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Sample records for mixed culture sulphate-reducing

  1. [Development of mono- and associative cultures of sulphate-reducing bacteria and formation of exopolymeric complex].

    PubMed

    Purish, L M; Asaulenko, L H; Ostapchuk, A M

    2009-01-01

    Differences were found in development of the monoculture of sulphate-reducing bacteria Desulfovibrio sp. Kyiv-10 and artificial associations of cultures of sulphate reducing bacteria with heterotrophic satellites under development in a form of biofilm or plankton. Correlation between exopolymers synthesis in the biofilm and steel corrosion velocity has been found. Glucose, galactose, mannose, xylose, rhibose and nonidentified carbohydrates were found in the composition of exopolymers synthesized by monoculture Desulfovibrio sp. Kyiv-10 under its development in a form of biofilm. The biofilm and plankton cells of associative cultures synthesized exopolysaccharide which included rhamnose, arabinose and fucose. Glucose content in biofilm EPM was considerably higher (41.0055.9%) than in EPM of plankton cells (24.7-32.8).

  2. Effect of uranium (VI) on two sulphate-reducing bacteria cultures from a uranium mine site.

    PubMed

    Martins, Mónica; Faleiro, Maria Leonor; Chaves, Sandra; Tenreiro, Rogério; Costa, Maria Clara

    2010-05-15

    This work was conducted to assess the impact of uranium (VI) on sulphate-reducing bacteria (SRB) communities obtained from environmental samples collected on the Portuguese uranium mining area of Urgeiriça. Culture U was obtained from a sediment, while culture W was obtained from sludge from the wetland of that mine. Temperature gradient gel electrophoresis (TGGE) was used to monitor community changes under uranium stress conditions. TGGE profiles of dsrB gene fragment demonstrated that the initial cultures were composed of SRB species affiliated with Desulfovibrio desulfuricans, Desulfovibrio vulgaris and Desulfomicrobium spp. (sample U), and by species related to D. desulfuricans (sample W). A drastic change in SRB communities was observed as a result of uranium (VI) exposure. Surprisingly, SRB were not detected in the uranium removal communities. Such findings emphasize the need of monitoring the dominant populations during bio-removal studies. TGGE and phylogenetic analysis of the 16S rRNA gene fragment revealed that the uranium removal consortia are composed by strains affiliated to Clostridium genus, Caulobacteraceae and Rhodocyclaceae families. Therefore, these communities can be attractive candidates for environmental biotechnological applications associated to uranium removal. PMID:20334901

  3. The sulphate-reducing bacteria

    SciTech Connect

    Postgate, J.R.

    1984-01-01

    This monograph surveys knowledge about an unusual and little-studied group of microbes, bringing together information that has hitherto been widely scattered throughout the scientific literature. The sulphate-reducing bacteria cannot grow in air; they respire sulphates instead of oxygen and are difficult to isolate and study. Nevertheless, much progress has been made in recent years and has revealed novelties of biochemistry and physiology. Sulphate-reducing bacteria affect man in a variety of subtle and occasionally blatant ways although, unlike many bacteria, they cause no disease. Among harmful attributes are being agents of pollution, corrosion and spoilage of food and materials. Their beneficial attributes include the generation of most of the world's sulphur supplies and several other mineral resources, as well as contributing to the oil reserves of this planet. They grow in oil wells, sulphur springs, natural gas stores, sewage sludge and comparable habitats. They are not only of great academic interest but also of increasing practical importance in oil, gas, mineral and corrosion technology.

  4. In vitro batch cultures of gut microbiota from healthy and ulcerative colitis (UC) subjects suggest that sulphate-reducing bacteria levels are raised in UC and by a protein-rich diet.

    PubMed

    Khalil, Nazeha A; Walton, Gemma E; Gibson, Glenn R; Tuohy, Kieran M; Andrews, Simon C

    2014-02-01

    Imbalances in gut microbiota composition during ulcerative colitis (UC) indicate a role for the microbiota in propagating the disorder. Such effects were investigated using in vitro batch cultures (with/without mucin, peptone or starch) inoculated with faecal slurries from healthy or UC patients; the growth of five bacterial groups was monitored along with short-chain fatty acid (SCFA) production. Healthy cultures gave two-fold higher growth and SCFA levels with up to ten-fold higher butyrate production. Starch gave the highest growth and SCFA production (particularly butyrate), indicating starch-enhanced saccharolytic activity. Sulphate-reducing bacteria (SRB) were the predominant bacterial group (of five examined) for UC inocula whereas they were the minority group for the healthy inocula. Furthermore, SRB growth was stimulated by peptone presumably due to the presence of sulphur-rich amino acids. The results suggest raised SRB levels in UC, which could contribute to the condition through release of toxic sulphide.

  5. Bioremoval of arsenic species from contaminated waters by sulphate-reducing bacteria.

    PubMed

    Teclu, Daniel; Tivchev, George; Laing, Mark; Wallis, Mike

    2008-12-01

    A mixed culture of sulphate-reducing bacteria was used to study the bioremoval of arsenic species (As(III) or As(V)) from groundwater. During growth of a mixed SRB culture adapted to 0.1mg/L arsenic species through repeated sub-culturing, 1mg/L of either As(III) or As(V) was reduced to 0.3 and 0.13mg/L respectively. Sorption experiments on the precipitate produced by batch cultured sulphate-reducing bacteria (SRB-PP) indicated a removal of about 77 and 55% of As(V) and As(III) respectively under the following conditions: pH 6.9; biomass (2g/L); 24h contact time; initial arsenic concentration, 1mg/L of either species. These results were compared with synthetic iron sulphide as adsorbent. The adsorption data were fitted to Langmuir and Freundlich isotherms. Energy dispersive X-ray analysis showed the SRB-PP contained elements such as sulphur, iron, calcium and phosphorus. Biosorption studies indicated that SRB cell pellets removed about 6.6% of the As(III) and 10.5% of the As(V) from water containing an initial concentration of 1mg/L of either arsenic species after 24h contact.

  6. Influence of headspace composition on product diversity by sulphate reducing bacteria biocathode.

    PubMed

    Sharma, Mohita; Varanasi, Jhansi L; Jain, Pratiksha; Dureja, Prem; Lal, Banwari; Dominguez-Benetton, Xochitl; Pant, Deepak; Sarma, Priyangshu M

    2014-08-01

    Mixed culture of sulphate reducing bacteria named TERI-MS-003 was used for development of biocathode on activated carbon fabric fastened to stainless steel mesh for conversion of volatile fatty acids to reduced organic compounds under chronoamperometric conditions of -0.85V vs. Ag/AgCl (3.5M KCl). A range of chemicals were bioelectrosynthesized, however the gases present in headspace environment of the bioelectrochemical reactor governed the product profile. Succinate, ethanol, hydrogen, glycerol and propionate were observed to be the predominant products when the reactor was hermetically sealed. On the other hand, acetone, propionate, isopropanol, propanol, isobutyrate, isovalerate and heptanoate were the predominant products when the reactor was continuously sparged with nitrogen. This study highlights the importance of head space composition in order to manoeuvre the final product profile desired during a microbial electro-synthesis operation and the need for simultaneously developing effective separation and recovery strategies from an economical and practical standpoint. PMID:24726774

  7. Phylogenetic and physiological diversity of sulphate-reducing bacteria isolated from a salt marsh sediment.

    PubMed

    Rooney-Varga, J N; Genthner, B R; Devereux, R; Willis, S G; Friedman, S D; Hines, M E

    1998-12-01

    The phylogenetic and physiological diversity of sulphate-reducing bacteria inhabiting a salt marsh rhizosphere were investigated. Sulphate-reducing bacteria were isolated from a salt marsh rhizosphere using enrichment cultures with electron donors thought to be prevalent in the rhizosphere of Spartina alterniflora. The relationship between phylogeny and nutritional characteristics of 10 strains was investigated. None of the isolates had 16S rRNA sequences identical to other delta subclass sulphate-reducers, sharing 85.3 to 98.1% sequence similarity with 16S rRNA sequences of their respective closest relatives. Phylogenetic analysis placed two isolates, obtained with ethanol as an electron donor, within the Desulfovibrionaceae. Seven isolates, obtained with acetate, butyrate, propionate, or benzoate, were placed within the Desulfobacteriaceae. One isolate, obtained with butyrate, fell within the Desulfobulbus assemblage, which is currently considered part of the Desulfobacteriaceae family. However, due to the phylogenetic breadth and physiological traits of this group, we propose that it be considered a new family, the "Desulfobulbusaceae." The isolates utilised an array of electron donors similar to their closest relatives with a few exceptions. As a whole, the phylogenetic and physiological data indicate isolation of several sulphate-reducing bacteria which might be considered as new species and representative of new genera. Comparison of the Desulfobacteriaceae isolates' 16S rRNA sequences to environmental clones originating from the same study site revealed that none shared more than 86% sequence similarity. The results provide further insight into the diversity of sulphate-reducing bacteria inhabiting the salt marsh ecosystem, as well as supporting general trends in the phylogenetic coherence of physiological traits of delta Proteobacteria sulphate reducers.

  8. Sulphate reducing activity detected in soil samples from Antarctica, Ecology Glacier Forefield, King George Island.

    PubMed

    Wolicka, Dorota; Zdanowski, Marek K; Żmuda-Baranowska, Magdalena J; Poszytek, Anna; Grzesiak, Jakub

    2014-01-01

    We determined sulphate-reducing activities in media inoculated with soils and with kettle lake sediments in order to investigate their potential in geomicrobiological processes in low-temperature, terrestrial maritime Antarctic habitats. Soil and sediment samples were collected in a glacier valley abandoned by Ecology Glacier during the last 30 years: from a new formed kettle lake sediment and forefield soil derived from ground moraine. Inoculated with these samples, liquid Postgate C and minimal media supplemented with various carbon sources as electron donors were incubated for 8 weeks at 4°C. High rates of sulphate reduction were observed only in media inoculated with soil. No sulphate reduction was detected in media inoculated with kettle lake sediments. In soil samples culture media calcite and elemental sulphur deposits were observed, demonstrating that sulphate-reducing activity is associated with a potential to mineral formation in cold environments. Cells observed on scanning microscopy (SEM) micrographs of post-culture-soil deposits could be responsible for sulphate-reducing activity. PMID:25804064

  9. Sulphate reducing activity detected in soil samples from Antarctica, Ecology Glacier Forefield, King George Island.

    PubMed

    Wolicka, Dorota; Zdanowski, Marek K; Żmuda-Baranowska, Magdalena J; Poszytek, Anna; Grzesiak, Jakub

    2014-01-01

    We determined sulphate-reducing activities in media inoculated with soils and with kettle lake sediments in order to investigate their potential in geomicrobiological processes in low-temperature, terrestrial maritime Antarctic habitats. Soil and sediment samples were collected in a glacier valley abandoned by Ecology Glacier during the last 30 years: from a new formed kettle lake sediment and forefield soil derived from ground moraine. Inoculated with these samples, liquid Postgate C and minimal media supplemented with various carbon sources as electron donors were incubated for 8 weeks at 4°C. High rates of sulphate reduction were observed only in media inoculated with soil. No sulphate reduction was detected in media inoculated with kettle lake sediments. In soil samples culture media calcite and elemental sulphur deposits were observed, demonstrating that sulphate-reducing activity is associated with a potential to mineral formation in cold environments. Cells observed on scanning microscopy (SEM) micrographs of post-culture-soil deposits could be responsible for sulphate-reducing activity.

  10. Effects of hydrogen and acetate on benzene mineralisation under sulphate-reducing conditions.

    PubMed

    Rakoczy, Jana; Schleinitz, Kathleen M; Müller, Nicolai; Richnow, Hans H; Vogt, Carsten

    2011-08-01

    Syntrophic mineralisation of benzene, as recently proposed for a sulphate-reducing enrichment culture, was tested in product inhibition experiments with acetate and hydrogen, both putative intermediates of anaerobic benzene fermentation. Using [(13)C(6)]-benzene enabled tracking the inhibition of benzene mineralisation sensitively by analysis of (13)CO(2). In noninhibited cultures, hydrogen was detected at partial pressures of 2.4 × 10(-6) ± 1.5 × 10(-6) atm. Acetate was detected at concentrations of 17 ± 2 μM. Spiking with 0.1 atm hydrogen produced a transient inhibitory effect on (13)CO(2) formation. In cultures spiked with higher amounts of hydrogen, benzene mineralisation did not restart after hydrogen consumption, possibly due to the toxic effects of the sulphide produced. An inhibitory effect was also observed when acetate was added to the cultures (0.3, 3.5 and 30 mM). Benzene mineralisation resumed after acetate was degraded to concentrations found in noninhibited cultures, indicating that acetate is another key intermediate in anaerobic benzene mineralisation. Although benzene mineralisation by a single sulphate reducer cannot be ruled out, our results strongly point to an involvement of syntrophic interactions in the process. Thermodynamic calculations revealed that, under in situ conditions, benzene fermentation to hydrogen and acetate yielded a free energy change of ΔG'=-83.1 ± 5.6 kJ mol(-1). Benzene mineralisation ceased when ΔG' values declined below -61.3 ± 5.3 kJ mol(-1) in the presence of acetate, indicating that ATP-consuming reactions are involved in the pathway.

  11. Copper remediation by Eichhornia spp. and sulphate-reducing bacteria.

    PubMed

    Dave, Shailesh; Damani, Maitry; Tipre, Devayani

    2010-01-15

    Eichhornia spp. biomass was collected from Chandola Lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2-3h contact time as optimum conditions for copper sorption with 67.25% copper removal. At the end of 24h of contact time, copper removal reached to 85.0%, from 100 ppm copper containing solution. Copper loading capacity of the biomass ranged between 9.9 and 28.5 mg g(-1) of biomass. To understand the interaction among pH, temperature, presence of nickel and zinc in the system, 2(4) factorial experiment was performed. Under the experimental conditions pH and interactions between pH-nickel, temperature-pH and temperature-pH-nickel-zinc were found to be significant with 60-74.7% copper removal. Langmuir isotherm was better fit as compared to Freundlich isotherm and pseudo-second order equation gave R(2) of 0.999 for biosorption kinetic of Eichhornia biomass. Reactor study showed 90% overall copper removal from 24 L of copper containing waste studied and sulphate-reducing bacteria played a significant role. SEMquant element analysis showed increase from 41.66% to 53.93%, 1.02-19.73% and 0.0-12.39% of chloride, aluminium and copper respectively in the loaded biomass as compare to unexposed biomass.

  12. Copper remediation by Eichhornia spp. and sulphate-reducing bacteria.

    PubMed

    Dave, Shailesh; Damani, Maitry; Tipre, Devayani

    2010-01-15

    Eichhornia spp. biomass was collected from Chandola Lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2-3h contact time as optimum conditions for copper sorption with 67.25% copper removal. At the end of 24h of contact time, copper removal reached to 85.0%, from 100 ppm copper containing solution. Copper loading capacity of the biomass ranged between 9.9 and 28.5 mg g(-1) of biomass. To understand the interaction among pH, temperature, presence of nickel and zinc in the system, 2(4) factorial experiment was performed. Under the experimental conditions pH and interactions between pH-nickel, temperature-pH and temperature-pH-nickel-zinc were found to be significant with 60-74.7% copper removal. Langmuir isotherm was better fit as compared to Freundlich isotherm and pseudo-second order equation gave R(2) of 0.999 for biosorption kinetic of Eichhornia biomass. Reactor study showed 90% overall copper removal from 24 L of copper containing waste studied and sulphate-reducing bacteria played a significant role. SEMquant element analysis showed increase from 41.66% to 53.93%, 1.02-19.73% and 0.0-12.39% of chloride, aluminium and copper respectively in the loaded biomass as compare to unexposed biomass. PMID:19747776

  13. Phylogenetic and functional diversity within toluene-degrading, sulphate-reducing consortia enriched from a contaminated aquifer.

    PubMed

    Kuppardt, Anke; Kleinsteuber, Sabine; Vogt, Carsten; Lüders, Tillmann; Harms, Hauke; Chatzinotas, Antonis

    2014-08-01

    Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers.

  14. Detection of Sulphate-Reducing Bacteria and Others Cultivable Facultative Bacteria in Dental Tissues

    PubMed Central

    Gonçalves, Lúcio de Souza; Dias, Eliane Pedra; Heggendorn, Christiane; Lutterbach, Márcia T. S.

    2014-01-01

    Aim To detect for the presence of sulphate-reducing bacteria (SRB) and evaluate the possible association between SRB and cultivable facultative bacterial of oral sites with different periodontal conditions. Methods The study was carried out on 9 samples from different oral sites in 8 patients (two samples were collected from the same patient). Material was collected using modified Postgate E culture medium, indicated for the growth and isolation of SRB. In addition, a reducing solution for anaerobic bacteria was used as a transport solution for facultative bacteria and identified by polymerase chain reaction amplification (PCR) and sequencing of the 16S rRNA gene. Results SRB was found in 3 patient samples: the first in a root fragment, the second in a root fragment and a healthy tooth with vertical bone loss and a mobility degree of 3; and the third in a healthy tooth extracted for orthodontic treatment. In the final patient, the cultivable facultative species Lactobacillus casei was identified. Other facultative bacterial species were identified in patient 5 (Kurthia Gibsonii) and patient 7 (Pseudomonas aeruginosa). Conclusions The detection of SRB in different dental tissues with distinct periodontal features demonstrated that new studies need to be developed in order to determine the true role of SRB in the oral microbiota. In addition, it was possible to verify the presence of Lactobacillus casei together with SRB in one sample.

  15. Microbial fouling community analysis of the cooling water system of a nuclear test reactor with emphasis on sulphate reducing bacteria.

    PubMed

    Balamurugan, P; Joshi, M Hiren; Rao, T S

    2011-10-01

    Culture and molecular-based techniques were used to characterize bacterial diversity in the cooling water system of a fast breeder test reactor (FBTR). Techniques were selected for special emphasis on sulphate-reducing bacteria (SRB). Water samples from different locations of the FBTR cooling water system, in addition to biofilm scrapings from carbon steel coupons and a control SRB sample were characterized. Whole genome extraction of the water samples and SRB diversity by group specific primers were analysed using nested PCR and denaturing gradient gel electrophoresis (DGGE). The results of the bacterial assay in the cooling water showed that the total culturable bacteria (TCB) ranged from 10(3) to 10(5) cfu ml(-1); iron-reducing bacteria, 10(3) to 10(5) cfu ml(-1); iron oxidizing bacteria, 10(2) to 10(3) cfu ml(-1) and SRB, 2-29 cfu ml(-1). However, the counts of the various bacterial types in the biofilm sample were 2-3 orders of magnitude higher. SRB diversity by the nested PCR-DGGE approach showed the presence of groups 1, 5 and 6 in the FBTR cooling water system; however, groups 2, 3 and 4 were not detected. The study demonstrated that the PCR protocol influenced the results of the diversity analysis. The paper further discusses the microbiota of the cooling water system and its relevance in biofouling.

  16. Aluminum and sulphate removal by a highly Al-resistant dissimilatory sulphate-reducing bacteria community.

    PubMed

    Martins, Mónica; Taborda, Rita; Silva, Gonçalo; Assunção, Ana; Matos, António Pedro; Costa, Maria Clara

    2012-09-01

    A highly Al-resistant dissimilatory sulphate-reducing bacteria community was isolated from sludge of the wetland of Urgeiriça mine (community W). This community showed excellent sulphate removal at the presence of Al³⁺. After 27 days of incubation, 73, 86 and 81% of sulphate was removed in the presence of 0.48, 0.90 and 1.30 mM of Al³⁺, respectively. Moreover, Al³⁺ was simultaneously removed: 55, 85 and 78% of metal was removed in the presence of 0.48, 0.90 and 1.30 mM of Al³⁺, respectively. The dissociation of aluminium-lactate soluble complexes due to lactate consumption by dissimilatory sulphate-reducing bacteria can be responsible for aluminum removal, which probably precipitates as insoluble aluminium hydroxide. Phylogenetic analysis of 16S rRNA gene showed that this community was mainly composed by bacteria closely related to Desulfovibrio desulfuricans. However, bacteria affiliated to Proteus and Ralstonia were also present in the community.

  17. Code Mixing and Modernization across Cultures.

    ERIC Educational Resources Information Center

    Kamwangamalu, Nkonko M.

    A review of recent studies addressed the functional uses of code mixing across cultures. Expressions of code mixing (CM) are not random; in fact, a number of functions of code mixing can easily be delineated, for example, the concept of "modernization.""Modernization" is viewed with respect to how bilingual code mixers perceive themselves, how…

  18. How sulphate-reducing microorganisms cope with stress: Lessons from systems biology

    SciTech Connect

    Zhou, J.; He, Q.; Hemme, C.L.; Mukhopadhyay, A.; Hillesland, K.; Zhou, A.; He, Z.; Nostrand, J.D. Van; Hazen, T.C.; Stahl, D.A.; Wall, J.D.; Arkin, A.P.

    2011-04-01

    Sulphate-reducing microorganisms (SRMs) are a phylogenetically diverse group of anaerobes encompassing distinct physiologies with a broad ecological distribution. As SRMs have important roles in the biogeochemical cycling of carbon, nitrogen, sulphur and various metals, an understanding of how these organisms respond to environmental stresses is of fundamental and practical importance. In this Review, we highlight recent applications of systems biology tools in studying the stress responses of SRMs, particularly Desulfovibrio spp., at the cell, population, community and ecosystem levels. The syntrophic lifestyle of SRMs is also discussed, with a focus on system-level analyses of adaptive mechanisms. Such information is important for understanding the microbiology of the global sulphur cycle and for developing biotechnological applications of SRMs for environmental remediation, energy production, biocorrosion control, wastewater treatment and mineral recovery.

  19. Optimization study for Pb(II) and COD sequestration by consortium of sulphate-reducing bacteria

    NASA Astrophysics Data System (ADS)

    Verma, Anamika; Bishnoi, Narsi R.; Gupta, Asha

    2016-04-01

    In this study, initial minimum inhibitory concentration (MIC) of Pb(II) ions was analysed to check optimum concentration of Pb(II) ions at which the growth of sulphate-reducing consortium (SRC) was found to be maximum. 80 ppm of Pb(II) ions was investigated as minimum inhibitory concentration for SRC. Influence of electron donors such as lactose, sucrose, glucose and sodium lactate was examined to investigate best carbon source for growth and activity of sulphate-reducing bacteria. Sodium lactate was found to be the prime carbon source for SRC. Later optimization of various parameters was executed using Box-Behnken design model of response surface methodology to explore the effectiveness of three independent operating variables, namely, pH (5.0-9.0), temperature (32-42 °C) and time (5.0-9.0 days), on dependent variables, i.e. protein content, precipitation of Pb(II) ions, and removal of COD by SRC biomass. Maximum removal of COD and Pb(II) was observed to be 91 and 98 %, respectively, at pH 7.0 and temperature 37 °C and incubation time 7 days. According to response surface analysis and analysis of variance, the experimental data were perfectly fitted to the quadratic model, and the interactive influence of pH, temperature and time on Pb(II) and COD removal was highly significant. A high regression coefficient between the variables and response (r 2 = 0.9974) corroborate eminent evaluation of experimental data by second-order polynomial regression model. SEM and Fourier transform infrared analysis was performed to investigate morphology of PbS precipitates, sorption mechanism and involved functional groups in metal-free and metal-loaded biomass of SRC for Pb(II) binding.

  20. Endosymbiotic sulphate-reducing and sulphide-oxidizing bacteria in an oligochaete worm.

    PubMed

    Dubilier, N; Mülders, C; Ferdelman, T; de Beer, D; Pernthaler, A; Klein, M; Wagner, M; Erséus, C; Thiermann, F; Krieger, J; Giere, O; Amann, R

    2001-05-17

    Stable associations of more than one species of symbiont within a single host cell or tissue are assumed to be rare in metazoans because competition for space and resources between symbionts can be detrimental to the host. In animals with multiple endosymbionts, such as mussels from deep-sea hydrothermal vents and reef-building corals, the costs of competition between the symbionts are outweighed by the ecological and physiological flexibility gained by the hosts. A further option for the coexistence of multiple symbionts within a host is if these benefit directly from one another, but such symbioses have not been previously described. Here we show that in the gutless marine oligochaete Olavius algarvensis, endosymbiotic sulphate-reducing bacteria produce sulphide that can serve as an energy source for sulphide-oxidizing symbionts of the host. Thus, these symbionts do not compete for resources but rather share a mutalistic relationship with each other in an endosymbiotic sulphur cycle, in addition to their symbiotic relationship with the oligochaete host.

  1. Desulfovibrio alkalitolerans sp. nov., a novel alkalitolerant, sulphate-reducing bacterium isolated from district heating water.

