, the most valuable species in forest ecosystems, conservation of large forest areas should be promoted. PMID:21924813

  16. Effects of chestnut tannins and coconut oil on growth performance, methane emission, ruminal fermentation, and microbial populations in sheep.

    PubMed

    Liu, H; Vaddella, V; Zhou, D

    2011-12-01

    This study was conducted to evaluate the effects of chestnut tannins (CT) and coconut oil (CO) on growth performance, methane (CH₄) emission, ruminal fermentation, and microbial populations in sheep. A total of 48 Rideau Arcott sheep (average body weight 31.5±1.97 kg, 16 wk old) were randomly assigned into 6 treatment groups in a 3 × 2 factorial design, with CT and CO as the main effects (8 sheep per group). The treatments were control diet (CTR), 10 or 30 g of CT/kg of diet (CT10 and CT30), 25 g of CO/kg of concentrate (CO25), and 10 or 30 g of CT/kg of diet+25 g of CO/kg of concentrate (CT10CO25 and CT30CO25). After the feeding trial (60 d), all sheep were moved to respiratory chambers to measure CH₄ emission. After CH₄ emission measurements, all sheep were slaughtered to obtain rumen fluid samples. Results showed that the addition of CT, CO, and CT+CO had no significant effects on growth performance of sheep but reduced CH₄ emission. Addition of CT reduced the NH₃-N concentration in rumen fluid in CT30. Addition of CO decreased the concentration of total volatile fatty acids in rumen fluid. No significant differences were observed in pH and molar proportion of volatile fatty acids among treatments. Addition of CT, CO, and CT+CO significantly decreased methanogen and protozoa populations. Moreover, CO decreased counts of Fibrobacter succinogenes. No significant differences were observed in populations of fungi, Ruminococcus flavefaciens, or Ruminococcus albus among treatments. In conclusion, supplementation of CT and CO seemed to be a feasible means of decreasing emissions of CH₄ from sheep by reduction of methanogen and protozoa populations with no negative effect on growth performance. PMID:22118094

  17. Microbial background flora in small-scale cheese production facilities does not inhibit growth and surface attachment of Listeria monocytogenes.

    PubMed

    Schirmer, B C T; Heir, E; Møretrø, T; Skaar, I; Langsrud, S

    2013-10-01

    The background microbiota of 5 Norwegian small-scale cheese production sites was examined and the effect of the isolated strains on the growth and survival of Listeria monocytogenes was investigated. Samples were taken from the air, food contact surfaces (storage surfaces, cheese molds, and brine) and noncontact surfaces (floor, drains, and doors) and all isolates were identified by sequencing and morphology (mold). A total of 1,314 isolates were identified and found to belong to 55 bacterial genera, 1 species of yeast, and 6 species of mold. Lactococcus spp. (all of which were Lactococcus lactis), Staphylococcus spp., Microbacterium spp., and Psychrobacter sp. were isolated from all 5 sites and Rhodococcus spp. and Chryseobacterium spp. from 4 sites. Thirty-two genera were only found in 1 out of 5 facilities each. Great variations were observed in the microbial background flora both between the 5 producers, and also within the various production sites. The greatest diversity of bacteria was found in drains and on rubber seals of doors. The flora on cheese storage shelves and in salt brines was less varied. A total of 62 bacterial isolates and 1 yeast isolate were tested for antilisterial activity in an overlay assay and a spot-on-lawn assay, but none showed significant inhibitory effects. Listeria monocytogenes was also co-cultured on ceramic tiles with bacteria dominating in the cheese production plants: Lactococcus lactis, Pseudomonas putida, Staphylococcus equorum, Rhodococcus spp., or Psychrobacter spp. None of the tested isolates altered the survival of L. monocytogenes on ceramic tiles. The conclusion of the study was that no common background flora exists in cheese production environments. None of the tested isolates inhibited the growth of L. monocytogenes. Hence, this study does not support the hypothesis that the natural background flora in cheese production environments inhibits the growth or survival of L. monocytogenes. PMID:23891302

  18. Mechanical signatures of microbial biofilms in micropillar-embedded growth chambers.

    PubMed

    Chew, S C; Kundukad, B; Teh, W K; Doyle, P; Yang, L; Rice, S A; Kjelleberg, S

    2016-06-21

    Biofilms are surface-attached communities of microorganisms embedded in an extracellular matrix and are essential for the cycling of organic matter in natural and engineered environments. They are also the leading cause of many infections, for example, those associated with chronic wounds and implanted medical devices. The extracellular matrix is a key biofilm component that determines its architecture and defines its physical properties. Herein, we used growth chambers embedded with micropillars to study the net mechanical forces (differential pressure) exerted during biofilm formation in situ. Pressure from the biofilm is transferred to the micropillars via the extracellular matrix, and reduction of major matrix components decreases the magnitude of micropillar deflections. The spatial arrangement of micropillar deflections caused by pressure differences in the different biofilm strains may potentially be used as mechanical signatures for biofilm characterization. Hence, we submit that micropillar-embedded growth chambers provide insights into the mechanical properties and dynamics of the biofilm and its matrix. PMID:27191395

  19. Single-cell genomics reveals metabolic strategies for microbial growth and survival in an oligotrophic aquifer.

    PubMed

    Wilkins, Michael J; Kennedy, David W; Castelle, Cindy J; Field, Erin K; Stepanauskas, Ramunas; Fredrickson, James K; Konopka, Allan E

    2014-02-01

    Bacteria from the genus Pedobacter are a major component of microbial assemblages at Hanford Site (a largely decommissioned nuclear production complex) in eastern Washington state, USA, and have been shown to change significantly in abundance in response to the subsurface intrusion of Columbia River water. Here we employed single-cell genomics techniques to shed light on the physiological niche of these micro-organisms. Analysis of four Pedobacter single amplified genomes (SAGs) from Hanford Site sediments revealed a chemoheterotrophic lifestyle, with the potential to exist under both aerobic and microaerophilic conditions via expression of both aa3-type and cbb3-type cytochrome c oxidases. These SAGs encoded a wide range of both intra- and extracellular carbohydrate-active enzymes, potentially enabling the degradation of recalcitrant substrates such as xylan and chitin, and the utilization of more labile sugars such as mannose and fucose. Coupled to these enzymes, a diversity of transporters and sugar-binding molecules were involved in the uptake of carbon from the extracellular local environment. The SAGs were enriched in TonB-dependent receptors, which play a key role in uptake of substrates resulting from degradation of recalcitrant carbon. Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-Cas mechanisms for resisting viral infections were identified in all SAGs. These data demonstrate the potential mechanisms utilized for persistence by heterotrophic micro-organisms in a carbon-limited aquifer, and hint at potential linkages between observed Pedobacter abundance shifts within the 300 Area (in the south-eastern corner of the site) subsurface and biogeochemical shifts associated with Columbia River water intrusion. PMID:24324032

  20. Influence of chromium compounds on microbial growth and nucleic acid synthesis

    SciTech Connect

    Ogawa, Toshihiko; Usui, Masauji; Yatome, Chizuko; Idaka, Eiichi )

    1989-08-01

    The wastewaters of the dyeing and the tanning industry contain often various chromium compounds, e.g. K{sub 2}Cr{sub 2}O{sub 7} and CrCl{sub 3}, with a large quantity of organic substances. Biological treatments have generally been employed in these industrial factories for the biodegradation of organic substances. The toxicity of the chromium compounds have been studied regarding mutagenicity and carcinogenicity from the medical view point. This is also of interest from the view point of wastewater biological treatments. The inhibitory effects of the compounds on the cell growth and the respiration in activated sludge have been reported in detail, but mechanisms have not been sufficiently elucidated. Therefore, the influence of K{sub 2}Cr{sub 2}O{sub 7} and CrCl{sub 3} on the cell growth and on the nucleic acid content was measured. Both compounds were the inhibitors of DNA synthesis. These action resulted in increased generation time a decrease in cell division. Chromium compounds and dyes coexist often in the wastewaters of the dyeing industries. The growth inhibitions of the mixed solution were measured.

  1. Effects of X-ray irradiation on the microbial growth and quality of flue-cured tobacco during aging

    NASA Astrophysics Data System (ADS)

    Wang, J. J.; Xu, Z. C.; Fan, J. L.; Wang, Y.; Tian, Z. J.; Chen, Y. T.

    2015-06-01

    X-ray irradiation was evaluated for improving microbial safety and the quality of flue-cured tobacco during aging. Tobacco samples were irradiated at doses of 0, 1, 2, 3 and 5 kGy and stored for 12 months under normal storage conditions or in a high-humidity (RH>70%) room. Microbiological data indicated that the population of total aerobic bacteria was significantly decreased with increasing irradiation doses. In particular, a dose of 2 kGy was effective for the decontamination of fungi from the tested samples, with a 0.93 log CFU/g reduction for bacteria. The control and 1 kGy X-ray treated tobacco samples were became rotted and moldy after the 12th month, whereas those treated with 2, 3 and 5 kGy had no detectable mold during 12 months of storage at high humidity. Chemical measurements showed that irradiation up to 3 kGy did not affect the total nitrogen, nicotine, reducing and total sugars, ratio of total nitrogen to nicotine and sugar-to-nicotine ratio. Furthermore, sensory evaluation results also showed that X-ray irradiation did not affect sensory scores with irradiation at a dose <3 kGy. Based on these results, X-ray irradiation dose in the range of 2-3 kGy is recommended for the decontamination of fungi from flue-cured tobacco.

  2. Quantitation of microbial products and their effectiveness in enhanced oil recovery. Annual report, January 1, 1992--December 31, 1992

    SciTech Connect

    McInerney, M.J.; Knapp, R.M.

    1992-12-31

    Rapid rates of growth and extracellular polymer production by a halotolerant, thermotolerant, facultative anaerobe were observed at the salinity, temperature, and redox conditions found in many Oklahoma oil reservoirs. The effects of different mineral surfaces on microbial growth and metabolism was also determined. The presence of different mineral surfaces did not affect the main fermentation pathway but did affect the concentration and relative amounts of certain products. These studies provided the quantitative information needed for accurate modeling of microbial processes. Other studies showed that microorganisms rapidly penetrate porous materials in the absence of fluid flow, and that growth is an important mechanism controlling microbial movement in porous materials. These studies also showed that pore size restricts microbial growth and activity, and may be the dominant physical mechanism that controls the distribution of bacteria in subsurface environments. New experimental and mathematical approaches were developed to measure and quantify microbial growth and activity in porous materials.

  3. Reduction in DNA topoisomerase I level affects growth, phenotype and nucleoid architecture of Mycobacterium smegmatis.