    PubMed

    Abildgaard, Lone; Nielsen, Marie Bank; Kjeldsen, Kasper Urup; Ingvorsen, Kjeld

    2006-05-01

    A novel alkalitolerant, sulphate-reducing bacterium (strain RT2T) was isolated from alkaline district heating water. Strain RT2T was a motile vibrio (0.5-0.8 microm wide and 1.4-1.9 microm long) and grew at pH 6.9-9.9 (optimum at pH 9.0-9.4) and at 16-47 degrees C (optimum at 43 degrees C). The genomic DNA G+C content was 64.7 mol%. A limited number of compounds were used as electron donors with sulphate as electron acceptor, including lactate, pyruvate, formate and hydrogen/acetate. Sulphite and thiosulphate also served as electron acceptors. Based on physiological and genotypic properties, the isolate was considered to represent a novel species of the genus Desulfovibrio, for which the name Desulfovibrio alkalitolerans sp. nov. is proposed. The type strain is RT2T (=DSM 16529T=JCM 12612T). The strain is the first alkali-tolerant member of the genus Desulfovibrio to be described.

  2. Monitoring structural transformation of hydroxy-sulphate green rust in the presence of sulphate reducing bacteria

    NASA Astrophysics Data System (ADS)

    Abdelmoula, M.; Zegeye, A.; Jorand, F.; Carteret, C.

    The activities of bacterial consortia enable organisms to maximize their metabolic capabilities. This article assesses the synergetic relationship between iron reducing bacteria (IRB), Shewanella putrefaciens and sulphate reducing bacteria (SRB) Desulfovibrio alaskensis. Thus, the aim of this study was first to form a biogenic hydroxysulpahte green rust GR2(SO{4/2-}) through the bioreduction of lepidocrocite by S. putrefaciens and secondly to investigate if sulfate anions intercalated in the biogenic GR2(SO{4/2-}) could serve as final electron acceptor for a sulfate reducing bacterium, D. alaskensis. The results indicate that the IRB lead to the formation of GR2(SO{4/2-}) and this mineral serve as an electron acceptor for SRB. GR2(SO{4/2-}) precipitation and its transformation was demonstrated by using X-ray diffraction (DRX), Mössbauer spectroscopy (TMS) and transmission electron spectroscopy (TEM). These observations point out the possible acceleration of steel corrosion in marine environment in presence of IRB/SRB consortia.

  3. Monitoring structural transformation of hydroxy-sulphate green rust in the presence of sulphate reducing bacteria

    NASA Astrophysics Data System (ADS)

    Abdelmoula, M.; Zegeye, A.; Jorand, F.; Carteret, C.

    2006-01-01

    The activities of bacterial consortia enable organisms to maximize their metabolic capabilities. This article assesses the synergetic relationship between iron reducing bacteria (IRB), Shewanella putrefaciens and sulphate reducing bacteria (SRB) Desulfovibrio alaskensis. Thus, the aim of this study was first to form a biogenic hydroxy-sulpahte green rust GR2( {text{SO}}_{{text{4}}} ^{{2 - }} ) through the bioreduction of lepidocrocite by S. putrefaciens and secondly to investigate if sulfate anions intercalated in the biogenic GR2( {text{SO}}_{{text{4}}} ^{{2 - }} ) could serve as final electron acceptor for a sulfate reducing bacterium, D. alaskensis. The results indicate that the IRB lead to the formation of GR2( {text{SO}}_{{text{4}}} ^{{2 - }} ) and this mineral serve as an electron acceptor for SRB. GR2( {text{SO}}_{{text{4}}} ^{{2 - }} ) precipitation and its transformation was demonstrated by using X-ray diffraction (DRX), Mössbauer spectroscopy (TMS) and transmission electron spectroscopy (TEM). These observations point out the possible acceleration of steel corrosion in marine environment in presence of IRB/SRB consortia.

  4. Influence of respiratory substrate in carbon steel corrosion by a Sulphate Reducing Prokaryote model organism.

    PubMed

    Dall'agnol, Leonardo T; Cordas, Cristina M; Moura, José J G

    2014-06-01

    Sulphate Reducing Prokaryotes (SRP) are an important group of microorganisms involved in biocorrosion processes. Sulphide production is recognized as a fundamental cause of corrosion and nitrate is often used as treatment. The present work analyses the influence of respiratory substrates in the metal, from off-shore installations, SRP influenced corrosion, using Desulfovibrio desulfuricans ATTC 27774 as model organism, since this can switch from sulphate to nitrate. Open Circuit Potential over 6days in different conditions was measured, showing an increase around 200 and 90mV for the different media. Tafel plots were constructed allowing Ecorr and jcorr calculations. For SRP in sulphate and nitrate media Ecorr values of -824 and -728mV, and jcorr values of 2.5 and 3.7μAcm(-2), respectively, were attained indicating that in nitrate, the resultant corrosion rate is larger than in sulphate. Also, it is shown that the equilibrium of sulphide in the solution/gas phases is a key factor to the evolution of corrosion Nitrate prevents pitting but promotes general corrosion and increases the corrosion potential and iron dissolution 40 times when compared to sulphate. Our results demonstrate that nitrate injection strategy in oil fields has to be considered carefully as option to reduce souring and localized corrosion.

  5. Sulphur-oxidizing and sulphate-reducing communities in Brazilian mangrove sediments.

    PubMed

    Varon-Lopez, Maryeimy; Dias, Armando Cavalcante Franco; Fasanella, Cristiane Cipolla; Durrer, Ademir; Melo, Itamar Soares; Kuramae, Eiko Eurya; Andreote, Fernando Dini

    2014-03-01

    Mangrove soils are anaerobic environments rich in sulphate and organic matter. Although the sulphur cycle is one of the major actors in this ecosystem, little is known regarding the sulphur bacteria communities in mangrove soils. We investigated the abundance, composition and diversity of sulphur-oxidizing (SOB) and sulphate-reducing (SRB) bacteria in sediments from three Brazilian mangrove communities: two contaminated, one with oil (OilMgv) and one with urban waste and sludge (AntMgv), and one pristine (PrsMgv). The community structures were assessed using quantitative real-time polymerase chain reaction (qPCR), polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and clone libraries, using genes for the enzymes adenosine-5'-phosphosulphate reductase (aprA) and sulphite reductase (Dsr) (dsrB). The abundance for qPCR showed the ratio dsrB/aprA to be variable among mangroves and higher according to the gradient observed for oil contamination in the OilMgv. The PCR-DGGE patterns analysed by Nonmetric Multidimensional Scaling revealed differences among the structures of the three mangrove communities. The clone libraries showed that Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria were the most abundant groups associated with sulphur cycling in mangrove sediments. We conclude that the microbial SOB and SRB communities in mangrove soils are different in each mangrove forest and that such microbial communities could possibly be used as a proxy for contamination in mangrove forests.

  6. Impact of sulphate-reducing bacteria on the performance of engineering materials.

    PubMed

    Javaherdashti, Reza

    2011-09-01

    Microbiologically Influenced Corrosion (MIC) is an electrochemical corrosion influenced by the presence/action of biological agents such as, but not limited to, bacteria. One of the key elements of MIC is sulphate-reducing bacteria (SRB). There are still many misunderstandings about these bacteria, their role in the deterioration of engineering materials and their importance over other types of corrosion-related micro-/macro-organisms. SRB do not require oxygen, yet they can be found in oxygenated environments; they are capable of tolerating a relative wide range of temperature, pH, chloride concentration and pressure values. Not only can SRB have deteriorating impact on engineering materials, they are also capable of inducing harm to health and agriculture. In this paper, after reviewing facts and figures regarding ecological and economical impacts of corrosion in general and MIC, in particular, the central concept of MIC, that is, biofilm formation and its deterioration mechanisms and the role of SRB in such mechanisms are described. Also, the possible enhancing role of SRB on stress corrosion cracking of steels and the controversial concept of no relationship between the number of SRB and corrosion rate are addressed and reviewed.

  7. Biological treatment of acidic coal refuse using sulphate-reducing bacteria with chicken manure as carbon source.

    PubMed

    Zhang, Mingliang; Wang, Haixia

    2014-01-01

    The performance of using chicken manure as carbon source to promote sulphate-reducing bacteria (SRB) activity within acidic coal refuse to prevent the generation of acidic leachate was investigated in batch and column bioreactors. The bioreactors showed satisfactory performance in biological sulphate reduction, evidenced by the increase in effluent pH, high removal efficiencies of sulphate and metals, and the presence of large numbers of SRB. Scanning electron microscope-energy dispersive spectrometry (EDS) analysis of the formed precipitate indicated the formation of metal sulphides. Chicken manure was observed to play an important role in this treatment, which could not only provide carbon source but also reduce the adverse effect of strong acidity and metal toxicity on SRB activity. Metal removal could be mainly attributed to sulphides precipitation and sorption to chicken manure. This study indicated that SRB with chicken manure could be a novel alternative used for the prevention of acidic leachate from coal refuse.

  8. Isolation and quantification of cadmium removal mechanisms in batch reactors inoculated by sulphate reducing bacteria: biosorption versus bioprecipitation.

    PubMed

    Pagnanelli, Francesca; Cruz Viggi, Carolina; Toro, Luigi

    2010-05-01

    Biosorbing properties of sulphate reducing bacteria were tested to distinguish the amount of cadmium removed by bioprecipitation from that bound onto biomass surface (biosorption). Experimental results of cadmium abatement in batch growth tests (bioprecipitation tests) were then compared with metabolism-independent binding properties of SRB cell wall surface (biosorption tests performed with dead biomass). Experimental results showed that SRB inoculum removed 59 + or - 5% of sulphates in 21 days even in presence of cadmium (0-36 mmol L(-1)), while non-monotonous kinetic effects were observed for increasing Cd concentrations. Comparison between bioprecipitation and biosorption tests denoted a significant contribution of biosorption (77%) in total Cd removal (0.40 + or - 0.01 mmol g(-1)). Characterisation of bacterial acid-base surface properties by potentiometric titrations and mechanistic modelling denoted that carboxylic, phosphate and amino groups of cell wall are the main responsible of metal removal by biosorption mechanism.

  9. Determination of the elemental composition of molasses and its suitability as carbon source for growth of sulphate-reducing bacteria.

    PubMed

    Teclu, Daniel; Tivchev, George; Laing, Mark; Wallis, Mike

    2009-01-30

    Bioremediation of arsenic-contaminated water could be a cost-effective process provided a cheap carbon source is used. In this work molasses was tested as a possible source of carbon for the growth of sulphate-reducing bacteria (SRB). Its elemental composition and the tolerance of SRB toward different arsenic species (As (III) and As (V)) were also investigated. Batch studies were carried out to assess the suitability of 1, 2.5 and 5 g/l molasses concentrations for SRB growth. The results indicated that molasses does support SRB growth, the level of response being dependant on the concentration. The percentage of sulphate reduction with molasses at 1, 2.5 and 5 g/l was not significantly different. However, growth on molasses was not as good as that obtained when lactate was used as carbon source. Molasses contained the heavy metals Al, As, Cu, Fe, Mn and Zn in concentrations of 0.54, 0.24, 8.7, 0.35, 11.1 and 19.7 microg/g, respectively. Arsenic tolerance, growth response and sulphate-reducing activity of the SRB were investigated using arsenite and arsenate solutions at final concentrations of 1, 5 and 20 mg/l for each species. The results revealed that very little SRB growth occurred at concentrations of 20 mg/l As(III) or As(V). At lower concentrations (1 mg/l) the SRB grew better with As(V) than with As(III). Arsenic pollution in most groundwater sources is below this level (1 mg/l).

  10. Intelligent control of mixed-culture bioprocesses

    SciTech Connect

    Stoner, D.L.; Larsen, E.D.; Miller, K.S.

    1995-12-31

    A hierarchical control system is being developed and applied to a mixed culture bioprocess in a continuous stirred tank reactor. A bioreactor, with its inherent complexity and non-linear behavior was an interesting, yet, difficult application for control theory. The bottom level of the hierarchy was implemented as a number of integrated set point controls and data acquisition modules. Within the second level was a diagnostic system that used expert knowledge to determine the operational status of the sensors, actuators, and control modules. A diagnostic program was successfully implemented for the detection of stirrer malfunctions, and to monitor liquid delivery rates and recalibrate the pumps when deviations from desired flow rates occurred. The highest control level was a supervisory shell that was developed using expert knowledge and the history of the reactor operation to determine the set points required to meet a set of production criteria. At this stage the supervisory shell analyzed the data to determine the state of the system. In future implementations, this shell will determine the set points required to optimize a cost function using expert knowledge and adaptive learning techniques.

  11. Degradation of mix hydrocarbons by immobilized cells of mix culture using a trickle fluidized bed reactor

    SciTech Connect

    Chapatwala, K.D.

    1993-01-01

    The microorganisms, capable of degrading mix hydrocarbons were isolated from the soil samples collected from the hydrocarbon contaminated sites. The mix cultures were immobilized in calcium alginate solution in the form of beads. A trickle fluidized bed air-uplift-type reactor designed to study the degradation of mix hydrocarbons was filled with 0.85% normal saline containing the immobilized cells of mix culture. The immobilized beads were aerated with CO[sub 2]-free air at 200 ml/min. The degradation of different concentrations of hydrocarbons in the presence/absence of commercially available fertilizers by the immobilized cells of mix culture is now in progress.

  12. A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes.

    PubMed

    Rabus, Ralf; Venceslau, Sofia S; Wöhlbrand, Lars; Voordouw, Gerrit; Wall, Judy D; Pereira, Inês A C

    2015-01-01

    Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored.

  13. Comparison of Sulphate-reducing Bacterial Communities in Japanese Fish Farm Sediments with Different Levels of Organic Enrichment

    PubMed Central

    Kondo, Ryuji; Mori, Yumi; Sakami, Tomoko

    2012-01-01

    Fish farm sediments receive a large amount of organic matter from uneaten food and fecal material. This nutrient enrichment, or organic pollution, causes the accumulation of sulphide in the sediment from the action of sulphate-reducing bacteria (SRB). We investigated the effect of organic enrichment around coastal fish farms comparing the SRB community structure in these sediments. Sediment samples with different levels of organic pollution classified based upon the contents of acid-volatile sulphide and chemical oxygen demand were collected at three stations on the coast of western Japan. The SRB community composition was assessed using PCR amplification, cloning, sequencing and phylogenetic analysis of the dissimilatory sulphite reductase β-subunit gene (dsrB) fragments using directly extracted sediment DNA. Sequencing of the cloned PCR products of dsrB showed the existence of different SRB groups in the sediments. The majority of dsrB sequences were associated with the families Desulfobacteraceae and Desulfobulbaceae. Clones related to the phylum Firmicutes were also detected from all sediment samples. Statistical comparison of sequences revealed that community compositions of SRB from polluted sediments significantly differed from those of moderately polluted sediments and unpolluted sediments (LIBSHUFF, p<0.05), showing a different distribution of SRB in the fish farm sediments. There is evidence showing that the organic enrichment of sediments influences the composition of SRB communities in sediments at marine fish farms. PMID:22791053

  14. A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes.

    PubMed

    Rabus, Ralf; Venceslau, Sofia S; Wöhlbrand, Lars; Voordouw, Gerrit; Wall, Judy D; Pereira, Inês A C

    2015-01-01

    Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored. PMID:26210106

  15. dsrAB-based analysis of sulphate-reducing bacteria in moving bed biofilm reactor (MBBR) wastewater treatment plants.

    PubMed

    Biswas, Kristi; Taylor, Michael W; Turner, Susan J

    2014-08-01

    Sulphate-reducing bacteria (SRB) are important members of the sulphur cycle in wastewater treatment plants (WWTPs). In this study, we investigate the diversity and activity of SRB within the developing and established biofilm of two moving bed biofilm reactor (MBBR) systems treating municipal wastewater in New Zealand. The larger of the two WWTPs (Moa Point) generates high levels of sulphide relative to the smaller Karori plant. Clone libraries of the dissimilatory (bi)sulphite reductase (dsrAB) genes and quantitative real-time PCR targeting dsrA transcripts were used to compare SRB communities between the two WWTPs. Desulfobulbus (35-53 % of total SRB sequences) and genera belonging to the family Desulfobacteraceae (27-41 %) dominated the SRB fraction of the developing biofilm on deployed plastic carriers at both sites, whereas Desulfovibrio and Desulfomicrobium were exclusively found at Moa Point. In contrast, the established biofilms from resident MBBR carriers were largely dominated by Desulfomonile tiedjei-like organisms (58-100 % of SRB sequences). The relative transcript abundance of dsrA genes (signifying active SRBs) increased with biofilm weight yet remained low overall, even in the mature biofilm stage. Our results indicate that although SRB are both present and active in the microbial community at both MBBR study sites, differences in the availability of sulphate may be contributing to the observed differences in sulphide production at these two plants.

  16. Mixed-culture transcriptome analysis reveals the molecular basis of mixed-culture growth in Streptococcus thermophilus and Lactobacillus bulgaricus.

    PubMed

    Sieuwerts, Sander; Molenaar, Douwe; van Hijum, Sacha A F T; Beerthuyzen, Marke; Stevens, Marc J A; Janssen, Patrick W M; Ingham, Colin J; de Bok, Frank A M; de Vos, Willem M; van Hylckama Vlieg, Johan E T

    2010-12-01

    Many food fermentations are performed using mixed cultures of lactic acid bacteria. Interactions between strains are of key importance for the performance of these fermentations. Yogurt fermentation by Streptococcus thermophilus and Lactobacillus bulgaricus (basonym, Lactobacillus delbrueckii subsp. bulgaricus) is one of the best-described mixed-culture fermentations. These species are believed to stimulate each other's growth by the exchange of metabolites such as folic acid and carbon dioxide. Recently, postgenomic studies revealed that an upregulation of biosynthesis pathways for nucleotides and sulfur-containing amino acids is part of the global physiological response to mixed-culture growth in S. thermophilus, but an in-depth molecular analysis of mixed-culture growth of both strains remains to be established. We report here the application of mixed-culture transcriptome profiling and a systematic analysis of the effect of interaction-related compounds on growth, which allowed us to unravel the molecular responses associated with batch mixed-culture growth in milk of S. thermophilus CNRZ1066 and L. bulgaricus ATCC BAA-365. The results indicate that interactions between these bacteria are primarily related to purine, amino acid, and long-chain fatty acid metabolism. The results support a model in which formic acid, folic acid, and fatty acids are provided by S. thermophilus. Proteolysis by L. bulgaricus supplies both strains with amino acids but is insufficient to meet the biosynthetic demands for sulfur and branched-chain amino acids, as becomes clear from the upregulation of genes associated with these amino acids in mixed culture. Moreover, genes involved in iron uptake in S. thermophilus are affected by mixed-culture growth, and genes coding for exopolysaccharide production were upregulated in both organisms in mixed culture compared to monocultures. The confirmation of previously identified responses in S. thermophilus using a different strain combination

  17. Structural and magnetic studies on heavy-metal-adsorbing iron sulphide nanoparticles produced by sulphate-reducing bacteria

    NASA Astrophysics Data System (ADS)

    Watson, J. H. P.; Cressey, B. A.; Roberts, A. P.; Ellwood, D. C.; Charnock, J. M.; Soper, A. K.

    2000-05-01

    In previous and in work to be published, it has been shown that iron sulphide material, produced by sulphate-reducing bacteria (SRB), is an excellent adsorbent for a wide range of heavy metals. The material adsorbs between 100 and 400 mg g -1 and residual levels in solutions can be of the order of pg per litre. Further, strongly magnetic forms of this material can now be produced which can be effectively and cheaply removed from suspension together with the adsorbate by magnetic separation. This paper examines the structure of weakly magnetic and strongly magnetic iron sulphide material produced by SRB with a view to increasing the understanding of its adsorbent and the magnetic properties. The structural properties have been examined using high-resolution imaging and electron diffraction in a transmission electron microscope (TEM), the measurements of magnetisation versus field and temperature, extended X-ray absorption fine-structure (EXAFS) spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy and neutron diffraction. Before drying the surface area of both the weakly magnetic and the strongly magnetic iron sulphide is of the order of 400-500 m 2 g -1 as revealed by the magnetic properties, neutron scattering and the adsorption of a number of heavy metals. After freeze-drying the surface area falls to between 18 and 19 m 2 g -1. The initial inocula came from a semi-saline source and when fed with nutrient containing Fe 2+ and Fe 3+ produced a weakly magnetic iron sulphide (Watson et al., Minerals Eng. 8 (1995) 1097) and a few % of a more strongly magnetic material. Further work using a novel method (Keller-Besrest, Collin, J. Solid State Chem. 84 (1990) 211) produced a strongly magnetic iron sulphide material. EXAFS and XANES spectroscopy revealed (Keller-Besrest and Collin, 1990) that the weakly magnetic iron sulphide material had the Ni-As structure in which the Fe is tetrahedrally coordinated with the composition Fe 1- xS. The strongly

  18. Thermophilic Mixed Culture of Bacteria Utilizing Methanol for Growth1

    PubMed Central

    Snedecor, Bradley; Cooney, Charles L.

    1974-01-01

    A thermophilic mixed population of bacteria, capable of utilizing methanol as its sole carbon-energy source at temperatures up to 65 C, was selected by enrichment and studied. A maximal cellular yield of 0.42 g per g of methanol was observed at 50 to 56 C. The maximal specific growth rate of the mixed population in continuous culture at 56 C was greater than 0.32 per h. The amino acid profile of the mixed culture indicated that a high quality protein was produced and the protein content was 71%. The properties of this culture and its ability to grow at elevated temperatures are discussed in terms of single-cell protein production and the treatment of industrial waste. Images PMID:16349996

  19. Microbe-microbe interactions in mixed culture food fermentations.

    PubMed

    Smid, Eddy J; Lacroix, Christophe

    2013-04-01

    Most known natural and industrial food fermentation processes are driven by either simple or complex communities of microorganisms. Obviously, these fermenting microbes will not only interact with the fermentable substrate but also with each other. These microbe-microbe interactions are complex but thought to be crucial for obtaining the desired product characteristics. Microbial interactions are mediated through a variety of molecular and physiological mechanisms. Examples of interaction mechanisms which have an impact on the outcome of food fermentation processes will be discussed. Finally, the technological and scientific challenges associated with the production and propagation of complex mixed starter cultures are briefly addressed. Research on the composition and functionality of complex microbial consortia is gaining momentum and will open new avenues for controlling and improving food fermentation processes, and developing new applications for mixed cultures.

  20. Transferrin receptor expression by stimulated cells in mixed lymphocyte culture.

    PubMed Central

    Salmon, M; Bacon, P A; Symmons, D P; Walton, K W

    1985-01-01

    Transferrin receptor (TRFr) expression by cells in mixed lymphocyte culture increases steadily for the first 5 days, but then reaches a plateau. By the sixth day in culture, about 20% of viable cells express TRFr in two-way mixed lymphocyte reactions. This subpopulation of TRFr-positive cells represents the proliferating population; it is heterogeneous, containing T-cell blasts and smaller cells which are a mixture of T and non-T cells. A small group of non-T cells have phenotypic similarity to natural killer (NK) cells. T cells appear to divide earlier in the course of the response than non-T cells. The biphasic nature of this response and the slower non-T reactivity may be due to a secondary stimulation of non-T cells by factors released from activated T cells (such as interleukin-2). PMID:2982734

  1. Influence of H(2) and O(2) on sulphate-reducing activity of a subterranean community and the coupled response in redox potential.

    PubMed

    Pedersen, Karsten

    2012-12-01

    Deep Fennoscandian groundwater is anaerobic, reducing in character and populated by a large diversity of obligate and facultative anaerobic microorganisms. Concentrations of H(2) and carbon monoxide are often 0.01-1 μM and of dissolved organic carbon (DOC) and methane 0.01-1 mM. Microbial activity involving these electron and energy donors may help keep deep groundwater anaerobic and reduced. H(2) was added in concentrations of 0.1-10 mM to a sulphate-reducing community attached to crushed rock in groundwater under a pressure of 2.0 MPa and in situ geochemical conditions. Experiments reported a threshold concentration of approximately 1 μM H(2) at which sulphate reduction ceased, despite the presence of DOC and acetate, suggesting that H(2) was needed for sulphate-reducing activity. δ(13)C values of acetate and DOC data suggested that organic material was degraded to acetate by means of a heterotrophic process. New pressure-resistant micro-sensors for measuring E(h) indicated an H(2)-concentration-dependent decrease in E(h). The investigated community rapidly mitigated the increase in E(h) caused by repeated additions of 0.1-0.2 mM pulses of O(2) as long as H(2) was available. The results imply that sulphate reduction to sulphide with H(2) may dominate sulphate-rich groundwater, which may have implications for metallic underground constructions.

  2. Enrichment of an endosulfan-degrading mixed bacterial culture.

    PubMed

    Sutherland, T D; Horne, I; Lacey, M J; Harcourt, R L; Russell, R J; Oakeshott, J G

    2000-07-01

    An endosulfan-degrading mixed bacterial culture was enriched from soil with a history of endosulfan exposure. Enrichment was obtained by using the insecticide as the sole source of sulfur. Chemical hydrolysis was minimized by using strongly buffered culture medium (pH 6.6), and the detergent Tween 80 was included to emulsify the insecticide, thereby increasing the amount of endosulfan in contact with the bacteria. No growth occurred in control cultures in the absence of endosulfan. Degradation of the insecticide occurred concomitant with bacterial growth. The compound was both oxidized and hydrolyzed. The oxidation reaction favored the alpha isomer and produced endosulfate, a terminal pathway product. Hydrolysis involved a novel intermediate, tentatively identified as endosulfan monoaldehyde on the basis of gas chromatography-mass spectrometry and chemical derivatization results. The accumulation and decline of metabolites suggest that the parent compound was hydrolyzed to the putative monoaldehyde, thereby releasing the sulfite moiety required for growth. The monoaldehyde was then oxidized to endosulfan hydroxyether and further metabolized to (a) polar product(s). The cytochrome P450 inhibitor, piperonyl butoxide, did not prevent endosulfan oxidation or the formation of other metabolites. These results suggest that this mixed culture is worth investigating as a source of endosulfan-hydrolyzing enzymes for use in enzymatic bioremediation of endosulfan residues.

  3. Polycyclic aromatic hydrocarbon biodegradation by a mixed bacterial culture

    SciTech Connect

    Dreyer, G.; Koenig, J.; Ringpfeil, M.

    1995-12-31

    Biodegradation of polycyclic aromatic hydrocarbons (PAHs), which are a complex mixture of organic compounds, was demonstrated using a bacterial mixed culture selected from a contaminated site by the BIOPRACT GmbH. The investigations were carried out in a laboratory fermenter using emulsified tar oil as the substrate to determine the following: (1) concentration of the single PAH and of the sum of PAHs relative to fermentation time, (2) carbon dioxide (CO{sub 2}) and oxygen (O{sub 2}) content in the outflowing air during fermentation, (3) chemical oxygen demand (COD) of the broth, and (4) toxicity of the broth before and after fermentation according to the bioluminescence test (DIN 38412, part 34/1). The results of this model experiment indicated that the investigated mixed culture is able to effectively metabolize the PAHs contained in tar oil, including the higher condensed compounds such as benzo(a)pyrene. In the first 8 days of fermentation, the PAH sum decreased to below 5% of the starting concentration connected with a five-fold reduction of the toxic effect on Vibrio fischeri. The PAH degradation rate correlated with the rate of COD decrease, the rate of evolving CO{sub 2}, and the consumption of O{sub 2}.

  4. Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures.

    PubMed

    Laycock, Bronwyn; Arcos-Hernandez, Monica V; Langford, Alexandra; Pratt, Steven; Werker, Alan; Halley, Peter J; Lant, Paul A

    2014-06-25

    Poly[R-3-hydroxybutyrate-co-(R-3-hydroxyvalerate)] (PHBV) copolymers were produced from mixed cultures of biomass (activated sludge) fed with acetic acid (HAc) and propionic acid (HPr). Feeding was performed in such a way as to produce materials with a wide range of monomer compositions and microstructures. Solvent-cast thin films of these materials have recently been shown to exhibit a narrow range of mechanical properties similar to those of the homopolymer poly(R-3-hydroxybutyrate) (PHB) [1]. In this work, more detailed analyses of the thermal and crystallisation properties of these mixed-culture polyesters have revealed that they like comprise complex blends with broad compositional distribution of random and/or blocky copolymers of very different 3-hydroxyvalerate (3HV) contents and melting temperatures and thus have very different respective crystallisation kinetics. This blend complexity was confirmed by solvent fractionation of selected samples. The findings support the hypothesis that overall mechanical properties of these complex copolymer blend materials will be strongly influenced by the more rapidly crystallising components that form the matrix within which the slower crystallising components exist as microdomains. New opportunities in the material development of PHAs are likely to be found in establishing and exploiting such structure-function relationships.

  5. Dual polarization of microglia isolated from mixed glial cell cultures.

    PubMed

    Ju, Lili; Zeng, Hui; Chen, Yun; Wu, Yanhong; Wang, Beibei; Xu, Qunyuan

    2015-09-01

    Microglia are versatile immune effector cells of the CNS and are sensitive to various stimuli. The different methods used to isolate microglia may affect some of their characteristics, such as their polarization state. The influence of cell sorting methods on the polarization state of microglia has never been studied. Mixed glial culture system (MGCS) and magnetic activated cell sorting (MACS) are two methods that are commonly used to purify microglia. This study compares the immunological states between microglia isolated by MGCS and microglia isolated by MACS. We show that microglia isolated by MGCS exhibit a stronger immune-activated state than microglia isolated by MACS. They present an elevated phagocytic ability and high levels of markers associated with classical activation (M1) and alternative activation (M2). In addition, high levels of M1-type and M2-type chemokine (C-C motif) ligand 2 and transforming growth factor-β1 were detected in the culture medium of mixed glial cells. Our results show that microglia isolated by MGCS are in an immune-activated state, whereas microglia isolated by MACS appear to be closer to their primary in vivo state. Therefore, the immune status of microglia, depending on the protocol used to purify them, should be carefully considered in neuropathology research.

  6. Comparison of mixed-acid fermentations inoculated with six different mixed cultures.

    PubMed

    Forrest, Andrea K; Hollister, Emily B; Gentry, Terry J; Wilkinson, Heather H; Holtzapple, Mark T

    2012-08-01

    The MixAlco™ process biologically converts biomass to carboxylate salts that may be converted to a variety of chemicals and fuels. This study examines the fermentation performance of six different mixed cultures, and how the performance was affected by the bacterial composition of each community. All six countercurrent fermentations had very similar performance, but were dissimilar in microbial community composition. The acid concentrations varied by only 12% between fermentation trains and the conversions varied only by 6%. The microbial communities were profiled using 16S rRNA tag-pyrosequencing, which revealed the presence of dynamic communities that were dominated by bacteria resembling Clostridia, but they shared few taxa in common. Yue-Clayton similarity calculations of the communities revealed that they were extremely different. The presence of different but functionally similar microbial communities in this study suggests that it is the operating parameters that determine the fermentation end-products. PMID:22705541

  7. Effects of storage on mixed-culture biological electrodes

    PubMed Central

    Saheb Alam, Soroush; Persson, Frank; Wilén, Britt-Marie; Hermansson, Malte; Modin, Oskar

    2015-01-01

    Storage methods are important to preserve the viability and biochemical characteristics of microbial cultures between experiments or during periods when bioreactors are inactive. Most of the research on storage has focused on isolates; however, there is an increasing interest in methods for mixed cultures, which are of relevance in environmental biotechnology. The purpose of this study was to investigate the effect of different storage methods on electrochemically active enrichment cultures. Acetate-oxidizing bioanodes generating a current density of about 5 A m−2 were enriched in a microbial electrolysis cell. The effect of five weeks of storage was evaluated using electrochemical techniques and microbial community analysis. Storage by refrigeration resulted in quicker re-activation than freezing in 10% glycerol, while the bioelectrochemical activity was entirely lost after storage using dehydration. The results showed that the bioelectrochemical activity of bioanodes stored at low temperature could be retained. However, during the re-activation period the bioanodes only recovered 75% of the current density generated before storage and the bacterial communities were different in composition and more diverse after storage than before. PMID:26678949

  8. Effects of storage on mixed-culture biological electrodes.

    PubMed

    Saheb Alam, Soroush; Persson, Frank; Wilén, Britt-Marie; Hermansson, Malte; Modin, Oskar

    2015-01-01

    Storage methods are important to preserve the viability and biochemical characteristics of microbial cultures between experiments or during periods when bioreactors are inactive. Most of the research on storage has focused on isolates; however, there is an increasing interest in methods for mixed cultures, which are of relevance in environmental biotechnology. The purpose of this study was to investigate the effect of different storage methods on electrochemically active enrichment cultures. Acetate-oxidizing bioanodes generating a current density of about 5 A m(-2) were enriched in a microbial electrolysis cell. The effect of five weeks of storage was evaluated using electrochemical techniques and microbial community analysis. Storage by refrigeration resulted in quicker re-activation than freezing in 10% glycerol, while the bioelectrochemical activity was entirely lost after storage using dehydration. The results showed that the bioelectrochemical activity of bioanodes stored at low temperature could be retained. However, during the re-activation period the bioanodes only recovered 75% of the current density generated before storage and the bacterial communities were different in composition and more diverse after storage than before. PMID:26678949

  9. Competition of Invertebrates Mixed Culture in the Closed Aquatic System

    NASA Astrophysics Data System (ADS)

    Pisman, Tamara

    The study considers the experimental model of interactions between invertebrates (the cilates Paramecium caudatum, Paramecium bursaria and the rotifers Brachionis plicatilis) in the closed aquatic system. The infusoria P.caudatum can feed on yeast, bacteria and chlorella; in this experiment growth and reproduction were maintained by bacteria only. The P.bursaria - zoochlorella endosymbiosis is a natural model of a simple biotic cycle. P.bursaria consumes glucose and oxygen released by zoochlorella in the process of biosynthesis and releases nitrogenous compounds and carbon dioxide necessary for algal photosynthesis. The rotifers Br. plicatilis can consume algae, bacteria and detritus. Thus in experiment with the mixed culture of invertebrates they can use different food sources. However with any initial percentage of the invertebrates the end portion of P.bursaria reaches 90-99

  10. Exploring Race, Culture, and Family in the Identities of Mixed Heritage Students

    ERIC Educational Resources Information Center

    Johnston-Guerrero, Marc P.; Pecero, Veronica

    2016-01-01

    Family plays an integral role in racial and cultural socialization, yet how mixed heritage students understand the concepts of race and culture in relation to family is unclear. This qualitative study explored the interplay of race, culture, and family in the identity constructions of 25 mixed heritage students. Findings suggest the centrality of…

  11. A Mixed-Culture Biofilm Model with Cross-Diffusion.

    PubMed

    Rahman, Kazi A; Sudarsan, Rangarajan; Eberl, Hermann J

    2015-11-01

    We propose a deterministic continuum model for mixed-culture biofilms. A crucial aspect is that movement of one species is affected by the presence of the other. This leads to a degenerate cross-diffusion system that generalizes an earlier single-species biofilm model. Two derivations of this new model are given. One, like cellular automata biofilm models, starts from a discrete in space lattice differential equation where the spatial interaction is described by microscopic rules. The other one starts from the same continuous mass balances that are the basis of other deterministic biofilm models, but it gives up a simplifying assumption of these models that has recently been criticized as being too restrictive in terms of ecological structure. We show that both model derivations lead to the same PDE model, if corresponding closure assumptions are introduced. To investigate the role of cross-diffusion, we conduct numerical simulations of three biofilm systems: competition, allelopathy and a mixed system formed by an aerobic and an anaerobic species. In all cases, we find that accounting for cross-diffusion affects local distribution of biomass, but it does not affect overall lumped quantities such as the total amount of biomass in the system. PMID:26582360

  12. A Mixed-Culture Biofilm Model with Cross-Diffusion.

    PubMed

    Rahman, Kazi A; Sudarsan, Rangarajan; Eberl, Hermann J

    2015-11-01

    We propose a deterministic continuum model for mixed-culture biofilms. A crucial aspect is that movement of one species is affected by the presence of the other. This leads to a degenerate cross-diffusion system that generalizes an earlier single-species biofilm model. Two derivations of this new model are given. One, like cellular automata biofilm models, starts from a discrete in space lattice differential equation where the spatial interaction is described by microscopic rules. The other one starts from the same continuous mass balances that are the basis of other deterministic biofilm models, but it gives up a simplifying assumption of these models that has recently been criticized as being too restrictive in terms of ecological structure. We show that both model derivations lead to the same PDE model, if corresponding closure assumptions are introduced. To investigate the role of cross-diffusion, we conduct numerical simulations of three biofilm systems: competition, allelopathy and a mixed system formed by an aerobic and an anaerobic species. In all cases, we find that accounting for cross-diffusion affects local distribution of biomass, but it does not affect overall lumped quantities such as the total amount of biomass in the system.

  13. Dimethylamine biodegradation by mixed culture enriched from drinking water biofilter.

    PubMed

    Liao, Xiaobin; Chen, Chao; Zhang, Jingxu; Dai, Yu; Zhang, Xiaojian; Xie, Shuguang

    2015-01-01

    Dimethylamine (DMA) is one of the important precursors of drinking water disinfection by-product N-nitrosodimethylamine (NDMA). Reduction of DMA to minimize the formation of carcinogenic NDMA in drinking water is of practical importance. Biodegradation plays a major role in elimination of DMA pollution in the environment, yet information on DMA removal by drinking water biofilter is still lacking. In this study, microcosms with different treatments were constructed to investigate the potential of DMA removal by a mixed culture enriched from a drinking water biofilter and the effects of carbon and nitrogen sources. DMA could be quickly mineralized by the enrichment culture. Amendment of a carbon source, instead of a nitrogen source, had a profound impact on DMA removal. A shift in bacterial community structure was observed with DMA biodegradation, affected by carbon and nitrogen sources. Proteobacteria was the predominant phylum group in DMA-degrading microcosms. Microorganisms from a variety of bacterial genera might be responsible for the rapid DMA mineralization.

  14. Lindane removal by pure and mixed cultures of immobilized actinobacteria.

    PubMed

    Saez, Juliana M; Benimeli, Claudia S; Amoroso, María J

    2012-11-01

    Lindane (γ-HCH) is an organochlorine insecticide that has been widely used in developing countries. It is known to persist in the environment and can cause serious health problems. One of the strategies adopted to remove lindane from the environment is bioremediation using microorganisms. Immobilized cells present advantages over free suspended cells, like their high degradation efficiency and protection against toxins. The aims of this work were: (1) To evaluate the ability of Streptomyces strains immobilized in four different matrices to remove lindane, (2) To select the support with optimum lindane removal by pure cultures, (3) To assay the selected support with consortia and (4) To evaluate the reusability of the immobilized cells. Four Streptomyces sp. strains had previously shown their ability to grow in the presence of lindane. Lindane removal by microorganisms immobilized was significantly higher than in free cells. Specifically immobilized cells in cloth sachets showed an improvement of around 25% in lindane removal compared to the abiotic control. Three strains showed significantly higher microbial growth when they were entrapped in silicone tubes. Strains immobilized in PVA-alginate demonstrated lowest growth. Mixed cultures immobilized inside cloth sachets showed no significant enhancement compared to pure cultures, reaching a maximum removal of 81% after 96 h for consortium I, consisting of the four immobilized strains together. Nevertheless, the cells could be reused for two additional cycles of 96 h each, obtaining a maximum removal efficiency of 71.5% when each of the four strains was immobilized in a separate bag (consortium III). PMID:22840534

  15. Comparisons of growth and biochemical composition between mixed culture of alga and yeast and monocultures.

    PubMed

    Cai, Shiqing; Hu, Chaoqun; Du, Shaobo

    2007-11-01

    The alga Isochrysis galbana 8701 and the yeast Ambrosiozyma cicatricosa were mix-cultivated in the same medium for 7 d to compare their growth performance and biochemical composition with those of the same organisms cultured under monoculture conditions. The specific growth rates of both species were significantly higher (p<0.05) in the mixed culture than in the monocultures during the corresponding experimental phases. At the end of experiment, the biomass concentration obtained in the mixed culture reached 1.32+/-0.04 g/l of dry weight, which was significantly higher (p<0.05) than those obtained in monocultures, and the alga I. galbana in the mixed culture dominated the cell numbers making up 96.64% of the cells. The biochemical profile of the mixed culture is similar to that of the I. galbana monoculture with some variations; The percentages of both the fatty acids 14:00 and 18:00 detected in the mixed culture were significantly higher (p<0.05) than those detected in the I. galbana monoculture, while the content of the fatty acid 18:2(n-6) detected in the mixed culture was significantly lower (p<0.05) than that detected in the I. galbana monoculture. This study indicates the improved growth performance in mixed culture compared with monocultures and the similarities between the biochemical compositions of the mixed culture and the I. galbana monoculture.

  16. Transformation of toluene and benzene by mixed methanogenic cultures.

    PubMed Central

    Grbić-Galić, D; Vogel, T M

    1987-01-01

    The aromatic hydrocarbons toluene and benzene were anaerobically transformed by mixed methanogenic cultures derived from ferulic acid-degrading sewage sludge enrichments. In most experiments, toluene or benzene was the only semicontinuously supplied carbon and energy source in the defined mineral medium. No exogenous electron acceptors other than CO2 were present. The cultures were fed 1.5 to 30 mM unlabeled or 14C-labeled aromatic substrates (ring-labeled toluene and benzene or methyl-labeled toluene). Gas production from unlabeled substrates and 14C activity distribution in products from the labeled substrates were monitored over a period of 60 days. At least 50% of the substrates were converted to CO2 and methane (greater than 60%). A high percentage of 14CO2 was recovered from the methyl group-labeled toluene, suggesting nearly complete conversion of the methyl group to CO2 and not to methane. However, a low percentage of 14CO2 was produced from ring-labeled toluene or from benzene, indicating incomplete conversion of the ring carbon to CO2. Anaerobic transformation pathways for unlabeled toluene and benzene were studied with the help of gas chromatography-mass spectrometry. The intermediates detected are consistent with both toluene and benzene degradation via initial oxidation by ring hydroxylation or methyl oxidation (toluene), which would result in the production of phenol, cresols, or aromatic alcohol. Additional reactions, such as demethylation and ring reduction, are also possible. Tentative transformation sequences based upon the intermediates detected are discussed. PMID:3105454

  17. Xylose anaerobic conversion by open-mixed cultures.

    PubMed

    Temudo, Margarida F; Mato, Tania; Kleerebezem, Robbert; van Loosdrecht, Mark C M

    2009-02-01

    Xylose is, after glucose, the dominant sugar in agricultural wastes. In anaerobic environments, carbohydrates are converted into volatile fatty acids and alcohols. These can be used as building blocks in biotechnological or chemical processes, e.g., to produce bioplastics. In this study, xylose fermentation by mixed microbial cultures was investigated and compared with glucose under the same conditions. The product spectrum obtained with both substrates was comparable. It was observed that, in the case of xylose, a higher fraction of the carbon was converted into catabolic products (butyrate, acetate, and ethanol) and the biomass yield was approximately 20% lower than on glucose, 0.16 versus 0.21 Cmol X/Cmol S. This lower yield is likely related to the need of an extra ATP during xylose uptake. When submitted to a pulse of glucose, the population cultivated on xylose could instantaneously convert the glucose. No substrate preference was observed when glucose and xylose were fed simultaneously to the continuously operated bioreactor. PMID:19015850

  18. KINETICS OF CHROMATE REDUCTION DURING NAPHTHALENE DEGRADATION IN A MIXED CULTURE

    EPA Science Inventory

    A mixed culture of Bacillus sp. K1 and Sphingomonas paucimobilis EPA 505 was exposed to chromate and naphthalene. Batch experiments showed that chromate was reduced and naphthalene was degraded by the mixed culture. Chromate reduction occurred initially at a high rate followed by...

  19. Kinetics of chromate reduction during naphthalene degradation in a mixed culture

    SciTech Connect

    Shen, H.; Sewell, G.W.; Pritchard, P.H.

    1996-11-05

    A mixed culture of Bacillus sp. K1 and Sphingomonas paucimobilis EPA 505 was exposed to chromate and naphthalene. Batch experiments showed that chromate was reduced and naphthalene was degraded by the mixed culture. Chromate reduction occurred initially at a high rate followed by a decrease in rate until chromate reduction ceased. Chromate reduction decreased in the mixed culture when a lower ratio of S. paucimobilis EPA 505 to Bacillus sp. K1 was utilized. A kinetic model incorporating a term for the cell density ratio is proposed to describe chromate reduction in the mixed culture under both chromate limited and electron donor limited conditions. The validity of the model, and its parameter values, was verified by experimental data generated under a variety of initial population compositions and a broad range of chromate concentrations. The consistent result of experimental data with model predictions implies that the model is useful for evaluating the interactions and the use of mixed culture for chromate removal.

  20. A Mixed Methodological Analysis of the Role of Culture in the Clinical Decision-Making Process

    ERIC Educational Resources Information Center

    Hays, Danica G.; Prosek, Elizabeth A.; McLeod, Amy L.

    2010-01-01

    Even though literature indicates that particular cultural groups receive more severe diagnoses at disproportionate rates, there has been minimal research that addresses how culture interfaces specifically with clinical decision making. This mixed methodological study of 41 counselors indicated that cultural characteristics of both counselors and…

  1. A Review of International Cross-Cultural Mixed Messages and Their Implications for Human Resource Development

    ERIC Educational Resources Information Center

    Altman, Brian A.

    2013-01-01

    This paper presents a literature review on the concept of international cross-cultural mixed messages. Although there is limited literature on this topic, the review suggests that messages from one's home culture and a second culture can result in conflicting expectations for one's own behavior and for the behavior of others. Double bind theory is…

  2. Effects of transgenic soybean on growth and phosphorus acquisition in mixed culture system.

    PubMed

    Xie, Jianna; Zhou, Jia; Wang, Xiurong; Liao, Hong

    2015-05-01

    Transgenic soybean plants overexpressing the Arabidopsis purple acid phosphatase gene AtPAP15 (OXp) or the soybean expansin gene GmEXPB2 (OXe) can improve phosphorous (P) efficiency in pure culture by increasing Apase secretion or changing root morphology. In this study, soybean-soybean mixed cultures were employed to illuminate P acquisition among plants in mixed stands of transgenic and wild-type soybean. Our results showed that transgenic soybean plants were much more competitive, and had greater growth and P uptake than wild-type soybean in mixed culture in both low P calcareous and acid soils. Furthermore, OXe plants had an advantage in calcareous soils when mixed with OXp, whereas the latter performed much better in acid soils. In soybean-maize mixed culture, transgenic soybean had no impact on maize growth compared to controls in both acid and calcareous soils with different P conditions. As for soybean in mixed culture, OXp plants had no significant advantages regardless of P availability or soil type, while P efficiency improved in OXe in calcareous soils compared to controls. These results imply that physiological traits could be easily affected by the mixed maize. Transgenic soybean plants with enhanced root traits had more competitive advantages than those with improved root physiology in mixed culture. PMID:25048220

  3. Effects of transgenic soybean on growth and phosphorus acquisition in mixed culture system.

    PubMed

    Xie, Jianna; Zhou, Jia; Wang, Xiurong; Liao, Hong

    2015-05-01

    Transgenic soybean plants overexpressing the Arabidopsis purple acid phosphatase gene AtPAP15 (OXp) or the soybean expansin gene GmEXPB2 (OXe) can improve phosphorous (P) efficiency in pure culture by increasing Apase secretion or changing root morphology. In this study, soybean-soybean mixed cultures were employed to illuminate P acquisition among plants in mixed stands of transgenic and wild-type soybean. Our results showed that transgenic soybean plants were much more competitive, and had greater growth and P uptake than wild-type soybean in mixed culture in both low P calcareous and acid soils. Furthermore, OXe plants had an advantage in calcareous soils when mixed with OXp, whereas the latter performed much better in acid soils. In soybean-maize mixed culture, transgenic soybean had no impact on maize growth compared to controls in both acid and calcareous soils with different P conditions. As for soybean in mixed culture, OXp plants had no significant advantages regardless of P availability or soil type, while P efficiency improved in OXe in calcareous soils compared to controls. These results imply that physiological traits could be easily affected by the mixed maize. Transgenic soybean plants with enhanced root traits had more competitive advantages than those with improved root physiology in mixed culture.