    PubMed

    Ahmed, Wareed; Menon, Shruti; Karthik, Pullela V; Nagaraja, Valakunja

    2015-02-01

    The steady-state negative supercoiling of eubacterial genomes is maintained by the action of DNA topoisomerases. Topoisomerase distribution varies in different species of mycobacteria. While Mycobacterium tuberculosis (Mtb) contains a single type I (TopoI) and a single type II (Gyrase) enzyme, Mycobacterium smegmatis (Msm) and other members harbour additional relaxases. TopoI is essential for Mtb survival. However, the necessity of TopoI or other relaxases in Msm has not been investigated. To recognize the importance of TopoI for growth, physiology and gene expression of Msm, we have developed a conditional knock-down strain of TopoI in Msm. The TopoI-depleted strain exhibited extremely slow growth and drastic changes in phenotypic characteristics. The cessation of growth indicates the essential requirement of the enzyme for the organism in spite of having additional DNA relaxation enzymes in the cell. Notably, the imbalance in TopoI level led to the altered expression of topology modulatory proteins, resulting in a diffused nucleoid architecture. Proteomic and transcript analysis of the mutant indicated reduced expression of the genes involved in central metabolic pathways and core DNA transaction processes. RNA polymerase (RNAP) distribution on the transcription units was affected in the TopoI-depleted cells, suggesting global alteration in transcription. The study thus highlights the essential requirement of TopoI in the maintenance of cellular phenotype, growth characteristics and gene expression in mycobacteria. A decrease in TopoI level led to altered RNAP occupancy and impaired transcription elongation, causing severe downstream effects. PMID:25516959

  4. Survivin inhibitor YM155 suppresses gastric cancer xenograft growth in mice without affecting normal tissues

    PubMed Central

    Cheng, Xiao Jiao; Lin, Jia Cheng; Ding, Yan Fei; Zhu, Liming; Ye, Jing; Tu, Shui Ping

    2016-01-01

    Survivin overexpression is associated with poor prognosis of human gastric cancer, and is a target for gastric cancer therapy. YM155 is originally identified as a specific inhibitor of survivin. In this study, we investigated the antitumor effect of YM155 on human gastric cancer. Our results showed that YM155 treatment significantly inhibited cell proliferation, reduced colony formation and induced apoptosis of gastric cancer cells in a dose-dependent manner. Accordingly, YM155 treatment significantly decreased survivin expression without affecting XIAP expression and increased the cleavage of apoptosis-associated proteins caspase 3, 7, 8, 9. YM155 significantly inhibited sphere formation of gastric cancer cells, suppressed expansion and growth of the formed spheres (cancer stem cell-like cells, CSCs) and downregulated the protein levels of β-catenin, c-Myc, Cyclin D1 and CD44 in gastric cancer cells. YM155 infusion at 5 mg/kg/day for 7 days markedly inhibited growth of gastric cancer xenograft in a nude mouse model. Immunohistochemistry staining and Western Blot showed that YM155 treatment inhibited expression of survivin and CD44, induced apoptosis and reduced CD44+ CSCs in xenograft tumor tissues in vivo. No obvious pathological changes were observed in organs (e.g. heart, liver, lung and kidney) in YM155-treated mice. Our results demonstrated that YM155 inhibits cell proliferation, induces cell apoptosis, reduces cancer stem cell expansion, and inhibits xenograft tumor growth in gastric cancer cells. Our results elucidate a new mechanism by which YM155 inhibits gastric cancer growth by inhibition of CSCs. YM155 may be a promising agent for gastric cancer treatment. PMID:26771139

  5. Survivin inhibitor YM155 suppresses gastric cancer xenograft growth in mice without affecting normal tissues.

    PubMed

    Cheng, Xiao Jiao; Lin, Jia Cheng; Ding, Yan Fei; Zhu, Liming; Ye, Jing; Tu, Shui Ping

    2016-02-01

    Survivin overexpression is associated with poor prognosis of human gastric cancer, and is a target for gastric cancer therapy. YM155 is originally identified as a specific inhibitor of survivin. In this study, we investigated the antitumor effect of YM155 on human gastric cancer. Our results showed that YM155 treatment significantly inhibited cell proliferation, reduced colony formation and induced apoptosis of gastric cancer cells in a dose-dependent manner. Accordingly, YM155 treatment significantly decreased survivin expression without affecting XIAP expression and increased the cleavage of apoptosis-associated proteins caspase 3, 7, 8, 9. YM155 significantly inhibited sphere formation of gastric cancer cells, suppressed expansion and growth of the formed spheres (cancer stem cell-like cells, CSCs) and downregulated the protein levels of β-catenin, c-Myc, Cyclin D1 and CD44 in gastric cancer cells. YM155 infusion at 5 mg/kg/day for 7 days markedly inhibited growth of gastric cancer xenograft in a nude mouse model. Immunohistochemistry staining and Western Blot showed that YM155 treatment inhibited expression of survivin and CD44, induced apoptosis and reduced CD44+ CSCs in xenograft tumor tissues in vivo. No obvious pathological changes were observed in organs (e.g. heart, liver, lung and kidney) in YM155-treated mice. Our results demonstrated that YM155 inhibits cell proliferation, induces cell apoptosis, reduces cancer stem cell expansion, and inhibits xenograft tumor growth in gastric cancer cells. Our results elucidate a new mechanism by which YM155 inhibits gastric cancer growth by inhibition of CSCs. YM155 may be a promising agent for gastric cancer treatment. PMID:26771139

  6. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    PubMed Central

    Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

    2016-01-01

    Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions. PMID:26735689

  7. Impact of flue gas desulfurization-calcium sulfite and gypsum on soil microbial activity and wheat growth

    SciTech Connect

    Lee, Y.B.; Bigham, J.M.; Dick, W.A.; Kim, P.J.

    2008-08-15

    We conducted greenhouse tests to evaluate the effects of FGD-CaSO{sub 3} applied at rates of 0, 2.2, 4.4, and 8.8 Mg ha(-1) on wheat growth, soil enzyme activities, and the chemical properties of two soils with differing pH (4.0 vs. 6.2). A gypsum treatment applied at the rate of 2.2 Mg ha{sup -1} was used as a positive control. Exchangeable Ca{sup 2+} and water-extractable Ca{sup 2+} and SO{sub 4}{sup 2-} increased significantly with increasing FGD-CaSO{sub 3} application. SO{sub 4}{sup 2-} increased in both soils, indicating rapid oxidation of SO{sub 3}{sup 2-} to SO{sub 4}{sup 2-} when neither water nor oxygen was limiting. No changes in soil pH were measured. Applications of 2.2, 4.4, or 8.8 Mg CaSO{sub 3} ha{sup -1} to the pH 6.2 soil produced no effect on wheat growth or the uptake of N, P, Ca{sup 2+}, and Mg{sup 2+}. The uptake of SO{sub 4}{sup 2-} -S increased, whereas K uptake decreased. No significant differences in the activities of urease, {beta}-glucosidase, alkaline phosphatase, or arylsulfatase were observed relative to a control. In the acid soil, an application of 2.2 Mg ha{sup -1} FGD-CaSO{sub 3} increased wheat root growth and dry matter yield compared with an untreated control. The uptake of N, P, Ca{sup 2+}, and K{sup +} also increased presumably because of enhanced root development resulting from decreases in exchangeable Al{sup 3+} and increases in soluble Ca{sup 2+}. Wheat growth and alkaline phosphatase and arylsulfatase activities were significantly inhibited by addition of 8.8 Mg ha{sup -1} of FGD-CaSO{sub 3} compared with the untreated control or the same soil receiving 2.2 Mg ha{sup -1} gypsum. We conclude that surface applications of FGD-CaSO{sub 3} may be as effective as gypsum for inhibiting soil crusting, improving water infiltration, and promoting the movement of Ca{sup 2+} into acid subsoils. Moreover, application rates of equal to or less than 4.4 Mg ha-1 should have no negative impact on soil microbial activities or plant growth.

  8. Factors affecting the performance of a single-chamber microbial fuel cell-type biological oxygen demand sensor.

    PubMed

    Yang, Gai-Xiu; Sun, Yong-Ming; Kong, Xiao-Ying; Zhen, Feng; Li, Ying; Li, Lian-Hua; Lei, Ting-Zhou; Yuan, Zhen-Hong; Chen, Guan-Yi

    2013-01-01

    Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to degrade organic matter or sludge present in wastewater (WW), and thereby generate electricity. We developed a simple, low-cost single-chamber microbial fuel cell (SCMFC)-type biochemical oxygen demand (BOD) sensor using carbon felt (anode) and activated sludge, and demonstrated its feasibility in the construction of a real-time BOD measurement system. Further, the effects of anodic pH and organic concentration on SCMFC performance were examined, and the correlation between BOD concentration and its response time was analyzed. Our results demonstrated that the SCMFC exhibited a stable voltage after 132 min following the addition of synthetic WW (BOD concentration: 200 mg/L). Notably, the response signal increased with an increase in BOD concentration (range: 5-200 mg/L) and was found to be directly proportional to the substrate concentration. However, at higher BOD concentrations (>120 mg/L) the response signal remained unaltered. Furthermore, we optimized the SCMFC using synthetic WW, and tested it with real WW. Upon feeding real WW, the BOD values exhibited a standard deviation from 2.08 to 8.3% when compared to the standard BOD5 method, thus demonstrating the practical applicability of the developed system to real treatment effluents. PMID:24225089

  9. Microbial populations and hydrocarbon biodegradation potentials in fertilized shoreline sediments affected by the T/V Exxon Valdez oil spill

    SciTech Connect

    Lindstrom, J.E.; Yeager, T.R.; Braddock, J.F.; Brown, E.J. ); Prince, R.C.; Grossman, M.J. ); Clark, J.C. )

    1991-09-01

    The effort to clean up the T/V Exxon Valdez oil spill in Prince William Sound, Alaska, included the use of fertilizers to accelerate natural microbial degradation of stranded oil. A program to monitor various environmental parameter associated with this technique took place during the summer of 1990. Microbiological assays for numbers of heterotrophic and oil-degrading microbes and their hydrocarbon mineralization potentials were performed in support of this program. Fertilizer addition resulted in higher hexadecane and phenanthrene mineralization potentials on treated plots than on untreated reference plots. Microbial numbers in treated and reference surface sediments were not significantly different immediately after the first nutrient application in May 1990. However, subsurface sediments different immediately after the first nutrient application in May 1990. However, subsurface sediments from treated plots had higher numbers of hydrocarbon degraders than did reference sediments shortly after treatment. The second application of fertilizer, later in summer, resulted in surface and subsurface increases in numbers of hydrocarbon degraders with respect to reference sediments at two of three study sites. Elevated mineralization potentials, coupled with increased numbers of hydrocarbon degraders, indicated that natural hydrocarbon biodegradation was enhanced. However, these microbiological measurements alone are not sufficient to determine in situ rates of crude oil biodegradation.

  10. Microbial populations and hydrocarbon biodegradation potentials in fertilized shoreline sediments affected by the T/V Exxon Valdez oil spill.

    PubMed

    Lindstrom, J E; Prince, R C; Clark, J C; Grossman, M J; Yeager, T R; Braddock, J F; Brown, E J

    1991-09-01

    The effort of clean up the T/V Exxon Valdez oil spill in Prince William Sound, Alaska, included the use of fertilizers to accelerate natural microbial degradation of stranded oil. A program to monitor various environmental parameters associated with this technique took place during the summer of 1990. Microbiological assays for numbers of heterotrophic and oil-degrading microbes and their hydrocarbon mineralization potentials were performed in support of this program. Fertilizer addition resulted in higher hexadecane and phenanthrene mineralization potentials on treated plots than on untreated reference plots. Microbial numbers in treated and reference surface sediments were not significantly different immediately after the first nutrient application in May 1990. However, subsurface sediments from treated plots had higher numbers of hydrocarbon degraders than did reference sediments shortly after treatment. The second application of fertilizer, later in summer, resulted in surface and subsurface increases in numbers of hydrocarbon degraders with respect to reference sediments at two of the three study sites. Elevated mineralization potentials, coupled with increased numbers of hydrocarbon degraders, indicated that natural hydrocarbon biodegradation was enhanced. However, these microbiological measurements alone are not sufficient to determine in situ rates of crude oil biodegradation. PMID:1662935

  11. Fibroblast growth factor 9 is a novel modulator of negative affect

    PubMed Central

    Aurbach, Elyse L.; Inui, Edny Gula; Turner, Cortney A.; Hagenauer, Megan H.; Prater, Katherine E.; Li, Jun Z.; Absher, Devin; Shah, Najmul; Blandino, Peter; Bunney, William E.; Myers, Richard M.; Barchas, Jack D.; Schatzberg, Alan F.; Watson, Stanley J.; Akil, Huda

    2015-01-01

    Both gene expression profiling in postmortem human brain and studies using animal models have implicated the fibroblast growth factor (FGF) family in affect regulation and suggest a potential role in the pathophysiology of major depressive disorder (MDD). FGF2, the most widely characterized family member, is down-regulated in the depressed brain and plays a protective role in rodent models of affective disorders. By contrast, using three microarray analyses followed by quantitative RT-PCR confirmation, we show that FGF9 expression is up-regulated in the hippocampus of individuals with MDD, and that FGF9 expression is inversely related to the expression of FGF2. Because little is known about FGF9’s function in emotion regulation, we used animal models to shed light on its potential role in affective function. We found that chronic social defeat stress, an animal model recapitulating some aspects of MDD, leads to a significant increase in hippocampal FGF9 expression, paralleling the elevations seen in postmortem human brain tissue. Chronic intracerebroventricular administration of FGF9 increased both anxiety- and depression-like behaviors. In contrast, knocking down FGF9 expression in the dentate gyrus of the hippocampus using a lentiviral vector produced a decrease in FGF9 expression and ameliorated anxiety-like behavior. Collectively, these results suggest that high levels of hippocampal FGF9 play an important role in the development or expression of mood and anxiety disorders. We propose that the relative levels of FGF9 in relation to other members of the FGF family may prove key to understanding vulnerability or resilience in affective disorders. PMID:26351673

  12. Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities

    PubMed Central

    Lara, Lidia Susana; Rodriguez, Alia; Uribe-Vélez, Daniel; Sanders, Ian R.

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing Pseudomonas bacteria (PSB) could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities. PMID:27253975

  13. Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities.

    PubMed

    Ordoñez, Yuli Marcela; Fernandez, Belen Rocio; Lara, Lidia Susana; Rodriguez, Alia; Uribe-Vélez, Daniel; Sanders, Ian R

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing Pseudomonas bacteria (PSB) could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities. PMID:27253975

  14. The protective function of personal growth initiative among a genocide-affected population in Rwanda.

    PubMed

    Blackie, Laura E R; Jayawickreme, Eranda; Forgeard, Marie J C; Jayawickreme, Nuwan

    2015-07-01

    The aim of the current study was to investigate the extent to which individual differences in personal growth initiative (PGI) were associated with lower reports of functional impairment of daily activities among a genocide-affected population in Rwanda. PGI measures an individual's motivation to develop as a person and the extent to which he or she is active in setting goals that work toward achieving self-improvement. We found that PGI was negatively associated with functional impairment when controlling for depression, posttraumatic stress disorder, and other demographic factors. Our results suggest that PGI may constitute an important mindset for facilitating adaptive functioning in the aftermath of adversity and in the midst of psychological distress, and as such they might have practical applications for the development of intervention programs. PMID:26147518

  15. Fighting fish (Betta splendens) bubble nests do not inhibit microbial growth.

    PubMed

    Brown, Alexandria C; Clotfelter, Ethan D

    2012-12-01

    Some organisms produce antimicrobial substances in nesting foam to favorably manipulate the environment to which their developing offspring are exposed. We tested if fighting fish Betta splendens foamy nest material, which is comprised of bubbles produced in the oral cavity of nesting males, has antimicrobial properties against a pathogenic bacteria (Edwardsiella tarda), a nonpathogenic bacteria (Escherichia coli), or a pathogenic oomycete (Saprolegnia parasitica). We also tested if exposure to nest material increases larval survival by performing in vitro fertilizations and individually incubating eggs in bubble nest extract or tank water (control). Our results show no evidence of antimicrobial properties of bubble nests. On the contrary, bubble nests provided favorable microenvironments for the growth of Saprolegnia parasitica. Our results confirm earlier work citing the importance of male nest attendance, and suggest that the mechanism responsible for decreased survival in the absence of attending males is pathogenic microbes. PMID:22753365

  16. Optimization of marine waste based-growth media for microbial lipase production using mixture design methodology.

    PubMed

    Sellami, Mohamed; Kedachi, Samiha; Frikha, Fakher; Miled, Nabil; Ben Rebah, Faouzi

    2013-01-01

    Lipase production by Staphylococcus xylosus and Rhizopus oryzae was investigated using a culture medium based on a mixture of synthetic medium and supernatants generated from tuna by-products and Ulva rigida biomass. The proportion of the three medium components was optimized using the simplex-centroid mixture design method (SCMD). Results indicated that the experimental data were in good agreement with predicted values, indicating that SCMD was a reliable method for determining the optimum mixture proportion of the growth medium. Maximal lipase activities of 12.5 and 23.5 IU/mL were obtained with a 50:50 (v:v) mixture of synthetic medium and tuna by-product supernatant for Staphylococcus xylosus and Rhizopus oryzae, respectively. The predicted responses from these mixture proportions were also validated experimentally. PMID:24350480

  17. Accuracy of microbial growth predictions with square root and polynomial models.

    PubMed

    Delignette-Muller, M L; Rosso, L; Flandrois, J P

    1995-10-01

    The results of growth predictions using square root and polynomial models published in 14 papers were studied. Errors on quantities of practical interest such as lag time, generation time or the time required to reach a given increase in number of cells, are analyzed. The distribution of these errors was examined with the perspective of the practical use of predictive models in food industry. Highly unsafe predictions and significant average errors were observed in some cases. A good knowledge of predictive models accuracy seems essential for their efficient and safe use, for example to predict the shelf life of a product. Yet, authors generally gave no pragmatic information on such things as the average relative error or the range of errors on predicted variables. Problems of robustness of models when tested in different conditions were noticed, which corroborates the necessity of a systematic validation of models on new data. PMID:8579985

  18. Composting of waste paint sludge containing melamine resin as affected by nutrients and gypsum addition and microbial inoculation.

    PubMed

    Tian, Yongqiang; Chen, Liming; Gao, Lihong; Michel, Frederick C; Wan, Caixia; Li, Yebo; Dick, Warren A

    2012-03-01

    Melamine formaldehyde resins have hard and durable properties and are found in many products, including automobile paints. These resins contain high concentrations of nitrogen and, if properly composted, can yield valuable products. We evaluated the effects of starter compost, nutrients, gypsum and microbial inoculation on composting of paint sludge containing melamine resin. A bench-scale composting experiment was conducted at 55 °C for 91 days and then at 30 °C for an additional 56 days. After 91 days, the composts were inoculated with a mixed population of melamine-degrading microorganisms. Melamine resin degradation after the entire 147 days of composting varied between 73 and 95% for the treatments with inoculation of microorganisms compared to 55-74% for the treatments without inoculation. Degradation was also enhanced by nutrients and gypsum additions. Our results infer that large scale composting of melamine resins in paint sludge is possible. PMID:22243857

  19. Exposure to vancomycin causes a shift in the microbial community structure without affecting nitrate reduction rates in river sediments.

    PubMed

    Laverman, Anniet M; Cazier, Thibaut; Yan, Chen; Roose-Amsaleg, Céline; Petit, Fabienne; Garnier, Josette; Berthe, Thierry

    2015-09-01

    Antibiotics and antibiotic resistance genes have shown to be omnipresent in the environment. In this study, we investigated the effect of vancomycin (VA) on denitrifying bacteria in river sediments of a Waste Water Treatment Plant, receiving both domestic and hospital waste. We exposed these sediments continuously in flow-through reactors to different VA concentrations under denitrifying conditions (nitrate addition and anoxia) in order to determine potential nitrate reduction rates and changes in sedimentary microbial community structures. The presence of VA had no effect on sedimentary nitrate reduction rates at environmental concentrations, whereas a change in bacterial (16S rDNA) and denitrifying (nosZ) community structures was observed (determined by polymerase chain reaction-denaturing gradient gel electrophoresis). The bacterial and denitrifying community structure within the sediment changed upon VA exposure indicating a selection of a non-susceptible VA population. PMID:25663374

  20. Temperature and humidity measurements within desert barchan sand dunes, relation to dune aeolian mobility and microbial growth

    NASA Astrophysics Data System (ADS)

    Louge, Michel; Hay, Anthony; Richer, Renee; Valance, Alexandre; Ould el Moctar, Ahmed; Xu, Jin; Abdul-Majid, Sara

    2013-04-01

    We present diurnal variations of temperature and humidity profiles below the surface of hyper-arid aeolian crescent-shaped "barchan" dunes in Qatar and Mauritania, measured using a thermal probe and a new ultra-sensitive capacitance instrument that we developed for this purpose. We also report long-term measurements from a probe sunk on the downwind avalanche face of a mobile Qatar barchan, recording temperature and humidity until it emerged on the upwind slope 15 months later. We interpret the data by modeling heat and moisture transfer at the surface in terms of measured net surface radiation, wind, and atmospheric conditions. We demonstrate the presence of microbes on sand grains within these mobile dunes using microscopic observations, fluorescence counts, metagenomic sequencing, and C12/C13 isotope analysis of carbon dioxide sampled below the surface. By determining how water activity grows with moisture adsorbed on these sands, we delimit regions within the dune where our instruments recorded humidity conducive to microbial growth. Finally, we compare the mobility of two adjacent Mauritania barchans having distinct surface grain size, shape, and depth humidity profiles. Armored by large grains on its surface, the smaller dune was more oblong. As a result, it lacked flow recirculation in its wake, trapped less aeolian sand downwind, and was much less mobile than its smaller size would suggest. This slower mobility led to greater humidity and cohesion at depth than the larger dune exposed to the same atmospheric and wind conditions.