  4. Sequential Mixed Cultures: From Syngas to Malic Acid.

    PubMed

    Oswald, Florian; Dörsam, Stefan; Veith, Nicolas; Zwick, Michaela; Neumann, Anke; Ochsenreither, Katrin; Syldatk, Christoph

    2016-01-01

    Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C4-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H2, 16 vol-% CO2, and 19 vol-% N2) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH4Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave YP∕S values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion

  5. Sequential Mixed Cultures: From Syngas to Malic Acid.

    PubMed

    Oswald, Florian; Dörsam, Stefan; Veith, Nicolas; Zwick, Michaela; Neumann, Anke; Ochsenreither, Katrin; Syldatk, Christoph

    2016-01-01

    Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C4-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H2, 16 vol-% CO2, and 19 vol-% N2) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH4Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave YP∕S values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion

  6. Sequential Mixed Cultures: From Syngas to Malic Acid

    PubMed Central

    Oswald, Florian; Dörsam, Stefan; Veith, Nicolas; Zwick, Michaela; Neumann, Anke; Ochsenreither, Katrin; Syldatk, Christoph

    2016-01-01

    Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C4-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H2, 16 vol-% CO2, and 19 vol-% N2) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH4Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave YP∕S values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion

  7. Spatial distributions of sulphur species and sulphate-reducing bacteria provide insights into sulphur redox cycling and biodegradation hot-spots in a hydrocarbon-contaminated aquifer

    NASA Astrophysics Data System (ADS)

    Einsiedl, Florian; Pilloni, Giovanni; Ruth-Anneser, Bettina; Lueders, Tillman; Griebler, Christian

    2015-05-01

    Dissimilatory sulphate reduction (DSR) has been proven to be one of the most relevant redox reactions in the biodegradation of contaminants in groundwater. However, the possible role of sulphur species of intermediate oxidation state, as well as the role of potential re-oxidative sulphur cycling in biodegradation particularly at the groundwater table are still poorly understood. Here we used a combination of stable isotope measurements of SO42-, H2S, and S0 as well as geochemical profiling of sulphur intermediates with special emphasis on SO32-, S2O32-, and S0 to unravel possible sulphur cycling in the biodegradation of aromatics in a hydrocarbon-contaminated porous aquifer. By linking these results to the quantification of total bacterial rRNA genes and respiratory genes of sulphate reducers, as well as pyrotag sequencing of bacterial communities over depth, light is shed on possible key-organisms involved. Our results substantiate the role of DSR in biodegradation of hydrocarbons (mainly toluene) in the highly active plume fringes above and beneath the plume core. In both zones the concentration of sulphur intermediates (S0, SO32- and S2O32-) was almost twice that of other sampling-depths, indicating intense sulphur redox cycling. The dual isotopic fingerprint of oxygen and sulphur in dissolved sulphate suggested a re-oxidation of reduced sulphur compounds to sulphate especially at the upper fringe zone. An isotopic shift in δ34S of S0 of nearly +4‰ compared to the δ34S values of H2S from the same depth linked to a high abundance (∼10%) of sequence reads related to Sulphuricurvum spp. (Epsilonproteobacteria) in the same depth were indicative of intensive oxidation of S0 to sulphate in this zone. At the lower plume fringe S0 constituted the main inorganic sulphur species, possibly formed by abiotic re-oxidation of H2S with Fe(III)oxides subsequent to sulphate reduction. These results provide first insights into intense sulphur redox cycling in a hydrocarbon

  8. Methodological issues in life cycle assessment of mixed-culture polyhydroxyalkanoate production utilising waste as feedstock.

    PubMed

    Heimersson, Sara; Morgan-Sagastume, Fernando; Peters, Gregory M; Werker, Alan; Svanström, Magdalena

    2014-06-25

    Assessing the environmental performance of emerging technologies using life cycle assessment (LCA) can be challenging due to a lack of data in relation to technologies, application areas or other life cycle considerations, or a lack of LCA methodology that address the specific concerns. Nevertheless, LCA can be a valuable tool in the environmental optimisation in the technology development phase. One emerging technology is the mixed-culture production of polyhydroxyalkanoates (PHAs). PHA production by pure microbial cultures has been developed and assessed in several LCAs during the previous decade. Recent developments within mixed-culture PHA production call for environmental assessment to guide in technology development. Mixed-culture PHA production can use the organic content in wastewater as a feedstock; the production may then be integrated with wastewater treatment (WWT) processes. This means that mixed-culture PHA is produced as a by-product from services in the WWT. This article explores different methodological challenges for LCA of mixed-culture PHA production using organic material in wastewater as feedstock. LCAs of both pure- and mixed-culture PHA production were reviewed. Challenges, similarities and differences when assessing PHA production by mixed- or pure-cultures were identified and the resulting implications for methodological choices in LCA were evaluated and illustrated, using a case study with mixed- and pure-culture PHA model production systems, based on literature data. Environmental impacts of processes producing multiple products or services need to be allocated between the different products or services. Such situations occur both in feedstock production and when the studied system is providing multiple functions. The selection of allocation method is shown to determine the LCA results. The type of data used, for electricity in the energy system, is shown to be important for the results, which indicates, a strong regional dependency of

  9. Lactic Acid Production in a Mixed-Culture Biofilm Reactor †

    PubMed Central

    Demirci, Ali; Pometto, Anthony L.; Johnson, Kenneth E.

    1993-01-01

    Novel solid supports, consisting of polypropylene blended with various agricultural materials (pp composite), were evaluated as supports for pure- and mixed-culture continuous lactic acid fermentations in biofilm reactors. Streptomyces viridosporus T7A (ATCC 39115) was used to form a biofilm, and Lactobacillus casei subsp. rhamnosus (ATCC 11443) was used for lactic acid production. For mixed-culture fermentations, a 15-day continuous fermentation of S. viridosporus was performed initially to establish the biofilm. The culture medium was then inoculated with L. casei subsp. rhamnosus. For pure-culture fermentation, L. casei subsp. rhamnosus was inoculated directly into the reactors containing sterile pp composite chips. The biofilm reactors containing various pp composite chips were compared with a biofilm reactor containing pure polypropylene chips and with a reactor containing a suspension culture. Continuous fermentation was started, and each flow rate (0.06 to 1.92 ml/min) was held constant for 24 h; steady state was achieved after 10 h. Lactic acid production was determined throughout the 24-h period by high-performance liquid chromatography. Production rates that were two to five times faster than those of the suspension culture (control) were observed for the pure- and mixed-culture bioreactors. Both lactic acid production rates and lactic acid concentrations in the culture medium were consistently higher in mixed-culture than in pure-culture fermentations. Biofilm formation on the chips was detected at harvest by chip clumping and Gram staining. PMID:16348843

  10. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination.

    PubMed

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-06-10

    Fermentative hydrogen production from wastes has many advantages compared to various chemical methods. Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack of such kind of standardized methodologies. In the present study, a new index, i.e., the maximum specific hydrogen-producing activity (SHAm) of anaerobic mixed cultures, was proposed, and consequently a reliable and simple method, named SHAm test, was developed to determine it. Furthermore, the influences of various parameters on the SHAm value determination of anaerobic mixed cultures were evaluated. Additionally, this SHAm assay was tested for different types of substrates and bacterial inocula. Our results demonstrate that this novel SHAm assay was a rapid, accurate and simple methodology for determining the hydrogen-producing activity of anaerobic mixed cultures. Thus, application of this approach is beneficial to establishing a stable anaerobic hydrogen-producing system.

  11. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination

    NASA Astrophysics Data System (ADS)

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-06-01

    Fermentative hydrogen production from wastes has many advantages compared to various chemical methods. Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack of such kind of standardized methodologies. In the present study, a new index, i.e., the maximum specific hydrogen-producing activity (SHAm) of anaerobic mixed cultures, was proposed, and consequently a reliable and simple method, named SHAm test, was developed to determine it. Furthermore, the influences of various parameters on the SHAm value determination of anaerobic mixed cultures were evaluated. Additionally, this SHAm assay was tested for different types of substrates and bacterial inocula. Our results demonstrate that this novel SHAm assay was a rapid, accurate and simple methodology for determining the hydrogen-producing activity of anaerobic mixed cultures. Thus, application of this approach is beneficial to establishing a stable anaerobic hydrogen-producing system.

  12. Mixed culture syngas fermentation and conversion of carboxylic acids into alcohols.

    PubMed

    Liu, Kan; Atiyeh, Hasan K; Stevenson, Bradley S; Tanner, Ralph S; Wilkins, Mark R; Huhnke, Raymond L

    2014-01-01

    Higher alcohols such as n-butanol and n-hexanol have higher energy density than ethanol, are more compatible with current fuel infrastructure, and can be upgraded to jet and diesel fuels. Several organisms are known to convert syngas to ethanol, but very few can produce higher alcohols alone. As a potential solution, mixed culture fermentation between the syngas fermenting Alkalibaculum bacchi strain CP15 and propionic acid producer Clostridium propionicum was studied. The monoculture of CP15 produced only ethanol from syngas without initial addition of organic acids to the fermentation medium. However, the mixed culture produced ethanol, n-propanol and n-butanol from syngas. The addition of propionic acid, butyric acid and hexanoic acid to the mixed culture resulted in a 50% higher conversion efficiency of these acids to their respective alcohols compared to CP15 monoculture. These findings illustrate the great potential of mixed culture syngas fermentation in production of higher alcohols.

  13. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions

    EPA Science Inventory

    The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under drinking water relevant conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Three batch reactors were used in each ...

  14. 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

  15. Ethanol production from starch by a coimmobilized mixed culture system of Aspergillus awamori and Zymomonas mobilis

    SciTech Connect

    Tanaka, H.; Kurosawa, H.; Murakami, H.

    1986-01-01

    The production of ethanol from starch by a coimmobilized mixed culture system of aerobic and anaerobic microorganisms in Ca-alginate gel beads was investigated. The mold Aspergillus awamori was used as an aerobic amylolytic microorganism and an anaerobic bacterium, Zymomonas mobilis, as an ethanol producer. By controlling the mixing ratio of the microorganisms in the inoculum size, a desirable coimmobilized mixed culture system, in which the aerobic mycelia grew on and near the oxygen-rich surface of the gel beads while the anaerobic bacterial cells mainly grew in the oxygen-deficient central part of the gel beads, was naturally established under the aerobic culture conditions, and ethanol could be directly produced from starch by the system. The ethanol productivity by the system in flask culture was particularly affected by the shear stress (dependent on the shaking speed) which controlled the mycelial growth on the surface of the gel beads. Under optimum culture conditions in the flask culture, the glucose produced was instantly consumed, and was not observed in the culture broth; the final concentration of ethanol produced from 100 g/L starch was 25 g/L and the yield coefficient for ethanol, Y/sub p/s/, was 0.38. The ethanol productivity by the coimmobilized mixed culture system was compared with those by other various culture systems and the advantages of the system were clarified.

  16. Preparation of Rodent Primary Cultures for Neuron–Glia, Mixed Glia, Enriched Microglia, and Reconstituted Cultures with Microglia

    PubMed Central

    Chen, Shih-Heng; Oyarzabal, Esteban A.; Hong, Jau-Shyong

    2016-01-01

    Microglia, neurons, and macroglia (astrocytes and oligodendrocytes) are the major cell types in the central nervous system. In the past decades, primary microglia-enriched cultures have been widely used to study the biological functions of microglia in vitro. In order to study the interactions between microglia and other brain cells, neuron–glia, neuron–microglia, and mixed glia cultures were developed. The aim of this chapter is to provide basic and adaptable protocols for the preparation of these microglia-containing primary cultures from rodent. Meanwhile, we also want to provide a collection of tips from our collective experiences doing primary brain cell cultures. PMID:23813383

  17. Degradation of mix hydrocarbons by immobilized cells of mix culture using a trickle fluidized bed reactor. Annual progress report, June 1992--May 1993

    SciTech Connect

    Chapatwala, K.D.

    1993-06-01

    The microorganisms, capable of degrading mix hydrocarbons were isolated from the soil samples collected from the hydrocarbon contaminated sites. The mix cultures were immobilized in calcium alginate solution in the form of beads. A trickle fluidized bed air-uplift-type reactor designed to study the degradation of mix hydrocarbons was filled with 0.85% normal saline containing the immobilized cells of mix culture. The immobilized beads were aerated with CO{sub 2}-free air at 200 ml/min. The degradation of different concentrations of hydrocarbons in the presence/absence of commercially available fertilizers by the immobilized cells of mix culture is now in progress.

  18. FT-IR microspectroscopy in rapid identification of bacteria in pure and mixed culture

    NASA Astrophysics Data System (ADS)

    Fontoura, Inglid; Belo, Ricardo; Sakane, Kumiko; Cardoso, Maria Angélica Gargione; Khouri, Sônia; Uehara, Mituo; Raniero, Leandro; Martin, Airton A.

    2010-02-01

    In recent years FT-IR microspectroscopy has been developed for microbiology analysis and applied successfully in pure cultures of microorganisms to rapidly identify strains of bacteria, yeasts and fungi. The investigation and characterization of microorganism mixed cultures is also of growing importance, especially in hospitals where it is common to poly-microbial infections. In this work, the rapid identification of bacteria in pure and mixed cultures was studied. The bacteria were obtained from the Institute Oswaldo Cruz culture collection at Brazil. Escherichia coli ATCC 10799 and Staphylococcus aureus ATCC 14456 were analyzed, 3 inoculations were examined in triplicate: Escherichia coli, Staphylococcus aureus and a mixed culture of them. The inoculations were prepared according to McFarland 0.5, incubated at 37 ° C for 6 hours, diluted in saline, placed in the CaF2 window and store for one hour at 50°C to obtain thin film. The measurement was performed by Spectrum Spotlight 400 (Perkin-Elmer) equipment in the range of 4000-900 cm-1, with 32 scans using a transmittance technique with point and image modes. The data were processed (baseline, normalization, calculation of first derivate followed by smoothing with 9 point using a Savitzky-Golay algorithm) and a cluster analysis were done by Ward's algorithm and an excellent discrimination between pure and mixed culture was obtained. Our preliminary results indicate that the FT-IR microspectroscopy associated with cluster analysis can be used to discriminate between pure and mixed culture.

  19. Perceptions of Organizational Culture of a Multi-Campus Community College District: Mixed Methods in Concert

    ERIC Educational Resources Information Center

    Kuster Dale, Kimberly

    2012-01-01

    This concurrent, mixed-methods case study analyzed perceptions of current and preferred organizational culture within a rural, multi-campus community college district. This phenomenon was examined by analyzing and comparing data collected by surveying all full-time employees utilizing the Organizational Culture Assessment Instrument (OCAI) and…

  20. A simple eccentric stirred tank mini-bioreactor: mixing characterization and mammalian cell culture experiments.

    PubMed

    Bulnes-Abundis, David; Carrillo-Cocom, Leydi M; Aráiz-Hernández, Diana; García-Ulloa, Alfonso; Granados-Pastor, Marisa; Sánchez-Arreola, Pamela B; Murugappan, Gayathree; Alvarez, Mario M

    2013-04-01

    In industrial practice, stirred tank bioreactors are the most common mammalian cell culture platform. However, research and screening protocols at the laboratory scale (i.e., 5-100 mL) rely primarily on Petri dishes, culture bottles, or Erlenmeyer flasks. There is a clear need for simple-easy to assemble, easy to use, easy to clean-cell culture mini-bioreactors for lab-scale and/or screening applications. Here, we study the mixing performance and culture adequacy of a 30 mL eccentric stirred tank mini-bioreactor. A detailed mixing characterization of the proposed bioreactor is presented. Laser induced fluorescence (LIF) experiments and computational fluid dynamics (CFD) computations are used to identify the operational conditions required for adequate mixing. Mammalian cell culture experiments were conducted with two different cell models. The specific growth rate and the maximum cell density of Chinese hamster ovary (CHO) cell cultures grown in the mini-bioreactor were comparable to those observed for 6-well culture plates, Erlenmeyer flasks, and 1 L fully instrumented bioreactors. Human hematopoietic stem cells were successfully expanded tenfold in suspension conditions using the eccentric mini-bioreactor system. Our results demonstrate good mixing performance and suggest the practicality and adequacy of the proposed mini-bioreactor.

  1. A simple eccentric stirred tank mini-bioreactor: mixing characterization and mammalian cell culture experiments.

    PubMed

    Bulnes-Abundis, David; Carrillo-Cocom, Leydi M; Aráiz-Hernández, Diana; García-Ulloa, Alfonso; Granados-Pastor, Marisa; Sánchez-Arreola, Pamela B; Murugappan, Gayathree; Alvarez, Mario M

    2013-04-01

    In industrial practice, stirred tank bioreactors are the most common mammalian cell culture platform. However, research and screening protocols at the laboratory scale (i.e., 5-100 mL) rely primarily on Petri dishes, culture bottles, or Erlenmeyer flasks. There is a clear need for simple-easy to assemble, easy to use, easy to clean-cell culture mini-bioreactors for lab-scale and/or screening applications. Here, we study the mixing performance and culture adequacy of a 30 mL eccentric stirred tank mini-bioreactor. A detailed mixing characterization of the proposed bioreactor is presented. Laser induced fluorescence (LIF) experiments and computational fluid dynamics (CFD) computations are used to identify the operational conditions required for adequate mixing. Mammalian cell culture experiments were conducted with two different cell models. The specific growth rate and the maximum cell density of Chinese hamster ovary (CHO) cell cultures grown in the mini-bioreactor were comparable to those observed for 6-well culture plates, Erlenmeyer flasks, and 1 L fully instrumented bioreactors. Human hematopoietic stem cells were successfully expanded tenfold in suspension conditions using the eccentric mini-bioreactor system. Our results demonstrate good mixing performance and suggest the practicality and adequacy of the proposed mini-bioreactor. PMID:23124589

  2. Cultural Consensus and Cultural Diversity: A Mixed Methods Investigation of Human Service Providers' Models of Domestic Violence

    ERIC Educational Resources Information Center

    Collins, Cyleste C.; Dressler, William W.

    2008-01-01

    This study uses mixed methods and theory from cognitive anthropology to examine the cultural models of domestic violence among domestic violence agency workers, welfare workers, nurses, and a general population comparison group. Data collection and analysis uses quantitative and qualitative techniques, and the findings are integrated for…

  3. 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

  4. Batch fermentative hydrogen production by enriched mixed culture: Combination strategy and their microbial composition.

    PubMed

    Sivagurunathan, Periyasamy; Sen, Biswarup; Lin, Chiu-Yue

    2014-02-01

    The effect of individual and combined mixed culture on dark fermentative hydrogen production performance was investigated. Mixed cultures from cow dung (C1), sewage sludge (C2), and pig slurry (C3) were enriched under strict anaerobic conditions at 37°C with glucose as the sole carbon source. Biochemical hydrogen production test in peptone-yeast-glucose (PYG) and basal medium was performed for individual mixed cultures (C1, C2 and C3) and their combinations (C1-C2, C2-C3, C1-C3 and C1-C2-C3) at a glucose concentration of 10 g/L, 37°C and initial pH 7. Maximum hydrogen yields (HY) of 2.0 and 1.86 [Formula: see text] by C2, and 1.98 and 1.95 mol(H2)/mol(glucose) by C2-C3 were obtained in PYG and basal medium, respectively. Butyrate and acetate were the major soluble metabolites produced by all the cultures, and the ratio of butyrate to acetate was ∼2 fold higher in basal medium than PYG medium, indicating strong influence of media formulation on glucose catabolism. The major hydrogen-producing bacterial strains, observed in all mixed cultures, belonged to Clostridium butyricum, C. saccharobutylicum, C. tertium and C. perfringens. The hydrogen production performance of the combined mixed culture (C2-C3) was further evaluated on beverage wastewater (10 g/L) at pH 7 and 37°C. The results showed an HY of 1.92 mol(H2)/mol(glucose-equivalent). Experimental evidence suggests that hydrogen fermentation by mixed culture combination could be a novel strategy to improve the HY from industrial wastewater.

  5. Effect of culture phasing and mannanase on production of cellulase and hemicellulase by mixed culture of Trichoderma reesei D 1-6 and Aspergillus wentii Pt 2804

    SciTech Connect

    Ghose, T.K.; Panda, T.; Bisaria, V.S.

    1985-09-01

    Significant increase in extracellular cellulase and hemicellulase activities was observed in the biosynthesis of cellulase enzyme in mixed culture fermentation of Trichoderma reesei D 1-6 and Aspergillus wentii Pt 2804 when the A. wentii inoculation was phased by 15 hours. The optimal conditions of fermentation by the mixed culture have been established. Presence of mannanase has been found to affect the release as well as activity of cellulase enzyme produced in mixed culture.

  6. Culturally Mixed Groups on International Campuses: An Opportunity for Inter-Cultural Learning

    ERIC Educational Resources Information Center

    Volet, S. E.; Ang, G.

    2012-01-01

    One of the major educational goals of the internationalisation of higher education is to prepare students to function in an international and inter-cultural context. Cultural diversity on university campuses creates ideal social forums for inter-cultural learning, yet, one of the most disturbing aspects of the internationalisation of higher…

  7. Lactic acid production by mixed cultures of Kluyveromyces marxianus, Lactobacillus delbrueckii ssp. bulgaricus and Lactobacillus helveticus.

    PubMed

    Plessas, S; Bosnea, L; Psarianos, C; Koutinas, A A; Marchant, R; Banat, I M

    2008-09-01

    Lactic acid production using Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) individually or as mixed culture on cheese whey in stirred or static fermentation conditions was evaluated. Lactic acid production, residual sugar and cell biomass were the main features examined. Increased lactic acid production was observed, when mixed cultures were used in comparison to individual ones. The highest lactic acid concentrations were achieved when K. marxianus yeast was combined with L. delbrueckii ssp. bulgaricus, and when all the strains were used revealing possible synergistic effects between the yeast and the two lactic acid bacteria. The same synergistic effects were further observed and verified when the mixed cultures were applied in sourdough fermentations, proving that the above microbiological system could be applied in the food fermentations where high lactic acid production is sought.

  8. Mixing against culture vs mixing against nature: ontologization of prohibited interethnic relationships.

    PubMed

    Roncarati, Alessandra; Pérez, Juan A; Ravenna, Marcella; Navarro-Pertusa, Esperanza

    2009-02-01

    In this paper, we develop the theory of ontologization: Social representations that prevent members of minority and majority groups who are living in contact with each other to mingle. The process of ontologization consists of separating some humans from their own species, and anchoring them in another environment, that of an animal, for example. We propose that underlying the famous slogan "equal but separate" is the social representation of interracial mixing as a "counter-nature" phenomenon. It is predicted that a sexual relationship between people of different "races" leads to a greater degree of ontologization, and, as such, this miscegenation will be explained in terms of biologistic thinking, like an instinctive nature or atavistic animal impulse. An experiment (N = 360) features the case of a woman who, though already in a stable relationship, is unfaithful to her partner. In a 2×3 factor design, the ethnic-national identity of this woman (in-group: Spanish/Italian vs out-group: Senegalese) and the ethnic-national identity of her lovers (in-group: Spanish/Italian vs out-group: Rumanian vs out-group: Senegalese) were manipulated. In general, results fit the hypothesis of ontologization in interracial conditions better, rather than the customary in-group favouritism and/or out-group discrimination bias. We then go on to discuss the way in which a biologistic way of thinking enables a differentiation at the human level, in terms of culture groups and nature groups, in "races," so that an interracial sexual relationship is seen as evidence of a wild and irrepressible impulse, which stigmatizes the people involved in these relationships. This research was supported by the Italian/Spanish Integrated Action Program HI2004_0241 and the Spanish Ministerio de Ciencia y Tecnología BSO2003-00476/PSCE. Dans cet article, nous développons la théorie de l'ontologisation: des représentations sociales qui empêchent les membres des groupes minoritaire et majoritaire

  9. Mixing against culture vs mixing against nature: ontologization of prohibited interethnic relationships.

    PubMed

    Roncarati, Alessandra; Pérez, Juan A; Ravenna, Marcella; Navarro-Pertusa, Esperanza

    2009-02-01

    In this paper, we develop the theory of ontologization: Social representations that prevent members of minority and majority groups who are living in contact with each other to mingle. The process of ontologization consists of separating some humans from their own species, and anchoring them in another environment, that of an animal, for example. We propose that underlying the famous slogan "equal but separate" is the social representation of interracial mixing as a "counter-nature" phenomenon. It is predicted that a sexual relationship between people of different "races" leads to a greater degree of ontologization, and, as such, this miscegenation will be explained in terms of biologistic thinking, like an instinctive nature or atavistic animal impulse. An experiment (N = 360) features the case of a woman who, though already in a stable relationship, is unfaithful to her partner. In a 2×3 factor design, the ethnic-national identity of this woman (in-group: Spanish/Italian vs out-group: Senegalese) and the ethnic-national identity of her lovers (in-group: Spanish/Italian vs out-group: Rumanian vs out-group: Senegalese) were manipulated. In general, results fit the hypothesis of ontologization in interracial conditions better, rather than the customary in-group favouritism and/or out-group discrimination bias. We then go on to discuss the way in which a biologistic way of thinking enables a differentiation at the human level, in terms of culture groups and nature groups, in "races," so that an interracial sexual relationship is seen as evidence of a wild and irrepressible impulse, which stigmatizes the people involved in these relationships. This research was supported by the Italian/Spanish Integrated Action Program HI2004_0241 and the Spanish Ministerio de Ciencia y Tecnología BSO2003-00476/PSCE. Dans cet article, nous développons la théorie de l'ontologisation: des représentations sociales qui empêchent les membres des groupes minoritaire et majoritaire

  10. Metabolites from the Fungal Endophyte Aspergillus austroafricanus in Axenic Culture and in Fungal-Bacterial Mixed Cultures.