  1. Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof.

    PubMed

    Buckland-Nicks, Michael; Heim, Amy; Lundholm, Jeremy

    2016-05-15

    Green roofs provide ecosystem services, including stormwater retention and reductions in heat transfer through the roof. Microclimates, as well as designed features of green roofs, such as substrate and vegetation, affect the magnitude of these services. Many green roofs are partially shaded by surrounding buildings, but the effects of this within-roof spatial environmental heterogeneity on thermal performance and other ecosystem services have not been examined. We quantified the effects of spatial heterogeneity in solar radiation, substrate depth and other variables affected by these drivers on vegetation and ecosystem services in an extensive green roof. Spatial heterogeneity in substrate depth and insolation were correlated with differential growth, survival and flowering in two focal plant species. These effects were likely driven by the resulting spatial heterogeneity in substrate temperature and moisture content. Thermal performance (indicated by heat flux and substrate temperature) was influenced by spatial heterogeneity in vegetation cover and substrate depth. Areas with less insolation were cooler in summer and had greater substrate moisture, leading to more favorable conditions for plant growth and survival. Spatial variation in substrate moisture (7%-26% volumetric moisture content) and temperature (21°C-36°C) during hot sunny conditions in summer could cause large differences in stormwater retention and heat flux within a single green roof. Shaded areas promote smaller heat fluxes through the roof, leading to energy savings, but lower evapotranspiration in these areas should reduce stormwater retention capacity. Spatial heterogeneity can thus result in trade-offs between different ecosystem services. The effects of these spatial heterogeneities are likely widespread in green roofs. Structures that provide shelter from sun and wind may be productively utilized to design higher functioning green roofs and increase biodiversity by providing habitat

  2. Cronobacter sakazakii in foods and factors affecting its survival, growth, and inactivation.

    PubMed

    Beuchat, Larry R; Kim, Hoikyung; Gurtler, Joshua B; Lin, Li-Chun; Ryu, Jee-Hoon; Richards, Glenner M

    2009-12-31

    Cronobacter sakazakii has been isolated from a wide range of environmental sources and from several foods of animal and plant origin. While infections caused by C. sakazakii have predominantly involved neonates and infants, its presence on or in foods other than powdered infant formula raises concern about the safety risks these foods pose to immunocompromised consumers. We have done a series of studies to better understand the survival and growth characteristics of C. sakazakii in infant formula, infant cereal, fresh-cut produce, and juices made from fresh produce. Over a 12-month storage period, the pathogen survived better in dried formula and cereal at low a(w) (0.25-0.30) than at high a(w) (0.69-0.82) and at 4 degrees C compared to 30 degrees C. C. sakazakii grows in formulas and cereals reconstituted with water or milk and held at 12-30 degrees C. The composition of formulas or cereals does not markedly affect the rate of growth. C. sakazakii grows well on fresh-cut apple, cantaloupe, watermelon, cabbage, carrot, cucumber, lettuce, and tomato at 25 degrees C and in some types of produce at 12 degrees C. Treatment of fresh fruits and vegetables with sanitizers such as chlorine, chlorine dioxide, and a peroxyacetic acid-based solution causes reductions of 1.6-5.4 log CFU/apple, tomato, and lettuce. Cells of C. sakazakii in biofilms formed on stainless steel and enteral feeding tubes or dried on the surface of stainless steel have increased resistance to disinfectants. Death of cells in biofilms is affected by atmospheric relative humidity. These studies have contributed to a better understanding of the behavior of C. sakazakii in and on foods and on food-contact surfaces, thereby enabling the development of more effective strategies and interventions for its control. PMID:19346021

  3. Kinetics of Growth Retardant and Hormone Interactions in Affecting Cucumber Hypocotyl Elongation 1

    PubMed Central

    Moore, Thomas C.

    1967-01-01

    The capacities of indole-3-acetic acid (IAA) and gibberellin A3 (GA3) to counteract the inhibitory effects of (2-chloroethyl) trimethylammonium chloride (CCC), 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidinecarboxylate methyl chloride (Amo-1618), and N,N-dimethylaminosuccinamic acid (B-995) on hypocotyl elongation in light-grown cucumber (Cucumis sativus L.) seedlings were investigated. One μg of GA3 applied to the shoot tip was sufficient to completely nullify the effect of 10 μg of Amo-1618 or 25 μg of B-995 applied simultaneously to the shoot tip, and 10 μg of GA3 completely counteracted the effect of 10−3 m CCC added to the root medium. One μg of IAA counteracted the effect of 10−3 m CCC in the root medium, but IAA did not nullify the action of either Amo-1618 or B-995. Experiments were conducted using 2 growth retardants simultaneously, which indicated that Amo-1618 and CCC inhibit a common process, namely GA biosynthesis, essential to hypocotyl elongation. However, since the effect of CCC was overcome by applications of both GA and IAA, growth retardation resulting from treatment with CCC apparently is not due solely to inhibition of GA biosynthesis. B-995 did not interact additively with either Amo-1618 or CCC, which suggests that B-995 affects a process different from those affected by the other 2 retardants. Thus, while inhibition evoked by B-995 is reversible by applied GA, the action of B-995 does not appear to be inhibition of GA biosynthesis. PMID:16656555

  4. Ecosystem regime shifts have not affected growth and survivorship of eastern Beaufort Sea belugas.

    PubMed

    Luque, Sebastián P; Ferguson, Steven H

    2009-05-01

    Large-scale ocean-atmosphere physical dynamics can have profound impacts on the structure and organization of marine ecosystems. These changes have been termed "regime shifts", and five different episodes have been detected in the North Pacific Ocean, with concurrent changes also occurring in the Bering and Beaufort Seas. Belugas from the Eastern Beaufort Sea (EBS) use the Bering Sea during winter and the Beaufort Sea during summer, yet the potential effects of regime shifts on belugas have not been assessed. We investigated whether body size and survivorship of EBS belugas harvested in the Mackenzie River delta region between 1993 and 2003 have been affected by previous purported regime shifts in the North Pacific. Residuals from the relationship between body length and age were calculated and compared among belugas born between 1932 and 1989. Residual body size was not significantly related to birth year for any regime, nor to the age group individuals belonged to during any regime. The percentage deviation in number of belugas born in any given year that survived to be included in the hunt (survivorship) did not show any significant trend within or between regimes. Accounting for lags of 1-5 years did not reveal any evidence of delayed effects. Furthermore, neither population index was significantly related to changes in major climatic variables that precede regime shifts. Our results suggest that EBS beluga body size and survivorship have not been affected by the major regime shifts of the North Pacific and the adjacent Bering and Beaufort Seas. EBS belugas may have been able to modify their diet without compromising their growth and survivorship. Diet and reproductive analyses over large and small time scales can help understand the mechanisms enabling belugas to avoid significant growth and reproductive effects of past regime shifts. PMID:19229560

  5. Biodegradability of nonaqueous-phase liquids affects the mineralization of phenanthrene in soil because of microbial competition

    SciTech Connect

    Morrison, D.E.; Alexander, M.

    1997-08-01

    A study was conducted to determine the effects of biodegradability of nonaqueous-phase liquids (NAPLs) and microbial competition on the biodegradation in soil of a constituent of the NAPLs. The rates of mineralization of phenanthrene dissolved in 8 mg of 2,2,4,4,6,8,8-heptamethylnonane (HMN), di(2-ethylhexyl) phthalate (DEHP), or pristane per g of soil were faster than the rates when the compound was dissolved in hexadecane or dodecane. Addition of inorganic N and P to the soil increased the mineralization rate in the first two but not the last two NAPLs. N and P addition did not enhance mineralization of phenanthrene when added in 500 {micro}g of hexadecane, pristane, or HMN per g of soil. Hexadecane was rapidly degraded, pristane was slowly metabolized, DEHP was still slower, and HMN was not mineralized in the test period. Mixing the soil stimulated mineralization of phenanthrene dissolved in HMN but not in hexadecane. Mineralization of phenanthrene dissolved in HMN was the same if the gas phase contained 21%, 2.1%, or traces of O{sub 2}. In contrast, the biodegradation of phenanthrene dissolved in hexadecane, although the same at 21 and 2.1% O{sub 2}, was not observed if traces of O{sub 2} were present. The mineralization was slower in unshaken soil-water mixtures if phenanthrene was added in hexadecane than in HMN or pristane, but the rates with the 3 NAPLs were increased by shaking the suspensions. The authors suggest that the biodegradability of major components of NAPLs and microbial competition for N, P, or O{sub 2} will have a major impact on the rate of transformation of minor constituents of NAPLs.

  6. Climate change interactions affect soil carbon dioxide efflux and microbial functioning in a post-harvest forest.

    PubMed

    McDaniel, M D; Kaye, J P; Kaye, M W; Bruns, M A

    2014-04-01

    Forest disturbances, including whole-tree harvest, will increase with a growing human population and its rising affluence. Following harvest, forests become sources of C to the atmosphere, partly because wetter and warmer soils (relative to pre-harvest) increase soil CO2 efflux. This relationship between soil microclimate and CO2 suggests that climate changes predicted for the northeastern US may exacerbate post-harvest CO2 losses. We tested this hypothesis using a climate-manipulation experiment within a recently harvested northeastern US forest with warmed (H; +2.5 °C), wetted (W; +23% precipitation), warmed + wetted (H+W), and ambient (A) treatments. The cumulative soil CO2 effluxes from H and W were 35% (P = 0.01) and 22% (P = 0.07) greater than A. However, cumulative efflux in H+W was similar to A and W, and 24% lower than in H (P = 0.02). These findings suggest that with higher precipitation soil CO2 efflux attenuates rapidly to warming, perhaps due to changes in substrate availability or microbial communities. Microbial function measured as CO2 response to 15 C substrates in warmed soils was distinct from non-warmed soils (P < 0.001). Furthermore, wetting lowered catabolic evenness (P = 0.04) and fungi-to-bacteria ratios (P = 0.03) relative to non-wetted treatments. A reciprocal transplant incubation showed that H+W microorganisms had lower laboratory respiration on their home soils (i.e., home substrates) than on soils from other treatments (P < 0.01). We inferred that H+W microorganisms may use a constrained suite of C substrates that become depleted in their "home" soils, and that in some disturbed ecosystems, a precipitation-induced attenuation (or suppression) of soil CO2 efflux to warming may result from fine-tuned microbe-substrate linkages. PMID:24362535

  7. Factors affecting application of milk allantoin as an estimator of microbial protein flow to the duodenum under commercial conditions.

    PubMed

    Schager, W M; Harrison, J H; Gaskins, C T; Davidson, D

    2003-05-01

    Three experiments were conducted to determine the effect of diet change, milk sampling technique, and bovine somatotropin (bST) on allantoin output in milk and the use of allantoin as a practical, noninvasive method for estimating microbial protein flow in dairy cattle. In experiment 1, four lactating Holstein cows were used in a 2 x 2 Latin square design with two treatments (ratio of forage to concentrate) and two periods. In experiment 2, six Holstein cows were used in a completely randomized design, and milk was collected by 1) a strip sample collected immediately before milking, 2) a strip sample collected 3 min from start of milking, and 3) a composite sample taken with an autosampler. In experiment three, 10 cows were used in a randomized block design to determine the effect of bST on milk allantoin. Milk samples were taken daily for 21 d, 7 d before, and 14 d after bST administration. In experiment 1, allantoin output (mmol/d) was significantly greater for cows fed the higher ratio of concentrate to forage, and there was a significant change in the amount of allantoin in milk 12 h (first subsequent milking) after a diet change. There was no difference in milk yield or dry matter intake between treatments. In experiment 2, no difference was detected in milk allantoin concentration among the three sampling methods. In experiment 3, milk yield, allantoin concentration, and total allantoin output was significantly increased after bST administration even though dry matter intake (DMI) remained unchanged. During the first 14 d following bST administration, estimates of microbial protein production derived from milk allantoin may be inaccurate due to increased milk production without an increase in DMI. PMID:12778582

  8. Physicochemical Factors Affecting the Growth of Burkholderia pseudomallei in Soil Microcosm

    PubMed Central

    Wang-ngarm, Supunnipa; Chareonsudjai, Sorujsiri; Chareonsudjai, Pisit

    2014-01-01

    Burkholderia pseudomallei causes melioidosis, the third most common cause of death from infectious diseases in northeast Thailand. Four physicochemical factors were set so that their values covered the range of the northeast, which is an endemic area. The soil pH was set at pH 4–10, soil salinity was 0.0–5.0% NaCl, total iron was 50–150 mg/kg soil, and carbon to nitrogen ratio (C/N) was 10:1 to 40:1. The experiments were carried out at 37°C, and soil moisture was maintained for 7 days. The number of viable bacterial cells was counted daily. Soil pH, salinity, Fe, and C/N ratio affected the bacterial growth. The bacterial colony was significantly (P < 0.05) reduced at soil pH > 8, soil salinity > 1% NaCl, and C/N ratio > 40:1. However, the growth of B. pseudomallei was enhanced by increasing the concentrations of iron significantly (P < 0.05). We propose using these findings to control B. pseudomallei in situ. PMID:24445210

  9. Zebra pattern in rocks as a function of grain growth affected by second-phase particles

    NASA Astrophysics Data System (ADS)

    Kelka, Ulrich; Koehn, Daniel; Beaudoin, Nicolas

    2015-09-01

    In this communication we present a simple microdynamic model which can explain the beginning of the zebra pattern formation in rocks. The two dimensional model consists of two main processes, mineral replacement along a reaction front, and grain boundary migration affected by impurities. In the numerical model we assume that an initial distribution of second-phase particles is present due to sedimentary layering. The reaction front percolates the model and redistributes second-phase particles by shifting them until the front is saturated and drops the particles again. This produces and enhances initial layering. Grain growth is hindered in layers with high second-phase particle concentrations whereas layers with low concentrations coarsen. Due to the grain growth activity in layers with low second-phase particle concentrations these impurities are collected at grain boundaries and the crystals become very clean. Therefore the white layers in the pattern contain large grains with low concentration of second-phase particles, whereas the dark layers contain small grains with a large second-phase particle concentration.

  10. Transcriptional modulator ZBED6 affects cell cycle and growth of human colorectal cancer cells

    PubMed Central

    Akhtar Ali, Muhammad; Younis, Shady; Wallerman, Ola; Gupta, Rajesh; Andersson, Leif; Sjöblom, Tobias

    2015-01-01

    The transcription factor ZBED6 (zinc finger, BED-type containing 6) is a repressor of IGF2 whose action impacts development, cell proliferation, and growth in placental mammals. In human colorectal cancers, IGF2 overexpression is mutually exclusive with somatic mutations in PI3K signaling components, providing genetic evidence for a role in the PI3K pathway. To understand the role of ZBED6 in tumorigenesis, we engineered and validated somatic cell ZBED6 knock-outs in the human colorectal cancer cell lines RKO and HCT116. Ablation of ZBED6 affected the cell cycle and led to increased growth rate in RKO cells but reduced growth in HCT116 cells. This striking difference was reflected in the transcriptome analyses, which revealed enrichment of cell-cycle–related processes among differentially expressed genes in both cell lines, but the direction of change often differed between the cell lines. ChIP sequencing analyses displayed enrichment of ZBED6 binding at genes up-regulated in ZBED6-knockout clones, consistent with the view that ZBED6 modulates gene expression primarily by repressing transcription. Ten differentially expressed genes were identified as putative direct gene targets, and their down-regulation by ZBED6 was validated experimentally. Eight of these genes were linked to the Wnt, Hippo, TGF-β, EGF receptor, or PI3K pathways, all involved in colorectal cancer development. The results of this study show that the effect of ZBED6 on tumor development depends on the genetic background and the transcriptional state of its target genes. PMID:26056301

  11. Salivary enzymes and exhaled air affect Streptococcus salivarius growth and physiological state in complemented artificial saliva.

    PubMed

    Roger, P; Harn-Arsa, S; Delettre, J; Béal, C

    2011-12-01

    To better understand the phenomena governing the establishment of the oral bacterium Streptococcus salivarius in the mouth, the effect of some environmental factors has been studied in complemented artificial saliva, under oral pH and temperature conditions. Three salivary enzymes at physiological concentrations were tested: peroxidase, lysozyme and amylase, as well as injection of exhaled air. Injection of air containing 5% CO2 and 16% O2 induced a deleterious effect on S. salivarius K12, mainly by increasing redox potential. Addition of lysozyme slightly affected the physiological state of S. salivarius by altering membrane integrity. In contrast, peroxidase was not detrimental as it made it possible to decrease the redox potential. The addition of amylase reduced the specific growth rate of S. salivarius by formation of a complex with amylase and mucins, but led to high final biomass, as a result of enzymatic degradation of some nutrients. Finally, this work demonstrated that salivary enzymes had a slight impact on S. salivarius behaviour. It can thus be concluded that this bacterium was well adapted to in-mouth conditions, as it was able to resist certain salivary enzymes, even if tolerance to expired air was affected, as a result of an increased redox potential. PMID:21892611

  12. One-pot enzymatic conversion of carbon dioxide and utilization for improved microbial growth.

    PubMed

    Hong, Sung-Gil; Jeon, Hancheol; Kim, Han Sol; Jun, Seung-Hyun; Jin, EonSeon; Kim, Jungbae

    2015-04-01

    We developed a process for one-pot CO2 conversion and utilization based on simple conversion of CO2 to bicarbonate at ambient temperature with no energy input, by using the cross-linking-based composites of carboxylated polyaniline nanofibers (cPANFs) and carbonic anhydrase. Carbonic anhydrase was immobilized on cPANFs via the approach of magnetically separable enzyme precipitate coatings (Mag-EPC), which consists of covalent enzyme attachment, enzyme precipitation, and cross-linking with amine-functionalized magnetic nanoparticles. Mag-EPC showed a half-life of 236 days under shaking, even resistance to 70% ethanol sterilization, and recyclability via facile magnetic separation. For one-pot CO2 conversion and utilization, Mag-EPC was used to accelerate the growth of microalga by supplying bicarbonate from CO2, representing 1.8-fold increase of cell concentration when compared to the control sample. After two repeated uses via simple magnetic separation, the cell concentration with Mag-EPC was maintained as high as the first cycle. This one-pot CO2 conversion and utilization is an alternative as well as complementary process to adsorption-based CO2 capture and storage as an environmentally friendly approach, demanding no energy input based on the effective action of the stabilized enzyme system. PMID:25815899

  13. Pore-scale simulation of microbial growth using a genome-scale metabolic model: Implications for Darcy-scale reactive transport

    SciTech Connect

    Tartakovsky, Guzel D.; Tartakovsky, Alexandre M.; Scheibe, Timothy D.; Fang, Yilin; Mahadevan, Radhakrishnan; Lovley, Derek R.

    2013-09-07

    Recent advances in microbiology have enabled the quantitative simulation of microbial metabolism and growth based on genome-scale characterization of metabolic pathways and fluxes. We have incorporated a genome-scale metabolic model of the iron-reducing bacteria Geobacter sulfurreducens into a pore-scale simulation of microbial growth based on coupling of iron reduction to oxidation of a soluble electron donor (acetate). In our model, fluid flow and solute transport is governed by a combination of the Navier-Stokes and advection-diffusion-reaction equations. Microbial growth occurs only on the surface of soil grains where solid-phase mineral iron oxides are available. Mass fluxes of chemical species associated with microbial growth are described by the genome-scale microbial model, implemented using a constraint-based metabolic model, and provide the Robin-type boundary condition for the advection-diffusion equation at soil grain surfaces. Conventional models of microbially-mediated subsurface reactions use a lumped reaction model that does not consider individual microbial reaction pathways, and describe reactions rates using empirically-derived rate formulations such as the Monod-type kinetics. We have used our pore-scale model to explore the relationship between genome-scale metabolic models and Monod-type formulations, and to assess the manifestation of pore-scale variability (microenvironments) in terms of apparent Darcy-scale microbial reaction rates. The genome-scale model predicted lower biomass yield, and different stoichiometry for iron consumption, in comparisonto prior Monod formulations based on energetics considerations. We were able to fit an equivalent Monod model, by modifying the reaction stoichiometry and biomass yield coefficient, that could effectively match results of the genome-scale simulation of microbial behaviors under excess nutrient conditions, but predictions of the fitted Monod model deviated from those of the genome-scale model under

  14. Pore-scale simulation of microbial growth using a genome-scale metabolic model: Implications for Darcy-scale reactive transport

    NASA Astrophysics Data System (ADS)

    Scheibe, T. D.; Tartakovsky, G.; Tartakovsky, A. M.; Fang, Y.; Mahadevan, R.; Lovley, D. R.