    PubMed

    Ebrahim, Weaam; El-Neketi, Mona; Lewald, Laura-Isabell; Orfali, Raha S; Lin, Wenhan; Rehberg, Nidja; Kalscheuer, Rainer; Daletos, Georgios; Proksch, Peter

    2016-04-22

    The endophytic fungus Aspergillus austroafricanus isolated from leaves of the aquatic plant Eichhornia crassipes was fermented axenically on solid rice medium as well as in mixed cultures with Bacillus subtilis or with Streptomyces lividans. Chromatographic analysis of EtOAc extract of axenic cultures afforded two new metabolites, namely, the xanthone dimer austradixanthone (1) and the sesquiterpene (+)-austrosene (2), along with five known compounds (3-7). Austradixanthone (1) represents the first highly oxygenated heterodimeric xanthone derivative. When A. austroafricanus was grown in mixed cultures with B. subtilis or with S. lividans, several diphenyl ethers (8-11) including the new austramide (8) were induced up to 29-fold. The structures of new compounds were unambiguously elucidated using 1D- and 2D-NMR spectroscopy, HRESIMS, and chemical derivatization. Compound 7 exhibited weak cytotoxicity against the murine lymphoma L5178Y cell line (EC50 is 12.6 μM). In addition, compounds 9 and 10, which were enhanced in mixed fungal/bacterial cultures, proved to be active against Staphylococcus aureus (ATCC 700699) with minimal inhibitory concentrations (MICs) of 25 μM each (6.6 μg/mL), whereas compound 11 revealed moderate antibacterial activity against B. subtilis 168 trpC2 with an MIC value of 34.8 μM (8 μg/mL).

  11. Evaluation of mono or mixed cultures of lactic acid bacteria in type II sourdough system.

    PubMed

    Ekinci, Raci; Şimşek, Ömer; Küçükçuban, Ayca; Nas, Sebahattin

    2016-01-01

    The aim of this study was to evaluate the use of mono and mixed lactic acid bacteria (LAB) cultures to determine suitable LAB combinations for a type II sourdough system. In this context, previously isolated sourdough LAB strains with antimicrobial activity, which included Lactobacillus plantarum PFC22, Lactobacillus brevis PFC31, Pediococcus acidilactici PFC38, and Lactobacillus sanfranciscensis PFC80, were used as mono or mixed culture combinations in a fermentation system to produce type II sourdough, and subsequently in bread dough production. Compared to the monoculture fermentation of dough, the use of mixed cultures shortened the adaptation period by half. In addition, the use of mixed cultures ensured higher microbial viability, and enhanced the fruity flavor during bread dough production. It was determined that the combination of L. plantarum PFC22 + P. acidilactici PFC38 + L. sanfranciscensis PFC80 is a promising culture mixture that can be used in the production of type II sourdough systems, and that may also contribute to an increase in metabolic activity during bread production process.

  12. Enrichment of a mixed bacterial culture with a high polyhydroxyalkanoate storage capacity.

    PubMed

    Johnson, Katja; Jiang, Yang; Kleerebezem, Robbert; Muyzer, Gerard; van Loosdrecht, Mark C M

    2009-04-13

    Polyhydroxyalkanoates (PHAs) are microbial storage polymers that attract interest as bioplastics. PHAs can be produced with open mixed cultures if a suitable enrichment step based on the ecological role of PHA is used. An acetate-fed sequencing batch reactor operated with 1 day biomass residence time and with feast-famine cycles of 12 h was used to enrich a mixed culture of PHA producers. In subsequent fed-batch experiments under growth limiting conditions, the enriched mixed culture produced PHA up to a cellular content of 89 wt % within 7.6 h (average rate of 1.2 g/g/h). The PHA produced from acetate was the homopolymer polyhydroxybutyrate. The culture was dominated by a Gammaproteobacterium that showed little similarity on 16S rRNA level with known bacteria (<90% sequence similarity). The mixed culture process for PHA production does not require aseptic conditions. Waste streams rather than pure substrates could be used as raw materials. PMID:19193058

  13. Automated Static Culture System Cell Module Mixing Protocol and Computational Fluid Dynamics Analysis

    NASA Technical Reports Server (NTRS)

    Kleis, Stanley J.; Truong, Tuan; Goodwin, Thomas J,

    2004-01-01

    This report is a documentation of a fluid dynamic analysis of the proposed Automated Static Culture System (ASCS) cell module mixing protocol. The report consists of a review of some basic fluid dynamics principles appropriate for the mixing of a patch of high oxygen content media into the surrounding media which is initially depleted of oxygen, followed by a computational fluid dynamics (CFD) study of this process for the proposed protocol over a range of the governing parameters. The time histories of oxygen concentration distributions and mechanical shear levels generated are used to characterize the mixing process for different parameter values.

  14. Leaching of pyrite by acidophilic heterotrophic iron-oxidizing bacteria in pure and mixed cultures

    SciTech Connect

    Bacelar-Nicolau, P.; Johnson, D.B.

    1999-02-01

    Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS{sub 2}) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizing Thiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferroxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the indirect mechanism. Mixed cultures of three isolates (strains T-21, T-232, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotroph Thiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T -23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.

  15. Long-term effect of vital labelling on mixed Schwann cell cultures.

    PubMed

    Mosahebi, A; Woodward, B; Green, C; Martin, R; Terenghi, G

    2000-06-01

    Schwann cell transplantation following neuronal injury could encourage regeneration of spinal cord as well as improving peripheral nerve gap repair. In order to gain a better understanding of the role of transplanted Schwann cells in vivo, it is essential to be able to follow their behaviour after transplantation. Our aim was to evaluate the suitability of two vital fluorescent labels on the proliferation rate and phenotypic stability of Schwann cells, in either pure culture or mixed co-culture. Primary cultures of Schwann cells were obtained from Dark Agouti and Lewis neonatal rats and labelled with H33342 and PKH26, respectively. In mixed cultures, a 50: 50 mixture of Dark Agouti and Lewis Schwann cells was present. Labelled cultured cells were examined at 1, 2 and 4 weeks for viability and phenotypic marker expression of S100, GFAP, p75, MHC I, MHC II and compared with corresponding unlabelled cells. The results showed that although there was no deleterious interaction in the mixed cultures, the viability was reduced by the labelling after 2 weeks. Labelled cells could be distinguished up to 4 weeks, but there was leakage of H33342 label after 2 weeks. Labelled Schwann cells showed reduced expression of phenotypic markers, especially p75 when labelled with H33342. In conclusion, H33342 and PKH26 can be used as fluorescent markers of Schwann cells for short-term studies, for a maximum of 2 weeks, but different markers may be needed for longer experiments.

  16. Biodiesel production potential of mixed microalgal culture grown in domestic wastewater.

    PubMed

    Soydemir, Gulfem; Keris-Sen, Ulker Diler; Sen, Unal; Gurol, Mirat D

    2016-01-01

    In this study, a mixed microalgal culture grown in secondarily treated domestic wastewater effluent was investigated for biodiesel production using in situ transesterification method with conventional heating. The total lipid content of the mixed culture was found as 26.2% ± 0.6 by weight of dry biomass, and 74% of the lipids were contributed by total glycerides. In situ transesterification with conventional heating process under acidic conditions produced higher biodiesel yield with chloroform as the co-solvent (82.1% ± 3.9) compared to hexane (55.3% ± 3.9) under the same reaction conditions. The gas chromatography analysis showed that FAME composition was mainly composed of palmitic, palmitoleic, stearic, oleic, linoleic and linolenic acid methyl esters., and thus the mixed microalgal culture fed by domestic wastewaters has had comparable biodiesel conversion yields and FAME composition to mono-culture and pure cultures fed by synthetic culture media. Hence, this study showed that secondarily treated domestic wastewater could potentially be a suitable and sustainable medium for microalgae grown to be used as biodiesel feedstock.

  17. Mineralization of the s-triazine ring of atrazine by stable bacterial mixed cultures.

    PubMed Central

    Mandelbaum, R T; Wackett, L P; Allan, D L

    1993-01-01

    Enrichment cultures containing atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) at a concentration of 100 ppm (0.46 mM) as a sole nitrogen source were obtained from soils exposed to repeated spills of atrazine, alachlor, and metolachlor. Bacterial growth occurred concomitantly with formation of metabolites from atrazine and subsequent biosynthesis of protein. When ring-labeled [14C]atrazine was used, 80% or more of the s-triazine ring carbon atoms were liberated as 14CO2. Hydroxyatrazine may be an intermediate in the atrazine mineralization pathway. More than 200 pure cultures isolated from the enrichment cultures failed to utilize atrazine as a nitrogen source. Mixing pure cultures restored atrazine-mineralizing activity. Repeated transfer of the mixed cultures led to increased rates of atrazine metabolism. The rate of atrazine degradation, even at the elevated concentrations used, far exceeded the rates previously reported in soils, waters, and mixed and pure cultures of bacteria. PMID:8328795

  18. Quantification of Dehalospirillum multivorans in Mixed-Culture Biofilms with an Enzyme-Linked Immunosorbent Assay

    PubMed Central

    Bauer-Kreisel, P.; Eisenbeis, M.; Scholz-Muramatsu, H.

    1996-01-01

    A fast, highly selective and sensitive method to quantify specific biomasses in mixed-culture biofilms is described. It consists of detachment of a biofilm from its support material, resolution of the detached biofilm flocs in order to separate the enclosed cells and antigens, and quantification of specific biomass by an enzyme-linked immunosorbent assay. PMID:16535389

  19. 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.

  20. 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

  1. "Mixing Pop (Culture) and Politics": Cultural Resistance, Culture Jamming, and Anti-Consumption Activism as Critical Public Pedagogy

    ERIC Educational Resources Information Center

    Sandlin, Jennifer A.; Milam, Jennifer L.

    2008-01-01

    Culture jamming, the act of resisting and re-creating commercial culture in order to transform society, is embraced by groups and individuals who seek to critique and (re)form how culture is created and enacted in our daily lives. In this article, we explore how two groups--Adbusters and Reverend Billy and the Church of Stop Shopping--use culture…

  2. Electrical stimulation promotes the survival of oligodendrocytes in mixed cortical cultures.

    PubMed

    Gary, Devin S; Malone, Misti; Capestany, Paul; Houdayer, Thierry; McDonald, John W

    2012-01-01

    Oligodendrocyte (OLG) death plays a major role in white matter dysfunction and demyelination following injury to the CNS. Axonal contact, communication, and neuronal activity appear to promote OLG survival and function in cell culture and during development. The application of electrical stimulation to mixed neural cultures has been shown to promote OLG differentiation and the formation of myelin in vitro. Here we show that OLG viability can be significantly enhanced in mixed cortical cultures by applying biphasic pulses of electrical stimulation (ESTIM). Enhanced survival via ESTIM requires the presence of neurons and is suppressed by inhibition of voltage-gated sodium channels. Additionally, contact between the axon and OLG is necessary for ESTIM to promote OLG survival. This report suggests that patterned neuronal activity could repress delayed progression of white matter injury and promote CNS repair in neurological conditions that involve white matter damage.

  3. Control of mixed-substrate utilization in continuous cultures of Escherichia coli.

    PubMed

    Silver, R S; Mateles, R I

    1969-02-01

    The chemostat culture technique was used to study the control mechanisms which operate during utilization of mixtures of glucose and lactose and glucose and l-aspartic acid by populations of Escherichia coli B6. Constitutive mutants were rapidly selected during continuous culture on a mixture of glucose and lactose, and the beta-galactosidase level of the culture increased greatly. After mutant selection, the specific beta-galactosidase level of the culture was a decreasing function of growth rate. In cultures of both the inducible wild type and the constitutive mutant, glucose and lactose were simultaneously utilized at moderate growth rates, whereas only glucose was used in the inducible cultures at high growth rates. Catabolite repression was shown to be the primary mechanism of control of beta-galactosidase level and lactose utilization in continuous culture on mixed substrates. In batch culture, as in the chemostat, catabolite repression acting by itself on the lac enzymes was insufficient to prevent lactose utilization or cause diauxie. Interference with induction of the lac operon, as well as catabolite repression, was necessary to produce diauxic growth. Continuous cultures fed mixtures of glucose and l-aspartic acid utilized both substrates at moderate growth rates, even though the catabolic enzyme aspartase was linearly repressed with increasing growth rate. Although the repression of aspartase paralleled the catabolite repression of beta-galactosidase, l-aspartic acid could be utilized even at very low levels of the catabolic enzyme because of direct anabolic incorporation into protein. PMID:4886282

  4. Bacterial Growth in Mixed Cultures on Dissolved Organic Carbon from Humic and Clear Waters

    PubMed Central

    Tranvik, Lars J.; Höfle, Manfred G.

    1987-01-01

    Interactions between bacterial assemblages and dissolved organic carbon (DOC) from different sources were investigated. Mixed batch cultures were set up with water from a humic and a clear-water lake by a 1:20 dilution of the bacterial assemblage (1.0 μm of prefiltered lake water) with natural medium (sterile filtered lake water) in all four possible combinations of the two waters and their bacterial assemblages. Bacterial numbers and biomass, DOC, thymidine incorporation, ATP, and uptake of glucose and phenol were followed in these cultures. Growth curves and exponential growth rates were similar in all cultures, regardless of inoculum or medium. However, bacterial biomass produced was double in cultures based on water from the humic lake. The fraction of DOC consumed by heterotrophic bacteria during growth was in the same range, 15 to 22% of the total DOC pool, in all cultures. Bacterial growth efficiency, calculated from bacterial biomass produced and DOC consumed, was in the order of 20%. Glucose uptake reached a peak during exponential growth in all cultures. Phenol uptake was insignificant in the cultures based on the clear-water medium, but occurred in humic medium cultures after exponential growth. The similarity in the carbon budgets of all cultures indicated that the source of the bacterial assemblage did not have a significant effect on the overall carbon flux. However, fluxes of specific organic compounds differed, as reflected by glucose and phenol uptake, depending on the nature of the DOC and the bacterial assemblage. PMID:16347296

  5. The Cultural Politics of Mixed-Income Schools and Housing: A Racialized Discourse of Displacement, Exclusion, and Control

    ERIC Educational Resources Information Center

    Lipman, Pauline

    2009-01-01

    In this article, I examine the contested and racially coded cultural politics of creating mixed-income schools in mixed-income communities. Policymakers claim deconcentrating low-income people will reduce poverty and improve education. However, based on activist research in Chicago, I argue these policies are grounded in "culture of poverty"…

  6. Biopolymers Production by Mixed Culture and Their Applications in Water and Wastewater Treatment.

    PubMed

    More, Tanaji T; Yan, Song; Tyagi, Rajeshwar Dayal; Surampalli, Rao Y

    2015-06-01

    Thirteen extracellular polymeric substances (EPS) producing bacterial strains were cultivated (as pure/mixed culture) in sterilized sludge (suspended solids: 25 g/L). The mixed culture produced higher concentrations of EPS (4.9 g/L) as compared to that of the pure culture (2.7-3.7 g/L). The harvested EPS were examined for their flocculation performance (turbidity removal and dewatering) in jar tests using kaolin suspensions with Ca2+. Broth (B-EPS) revealed high kaolin flocculating activity (91.2%) at very low concentrations (0.8 mg B-EPS/g kaolin) and it was comparable to the chemical polymer, Magnafloc-155 (90.4% at 0.2 mg/g kaolin). B-EPS also exhibited very good flocculation performance (turbidity removal %) in river water (93.5%), municipal wastewater (91.7%) and brewery wastewater (81.8%). The study revealed that the mixed culture consortium could be used for the production of highly efficient flocculants.

  7. Biopolymers Production by Mixed Culture and Their Applications in Water and Wastewater Treatment.

    PubMed

    More, Tanaji T; Yan, Song; Tyagi, Rajeshwar Dayal; Surampalli, Rao Y

    2015-06-01

    Thirteen extracellular polymeric substances (EPS) producing bacterial strains were cultivated (as pure/mixed culture) in sterilized sludge (suspended solids: 25 g/L). The mixed culture produced higher concentrations of EPS (4.9 g/L) as compared to that of the pure culture (2.7-3.7 g/L). The harvested EPS were examined for their flocculation performance (turbidity removal and dewatering) in jar tests using kaolin suspensions with Ca2+. Broth (B-EPS) revealed high kaolin flocculating activity (91.2%) at very low concentrations (0.8 mg B-EPS/g kaolin) and it was comparable to the chemical polymer, Magnafloc-155 (90.4% at 0.2 mg/g kaolin). B-EPS also exhibited very good flocculation performance (turbidity removal %) in river water (93.5%), municipal wastewater (91.7%) and brewery wastewater (81.8%). The study revealed that the mixed culture consortium could be used for the production of highly efficient flocculants. PMID:26459822

  8. How-to-Do-It. Isolation of Pure Cultures from Mixed Cultures: A Modern Approach.

    ERIC Educational Resources Information Center

    Benathen, Isaiah A.

    1990-01-01

    Described is an alternative method of culture isolation that uses streaking on specialized media. An activity in which different media are tested for selectivity is presented including a list of materials and procedures. A chart of colony morphology is given. (CW)

  9. [Optimization of the composition of the medium for thrombolytic enzyme biosynthesis in pure and mixed cultures].

    PubMed

    Gesheva, V I; Maksimov, V N; Landau, N S; Egorov, N S

    1982-01-01

    The medium for the biosynthesis of exoproteases with the thrombolytic action in monocultures and mixed cultures of actinomycetes was optimized in several steps using the method of complete and fractional factor experiments. When Actinomyces rimosus was cultivated on the selected medium, the productivity of the mycelium rose, the fibrinolytic activity increased three-fold, and the caseinolytic activity became 2.2 times greater. During mixed cultivation of A. rimosus and A. violaceus on this medium, fibrinolysis increased six times comparing with the A. rimosus monoculture growth on the original medium while caseinolysis became only 3.7 times greater, which increased the specificity for fibrin twice. PMID:7045597

  10. Biodegradation of methyl tert-butyl ether by cold-adapted mixed and pure bacterial cultures.

    PubMed

    Zaitsev, G M; Uotila, J S; Häggblom, M M

    2007-04-01

    An aerobic mixed bacterial culture (CL-EMC-1) capable of utilizing methyl tert-butyl ether (MTBE) as the sole source of carbon and energy with a growth temperature range of 3 to 30 degrees C and optimum of 18 to 22 degrees C was enriched from activated sludge. Transient accumulation of tert-butanol (TBA) occurred during utilization of MTBE at temperatures from 3 degrees C to 14 degrees C, but TBA did not accumulate above 18 degrees C. The culture utilized MTBE at a concentration of up to 1.5 g l(-1) and TBA of up to 7 g l(-1). The culture grew on MTBE at a pH range of 5 to 9, with an optimum pH of 6.5 to 7.1. The specific growth rate of the CL-EMC-1 culture on 0.1 g l(-1) of MTBE at 22 degrees C and pH 7.1 was 0.012 h(-1), and the growth yield was 0.64 g (dry weight) g(-1). A new MTBE-utilizing bacterium, Variovorax paradoxus strain CL-8, isolated from the mixed culture utilized MTBE, TBA, 2-hydroxy isobutyrate, lactate, methacrylate, and acetate as sole sources of carbon and energy but not 2-propanol, acetone, methanol, formaldehyde, or formate. Two other isolates, Hyphomicrobium facilis strain CL-2 and Methylobacterium extorquens strain CL-4, isolated from the mixed culture were able to grow on C(1) compounds. The combined consortium could thus utilize all of the carbon of MTBE. PMID:17146651

  11. Lipid production by a mixed culture of oleaginous yeast and microalga from distillery and domestic mixed wastewater.

    PubMed

    Ling, Jiayin; Nip, Saiwa; Cheok, Wai Leong; de Toledo, Renata Alves; Shim, Hojae

    2014-12-01

    Lipid productivity by mixed culture of Rhodosporidium toruloides and Chlorella pyrenoidosa was studied using 1:1 mixed real wastewater from distillery and local municipal wastewater treatment plant with initial soluble chemical oxygen demand (SCOD) around 25,000 mg/L, initial cell density of 2×10(7) cells/mL (yeast) and 5×10(6) cells/mL (microalga), at 30 °C and 2.93 W/m2 (2000 lux, 12:12 h light and dark cycles). Lipid content and lipid yield achieved were 63.45±2.58% and 4.60±0.36 g/L with the associated removal efficiencies for SCOD, total nitrogen (TN), and total phosphorus (TP) at 95.34±0.07%, 51.18±2.17%, and 89.29±4.91%, respectively, after 5 days of cultivation without the pH adjustment. Inoculation of microalgae at 40 h of the initial yeast cultivation and harvesting part of inactive biomass at 72 h by sedimentation could improve both lipid production and wastewater treatment efficiency under non-sterile conditions.

  12. Biocatalytic Desulfurization Capabilities of a Mixed Culture during Non-Destructive Utilization of Recalcitrant Organosulfur Compounds

    PubMed Central

    Ismail, Wael; El-Sayed, Wael S.; Abdul Raheem, Abdul Salam; Mohamed, Magdy E.; El Nayal, Ashraf M.

    2016-01-01

    We investigated the biodesulfurization potential of a mixed culture AK6 enriched from petroleum hydrocarbons-polluted soil with dibenzothiophene (DBT) as a sulfur source. In addition to DBT, AK6 utilized the following compounds as sulfur sources: 4-methyldibenzothiophene (4-MDBT), benzothiophene (BT), and 4,6- dimethyldibenzothiophene (4,6-DM-DBT). None of these compounds supported the growth of AK6 as the sole carbon and sulfur source. AK6 could not grow on dibenzylsulfide (DBS) as a sulfur source. The AK6 community structure changed according to the provided sulfur source. The major DGGE bands represented members of the genera Sphingobacterium, Klebsiella, Pseudomonas, Stenotrophomonas, Arthrobacter, Mycobacterium, and Rhodococcus. Sphingobacterium sp. and Pseudomonas sp. were abundant across all cultures utilizing any of the tested thiophenic S-compounds. Mycobacterium/Rhodococcus spp. were restricted to the 4-MDBT culture. The 4-MDBT culture had the highest species richness and diversity. Biodesulfurization of DBT by resting cells of AK6 produced 2-hydroxybiphenyl (2-HBP) in addition to trace amounts of phenylacetate. AK6 transformed DBT to 2-hydroxybiphenyl with a specific activity of 9 ± 0.6 μM 2-HBP g dry cell weight−1 h−1. PCR confirmed the presence in the AK6 community of the sulfur-specific (4S) pathway genes dszB and dszC. Mixed cultures hold a better potential than axenic ones for the development of a biodesulfurization technology. PMID:26973637

  13. Biocatalytic Desulfurization Capabilities of a Mixed Culture during Non-Destructive Utilization of Recalcitrant Organosulfur Compounds.

    PubMed

    Ismail, Wael; El-Sayed, Wael S; Abdul Raheem, Abdul Salam; Mohamed, Magdy E; El Nayal, Ashraf M

    2016-01-01

    We investigated the biodesulfurization potential of a mixed culture AK6 enriched from petroleum hydrocarbons-polluted soil with dibenzothiophene (DBT) as a sulfur source. In addition to DBT, AK6 utilized the following compounds as sulfur sources: 4-methyldibenzothiophene (4-MDBT), benzothiophene (BT), and 4,6- dimethyldibenzothiophene (4,6-DM-DBT). None of these compounds supported the growth of AK6 as the sole carbon and sulfur source. AK6 could not grow on dibenzylsulfide (DBS) as a sulfur source. The AK6 community structure changed according to the provided sulfur source. The major DGGE bands represented members of the genera Sphingobacterium, Klebsiella, Pseudomonas, Stenotrophomonas, Arthrobacter, Mycobacterium, and Rhodococcus. Sphingobacterium sp. and Pseudomonas sp. were abundant across all cultures utilizing any of the tested thiophenic S-compounds. Mycobacterium/Rhodococcus spp. were restricted to the 4-MDBT culture. The 4-MDBT culture had the highest species richness and diversity. Biodesulfurization of DBT by resting cells of AK6 produced 2-hydroxybiphenyl (2-HBP) in addition to trace amounts of phenylacetate. AK6 transformed DBT to 2-hydroxybiphenyl with a specific activity of 9 ± 0.6 μM 2-HBP g dry cell weight(-1) h(-1). PCR confirmed the presence in the AK6 community of the sulfur-specific (4S) pathway genes dszB and dszC. Mixed cultures hold a better potential than axenic ones for the development of a biodesulfurization technology. PMID:26973637

  14. Detection of Specific Strains and Variants of Streptococcus cremoris in Mixed Cultures by Immunofluorescence

    PubMed Central

    Hugenholtz, Jeroen; Veldkamp, Hans; Konings, Wil N.