    2012-12-01

    Recent advances in microbiology have enabled the quantitative simulation of microbial metabolism and growth based on genome-scale characterization of metabolic pathways and fluxes. We have incorporated a genome-scale metabolic model of the iron-reducing bacteria Geobacter sulfurreducens into a pore-scale simulation of microbial growth based on coupling of iron reduction to oxidation of a soluble electron donor (acetate). In our model, fluid flow and solute transport is governed by a combination of the Navier-Stokes and advection-diffusion-reaction equations. Microbial growth occurs only on the surface of soil grains where solid-phase mineral iron oxides are available. Mass fluxes of chemical species associated with microbial growth are described by the genome-scale microbial model, implemented using a constraint-based metabolic model, and provide the Robin-type boundary condition for the advection-diffusion equation at soil grain surfaces. Conventional models of microbially-mediated subsurface reactions use a lumped reaction model that does not consider individual microbial reaction pathways, and describe reactions rates using empirically-derived rate formulations such as the Monod-type kinetics. We have used our pore-scale model to explore the relationship between genome-scale metabolic models and Monod-type formulations, and to assess the manifestation of pore-scale variability (microenvironments) in terms of apparent Darcy-scale microbial reaction rates. The genome-scale model predicted lower biomass yield, and different stoichiometry for iron consumption, in comparison to prior Monod formulations based on energetics considerations. We were able to fit an equivalent Monod model, by modifying the reaction stoichiometry and biomass yield coefficient, that could effectively match results of the genome-scale simulation of microbial behaviors under excess nutrient conditions, but predictions of the fitted Monod model deviated from those of the genome-scale model

  15. QMRAcatch - faecal microbial quality of water resources in a river-floodplain area affected by urban sources and recreational visitors

    NASA Astrophysics Data System (ADS)

    Derx, Julia; Schijven, Jack; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas H.; Blaschke, Alfred Paul

    2016-04-01

    QMRAcatch, a tool to simulate microbial water quality including infection risk assessment, was previously developed and successfully tested at a Danube river site (Schijven et al. 2015). In the tool concentrations of target faecal microorganisms and viruses (TMVs) are computed at a point of interest (PI) along the main river and the floodplain river at daily intervals for a one year period. Even though faecal microbial pathogen concentrations in water resources are usually below the sample limit of detection, this does not ensure, that the water quality complies with a certain required health based target. The aim of this study was therefore to improve the predictability of relevant human pathogenic viruses, i.e. enterovirus and norovirus, in the studied river/floodplain area. This was done by following an innovative calibration strategy based on human-associated microbial source tracking (MST) marker data which were determined following the HF183 TaqMan assay (Green et al. 2011). The MST marker is strongly associated with human faeces and communal sewage, occurring there in numbers by several magnitudes higher than for human enteric pathogens (Mayer et al 2015). The calibrated tool was then evaluated with measured enterovirus concentrations at the PI and in the floodplain river. In the simulation tool the discharges of 5 wastewater treatment plants (WWTPs) were considered with point discharges along a 200 km reach of the Danube river. The MST marker and target virus concentrations at the PI at a certain day were computed based on the concentrations of the previous day, plus the wastewater concentrations times the WWTP discharge divided by the river discharge. A ratio of the river width was also considered, over which the MST marker and virus particles have fully mixed with river water. In the tool, the excrements from recreational visitors frequenting the floodplain area every day were assumed to be homogeneously distributed in the area. A binomial distributed

  16. Interactions between allelochemicals and the microbial community affect weed suppresion following cover crop residue incorporation into soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study is to understand how soil microorganisms interact with cover crop-derived allelochemicals to suppress weed germination and growth following cover crop residue incorporation. We conducted a time series experiment by crossing sterilized and non-sterilized soil with four dif...

  17. Aluminum affects heterogeneous Fe(III) (Hydr)oxide nucleation, growth, and ostwald ripening.

    PubMed

    Hu, Yandi; Li, Qingyun; Lee, Byeongdu; Jun, Young-Shin

    2014-01-01

    Heterogeneous coprecipitation of iron and aluminum oxides is an important process for pollutant immobilization and removal in natural and engineered aqueous environments. Here, using a synchrotron-based small-angle X-ray scattering technique, we studied heterogeneous nucleation and growth of Fe(III) (hydr)oxide on quartz under conditions found in acid mine drainage (at pH = 3.7 ± 0.2, [Fe(3+)] = 10(-4) M) with different initial aqueous Al/Fe ratios (0:1, 1:1, and 5:1). Interestingly, although the atomic ratios of Al/Fe in the newly formed Fe(III) (hydr)oxide precipitates were less than 1%, the in situ particle size and volume evolutions of the precipitates on quartz were significantly influenced by aqueous Al/Fe ratios. At the end of the 3 h experiments, with aqueous Al/Fe ratios of 0:1, 1:1, and 5:1, the average radii of gyration of particles on quartz were 5.7 ± 0.3, 4.6 ± 0.1, and 3.7 ± 0.3 nm, respectively, and the ratio of total particle volumes on quartz was 1.7:3.4:1.0. The Fe(III) (hydr)oxide precipitates were poorly crystallized, and were positively charged in all solutions. In the presence of Al(3+), Al(3+) adsorption onto quartz changed the surface charge of quartz from negative to positive, which caused the slower heterogeneous growth of Fe(III) (hydr)oxide on quartz. Furthermore, Al affected the amount of water included in the Fe(III) (hydr)oxides, which can influence their adsorption capacity. This study yielded important information usable for pollutant removal not only in natural environments, but also in engineered water treatment processes. PMID:24289329

  18. Microbial field pilot study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Coates, J.D.; Chisholm, J.L.

    1993-05-01

    A multi-well microbially enhanced oil recovery field pilot has been performed in the Southeast Vassar Vertz Sand Unit in Payne County, Oklahoma. The primary emphasis of the experiment was preferential plugging of high permeability zones for the purpose of improving waterflood sweep efficiency. Studies were performed to determine reservoir chemistry, ecology, and indigenous bacteria populations. Growth experiments were used to select a nutrient system compatible with the reservoir that encouraged growth of a group of indigenous nitrate-using bacteria and inhibit growth of sulfate-reducing bacteria. A specific field pilot area behind an active line drive waterflood was selected. Surface facilities were designed and installed. Injection protocols of bulk nutrient materials were prepared to facilitate uniform distribution of nutrients within the pilot area. By the end of December, 1991, 82.5 tons (75.0 tonnes) of nutrients had been injected in the field. A tracer test identified significant heterogeneity in the SEVVSU and made it necessary to monitor additional production wells in the field. The tracer tests and changes in production behavior indicate the additional production wells monitored during the field trial were also affected. Eighty two and one half barrels (13.1 m[sup 3]) of tertiary oil have been recovered. Microbial activity has increased CO[sub 2] content as indicated by increased alkalinity. A temporary rise in sulfide concentration was experienced. These indicate an active microbial community was generated in the field by the nutrient injection. Pilot area interwell pressure interference test results showed that significant permeability reduction occurred. The interwell permeabilities in the pilot area between the injector and the three pilot production wells were made more uniform which indicates a successful preferential plugging enhanced oil recovery project.

  19. Chinese herbal medicine for miscarriage affects decidual micro-environment and fetal growth

    PubMed Central

    Piao, L.; Chen, C.-P.; Yeh, C.-C.; Basar, M.; Masch, R.; Cheng, Y.-C.; Lockwood, C. J.; Schatz, F.; Huang, S. J.

    2015-01-01

    Introduction Intrauterine growth restriction complicates 5 - 10% of pregnancies. This study aims to test the hypothesis that Chinese herbal formula, JLFC01, affects pregnancy and fetal development by modulating the pro-inflammatory decidual micro-environment. Methods Human decidua from gestational age-matched elective terminations or incomplete/missed abortion was immunostained using anti-CD68 + anti-CD86 or anti-CD163 antibodies. qRT-PCR and Luminex assay measured the effects of JLFC01 on IL-1β- or TNF-α-induced cytokine expression in first trimester decidual cells and on an established spontaneous abortion/intrauterine growth restriction (SA/IUGR)-prone mouse placentae. The effect of JLFC01 on human endometrial endothelial cell angiogenesis was evaluated by average area, length and numbers of branching points of tube formation. Food intake, litter size, fetal weight, placental weight and resorption rate were recorded in SA/IUGR-prone mouse treated with JLFC01. qRT-PCR, Western blot and immunohistochemistry assessed the expression of mouse placental IGF-I and IGF-IR. Results In spontaneous abortion, numbers of decidual macrophages expressing CD86 and CD163 are increased and decreased, respectively. JLFC01 reduces IL-1β- or TNF-α-induced GM-CSF, M-CSF, C-C motif ligand 2 (CCL2), interferon-γ-inducible protein-10 (IP-10), CCL5 and IL-8 production in first trimester decidual cells. JLFC01 suppresses the activity of IL-1β- or TNF-α-treated first trimester decidual cells in enhancing macrophage-inhibited angiogenesis. In SA/IUGR-prone mice, JLFC01 increases maternal food intake, litter size, fetal and placental weight, and reduces fetal resorption rate. JLFC01 induces IGF-I and IGF-IR expression and inhibits M-CSF, CCL2, CCL5, CCL11, CCL3 and G-CSF expression in the placentae. Discussion JLFC01 improves gestation by inhibiting decidual inflammation, enhancing angiogenesis and promoting fetal growth. PMID:25771406

  20. Microbial biofilm proliferation within sealer-root dentin interfaces is affected by sealer type and aging period

    PubMed Central

    Roth, Karina A; Friedman, Shimon; Lévesque, Céline M; Basrani, Bettina R; Finer, Yoav

    2012-01-01

    Background Root canal fillings are intended to prevent microbial proliferation over time in the canal after treatment. Objective To assess biofilm proliferation within the sealer-dentin interfaces of two methacrylate resin-based systems, self-etch (SE) and total-etch (TE), and an epoxy resin-based sealer (EP), aged for up to 6 months. Methods Standardized specimens (n=45) comprising the coronal 5 mm of human roots were filled with the test materials and gutta-percha. Specimens were either not pre-incubated (control; n=9), or incubated in sterile saline for 1 week, 1 month, 3 months or 6 months (n=3/group). Monospecies biofilms of Enterococcus faecalis were grown on the specimens for 7 days in a chemostat-based biofilm fermentor mimicking pathogenic oral conditions. The extent of E. faecalis proliferation within the sealer-dentin interface for each material and incubation period group was assessed using fluorescence microscopy of dihydroethidium-stained specimens. Results TE had less biofilm proliferation than both EP and SE (p<0.01). Deeper biofilm proliferation was detected in SE and EP specimens aged for 1 and 3 months than those aged for 1 week or 6 months (p<0.05). Maximum depth of biofilm penetration was recorded for SE at 1 month (p<0.05). Conclusion Within the test model used, the self-etch and epoxy resin-based sealers were more susceptible to interfacial biofilm proliferation than the total-etch restorative material. This susceptibility diminished after aging the materials’ interfaces for 6 months. PMID:22892745

  1. Chrysen-2-ol derivative from West Indian Wood Nettle Laportea aestuans (L.) Chew inhibits oxidation and microbial growth in vitro

    PubMed Central

    Oloyede, Ganiyat K.; Oyelola, Martha S.