    1987-01-01

    Antisera against four different strains of Streptococcus cremoris were raised by injecting rabbits with washed suspensions of whole cells. These antisera interacted specifically with the corresponding strain in a mixture of up to nine different S. cremoris strains. The antisera could be used for analyzing the composition of mixed cultures containing these strains by immunofluorescence. Competition experiments were performed in batch and continuous cultures under amino acid limitation. A bacteriophage-sensitive variant of S. cremoris SK11 (SK1128) could be distinguished from a bacteriophage-resistant variant (SK1143) by the same immunofluorescence technique. The competition between the two variants and the stability of both variants in pure cultures were followed with the specific antibodies. Antibodies against the purified proteolytic system of S. cremoris Wg2 were used to determine the presence of proteases by immunofluorescence in several S. cremoris strains under different culture conditions. The described immunofluorescence methods can be used to analyze complex mixed starter cultures common in the dairy industry as the strains and variants present in these mixtures can be recognized microscopically. Images PMID:16347256

  15. A Moderately Thermophilic Mixed Microbial Culture for Bioleaching of Chalcopyrite Concentrate at High Pulp Density

    PubMed Central

    Wang, Yuguang; Zeng, Weimin; Qiu, Guanzhou; Chen, Xinhua

    2014-01-01

    Three kinds of samples (acid mine drainage, coal mine wastewater, and thermal spring) derived from different sites were collected in China. Thereafter, these samples were combined and then inoculated into a basal salts solution in which different substrates (ferrous sulfate, elemental sulfur, and chalcopyrite) served as energy sources. After that, the mixed cultures growing on different substrates were pooled equally, resulting in a final mixed culture. After being adapted to gradually increasing pulp densities of chalcopyrite concentrate by serial subculturing for more than 2 years, the final culture was able to efficiently leach the chalcopyrite at a pulp density of 20% (wt/vol). At that pulp density, the culture extracted 60.4% of copper from the chalcopyrite in 25 days. The bacterial and archaeal diversities during adaptation were analyzed by denaturing gradient gel electrophoresis and constructing clone libraries of the 16S rRNA gene. The results show that the culture consisted mainly of four species, including Leptospirillum ferriphilum, Acidithiobacillus caldus, Sulfobacillus acidophilus, and Ferroplasma thermophilum, before adapting to a pulp density of 4%. However, L. ferriphilum could not be detected when the pulp density was greater than 4%. Real-time quantitative PCR was employed to monitor the microbial dynamics during bioleaching at a pulp density of 20%. The results show that A. caldus was the predominant species in the initial stage, while S. acidophilus rather than A. caldus became the predominant species in the middle stage. F. thermophilum accounted for the greatest proportion in the final stage. PMID:24242252

  16. Enhanced chrysene degradation by a mixed culture Biorem-CGBD using response surface design.

    PubMed

    Dave, Bharti P; Ghevariya, Chirag M; Bhatt, Jwalant K; Dudhagara, Dushyant R; Rajpara, Rahul K

    2015-05-01

    Degradation of chrysene, a four ringed highly carcinogenic polycyclic aromatic hydrocarbon (PAH) has been demonstrated by bacterial mixed culture Biorem-CGBD comprising Achromobacter xylosoxidans, Pseudomonas sp. and Sphingomonas sp., isolated from crude oil polluted saline sites at Bhavnagar coast, Gujarat, India. A full factorial Central Composite Design (CCD) using Response Surface Methodology (RSM) was applied to construct response surfaces, predicting 41.93% of maximum chrysene degradation with an experimental validation of 66.45% chrysene degradation on 15th day, using a combination of 0.175, 0.175 and 0.385 mL of OD600 = 1 inoculum of A. xylosoxidans, Pseudomonas sp. and Sphingomonas sp., respectively and a regression coefficient (R2) of 0.9485 indicating reproducibility of the experiment. It was observed that chrysene degradation can be successfully enhanced using RSM, making mixed culture Biorem-CGBD a potential bioremediation target for PAH contaminated saline sites.

  17. Comparative analysis of microbial community of novel lactic acid fermentation inoculated with different undefined mixed cultures.

    PubMed

    Liang, Shaobo; Gliniewicz, Karol; Mendes-Soares, Helena; Settles, Matthew L; Forney, Larry J; Coats, Erik R; McDonald, Armando G

    2015-03-01

    Three undefined mixed cultures (activated sludge) from different municipal wastewater treatment plants were used as seeds in a novel lactic acid fermentation process fed with potato peel waste (PPW). Anaerobic sequencing batch fermenters were run under identical conditions to produce predominantly lactic acid. Illumina sequencing was used to examine the 16S rRNA genes of bacteria in the three seeds and fermenters. Results showed that the structure of microbial communities of three seeds were different. All three fermentation products had unique community structures that were dominated (>96%) by species of the genus Lactobacillus, while members of this genus constituted <0.1% in seeds. The species of Lactobacillus sp. differed among the three fermentations. Results of this study suggest the structure of microbial communities in lactic acid fermentation of PPW with undefined mixed cultures were robust and resilient, which provided engineering prospects for the microbial utilization of carbohydrate wastes to produce lactic acid.

  18. Macrophage activation of allogeneic lymphocyte proliferation in the guinea pig mixed leukocyte culture.

    PubMed

    Greineder, D K; Rosenthal, A S

    1975-05-01

    The role of the macrophage in the guinea pig mixed leukocyte culture was investigated. Macrophages obtained from oil-induced peritoneal exudates, peritoneal wash-out cells, spleen, and alveolar washings were found to be effective stimulators of allogeneic lymph node and splenic lymphocyte DNA synthesis. The stimulatory properties of macrophages proved radioresistant but viability dependent. Unfractionated lymph node cells or adherence column purified lymph node lymphocytes and thymocytes were only minimally active as stimulators, even in the presence of macrophages syngeneic to the responder lymphocytes. Allogeneic fibroblasts, polymorphonuclear leukocytes, L2C leukemia cells, and xenogeneic (murine) macrophages failed to simulate. These data provide evidence that the macrophage is the predominant stimulator of the mixed leukocyte culture in the guinea pig.

  19. Enrichment of mixed cultures capable of aerobic degradation of 1,2-dibromoethane.

    PubMed

    Freitas dos Santos, L M; Leak, D J; Livingston, A G

    1996-12-01

    1,2-dibromoethane (DBE) is a common environmental contaminant; it is potentially carcinogenic and has been detected in soil and groundwater supplies. Most of the biodegradation studies to date have been performed under anaerobic conditions or in the context of soil remediation, where the pollutant concentration was in the parts per billion range. In this work a mixed bacterial culture capable of complete aerobic mineralization of concentrations of DBE up to 1 g liter(-1) under well-controlled laboratory conditions was enriched. In order to verify biodegradation, formation of biodegradation products as well as the disappearance of DBE from the biological medium were measured. Complete mineralization was verified by measuring stoichiometric release of the biodegradation products. This mixed culture was found to be capable of degrading other halogenated compounds, including bromoethanol, the degradation of which has not been reported previously.

  20. Effects of space flight and mixing on bacterial growth in low volume cultures

    NASA Technical Reports Server (NTRS)

    Kacena, M. A.; Manfredi, B.; Todd, P.

    1999-01-01

    Previous investigations have shown that liquid suspension bacterial cultures grow to higher cell concentrations in spaceflight than on Earth. None of these studies included ground-control experiments designed to evaluate the fluid effects potentially responsible for the reported increases. Therefore, the emphasis of this research was to both confirm differences in final cell concentration between 1g and microgravity cultures, and to examine the effects of mixing as a partial explanation for this difference. Flight experiments were performed in the Fluid Processing Apparatus (FPA), aboard Space Shuttle Missions STS-63 and STS-69, with simultaneous 1g static and agitated controls. Additional static 1g, agitated, and clino-rotated controls were performed in 9-ml culture tubes. This research revealed that both E. coli and B. subtilis samples cultured in space flight grew to higher final cell densities (120-345% increase) than simultaneous static 1g controls. The final cell concentration of E. coli cells cultured under agitation was 43% higher than in static 1g cultures and was 102% higher with clino-rotation. However, for B. subtilis cultures grown while being agitated on a shaker or clino-rotated, the final cell concentrations were nearly identical to those of the simultaneous static 1g controls. Therefore, these data suggest that the unique fluid quiescence in the microgravity environment (lack of sedimentation, creating unique transfer of nutrients and waste products), was responsible for the enhanced bacterial proliferation reported in this and other studies.

  1. Analysis of mixed cell cultures with quantitative digital holographic phase microscopy

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Wibbeling, Jana; Ketelhut, Steffi

    2014-05-01

    In order to study, for example, the influence of pharmaceuticals or pathogens on different cell types under identical measurement conditions and to analyze interactions between different cellular specimens a minimally-invasive quantitative observation of mixed cell cultures is of particular interest. Quantitative phase microscopy (QPM) provides high resolution detection of optical path length changes that is suitable for stain-free minimally-invasive live cell analysis. Due to low light intensities for object illumination, QPM minimizes the interaction with the sample and is in particular suitable for long term time-lapse investigations, e.g., for the detection of cell morphology alterations due to drugs and toxins. Furthermore, QPM has been demonstrated to be a versatile tool for the quantification of cellular growth, the extraction morphological parameters and cell motility. We studied the feasibility of QPM for the analysis of mixed cell cultures. It was explored if quantitative phase images provide sufficient information to distinguish between different cell types and to extract cell specific parameters. For the experiments quantitative phase imaging with digital holographic microscopy (DHM) was utilized. Mixed cell cultures with different types of human pancreatic tumor cells were observed with quantitative DHM phase contrast up to 35 h. The obtained series of quantitative phase images were evaluated by adapted algorithms for image segmentation. From the segmented images the cellular dry mass and the mean cell thickness were calculated and used in the further analysis as parameters to quantify the reliability the measurement principle. The obtained results demonstrate that it is possible to characterize the growth of cell types with different morphologies in a mixed cell culture separately by consideration of specimen size and cell thickness in the evaluation of quantitative DHM phase images.

  2. Short- and long-term temperature effects on aerobic polyhydroxybutyrate producing mixed cultures.

    PubMed

    Johnson, Katja; van Geest, Jorien; Kleerebezem, Robbert; van Loosdrecht, Mark C M

    2010-03-01

    Short- and long-term temperature effects on polyhydroxybutyrate (PHB) producing mixed cultures enriched in feast-famine sequencing batch reactors (SBRs) were investigated in a temperature range of 15-35 degrees C and 15-30 degrees C, respectively. After short-term temperature changes (i.e. 1 cycle) from the steady state temperature of 20 degrees C, reaction rate changes in the famine phase could be described over the whole temperature range with the Arrhenius equation with one temperature coefficient. For the feast phase different temperature coefficients were identified for acetate uptake, PHB production and growth. These were only valid for temperatures 5 degrees C higher or lower than the steady state temperature. Long-term temperature changes (i.e. new steady states) influenced not only the reaction rates but also the selective pressure in the SBR. At higher temperatures (30 degrees C) the SBR feast phase was short and the rates of acetate uptake and PHB storage were very high. This culture was characterized by a storage strategy with high yields of PHB and low yields of biomass in the feast phase. The PHB storage capacity of this culture was 84 wt% as evaluated in fed-batch experiments. At lower temperatures (15 degrees C) the feast phase was longer due to a lower rate of acetate uptake and the culture followed a strategy of direct growth on acetate rather than on PHB. This culture had a low maximal PHB storage capacity (about 35 wt%). The SBR culture enriched at 20 degrees C was able to store up to about 70 wt% PHB. The temperature at which fed-batch experiments were conducted did not influence the maximal PHB storage capacity. The SBR temperature was found to be an important factor to consider when designing a mixed culture PHB production process.

  3. Characterization of the liver-macrophages isolated from a mixed primary culture of neonatal swine hepatocytes.

    PubMed

    Kitani, Hiroshi; Yoshioka, Miyako; Takenouchi, Takato; Sato, Mitsuru; Yamanaka, Noriko

    2014-01-01

    We recently developed a novel procedure to obtain liver-macrophages in sufficient number and purity using a mixed primary culture of rat and bovine hepatocytes. In this study, we aim to apply this method to the neonatal swine liver. Swine parenchymal hepatocytes were isolated by a two-step collagenase perfusion method and cultured in T75 culture flasks. Similar to the rat and bovine cells, the swine hepatocytes retained an epithelial cell morphology for only a few days and progressively changed into fibroblastic cells. After 5-13 days of culture, macrophage-like cells actively proliferated on the mixed fibroblastic cell sheet. Gentle shaking of the culture flask followed by the transfer and brief incubation of the culture supernatant resulted in a quick and selective adhesion of macrophage-like cells to a plastic dish surface. After rinsing dishes with saline, the attached macrophage-like cells were collected at a yield of 10(6) cells per T75 culture flask at 2-3 day intervals for more than 3 weeks. The isolated cells displayed a typical macrophage morphology and were strongly positive for macrophage markers, such as CD172a, Iba-1 and KT022, but negative for cytokeratin, desmin and α-smooth muscle actin, indicating a highly purified macrophage population. The isolated cells exhibited phagocytosis of polystyrene microbeads and a release of inflammatory cytokines upon lipopolysaccharide stimulation. This shaking and attachment method is applicable to the swine liver and provides a sufficient number of macrophages without any need of complex laboratory equipments. PMID:24707456

  4. Effects of sequential mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae on apple cider fermentation.

    PubMed

    Ye, Mengqi; Yue, Tianli; Yuan, Yahong

    2014-09-01

    The fermentation of cider by mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae was carried out to study their effect on the cider quality. The results showed that growth of W. anomalus and S. cerevisiae was affected by each other during co-fermentation process. All the mixed cultures produced statistically the same level of ethanol as S. cerevisiae monoculture. The mixed fermentation could produce more variety and higher amounts of acetate esters, ethyl esters, higher alcohols, aldehydes, and ketones. Sensory evaluation demonstrated that ciders obtained from co-fermentation with W. anomalus gained higher scores than ciders fermented by pure S. cerevisiae, especially the co-fermentation cultures WS3, WS4, WS6, and WS8. Only 3 days of fermentation with W. anomalus in sequential mixtures were enough to improve the quality of cider. Wickerhamomyces anomalus could be used in association with S. cerevisiae to improve the quality of cider. The modulation of inoculation time may provide an effective means of manipulating cider aroma for different characteristics.

  5. Effects of sequential mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae on apple cider fermentation.

    PubMed

    Ye, Mengqi; Yue, Tianli; Yuan, Yahong

    2014-09-01

    The fermentation of cider by mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae was carried out to study their effect on the cider quality. The results showed that growth of W. anomalus and S. cerevisiae was affected by each other during co-fermentation process. All the mixed cultures produced statistically the same level of ethanol as S. cerevisiae monoculture. The mixed fermentation could produce more variety and higher amounts of acetate esters, ethyl esters, higher alcohols, aldehydes, and ketones. Sensory evaluation demonstrated that ciders obtained from co-fermentation with W. anomalus gained higher scores than ciders fermented by pure S. cerevisiae, especially the co-fermentation cultures WS3, WS4, WS6, and WS8. Only 3 days of fermentation with W. anomalus in sequential mixtures were enough to improve the quality of cider. Wickerhamomyces anomalus could be used in association with S. cerevisiae to improve the quality of cider. The modulation of inoculation time may provide an effective means of manipulating cider aroma for different characteristics. PMID:24931623

  6. Fermentation of residual glycerol by Clostridium acetobutylicum ATCC 824 in pure and mixed cultures.

    PubMed

    Dams, Rosemeri I; Guilherme, Alexandre A; Vale, Maria S; Nunes, Vanja F; Leitão, Renato C; Santaella, Sandra T

    2016-12-01

    The aim of this research was to estimate the production of hydrogen, organic acids and alcohols by the strain of Clostridium acetobutylicum ATCC 824 using residual glycerol as a carbon source. The experiments were carried out in pure and mixed cultures in batch experiments. Three different sources of inocula for mixed culture were used. Ruminal liquid from goats and sludge collected from two upflow anaerobic sludge blanket reactors treating municipal wastewater and brewery effluent were tested for hydrogen, organic acids and alcohols production with or without C. acetobutylicum ATCC 824. The main detected end-products from the glycerol fermentation were hydrogen, organic acids (acetic, propionic, butyric and caproic) and alcohol (ethanol and 1,3-propanediol - 1,3PD). High hydrogen (0.44 mol H2/mol glycerol consumed) and 1,3PD (0.32 mol 1,3PD/mol glycerol consumed) yields were obtained when the strain C. acetobutylicum ATCC 824 was bioaugmented into the sludge from municipal wastewater using 5 g/L of glycerol. Significant concentrations of n-caproic acid were detected in the ruminal liquid when amended with C. acetobutylicum ATCC 824. The results suggest that glycerol can be used for the generation of H2, 1,3PD and n-caproic acid using C. acetobutylicum ATCC 824 as agent in pure or mixed cultures.

  7. Total Degradation of EDTA by Mixed Cultures and a Bacterial Isolate

    PubMed Central

    Nörtemann, Bernd

    1992-01-01

    A bacterial mixed culture, which was obtained from sewage by a special enrichment procedure, utilized EDTA as the sole source of carbon and nitrogen for growth. High concentrations of mineral salts, particularly CaCl2, or the use of a mineral base without nitrogen protected the cells from inactivation after transfer into fresh medium containing 200-mg/liter (0.67 mM) EDTA. The chemical speciation did not influence the biodegradability of EDTA. However, when resting cells of the mixed culture were incubated with EDTA in the presence of an equivalent molar amount of FeCl3, the reaction came to a halt before the complete consumption of the substrate. A gram-negative isolate from the mixed population, BNC1, also metabolized EDTA in monoculture. Growth of the pure culture was promoted by biotin or folic acid but was always accompanied by the accumulation of unidentified metabolites and was slow (μmax, 0.024 h-1) compared with that of the original community (μmax, 0.036 h-1). Images PMID:16348653

  8. Metabolism of dibenzofuran by pseudomonas sp. strain HH69 and the mixed culture HH27

    SciTech Connect

    Fortnagel, P.; Harms, H.; Wittich, R.M. ); Krohn, S.; Meyer, H.; Sinnwell, V.; Wilkes, H.; Francke, W. )

    1990-04-01

    A Pseudomonas sp. strain, HH69, and a mixed culture, designated HH27, were isolated by selective enrichment from soil samples. The pure strain and the mixed culture grew aerobically on dibenzofuran as the sole source of carbon and energy. Degradation proceeded via salicylic acid which was branched into the gentisic acid and the catechol pathway. Both salicylic acid and gentisic acid accumulated in the culture medium of strain HH69. The acids were slowly metabolized after growth ceased. The enzymes responsible for their metabolism showed relatively low activities. Besides the above-mentioned acids, 2-hydroxyacetophenone, benzopyran-4-one (chrome), several 2-substituted chroman-4-ones, and traces of the four isomeric monohydroxydibenzofurans were identified in the culture medium. 2,2{prime},3-Trihydroxybiphenyl was isolated from the medium of a dibenzofuran-converting mutant derived from parent strain HH69, which can no longer grow on dibenzofuran. This gives evidence for a novel type of dioxygenases responsible for the attack on the biarylether structure of the dibenzofuran molecule. A meta-fission mechanism for cleavage of the dihydroxylated aromatic nucleus of 2,2{prime},3-trihydroxybiphenyl is suggested as the next enzymatic step in the degradative pathway.

  9. Degradation of mix hydrocarbons by immobilized cells of mix culture using a trickle fluidized bed reactor. Final report: June 1992--June 1994

    SciTech Connect

    Chapatwala, K.D.

    1994-12-01

    The microorganisms capable of degrading mix hydrocarbons were isolated from the soil samples collected from the hydrocarbon contaminated sites. The mix cultures were identified as Pseudomonas acidovorans, Flavobacterium indoltheticum and Phyllobacterium rubiaceum. The bacterial cells of mix cultures were immobilized in calcium-alginate solution in the form of beads. A trickle fluidized bed air-uplift-type reactor designed to study the degradation of mix hydrocarbons was filled with 0.85% normal saline containing the immobilized cells of mix culture. The immobilized beads were aerated with different amounts of CO{sub 2}-free air. The normal saline saturated with BTXs was circulated in the bioreactors at the rate of 2--4 ml/min. The biodegradation of BTXs by the immobilized beads of mix culture was monitored by determining the concentrations of the BTXs and the metabolites formed during their degradation in the samples at regular intervals using GC. The peaks obtained through the degradation of BTXs were not identified and quantified in this study.

  10. Mineral and iron oxidation at low temperatures by pure and mixed cultures of acidophilic microorganisms.

    PubMed

    Dopson, Mark; Halinen, Anna-Kaisa; Rahunen, Nelli; Ozkaya, Bestamin; Sahinkaya, Erkan; Kaksonen, Anna H; Lindström, E Börje; Puhakka, Jaakko A

    2007-08-01

    An enrichment culture from a boreal sulfide mine environment containing a low-grade polymetallic ore was tested in column bioreactors for simulation of low temperature heap leaching. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing revealed the enrichment culture contained an Acidithiobacillus ferrooxidans strain with high 16S rRNA gene similarity to the psychrotolerant strain SS3 and a mesophilic Leptospirillum ferrooxidans strain. As the mixed culture contained a strain that was within a clade with SS3, we used the SS3 pure culture to compare leaching rates with the At. ferrooxidans type strain in stirred tank reactors for mineral sulfide dissolution at various temperatures. The psychrotolerant strain SS3 catalyzed pyrite, pyrite/arsenopyrite, and chalcopyrite concentrate leaching. The rates were lower at 5 degrees C than at 30 degrees C, despite that all the available iron was in the oxidized form in the presence of At. ferrooxidans SS3. This suggests that although efficient At. ferrooxidans SS3 mediated biological oxidation of ferrous iron occurred, chemical oxidation of the sulfide minerals by ferric iron was rate limiting. In the column reactors, the leaching rates were much less affected by low temperatures than in the stirred tank reactors. A factor for the relatively high rates of mineral oxidation at 7 degrees C is that ferric iron remained in the soluble phase whereas, at 21 degrees C the ferric iron precipitated. Temperature gradient analysis of ferrous iron oxidation by this enrichment culture demonstrated two temperature optima for ferrous iron oxidation and that the mixed culture was capable of ferrous iron oxidation at 5 degrees C.

  11. Improved ethanol tolerance of Saccharomyces cerevisiae in mixed cultures with Kluyveromyces lactis on high-sugar fermentation.

    PubMed

    Yamaoka, Chizuru; Kurita, Osamu; Kubo, Tomoko

    2014-12-01

    The influence of non-Saccharomyces yeast, Kluyveromyces lactis, on metabolite formation and the ethanol tolerance of Saccharomyces cerevisiae in mixed cultures was examined on synthetic minimal medium containing 20% glucose. In the late stage of fermentation after the complete death of K. lactis, S. cerevisiae in mixed cultures was more ethanol-tolerant than that in pure culture. The chronological life span of S. cerevisiae was shorter in pure culture than mixed cultures. The yeast cells of the late stationary phase both in pure and mixed cultures had a low buoyant density with no significant difference in the non-quiescence state between both cultures. In mixed cultures, the glycerol contents increased and the alanine contents decreased when compared with the pure culture of S. cerevisiae. The distinctive intracellular amino acid pool concerning its amino acid concentrations and its amino acid composition was observed in yeast cells with different ethanol tolerance in the death phase. Co-cultivation of K. lactis seems to prompt S. cerevisiae to be ethanol tolerant by forming opportune metabolites such as glycerol and alanine and/or changing the intracellular amino acid pool.

  12. Profile of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus.

    PubMed

    Lee, P-R; Ong, Y-L; Yu, B; Curran, P; Liu, S-Q

    2010-10-01

    This study investigated the formation and utilization of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus. Time-course papaya juice fermentations were carried out using pure cultures of S. cerevisiae var. bayanus R2 and W. saturnus var. mrakii NCYC2251 and a mixed culture of the two yeasts at a ratio of 1:1000 (R2:NCYC2251). Changes in S. cerevisiae cell population, Brix, sugar consumption and pH were similar in the mixed culture and in the S. cerevisiae monoculture. There was an early growth arrest of W. saturnus in the mixed culture fermentation. A range of volatile compounds were produced during fermentation including fatty acids, alcohols, aldehydes and esters and some volatile compounds including those initially present in the juice were utilized. The mixed culture fermentation of S. cerevisiae and W. saturnus benefited from the presence of both yeasts, with more esters being produced than the S. cerevisiae monoculture and more alcohols being formed than the W. saturnus monoculture. The study suggests that papaya juice fermentation with a mixed culture of S. cerevisiae and W. saturnus may be able to result in the formation of more complex aroma compounds and higher ethanol level than those using single yeasts.

  13. [Changes in redox potentials during transitional processes in pure and mixed cultures of Escherichia coli and Serratia marcescens].

    PubMed

    Oktiabr'skiĭ, O N; Zelenin, E N; Smirnova, G V

    1984-01-01

    There were studied transitional processes accompanying the beginning of growth under glucose addition and stopping of growth under glucose exhaustion in pure and mixed aerobic cultures of Escherichia coli and Serratia marcescens. Continued record of Eh, pH, and CO2 showed that these processes sharply differ from each other in their character in pure and mixed cultures, it is particularly related to the changes of the redox potential. There is no characteristic change in the redox potential in pure culture of E. coli at growth termination in the case when S. marcescens cells are present in the culture.

  14. Culturing oil sands microbes as mixed species communities enhances ex situ model naphthenic acid degradation.

    PubMed

    Demeter, Marc A; Lemire, Joseph A; Yue, Gordon; Ceri, Howard; Turner, Raymond J

    2015-01-01

    Oil sands surface mining for bitumen results in the formation of oil sands process water (OSPW), containing acutely toxic naphthenic acids (NAs). Potential exists for OSPW toxicity to be mitigated by aerobic degradation of the NAs by microorganisms indigenous to the oil sands tailings ponds, the success of which is dependent on the methods used to exploit the metabolisms of the environmental microbial community. Having hypothesized that the xenobiotic tolerant biofilm mode-of-life may represent a feasible way to harness environmental microbes for ex situ treatment of OSPW NAs, we aerobically grew OSPW microbes as single and mixed species biofilm and planktonic cultures under various conditions for the purpose of assaying their ability to tolerate and degrade NAs. The NAs evaluated were a diverse mixture of eight commercially available model compounds. Confocal microscopy confirmed the ability of mixed and single species OSPW cultures to grow as biofilms in the presence of the NAs evaluated. qPCR enumeration demonstrated that the addition of supplemental nutrients at concentrations of 1 g L(-1) resulted in a more numerous population than 0.001 g L(-1) supplementation by approximately 1 order of magnitude. GC-FID analysis revealed that mixed species cultures (regardless of the mode of growth) are the most effective at degrading the NAs tested. All constituent NAs evaluated were degraded below detectable limits with the exception of 1-adamantane carboxylic acid (ACA); subsequent experimentation with ACA as the sole NA also failed to exhibit degradation of this compound. Single species cultures degraded select few NA compounds. The degradation trends highlighted many structure-persistence relationships among the eight NAs tested, demonstrating the effect of side chain configuration and alkyl branching on compound recalcitrance. Of all the isolates, the Rhodococcus spp. degraded the greatest number of NA compounds, although still less than the mixed species cultures

  15. Culturing oil sands microbes as mixed species communities enhances ex situ model naphthenic acid degradation

    PubMed Central

    Demeter, Marc A.; Lemire, Joseph A.; Yue, Gordon; Ceri, Howard; Turner, Raymond J.

    2015-01-01

    Oil sands surface mining for bitumen results in the formation of oil sands process water (OSPW), containing acutely toxic naphthenic acids (NAs). Potential exists for OSPW toxicity to be mitigated by aerobic degradation of the NAs by microorganisms indigenous to the oil sands tailings ponds, the success of which is dependent on the methods used to exploit the metabolisms of the environmental microbial community. Having hypothesized that the xenobiotic tolerant biofilm mode-of-life may represent a feasible way to harness environmental microbes for ex situ treatment of OSPW NAs, we aerobically grew OSPW microbes as single and mixed species biofilm and planktonic cultures under various conditions for the purpose of assaying their ability to tolerate and degrade NAs. The NAs evaluated were a diverse mixture of eight commercially available model compounds. Confocal microscopy confirmed the ability of mixed and single species OSPW cultures to grow as biofilms in the presence of the NAs evaluated. qPCR enumeration demonstrated that the addition of supplemental nutrients at concentrations of 1 g L-1 resulted in a more numerous population than 0.001 g L-1 supplementation by approximately 1 order of magnitude. GC-FID analysis revealed that mixed species cultures (regardless of the mode of growth) are the most effective at degrading the NAs tested. All constituent NAs evaluated were degraded below detectable limits with the exception of 1-adamantane carboxylic acid (ACA); subsequent experimentation with ACA as the sole NA also failed to exhibit degradation of this compound. Single species cultures degraded select few NA compounds. The degradation trends highlighted many structure-persistence relationships among the eight NAs tested, demonstrating the effect of side chain configuration and alkyl branching on compound recalcitrance. Of all the isolates, the Rhodococcus spp. degraded the greatest number of NA compounds, although still less than the mixed species cultures

  16. Bioleaching of electronic scrap by mixed culture of moderately thermophilic microorganisms

    NASA Astrophysics Data System (ADS)

    Ivǎnuş, D.; ǎnuş, R. C., IV; Cǎlmuc, F.

    2010-06-01

    A process for the metal recovery from electronic scrap using bacterial leaching was investigated. A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainages (AMDs) samples collected from several sulphide mines in Romania, and the bioleaching of electronic scrap was conducted both in shake flask and bioreactor. The results show that in the shake flask, the mixture can tolerate 50 g/L scrap after being acclimated to gradually increased concentrations of scrap. The copper extraction increases obviously in bioleaching of scrap with moderately thermophilic microorganisms supplemented with 0.4 g/L yeast extract at 180 r/min, 74% copper can be extracted in the pulp of 50 g/L scrap after 20 d. Compared with copper extractions of mesophilic culture, unacclimated culture and acclimated culture without addition of yeast extract, that of accliniated culture with addition of yeast extract is increased by 53%, 44% and 16%, respectively. In a completely stirred tank reactor, the mass fraction of copper and total iron extraction reach up to 81% and 56%, respectively. The results also indicate that it is necessary to add a large amount of acid to the pulp to extract copper from electronic scrap effectively.

  17. Insights into large-scale cell-culture reactors: I. Liquid mixing and oxygen supply.

    PubMed

    Sieblist, Christian; Jenzsch, Marco; Pohlscheidt, Michael; Lübbert, Andreas

    2011-12-01

    In the pharmaceutical industry, it is state of the art to produce recombinant proteins and antibodies with animal-cell cultures using bioreactors with volumes of up to 20 m(3) . Recent guidelines and position papers for the industry by the US FDA and the European Medicines Agency stress the necessity of mechanistic insights into large-scale bioreactors. A detailed mechanistic view of their practically relevant subsystems is required as well as their mutual interactions, i.e., mixing or homogenization of the culture broth and sufficient mass and heat transfer. In large-scale bioreactors for animal-cell cultures, different agitation systems are employed. Here, we discuss details of the flows induced in stirred tank reactors relevant for animal-cell cultures. In addition, solutions of the governing fluid dynamic equations obtained with the so-called computational fluid dynamics are presented. Experimental data obtained with improved measurement techniques are shown. The results are compared to previous studies and it is found that they support current hypotheses or models. Progress in improving insights requires continuous interactions between more accurate measurements and physical models. The paper aims at promoting the basic mechanistic understanding of transport phenomena that are crucial for large-scale animal-cell culture reactors.

  18. Insights into large-scale cell-culture reactors: I. Liquid mixing and oxygen supply.

    PubMed

    Sieblist, Christian; Jenzsch, Marco; Pohlscheidt, Michael; Lübbert, Andreas

    2011-12-01

    In the pharmaceutical industry, it is state of the art to produce recombinant proteins and antibodies with animal-cell cultures using bioreactors with volumes of up to 20 m(3) . Recent guidelines and position papers for the industry by the US FDA and the European Medicines Agency stress the necessity of mechanistic insights into large-scale bioreactors. A detailed mechanistic view of their practically relevant subsystems is required as well as their mutual interactions, i.e., mixing or homogenization of the culture broth and sufficient mass and heat transfer. In large-scale bioreactors for animal-cell cultures, different agitation systems are employed. Here, we discuss details of the flows induced in stirred tank reactors relevant for animal-cell cultures. In addition, solutions of the governing fluid dynamic equations obtained with the so-called computational fluid dynamics are presented. Experimental data obtained with improved measurement techniques are shown. The results are compared to previous studies and it is found that they support current hypotheses or models. Progress in improving insights requires continuous interactions between more accurate measurements and physical models. The paper aims at promoting the basic mechanistic understanding of transport phenomena that are crucial for large-scale animal-cell culture reactors. PMID:21818860

  19. Effects of pulsing with xylitol on mixed continuous cultures of oral streptococci.

    PubMed

    Rogers, A H; Pilowsky, K A; Zilm, P S; Gully, N J

    1991-06-01

    Continuous culture is a means whereby organisms can be grown at rates approaching those occurring naturally. Moreover, the effect of adding transient excesses of various nutrients to the culture vessel ('pulsing') simulates the effect of dietary challenge on dental plaque organisms. Mixed cultures of Streptococcus mutans T8 and Streptococcus milleri B448 were grown glucose-limited in a chemically defined medium under an atmosphere of 5 per cent carbon dioxide in nitrogen, at a dilution rate of D = 0.1 h-1 and controlled pH of 7.0. The level of arginine in the medium reservoir was adjusted so that Strep. milleri predominated over Strep. mutans in a stable coexistence. After equilibration, the culture vessel was pulsed with various carbohydrates to a final concentration of 5 x 10(-2)mol/L. Samples were then taken at regular intervals and differential viable counts of Strep. mutans and Strep. milleri were done on mitissalivarius agar. Results demonstrated that pulsing with glucose, fructose, 'coupling sugar', lactose, xylose and sorbitol gave Strep. mutans a clear ecological advantage. In direct contrast, pulsing with xylitol resulted in a marked antimicrobial effect on Strep. mutans while Strep. milleri was essentially unaffected. This supports recent findings by other workers that uptake of this pentitol by Strep. mutans in batch culture sets up a 'futile cycle', leading to depressed growth or even cell death.

  20. Experimental and mathematical model of the interactions in the mixed culture of links in the "producer-consumer" cycle

    NASA Astrophysics Data System (ADS)

    Pisman, T. I.; Galayda, Ya. V.

    The paper presents experimental and mathematical model of interactions between invertebrates the ciliates Paramecium caudatum and the rotifers Brachionus plicatilis and algae Chlorella vulgaris and Scenedesmus quadricauda in the producer -- consumer aquatic biotic cycle with spatially separated components The model describes the dynamics of the mixed culture of ciliates and rotifers in the consumer component feeding on the mixed algal culture of the producer component It has been found that metabolites of the algae Scenedesmus produce an adverse effect on the reproduction of the ciliates P caudatum Taking into account this effect the results of investigation of the mathematical model were in qualitative agreement with the experimental results In the producer -- consumer biotic cycle it was shown that coexistence is impossible in the mixed algal culture of the producer component and in the mixed culture of invertebrates of the consumer component The ciliates P caudatum are driven out by the rotifers Brachionus plicatilis

  1. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions.

    PubMed

    Maestre, Juan P; Wahman, David G; Speitel, Gerald E

    2016-06-21

    Chloramines are the second most used secondary disinfectant by United States water utilities. However, chloramination may promote nitrifying bacteria. Recently, monochloramine cometabolism by the pure culture ammonia-oxidizing bacteria, Nitrosomonas europaea, was shown to increase monochloramine demand. The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under more relevant drinking water conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Four types of batch kinetic experiments were conducted: (1) positive controls to estimate ammonia kinetic parameters, (2) negative controls to account for biomass reactivity, (3) utilization associated product (UAP) controls to account for UAP reactivity, and (4) cometabolism experiments to estimate cometabolism kinetic parameters. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to the experimental data. Cometabolism kinetics were best described by a first-order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism accounted for 30% of the observed monochloramine loss. These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; therefore, monochloramine cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems. PMID:27196729

  2. Degradation and total mineralization of monohalogenated biphenyls in natural sediment and mixed bacterial culture.

    PubMed Central

    Kong, H L; Sayler, G S

    1983-01-01

    Mixed bacterial cultures obtained from polychlorinated biphenyl-contaminated river sediments are capable of degrading monohalogenated biphenyls under simulated natural conditions. Culture conditions include river water as supportive medium and mixed bacterial cultures obtained from river sediments. Degradation occurs when the substrates are supplied as the sole carbon source or when added together with glucose. The degradation rates of 2-, 3-, and 4-chlorobiphenyl, at 30 micrograms ml-1, were 1.1, 1.6, and 2.0 micrograms ml-1 day-1, respectively. Monobrominated biphenyls, including 2-, 3-, and 4-bromobiphenyl, were degraded at rates of 2.3, 4.2, and 1.4 micrograms ml-1 day-1, respectively. Metabolites, including halogenated benzoates, were detected by high-performance liquid chromatography and mass spectrometry. By using chlorophenyl ring-labeled monochlorobiphenyls as substrates, total mineralization (defined as CO2 production from the chlorophenyl ring) was observed for 4-chlorobiphenyl but not for 2-chlorobiphenyl. Rates of total mineralization of 4-chlorobiphenyl (at 39 to 385 micrograms ml-1 levels) were dependent on substrate concentration, whereas variation of cell number in the range of 10(5) to 10(7) cells ml-1 had no significant effects. Simulated sunlight enhanced the rate of mineralization by ca. 400%. PMID:6639021

  3. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions.

    PubMed

    Maestre, Juan P; Wahman, David G; Speitel, Gerald E

    2016-06-21

    Chloramines are the second most used secondary disinfectant by United States water utilities. However, chloramination may promote nitrifying bacteria. Recently, monochloramine cometabolism by the pure culture ammonia-oxidizing bacteria, Nitrosomonas europaea, was shown to increase monochloramine demand. The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under more relevant drinking water conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Four types of batch kinetic experiments were conducted: (1) positive controls to estimate ammonia kinetic parameters, (2) negative controls to account for biomass reactivity, (3) utilization associated product (UAP) controls to account for UAP reactivity, and (4) cometabolism experiments to estimate cometabolism kinetic parameters. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to the experimental data. Cometabolism kinetics were best described by a first-order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism accounted for 30% of the observed monochloramine loss. These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; therefore, monochloramine cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems.

  4. Crude glycerol as feedstock for polyhydroxyalkanoates production by mixed microbial cultures.

    PubMed

    Moita, R; Freches, A; Lemos, P C

    2014-07-01

    The increase in global biodiesel production makes imperative the development of sustainable processes for the use of its main by-product, crude glycerol. In this study the feasibility of polyhydroxyalkanoates (PHA) production by a mixed microbial community using crude glycerol as feedstock was investigated. The selected culture had the ability to consume both glycerol and methanol fraction present in the crude. However, glycerol seemed to be the only carbon source contributing for the two biopolymers stored: poly-3-hydroxybutyrate (PHB) and glucose biopolymer (GB). In this work the culture reached a maximum PHB content of 47% (cdw) and a productivity of 0.27 g X/L.d, with an aerobic mixed cultures and a real waste substrate with non-volatile fatty acids (VFA) organic matter. The overall PHA yield on total substrate obtained was in the middle range of those reported in literature. The fact that crude glycerol can be used to produce PHA without any pre-treatment step, makes the overall production process economically more competitive, reducing polymer final cost.

  5. Coupled nutrient removal and biomass production with mixed algal culture: impact of biotic and abiotic factors.

    PubMed

    Su, Yanyan; Mennerich, Artur; Urban, Brigitte

    2012-08-01

    The influence of biotic (algal inoculum concentration) and abiotic factors (illumination cycle, mixing velocity and nutrient strength) on the treatment efficiency, biomass generation and settleability were investigated with selected mixed algal culture. Dark condition led to poor nutrient removal efficiency. No significant difference in the N, P removal and biomass settleability between continuous and alternating illumination was observed, but a higher biomass generation capability for the continuous illumination was obtained. Different mixing velocity led to similar phosphorus removal efficiencies (above 98%) with different retention times. The reactor with 300 rpm mixing velocity had the best N removal capability. For the low strength wastewater, the N rates were 5.4±0.2, 9.1±0.3 and 10.8±0.3 mg/l/d and P removal rates were 0.57±0.03, 0.56±0.03 and 0.72±0.05 mg/l/d for reactors with the algal inoculum concentration of 0.2, 0.5 and 0.8 g/l, respectively. Low nutrient removal efficiency and poor biomass settleability were obtained for high strength wastewater.

  6. Interactions of Pseudomonas aeruginosa in predominant biofilm or planktonic forms of existence in mixed culture with Escherichia coli in vitro.

    PubMed

    Kuznetsova, Marina V; Maslennikova, Irina L; Karpunina, Tamara I; Nesterova, Larisa Yu; Demakov, Vitaly A

    2013-09-01

    Pseudomonas aeruginosa and Escherichia coli are known to be involved in mixed communities in diverse niches. In this study we examined the influence of the predominant form of cell existence of and the exometabolite production by P. aeruginosa strains on interspecies interactions, in vitro. Bacterial numbers of P. aeruginosa and E. coli in mixed plankton cultures and biofilms compared with their numbers in single plankton cultures and biofilms changed in a different way, but were in accordance with the form of P. aeruginosa cell existence. The mass of a mixed-species biofilm was greater than the mass of a single-species biofilm. Among the mixed biofilms, the one with the "planktonic" P. aeruginosa strain had the least biomass. The total pyocyanin and pyoverdin levels were found to be lower in all mixed plankton cultures. Despite this, clinical P. aeruginosa strains irrespective of the predominant form of existence ("biofilm" or "planktonic") had a higher total concentration of exometabolites than did the reference strain in 12-24 h mixed cultures. The metabolism of E. coli, according to its bioluminescence, was reduced in mixed cultures, and the decrease was by 20- to 100-fold greater with the clinical Pseudomonas strains than the reference Pseudomonas strain. Thus, both the predominant form of existence of and the exometabolite production by distinct P. aeruginosa strains should be considered to fully understand the interspecies relationship and bacteria survival in natural communities.

  7. Slow conduction in mixed cultured strands of primary ventricular cells and stem cell-derived cardiomyocytes.

    PubMed

    Kucera, Jan P; Prudat, Yann; Marcu, Irene C; Azzarito, Michela; Ullrich, Nina D

    2015-01-01

    Modern concepts for the treatment of myocardial diseases focus on novel cell therapeutic strategies involving stem cell-derived cardiomyocytes (SCMs). However, functional integration of SCMs requires similar electrophysiological properties as primary cardiomyocytes (PCMs) and the ability to establish intercellular connections with host myocytes in order to contribute to the electrical and mechanical activity of the heart. The aim of this project was to investigate the properties of cardiac conduction in a co-culture approach using SCMs and PCMs in cultured cell strands. Murine embryonic SCMs were pooled with fetal ventricular cells and seeded in predefined proportions on microelectrode arrays to form patterned strands of mixed cells. Conduction velocity (CV) was measured during steady state pacing. SCM excitability was estimated from action potentials measured in single cells using the patch clamp technique. Experiments were complemented with computer simulations of conduction using a detailed model of cellular architecture in mixed cell strands. CV was significantly lower in strands composed purely of SCMs (5.5 ± 1.5 cm/s, n = 11) as compared to PCMs (34.9 ± 2.9 cm/s, n = 21) at similar refractoriness (100% SCMs: 122 ± 25 ms, n = 9; 100% PCMs: 139 ± 67 ms, n = 14). In mixed strands combining both cell types, CV was higher than in pure SCMs strands, but always lower than in 100% PCM strands. Computer simulations demonstrated that both intercellular coupling and electrical excitability limit CV. These data provide evidence that in cultures of murine ventricular cardiomyocytes, SCMs cannot restore CV to control levels resulting in slow conduction, which may lead to reentry circuits and arrhythmias.

  8. Slow conduction in mixed cultured strands of primary ventricular cells and stem cell-derived cardiomyocytes

    PubMed Central

    Kucera, Jan P.; Prudat, Yann; Marcu, Irene C.; Azzarito, Michela; Ullrich, Nina D.

    2015-01-01

    Modern concepts for the treatment of myocardial diseases focus on novel cell therapeutic strategies involving stem cell-derived cardiomyocytes (SCMs). However, functional integration of SCMs requires similar electrophysiological properties as primary cardiomyocytes (PCMs) and the ability to establish intercellular connections with host myocytes in order to contribute to the electrical and mechanical activity of the heart. The aim of this project was to investigate the properties of cardiac conduction in a co-culture approach using SCMs and PCMs in cultured cell strands. Murine embryonic SCMs were pooled with fetal ventricular cells and seeded in predefined proportions on microelectrode arrays to form patterned strands of mixed cells. Conduction velocity (CV) was measured during steady state pacing. SCM excitability was estimated from action potentials measured in single cells using the patch clamp technique. Experiments were complemented with computer simulations of conduction using a detailed model of cellular architecture in mixed cell strands. CV was significantly lower in strands composed purely of SCMs (5.5 ± 1.5 cm/s, n = 11) as compared to PCMs (34.9 ± 2.9 cm/s, n = 21) at similar refractoriness (100% SCMs: 122 ± 25 ms, n = 9; 100% PCMs: 139 ± 67 ms, n = 14). In mixed strands combining both cell types, CV was higher than in pure SCMs strands, but always lower than in 100% PCM strands. Computer simulations demonstrated that both intercellular coupling and electrical excitability limit CV. These data provide evidence that in cultures of murine ventricular cardiomyocytes, SCMs cannot restore CV to control levels resulting in slow conduction, which may lead to reentry circuits and arrhythmias. PMID:26442264

  9. Selection of an actinobacteria mixed culture for chlordane remediation. Pesticide effects on microbial morphology and bioemulsifier production.

    PubMed

    Fuentes, María S; Colin, Verónica L; Amoroso, María J; Benimeli, Claudia S

    2016-02-01

    Chlordane bioremediation using actinobacteria mixed culture is an attractive clean-up technique. Their ability to produce bioemulsifiers could increase the bioavailability of this pesticide. In order to select a defined actinobacteria mixed culture for chlordane remediation, compatibility assays were performed among six Streptomyces strains. The strains did not show growth inhibition, and they were assayed for chlordane removal, either as pure or as mixed cultures. In pure cultures, all of the strains showed specific dechlorination activity (1.42-24.20 EU mg(-1)) and chlordane removal abilities (91.3-95.5%). The specific dechlorination activity was mainly improved with cultures of three or four microorganisms. The mixed culture consisting of Streptomyces sp. A2-A5-A13 was selected. Their ability to produce bioemulsifiers in the presence of glucose or chlordane was tested, but no significant differences were observed (p > 0.05). However, the stability of the emulsions formed was linked to the carbon source used. Only in chlordane presence the emulsions retained 100% of their initial height. Finally, the selected consortium showed a high degree of sporulation in the pesticide presence. This is the first study on the effects that chlordane exerts on microbe morphology and emulsifier production for a defined mixed culture of Streptomyces with ability to remediate the pesticide. PMID:26554742

  10. Selection of an actinobacteria mixed culture for chlordane remediation. Pesticide effects on microbial morphology and bioemulsifier production.

    PubMed

    Fuentes, María S; Colin, Verónica L; Amoroso, María J; Benimeli, Claudia S

    2016-02-01

    Chlordane bioremediation using actinobacteria mixed culture is an attractive clean-up technique. Their ability to produce bioemulsifiers could increase the bioavailability of this pesticide. In order to select a defined actinobacteria mixed culture for chlordane remediation, compatibility assays were performed among six Streptomyces strains. The strains did not show growth inhibition, and they were assayed for chlordane removal, either as pure or as mixed cultures. In pure cultures, all of the strains showed specific dechlorination activity (1.42-24.20 EU mg(-1)) and chlordane removal abilities (91.3-95.5%). The specific dechlorination activity was mainly improved with cultures of three or four microorganisms. The mixed culture consisting of Streptomyces sp. A2-A5-A13 was selected. Their ability to produce bioemulsifiers in the presence of glucose or chlordane was tested, but no significant differences were observed (p > 0.05). However, the stability of the emulsions formed was linked to the carbon source used. Only in chlordane presence the emulsions retained 100% of their initial height. Finally, the selected consortium showed a high degree of sporulation in the pesticide presence. This is the first study on the effects that chlordane exerts on microbe morphology and emulsifier production for a defined mixed culture of Streptomyces with ability to remediate the pesticide.

  11. Comparative life cycle assessment and financial analysis of mixed culture polyhydroxyalkanoate production.

    PubMed

    Gurieff, Nicholas; Lant, Paul

    2007-12-01

    A life cycle assessment and financial analysis of mixed culture PHA (PHA(MC)) and biogas production was undertaken based on treating an industrial wastewater. Internal rate of return (IRR) and non-renewable CO(2)eq emissions were used to quantify financial viability and environmental impact. PHA(MC) was preferable to biogas production for treating the specified industrial effluent. PHA(MC) was also financially attractive in comparison to pure culture PHA production. Both PHA production processes had similar environmental impacts that were significantly lower than HDPE production. A large potential for optimisation exists for the PHA(MC) process as financial and environmental costs were primarily due to energy use for downstream processing. Under the conditions used in this work PHA(MC) was shown to be a viable biopolymer production process and an effective industrial wastewater treatment technology. This is the first study of its kind and provides valuable insight into the PHA(MC) process. PMID:17632000

  12. Starter Culture Selection for Making Chinese Sesame-Flavored Liquor Based on Microbial Metabolic Activity in Mixed-Culture Fermentation

    PubMed Central

    Wu, Qun; Ling, Jie

    2014-01-01

    Selection of a starter culture with excellent viability and metabolic activity is important for inoculated fermentation of traditional food. To obtain a suitable starter culture for making Chinese sesame-flavored liquor, the yeast and bacterium community structures were investigated during spontaneous and solid-state fermentations of this type of liquor. Five dominant species in spontaneous fermentation were identified: Saccharomyces cerevisiae, Pichia membranaefaciens, Issatchenkia orientalis, Bacillus licheniformis, and Bacillus amyloliquefaciens. The metabolic activity of each species in mixed and inoculated fermentations of liquor was investigated in 14 different cocultures that used different combinations of these species. The relationships between the microbial species and volatile metabolites were analyzed by partial least-squares (PLS) regression analysis. We found that S. cerevisiae was positively correlated to nonanal, and B. licheniformis was positively associated with 2,3-butanediol, isobutyric acid, guaiacol, and 4-vinyl guaiacol, while I. orientalis was positively correlated to butyric acid, isovaleric acid, hexanoic acid, and 2,3-butanediol. These three species are excellent flavor producers for Chinese liquor. Although P. membranaefaciens and B. amyloliquefaciens were not efficient flavor producers, the addition of them alleviated competition among the other three species and altered their growth rates and flavor production. As a result, the coculture of all five dominant species produced the largest amount of flavor compounds. The result indicates that flavor producers and microbial interaction regulators are important for inoculated fermentation of Chinese sesame-flavored liquor. PMID:24814798

  13. Mixed culture polyhydroxyalkanoates production from sugar molasses: the use of a 2-stage CSTR system for culture selection.