    2013-01-01

    Bio-active compounds present in West Indian Wood Nettle Laportea aestuans (L.) Chew (Urticaceae), used in ethno medicine as antioxidant and antimicrobial were studied. The aim of this research work was to isolate and characterize the bio-active compounds in the n-hexane fraction of L. aestuans, determine the toxicity and subject it to in-vitro antimicrobial and free radical scavenging activities. The chemical constituents were isolated by gradient elution column chromatographic technique and Ultra Violet/visible (UV), Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopies were used for structural elucidation. The free radical scavenging activity of the isolate was assessed using three methods; scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), hydroxyl radical generated from hydrogen peroxide and ferric thiocynate method. Antimicrobial screening was done by agar well diffusion method while toxicity was determined by Brine shrimp lethality test. Structures were proposed for the white crystalline solids isolated; (4E)-3,6-dimethylhep-4-en-3-ol (AB) and 1,2,3,4,4a,4b,5,6,6a,7,8,9,10,10a,10b,11-hexadecahydro-1,1,6a,10b-tetramethyl-7-((E)-4,7-dimethyloct-5-enyl) chrysen-2-ol (AC). Percentage yield of AC was 91.2 and was non-toxic with LC50 (µg/ml) value of 1581233000.0. AC significantly scavenged free radical at 0.0625 mg/ml in the DPPH (64.73 %) and hydrogen peroxide (99.22 %) tests. It also showed 65.23 % inhibition at 1.0 mg/ml in the ferric thiocyanate test. AC also inhibited microbial growth significantly when compared with gentamicin and tioconazole which are antibacterial and antifungal standards respectively. The presence of Chrysen-2-ol derivative in L. aestuans which was non-toxic and possessed significant antimicrobial and antioxidant activities supports its ethno medicinal application. PMID:27092035

  2. QMRAcatch - faecal microbial quality of water resources in a river-floodplain area affected by urban sources and recreational visitors

    NASA Astrophysics Data System (ADS)

    Derx, Julia; Schijven, Jack; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas H.; Blaschke, Alfred Paul

    2016-04-01

    QMRAcatch, a tool to simulate microbial water quality including infection risk assessment, was previously developed and successfully tested at a Danube river site (Schijven et al. 2015). In the tool concentrations of target faecal microorganisms and viruses (TMVs) are computed at a point of interest (PI) along the main river and the floodplain river at daily intervals for a one year period. Even though faecal microbial pathogen concentrations in water resources are usually below the sample limit of detection, this does not ensure, that the water quality complies with a certain required health based target. The aim of this study was therefore to improve the predictability of relevant human pathogenic viruses, i.e. enterovirus and norovirus, in the studied river/floodplain area. This was done by following an innovative calibration strategy based on human-associated microbial source tracking (MST) marker data which were determined following the HF183 TaqMan assay (Green et al. 2011). The MST marker is strongly associated with human faeces and communal sewage, occurring there in numbers by several magnitudes higher than for human enteric pathogens (Mayer et al 2015). The calibrated tool was then evaluated with measured enterovirus concentrations at the PI and in the floodplain river. In the simulation tool the discharges of 5 wastewater treatment plants (WWTPs) were considered with point discharges along a 200 km reach of the Danube river. The MST marker and target virus concentrations at the PI at a certain day were computed based on the concentrations of the previous day, plus the wastewater concentrations times the WWTP discharge divided by the river discharge. A ratio of the river width was also considered, over which the MST marker and virus particles have fully mixed with river water. In the tool, the excrements from recreational visitors frequenting the floodplain area every day were assumed to be homogeneously distributed in the area. A binomial distributed

  3. Improved microbial growth inhibition activity of bio-surfactant induced Ag-TiO2 core shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nithyadevi, D.; Kumar, P. Suresh; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.; Meena, P.

    2015-02-01

    Surfactant induced silver-titanium dioxide core shell nanoparticles within the size range of 10-50 nm were applied in the antibacterial agent to inhibit the growth of bacterial cells. The single crystalline silver was located in the core part of the composite powder and the titanium dioxide components were uniformly distributed in the shell part. HRTEM and XRD results indicated that silver was completely covered by titanium dioxide and its crystal structure was not affected after being coated by titanium dioxide. The effect of silver-titanium dioxide nanoparticles in the inhibition of bacterial cell growth was studied by means of disk diffusion method. The inhibition zone results reveal that sodium alginate induced silver-titanium dioxide nanoparticles exhibit 100% more antibacterial activity than that with cetyltrimethylbromide or without surfactant. UV-vis spectroscopic analysis showed a large concentration of silver was rapidly released into phosphate buffer solution (PBS) within a period of 1 day, with a much smaller concentration being released after this 1-day period. It was concluded that sodium alginate induced silver-titanium dioxide core shell nanoparticles could enhance long term cell growth inhibition in comparison with cetyltrimethylbromide or without surfactant. The surfactant mediated core shell nanoparticles have comparatively rapid, less expensive and wider applications in modern antibacterial therapy.

  4. [Influence of Mirabilis jalapa Linn. Growth on the Microbial Community and Petroleum Hydrocarbon Degradation in Petroleum Contaminated Saline-alkali Soil].

    PubMed

    Jiao, Hai-hua; Cui, Bing-jian; Wu, Shang-hua; Bai, Zhi-hui; Huang, Zhan-bin

    2015-09-01

    In order to explore the effect of Mirabilis jalapa Linn. growth on the structure characteristics of the microbial community and the degradation of petroleum hydrocarbon (TPH) in the petroleum-contaminated saline-alkali soil, Microbial biomass and species in the rhizosphere soils of Mirabilis jalapa Linn. in the contaminated saline soil were studied with the technology of phospholipid fatty acids (PLFAs) analysis. The results showed that comparing to CK soils without Mirabilis jalapa Linn., the ratio of PLFAs species varied were 71. 4%, 69. 2% and 33. 3% in the spring, summer and autumn season, respectively. In addition, there was distinct difference of the biomasses of the microbial community between the CK and rhizosphere soils and among the difference seasons of growth of Mirabilis jalapa Linn.. Compare to CK soil, the degradation rates of total petroleum hydrocarbon (TPH) was increased by 47. 6%, 28. 3%, and 18. 9% in spring, summer, and autumn rhizosphere soils, respectively. Correlation analysis was used to determine the correlation between TPH degradation and the soil microbial community. 77. 8% of the total soil microbial PLFAs species showed positive correlation to the TPH degradation (the correlation coefficient r > 0), among which, 55. 6% of PLFAs species showed high positive correlation(the correlation coefficient was r≥0. 8). In addition, the relative content of SAT and MONO had high correlation with TPH degradation in the CK sample soils, the corelation coefficient were 0. 92 and 0. 60 respectively; However, the percent of positive correlation was 42. 1% in the rhizosphere soils with 21. 1% of them had high positive correlation. The relative content of TBSAT, MONO and CYCLO had moderate or low correlation in rhizosphere soils, and the correlation coefficient were 0. 56, 0. 50, and 0. 07 respectively. Our study showed that the growth of mirabilis Mirabilis jalapa Linn. had a higher influence on the species and biomass of microbial community in the

  5. Histopathology of growth anomaly affecting the coral, Montipora capitata: implications on biological functions and population viability.

    PubMed

    Burns, John H R; Takabayashi, Misaki

    2011-01-01

    Growth anomalies (GAs) affect the coral, Montipora capitata, at Wai'ōpae, southeast Hawai'i Island. Our histopathological analysis of this disease revealed that the GA tissue undergoes changes which compromise anatomical machinery for biological functions such as defense, feeding, digestion, and reproduction. GA tissue exhibited significant reductions in density of ova (66.1-93.7%), symbiotic dinoflagellates (38.8-67.5%), mesenterial filaments (11.2-29.0%), and nematocytes (28.8-46.0%). Hyperplasia of the basal body wall but no abnormal levels of necrosis and algal or fungal invasion was found in GA tissue. Skeletal density along the basal body wall was significantly reduced in GAs compared to healthy or unaffected sections. The reductions in density of the above histological features in GA tissue were collated with disease severity data to quantify the impact of this disease at the colony and population level. Resulting calculations showed this disease reduces the fecundity of M. capitata colonies at Wai'ōpae by 0.7-49.6%, depending on GA severity, and the overall population fecundity by 2.41±0.29%. In sum, GA in this M. capitata population reduces the coral's critical biological functions and increases susceptibility to erosion, clearly defining itself as a disease and an ecological threat. PMID:22205976

  6. The GI-CDF module of Arabidopsis affects freezing tolerance and growth as well as flowering.

    PubMed

    Fornara, Fabio; de Montaigu, Amaury; Sánchez-Villarreal, Alfredo; Takahashi, Yasuyuki; Ver Loren van Themaat, Emiel; Huettel, Bruno; Davis, Seth J; Coupland, George

    2015-03-01

    Plants monitor and integrate temperature, photoperiod and light quality signals to respond to continuous changes in their environment. The GIGANTEA (GI) protein is central in diverse signaling pathways, including photoperiodic, sugar and light signaling pathways, stress responses and circadian clock regulation. Previously, GI was shown to activate expression of the key floral regulators CONSTANS (CO) and FLOWERING LOCUS T (FT) by facilitating degradation of a family of CYCLING DOF FACTOR (CDF) transcriptional repressors. However, whether CDFs are implicated in other processes affected by GI remains unclear. We investigated the contribution of the GI-CDF module to traits that depend on GI. Transcriptome profiling indicated that mutations in GI and the CDF genes have antagonistic effects on expression of a wider set of genes than CO and FT, whilst other genes are regulated by GI independently of the CDFs. Detailed expression studies followed by phenotypic assays showed that the CDFs function downstream of GI, influencing responses to freezing temperatures and growth, but are not necessary for proper clock function. Thus GI-mediated regulation of CDFs contributes to several processes in addition to flowering, but is not implicated in all of the traits influenced by GI. PMID:25600594

  7. Ice cover affects the growth of a stream-dwelling fish.

    PubMed

    Watz, Johan; Bergman, Eva; Piccolo, John J; Greenberg, Larry

    2016-05-01

    Protection provided by shelter is important for survival and affects the time and energy budgets of animals. It has been suggested that in fresh waters at high latitudes and altitudes, surface ice during winter functions as overhead cover for fish, reducing the predation risk from terrestrial piscivores. We simulated ice cover by suspending plastic sheeting over five 30-m-long stream sections in a boreal forest stream and examined its effects on the growth and habitat use of brown trout (Salmo trutta) during winter. Trout that spent the winter under the artificial ice cover grew more than those in the control (uncovered) sections. Moreover, tracking of trout tagged with passive integrated transponders showed that in the absence of the artificial ice cover, habitat use during the day was restricted to the stream edges, often under undercut banks, whereas under the simulated ice cover condition, trout used the entire width of the stream. These results indicate that the presence of surface ice cover may improve the energetic status and broaden habitat use of stream fish during winter. It is therefore likely that reductions in the duration and extent of ice cover due to climate change will alter time and energy budgets, with potentially negative effects on fish production. PMID:26787075

  8. Complementarity among plant growth promoting traits in rhizospheric bacterial communities promotes plant growth

    PubMed Central

    Singh, Mangal; Awasthi, Ashutosh; Soni, Sumit K.; Singh, Rakshapal; Verma, Rajesh K.; Kalra, Alok

    2015-01-01

    An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants. PMID:26503744

  9. Does milk treatment before cheesemaking affect microbial and chemical traits of ripened cheese? Grana Trentino as a case study.

    PubMed

    Franciosi, E; Gardini, F; Monfredini, L; Tabanelli, G; Fabris, A; Endrizzi, I; Poznanski, E; Gasperi, F; Cavazza, A

    2012-10-01

    The aim of this study was to evaluate the influence of different storage temperatures and delivery system of the milk on the microbiological and physicochemical characteristics of Grana Trentino, a long-ripened hard-cooked Italian cheese. In particular, 3 kinds of milk storage and delivery were studied: milk delivered to the dairy in the traditional manner without temperature control, milk delivered at 18°C, and milk stored at the farm and delivered at 12°C. Milk, natural whey starter, and cheeses after 18 mo of ripening were sampled for microbiological profiles, physicochemical analysis, and proteolysis evaluation, and a study of cheese volatile compounds through a solid-phase microextraction gas chromatography-mass spectrometry technique was performed. Milk microbiota was not affected by any of the treatments. At the end of ripening, free fatty acid and ester contents were significantly higher in cheeses from milk without temperature control. This was probably due to the milk delivery to the dairy in churns causing the fat globule membrane break during transport and, consequently, a greater release of fat and deeper lipolysis. Milk refrigeration at 12°C for 12h before delivery affected the distribution of nitrogen fractions in cheeses. Lower temperatures of milk storage favored a larger soluble nitrogen fraction and greater cheese proteolysis, probably caused by an enhanced plasmin activity. From this work, it is concluded that both milk temperature storage and transport system could affect cheese ripening, leading to significant differences in chemical compounds: if milk was delivered by churns, higher free fatty acid and ester content in cheeses was observed; if milk was stored at 12°C for 12h before delivery, greater cheese proteolysis was induced with consequent faster ripening. PMID:22863106

  10. Culture surfaces coated with various implant materials affect chondrocyte growth and metabolism.

    PubMed

    Hambleton, J; Schwartz, Z; Khare, A; Windeler, S W; Luna, M; Brooks, B P; Dean, D D; Boyan, B D

    1994-07-01

    The effect on chondrocyte metabolism of culture surfaces sputter-coated with various materials used for orthopaedic implants was studied and correlated with the stage of cartilage cell maturation. Confluent, fourth-passage chondrocytes from the costochondral resting zone and growth zone of rats were cultured for 6 or 9 days on 24-well plates sputter-coated with ultrathin films of titanium, titanium dioxide, aluminum oxide, zirconium oxide, and calcium phosphate (1.67:1). Corona-discharged tissue culture plastic served as the control. The effect of surface material was examined with regard to cell morphology; cell proliferation (cell number) and DNA synthesis ([3H]thymidine incorporation); RNA synthesis ([3H]uridine incorporation); collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen production; and alkaline phosphatase-specific activity, both in the cell layer and in trypsinized chondrocytes. Cell morphology was dependent on surface material; only cells cultured on titanium had an appearance similar to that of cells cultured on plastic. While titanium or titanium dioxide surfaces had no effect on cell number or [3H]thymidine incorporation, aluminum oxide, calcium phosphate, and zirconium oxide surfaces inhibited both parameters. Cells cultured on aluminum oxide, calcium phosphate, zirconium oxide, and titanium dioxide exhibited decreased collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen production, but [3H]uridine incorporation was decreased only in those chondrocytes cultured on aluminum oxide, calcium phosphate, or zirconium oxide. Chondrocytes cultured on titanium had greater alkaline phosphatase-specific activity than did cells cultured on plastic, but the incorporation of [3H]uridine and production of collagenase-digestible protein, noncollagenase-digestible protein, and percentage of collagen was comparable. The response of chondrocytes from the growth zone and resting zone

  11. Does seawater acidification affect survival, growth and shell integrity in bivalve juveniles?

    PubMed

    Bressan, M; Chinellato, A; Munari, M; Matozzo, V; Manci, A; Marčeta, T; Finos, L; Moro, I; Pastore, P; Badocco, D; Marin, M G

    2014-08-01

    Anthropogenic emissions of carbon dioxide are leading to decreases in pH and changes in the carbonate chemistry of seawater. Ocean acidification may negatively affect the ability of marine organisms to produce calcareous structures while also influencing their physiological responses and growth. The aim of this study was to evaluate the effects of reduced pH on the survival, growth and shell integrity of juveniles of two marine bivalves from the Northern Adriatic sea: the Mediterranean mussel Mytilus galloprovincialis and the striped venus clam Chamelea gallina. An outdoor flow-through plant was set up and two pH levels (natural seawater pH as a control, pH 7.4 as the treatment) were tested in long-term experiments. Mortality was low throughout the first experiment for both mussels and clams, but a significant increase, which was sensibly higher in clams, was observed at the end of the experiment (6 months). Significant decreases in the live weight (-26%) and, surprisingly, in the shell length (-5%) were observed in treated clams, but not in mussels. In the controls of both species, no shell damage was ever recorded; in the treated mussels and clams, damage proceeded via different modes and to different extents. The severity of shell injuries was maximal in the mussels after just 3 months of exposure to a reduced pH, whereas it progressively increased in clams until the end of the experiment. In shells of both species, the damaged area increased throughout the experiment, peaking at 35% in mussels and 11% in clams. The shell thickness of the treated and control animals significantly decreased after 3 months in clams and after 6 months in mussels. In the second experiment (3 months), only juvenile mussels were exposed to a reduced pH. After 3 months, the mussels at a natural pH level or pH 7.4 did not differ in their survival, shell length or live weight. Conversely, shell damage was clearly visible in the treated mussels from the 1st month onward. Monitoring the

  12. Compensatory growth strategies are affected by the strength of environmental time constraints in anuran larvae.

    PubMed

    Orizaola, Germán; Dahl, Emma; Laurila, Anssi

    2014-01-01

    Organisms normally grow at a sub-maximal rate. After experiencing a period of arrested growth, individuals often show compensatory growth responses by modifying their life-history, behaviour and physiology. However, the strength of compensatory responses may vary across broad geographic scales as populations differ in their exposition to varying time constraints. We examined differences in compensatory growth strategies in common frog (Rana temporaria) populations from southern and northern Sweden. Tadpoles from four populations were reared in the laboratory and exposed to low temperature to evaluate the patterns and mechanisms of compensatory growth responses. We determined tadpoles' growth rate, food intake and growth efficiency during the compensation period. In the absence of arrested growth conditions, tadpoles from all the populations showed similar (size-corrected) growth rates, food intake and growth efficiency. After being exposed to low temperature for 1 week, only larvae from the northern populations increased growth rates by increasing both food intake and growth efficiency. These geographic differences in compensatory growth mechanisms suggest that the strategies for recovering after a period of growth deprivation may depend on the strength of time constraints faced by the populations. Due to the costs of fast growth, only populations exposed to the strong time constraints are prone to develop fast recovering strategies in order to metamorphose before conditions deteriorate. Understanding how organisms balance the cost and benefits of growth strategies may help in forecasting the impact of fluctuating environmental conditions on life-history strategies of populations likely to be exposed to increasing environmental variation in the future. PMID:23996230

  13. Linking microbial carbon utilization with microbially-derived soil organic matter

    NASA Astrophysics Data System (ADS)

    Kallenbach, Cynthia M.; Grandy, A. Stuart

    2014-05-01

    Soil microbial communities are fundamental to plant C turnover, as all C inputs eventually pass through the microbial biomass. In turn, there is increasing evidence that this biomass accumulates as a significant portion of stable soil organic matter (SOM) via physiochemical interactions with the soil matrix. However, when exploring SOM dynamics, these two processes are often regarded as discrete from one another, despite potentially important linkages between microbial C utilization and the fate of that biomass C as SOM. Specifically, if stable SOM is largely comprised of microbial products, we need to better understand the soil C inputs that influence microbial biomass production and microbial C allocation. Microbial physiology, such as microbial growth efficiency (MGE), growth rate and turnover have direct influences on microbial biomass production and are highly sensitive to resource quality. Therefore, the importance of resource quality on SOM accumulation may not necessarily be a function of resistance to decay but the degree to which it optimizes microbial biomass production. To examine the relationship between microbial C utilization and microbial contributions to SOM, an ongoing 15-mo incubation experiment was set up using artificial, initially C- and microbial-free soils. Soil microcosms were constructed by mixing sand with either kaolinite or montmorillonite clays followed with a natural soil microbial inoculum. For both soil mineral treatments, weekly additions of glucose, cellobiose, or syringol are carried out, with an additional treatment of plant leachate to serve as a reference. This simplified system allows us to determine 1) if, in absence of plant-derived C, chemically complex SOM similar to natural soils can accumulate through the production of microbial residues and 2) how differences in C utilization of simple substrates, varying in energy yields, influence the quantity and chemistry of newly formed SOM. Over the course of the incubation, MGE

  14. Pre-Analytical Parameters Affecting Vascular Endothelial Growth Factor Measurement in Plasma: Identifying Confounders

    PubMed Central

    Walz, Johanna M.; Boehringer, Daniel; Deissler, Heidrun L.; Faerber, Lothar; Goepfert, Jens C.; Heiduschka, Peter; Kleeberger, Susannah M.; Klettner, Alexa; Krohne, Tim U.; Schneiderhan-Marra, Nicole; Ziemssen, Focke; Stahl, Andreas

    2016-01-01

    Background Vascular endothelial growth factor-A (VEGF-A) is intensively investigated in various medical fields. However, comparing VEGF-A measurements is difficult because sample acquisition and pre-analytic procedures differ between studies. We therefore investigated which variables act as confounders of VEGF-A measurements. Methods Following a standardized protocol, blood was taken at three clinical sites from six healthy participants (one male and one female participant at each center) twice one week apart. The following pre-analytical parameters were varied in order to analyze their impact on VEGF-A measurements: analyzing center, anticoagulant (EDTA v