    PubMed

    Albuquerque, M G E; Concas, S; Bengtsson, S; Reis, M A M

    2010-09-01

    Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers. The use of mixed microbial cultures (MMC) and low cost feedstocks have a positive impact on the cost-effectiveness of the process. It has typically been carried out in Sequencing Batch Reactors (SBR). In this study, a 2-stage CSTR system (under Feast and Famine conditions) was used to effectively select for PHA-storing organisms using fermented molasses as feedstock. The effect of influent substrate concentration (60-120 Cmmol VFA/L) and HRT ratio between the reactors (0.2-0.5h/h) on the system's selection efficiency was assessed. It was shown that Feast reactor residual substrate concentration impacted on the selective pressure for PHA storage (due to substrate-dependent kinetic limitation). Moreover, a residual substrate concentration coming from the Feast to the Famine reactor did not jeopardize the physiological adaptation required for enhanced PHA storage. The culture reached a maximum PHA content of 61%. This success opens new perspectives to the use of wastewater treatment infrastructure for PHA production, thus valorizing either excess sludge or wastewaters.

  14. A novel concept combining experimental and mathematical analysis for the identification of unknown interspecies effects in a mixed culture.

    PubMed

    Schmidt, Julia K; Riedele, Christian; Regestein, Lars; Rausenberger, Julia; Reichl, Udo

    2011-08-01

    Bacteria in natural habitats only occur in consortia together with various other species. Characterization of bacterial species, however, is normally done by laboratory testing of pure isolates. Any interactions that might appear during growth in mixed-culture are obviously missed by this approach. Existing experimental studies mainly focus on two-species mixed cultures with species specifically chosen for their known growth characteristics, and their anticipated interactions. Various theoretical mathematical studies dealing with mixed cultures and possible interspecies effects exist, but often models cannot be validated due to a lack of experimental data. Here, we present a concept for the identification of interspecies effects in mixed cultures with arbitrary and unknown single-species properties. Model structure and parameters were inferred from single-species experiments for the reproduction of mixed-culture experiments by simulation. A mixed culture consisting of the three-species Pseudomonas aeruginosa, Burkholderia cepacia, and Staphylococcus aureus served as a model system. For species-specific enumeration a quantitative terminal restriction length polymorphism (qT-RFLP) assay was used. Based on models fitted to single-species cultivations, the outcome of mixed-culture experiments was predicted. Deviations of simulation results and experimental findings were then used to design additional single-cell experiments, to modify the corresponding growth kinetics, and to update model parameters. Eventually, the resulting mixed-culture dynamics was predicted and compared again to experimental results. During this iterative cycle, it became evident that the observed coexistence of P. aeruginosa and B. cepacia in mixed-culture chemostat experiments cannot be explained on the basis of glucose as the only substrate. After extension of growth kinetics, that is, for use of amino acids as secondary substrates, mixed-culture simulations represented the experimental

  15. The highest inhibition coefficient of phenol biodegradation using an acclimated mixed culture.

    PubMed

    Mohseni, Mojtaba; Sharifi Abdar, Payman; Borghei, S Mehdi

    2016-01-01

    In this study a membrane biological reactor (MBR) was operated at 25 ± 1 °C and pH = 7.5 ± 0.5 to treat synthetic wastewater containing high phenol concentrations. Removal efficiencies of phenol and chemical oxygen demand (COD) were evaluated at four various hydraulic retention times (HRTs) of 24, 12, 8, and 4 hours. The removal rate of phenol (5.51 kg-Phenol kg-VSS(-1) d(-1)), observed at HRT of 4 h, was the highest phenol degradation rate in the literature. According to COD tests, there were no significant organic matter in the effluent, and phenol was degraded completely by mixed culture. Substrate inhibition was calculated from experimental growth parameters using the Haldane, Yano, and Edward equations. The results show that the Haldane equation is fitted to the experimental data in an excellent manner. Kinetic parameters were derived by nonlinear regression with a correlation coefficient (R(2)) of 0.974. The values for Haldane constants μmax, Ks, and Ki were 0.3085 h(-1), 416 mg L(-1) and 1,886 mg L(-1), respectively. The Ki value is the highest value obtained for mixed cultures degrading phenol under batch conditions.

  16. Metabolic Energy-Based Modelling Explains Product Yielding in Anaerobic Mixed Culture Fermentations

    PubMed Central

    González-Cabaleiro, Rebeca; Lema, Juan M.; Rodríguez, Jorge

    2015-01-01

    The fermentation of glucose using microbial mixed cultures is of great interest given its potential to convert wastes into valuable products at low cost, however, the difficulties associated with the control of the process still pose important challenges for its industrial implementation. A deeper understanding of the fermentation process involving metabolic and biochemical principles is very necessary to overcome these difficulties. In this work a novel metabolic energy based model is presented that accurately predicts for the first time the experimentally observed changes in product spectrum with pH. The model predicts the observed shift towards formate production at high pH, accompanied with ethanol and acetate production. Acetate (accompanied with a more reduced product) and butyrate are predicted main products at low pH. The production of propionate between pH 6 and 8 is also predicted. These results are mechanistically explained for the first time considering the impact that variable proton motive potential and active transport energy costs have in terms of energy harvest over different products yielding. The model results, in line with numerous reported experiments, validate the mechanistic and bioenergetics hypotheses that fermentative mixed cultures products yielding appears to be controlled by the principle of maximum energy harvest and the necessity of balancing the redox equivalents in absence of external electron acceptors. PMID:25992959

  17. Influence of the pH on (open) mixed culture fermentation of glucose: a chemostat study.

    PubMed

    Temudo, Margarida F; Kleerebezem, Robbert; van Loosdrecht, Mark

    2007-09-01

    Catabolic products from anaerobic fermentation processes are potentially of industrial interest. The volatile fatty acids and alcohols produced can be used as building blocks in chemical processes or applied directly as substrates in a mixed culture process to produce bioplastics. Development of such applications requires a predictable and controllable product spectrum of the fermentation process. The aim of the research described in this paper was (i) to investigate the product spectrum of an open mixed culture fermentation (MCF) process as a function of the pH, using glucose as substrate, and (ii) to relate the product spectrum obtained to generalized biochemical and thermodynamic considerations. A chemostat was operated under carbon and energy limitation in order to investigate the pH effect on the product spectrum in a MCF process. A transition from CO(2)/H(2) production at lower pH values to formate production at higher pH values was observed. The ratio of CO(2)/H(2) versus formate production was found to be related to the thermodynamics of formate dehydrogenation to CO(2)/H(2). This transition was associated with a shift in the catabolic products, from butyrate and acetate to ethanol and acetate, likely due to a decrease in the oxidation state of the electron carriers in the cell. The product spectrum of the MCF process as a function of the pH could largely be explained using general biochemical considerations. PMID:17657773

  18. Metabolic energy-based modelling explains product yielding in anaerobic mixed culture fermentations.

    PubMed

    González-Cabaleiro, Rebeca; Lema, Juan M; Rodríguez, Jorge

    2015-01-01

    The fermentation of glucose using microbial mixed cultures is of great interest given its potential to convert wastes into valuable products at low cost, however, the difficulties associated with the control of the process still pose important challenges for its industrial implementation. A deeper understanding of the fermentation process involving metabolic and biochemical principles is very necessary to overcome these difficulties. In this work a novel metabolic energy based model is presented that accurately predicts for the first time the experimentally observed changes in product spectrum with pH. The model predicts the observed shift towards formate production at high pH, accompanied with ethanol and acetate production. Acetate (accompanied with a more reduced product) and butyrate are predicted main products at low pH. The production of propionate between pH 6 and 8 is also predicted. These results are mechanistically explained for the first time considering the impact that variable proton motive potential and active transport energy costs have in terms of energy harvest over different products yielding. The model results, in line with numerous reported experiments, validate the mechanistic and bioenergetics hypotheses that fermentative mixed cultures products yielding appears to be controlled by the principle of maximum energy harvest and the necessity of balancing the redox equivalents in absence of external electron acceptors.

  19. Growth kinetics of Hyphomicrobium and Thiobacillus spp. in mixed cultures degrading dimethyl sulfide and methanol.

    PubMed

    Hayes, Alexander C; Liss, Steven N; Allen, D Grant

    2010-08-01

    The growth kinetics of Hyphomicrobium spp. and Thiobacillus spp. on dimethyl sulfide (DMS) and methanol (in the case of Hyphomicrobium spp.) in an enrichment culture created from a biofilter cotreating DMS and methanol were studied. Specific growth rates of 0.099 h(-1) and 0.11 h(-1) were determined for Hyphomicrobium spp. and Thiobacillus spp., respectively, growing on DMS at pH 7. These specific growth rates are double the highest maximum specific growth rate for bacterial growth on DMS reported to date in the literature. When the pH of the medium was decreased from pH 7 to pH 5, the specific growth rate of Hyphomicrobium spp. decreased by 85%, with a near 100-fold decline in the yield of Hyphomicrobium 16S rRNA gene copies in the mixed culture. Through the same pH shift, the specific growth rate and 16S rRNA gene yield of Thiobacillus spp. remained similar. When methanol was used as a substrate, the specific growth rate of Hyphomicrobium spp. declined much less over the same pH range (up to 30%) while the yield of 16S rRNA gene copies declined by only 50%. Switching from an NH(4)(+)-N-based source to a NO(3)(-)-N-based source resulted in the same trends for the specific growth rate of these microorganisms with respect to pH. This suggests that pH has far more impact on the growth kinetics of these microorganisms than the nitrogen source. The results of these mixed-culture batch experiments indicate that the increased DMS removal rates observed in previous studies of biofilters cotreating DMS and methanol are due to the proliferation of DMS-degrading Hyphomicrobium spp. on methanol at pH levels not conducive to high growth rates on DMS alone. PMID:20562269

  20. Bio-oil upgrading strategies to improve PHA production from selected aerobic mixed cultures.

    PubMed

    Moita Fidalgo, Rita; Ortigueira, Joana; Freches, André; Pelica, João; Gonçalves, Magarida; Mendes, Benilde; Lemos, Paulo C

    2014-06-25

    Recent research on polyhydroxyalkanoates (PHAs) has focused on developing cost-effective production processes using low-value or industrial waste/surplus as substrate. One of such substrates is the liquid fraction resulting from pyrolysis processes, bio-oil. In this study, valorisation of bio-oil through PHA production was investigated. The impact of the complex bio-oil matrix on PHA production by an enriched mixed culture was examined. The performance of the direct utilization of pure bio-oil was compared with the utilization of three defined substrates contained in this bio-oil: acetate, glucose and xylose. When compared with acetate, bio-oil revealed lower capacity for polymer production as a result of a lower polymer yield on substrate and a lower PHA cell content. Two strategies for bio-oil upgrade were performed, anaerobic fermentation and vacuum distillation, and the resulting liquid streams were tested for polymer production. The first one was enriched in volatile fatty acids and the second one mainly on phenolic and long-chain fatty acids. PHA accumulation assays using the upgraded bio-oils attained polymer yields on substrate similar or higher than the one achieved with acetate, although with a lower PHA content. The capacity to use the enriched fractions for polymer production has yet to be optimized. The anaerobic digestion of bio-oil could also open-up the possibility to use the fermented bio-oil directly in the enrichment process of the mixed culture. This would increase the selective pressure toward an optimized PHA accumulating culture selection. PMID:24189432

  1. Biodegradation of chlorinated ethenes by a methane-utilizing mixed culture.

    PubMed Central

    Fogel, M M; Taddeo, A R; Fogel, S

    1986-01-01

    Chlorinated ethenes are toxic substances which are widely distributed groundwater contaminants and are persistent in the subsurface environment. Reports on the biodegradation of these compounds under anaerobic conditions which might occur naturally in groundwater show that these substances degrade very slowly, if at all. Previous attempts to degrade chlorinated ethenes aerobically have produced conflicting results. A mixed culture containing methane-utilizing bacteria was obtained by methane enrichment of a sediment sample. Biodegradation experiments carried out in sealed culture bottles with radioactively labeled trichloroethylene (TCE) showed that approximately half of the radioactive carbon had been converted to 14CO2 and bacterial biomass. In addition to TCE, vinyl chloride and vinylidene chloride could be degraded to products which are not volatile chlorinated substances and are therefore likely to be further degraded to CO2. Two other chlorinated ethenes, cis and trans-1,2-dichloroethylene, were shown to degrade to chlorinated products, which appeared to degrade further. A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions. The biodegradation of TCE was inhibited by acetylene, a specific inhibitor of methane oxidation by methanotrophs. This observation supported the hypothesis that a methanotroph is responsible for the observed biodegradations. PMID:3085587

  2. Development and composition of a mixed culture for bioremediation of chlorinated ethenes and ethanes

    USGS Publications Warehouse

    Jones, E.J.P.; Voytek, M.A.; Lorah, M.M.

    2005-01-01

    Microbial organisms capable of dechlorinating 1,1,2,2 tetrachloroethane (TeCA) and its chlorinated ethane and ethylene daughter products were enriched in surface sediments collected from the West Branch Canal Creek wetland area, leading to the formation of two mixed cultures using slightly different enrichment methods. Both WBC-1 and WBC-2 were capable of rapid and complete reductive dechlorination of TeCA and its daughter products (1,1,2-trichloroethane, 1,2-dichloroethane, trichloroethylene, 1,2-dichloroethylene, and vinyl chloride) to ethylene, and addition of either culture to wetland sediment and to engineered peat/compost mixtures resulted in significant enhancement of dechlorination. However, the WBC-2 culture supported better sustained activity and was more readily scaled up for application in bioaugmentation treatments, whereas dechlorination activity was gradually lost in WBC-1. The microbial composition of WBC-1 and WBC-2 were determined by cloning and sequencing 500 base pairs of the 16S rDNA gene and the methyl co-reductase. Methanogens identified in the consortia were members of the Order Methanomicrobiales, which includes acetoclastic methanogens. This is an abstract of a paper presented at the Proceedings of the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).

  3. Comparison of utilization of pectins from various sources by pure cultures of pectinolytic rumen bacteria and mixed cultures of rumen microorganisms.

    PubMed

    Kasperowicz, A

    1994-01-01

    Utilization of citrus, lucerne, apple and sugar beet pulp pectins by pure strains of rumen bacteria, Prevotella ruminicola, Lachnospira multiparus and Butyrivibrio fibrisolvens was compared. Additionally, the utilization of pectins by mixed rumen microorganisms was evaluated. The comparison was based on the depletion of galacturonic acid from medium, content of cellular protein in the cultures and the amount of end products of pectin fermentation in cell-free culture fluids. It was found that citrus pectin was utilized best; utilization of lucerne, apple and sugar beet pectins was dependent on the species of bacteria. P. ruminicola and B. fibrisolvens utilized polygalacturonic acid from sugar beet pectins better than that from apple or lucerne pectin, while L. multiparus was capable of significantly better utilization of lucerne pectin than pectin from sugar beet or apple. The source of pectin was less important for mixed cultures of rumen microorganisms than for pure cultures of rumen bacteria. The amount of fermentation products in the culture fluids supported the conclusion that citrus pectin was utilized better than others. Microbial protein content in the cultures was found to be a less sensitive indicator of pectin utilization than the remaining examined parameters. P. ruminicola strains and mixed cultures of rumen microorganisms were shown to have the highest ability to utilize pectins, L. multiparus-moderate, while the B. fibrisolvens strains utilized pectin the least.

  4. Decolourisation of Acid Orange 7 recalcitrant auto-oxidation coloured by-products using an acclimatised mixed bacterial culture.

    PubMed

    Bay, Hui Han; Lim, Chi Kim; Kee, Thuan Chien; Ware, Ismail; Chan, Giek Far; Shahir, Shafinaz; Ibrahim, Zaharah

    2014-03-01

    This study focuses on the biodegradation of recalcitrant, coloured compounds resulting from auto-oxidation of Acid Orange 7 (AO7) in a sequential facultative anaerobic-aerobic treatment system. A novel mixed bacterial culture, BAC-ZS, consisting of Brevibacillus panacihumi strain ZB1, Lysinibacillus fusiformis strain ZB2, and Enterococcus faecalis strain ZL bacteria were isolated from environmental samples. The acclimatisation of the mixed culture was carried out in an AO7 decolourised solution. The acclimatised mixed culture showed 98 % decolourisation within 2 h of facultative anaerobic treatment using yeast extract and glucose as co-substrate. Subsequent aerobic post treatment caused auto-oxidation reaction forming dark coloured compounds that reduced the percentage decolourisation to 73 %. Interestingly, further agitations of the mixed culture in the solution over a period of 48 h significantly decolourise the coloured compounds and increased the decolourisation percentage to 90 %. Analyses of the degradation compounds using UV-visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) showed complete degradation of recalcitrant AO7 by the novel BAC-ZS. Phytotoxicity tests using Cucumis sativus confirmed the dye solution after post aerobic treatment were less toxic compared to the parent dye. The quantitative real-time PCR revealed that E. faecalis strain ZL was the dominant strain in the acclimatised mix culture. PMID:24293297

  5. Decolourisation of Acid Orange 7 recalcitrant auto-oxidation coloured by-products using an acclimatised mixed bacterial culture.

    PubMed

    Bay, Hui Han; Lim, Chi Kim; Kee, Thuan Chien; Ware, Ismail; Chan, Giek Far; Shahir, Shafinaz; Ibrahim, Zaharah

    2014-03-01

    This study focuses on the biodegradation of recalcitrant, coloured compounds resulting from auto-oxidation of Acid Orange 7 (AO7) in a sequential facultative anaerobic-aerobic treatment system. A novel mixed bacterial culture, BAC-ZS, consisting of Brevibacillus panacihumi strain ZB1, Lysinibacillus fusiformis strain ZB2, and Enterococcus faecalis strain ZL bacteria were isolated from environmental samples. The acclimatisation of the mixed culture was carried out in an AO7 decolourised solution. The acclimatised mixed culture showed 98 % decolourisation within 2 h of facultative anaerobic treatment using yeast extract and glucose as co-substrate. Subsequent aerobic post treatment caused auto-oxidation reaction forming dark coloured compounds that reduced the percentage decolourisation to 73 %. Interestingly, further agitations of the mixed culture in the solution over a period of 48 h significantly decolourise the coloured compounds and increased the decolourisation percentage to 90 %. Analyses of the degradation compounds using UV-visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) showed complete degradation of recalcitrant AO7 by the novel BAC-ZS. Phytotoxicity tests using Cucumis sativus confirmed the dye solution after post aerobic treatment were less toxic compared to the parent dye. The quantitative real-time PCR revealed that E. faecalis strain ZL was the dominant strain in the acclimatised mix culture.

  6. The Cellular State Determines the Effect of Melatonin on the Survival of Mixed Cerebellar Cell Culture

    PubMed Central

    Franco, Daiane Gil; Markus, Regina P.

    2014-01-01

    The constitutive activation of nuclear factor-κB (NF-κB), a key transcription factor involved in neuroinflammation, is essential for the survival of neurons in situ and of cerebellar granule cells in culture. Melatonin is known to inhibit the activation of NF-κB and has a cytoprotective function. In this study, we evaluated whether the cytoprotective effect of melatonin depends on the state of activation of a mixed cerebellar culture that is composed predominantly of granule cells; we tested the effect of melatonin on cultured rat cerebellar cells stimulated or not with lipopolysaccharide (LPS). The addition of melatonin (0.1 nM–1 µM) reduced the survival of naïve cells while inhibiting LPS-induced cell death. Melatonin (100 nM) transiently (15 min) inhibited the nuclear translocation of both NF-κB dimers (p50/p50, p50/RelA) and, after 60 min, increased the activation of p50/RelA. Melatonin-induced p50/RelA activity in naïve cells resulted in the transcription of inducible nitric oxide synthase (iNOS) and the production of NO. Otherwise, in cultures treated with LPS, melatonin blocked the LPS-induced activation of p50/RelA and the reduction in p50/p50 levels and inhibited iNOS expression and NO synthesis. Therefore, melatonin in vehicle-treated cells induces cell death, while it protects against LPS-induced cytotoxicity. In summary, we confirmed that melatonin is a neuroprotective drug when cerebellar cells are challenged; however, melatonin can also lead to cell death when the normal balance of the NF-κB pathway is disturbed. Our data provide a mechanistic basis for understanding the influence of cell context on the final output response of melatonin. PMID:25184316

  7. Inhibitory effect of 5- and 6-ring PAHs on pyrene mineralization by a mixed enrichment culture

    SciTech Connect

    Molina, M.; Agraujo, R.

    1995-12-31

    This research investigates the mineralization of pyrene in mixtures of PAHs to identify potential synergistic or antagonistic interactions that affect the degradation of individual compounds. Mineralization of {sup 14}C pyrene (25 RM) by a mixed enrichment culture was studied in systems containing mixtures of 5- and 6-ring PAHs in minimal salts medium (MSM). In the absence of the High Molecular Weight (HMW)-PAHs, the culture mineralized 62% of the added pyrene. Addition of an equal mixture of benzo(a)pyrene, dibenzanthracene, and benzo(g,h,i)peryiene (25 {micro}M total concentration) reduced pyrene mineralization to 25% after a 9-day lag phase. An increase on the molar concentration of the HMW-PAH mixture to 75 and 125 {micro}M decreased pyrene mineralization to 9.2 and 1%, respectively. Results from treatments containing individual (25 {micro}M each), or pairs of the HMW-compounds demonstrated that none of the three individual compounds caused a significant reduction in the extent of pyrene mineralization. However, the combination of benzo(a)pyrene and benzanthracene significantly inhibited pyrene activity. In addition, the presence of both benzo(a)pyrene and benzo(g,h,i)peryiene reduced mineralization by almost 23%. Determination of bacterial density by epifluorescence microscopy showed that mineralization of pyrene coincides with growth of the bacterial culture; presence of the 5- and 6-ring PAHs delayed growth with a concurrent inhibition of mineralization. When growth resumes, the inhibitory effect is reduced. A decrease of pyrene inhibition was also noted when MSM was replaced with sediment extract, or when sediment (1 {micro}g/ml) was added to the medium. These results suggest a synergistic inhibitory effect by combinations of specific HMW-PAHs rather than inhibition by individual compounds of the mixture on both the growth of the bacterial culture and the extent of pyrene mineralization.

  8. Development and use of a quantum dot probe to track multiple yeast strains in mixed culture

    PubMed Central

    Gustafsson, Frida S.; Whiteside, Matthew D.; Jiranek, Vladimir; Durall, Daniel M.

    2014-01-01

    Saccharomyces cerevisiae strains vary in their ability to develop and enhance sensory attributes of alcoholic beverages and are often found growing in mixed strain fermentations; however, quantifying individual strains is challenging due to quantification inaccuracies, low marker longevity, and compromised kinetics. We developed a fluorescent probe, consisting of glutathione molecules conjugated to a quantum dot (QD). Two S. cerevisiae strains were incubated with different coloured probes (QD attached to glutathione molecules, QD-GSH), fermented at multiple ratios, and quantified using confocal microscopy. The QD method was compared with a culture method using microsatellite DNA analysis (MS method). Probes were taken up by an ADP1 encoded transporter, transferred from mother cell to daughter cell, detectable in strains throughout fermentation, and were non-toxic. This resulted in a new quantification method that was more accurate and efficient than the MS method. PMID:25382600

  9. Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery.

    PubMed

    Samorì, Chiara; Abbondanzi, Federica; Galletti, Paola; Giorgini, Loris; Mazzocchetti, Laura; Torri, Cristian; Tagliavini, Emilio

    2015-01-01

    Polyhydroxyalkanoates (PHAs) can be extracted from mixed microbial cultures (MMCs) by means of dimethyl carbonate (DMC) or combination of DMC and sodium hypochlorite (NaClO). The protocol based on DMC, a green solvent never used before for the extraction of PHAs from MMC, allows an overall polymer recovery of 63%; also the purity and the molecular weight of the recovered polymers are good (98% and 1.2 MDa, respectively). The use of NaClO pretreatment before DMC extraction increases the overall PHA recovery (82%) but lowers the mean molecular weight to 0.6-0.2 MDa. A double extraction with DMC results to be the method of choice for the recovery of high quality PHAs from attractive but challenging MMCs. PMID:25889806

  10. Saccharomyces cerevisiae mixed culture of blackberry (Rubus ulmifolius L.) juice: synergism in the aroma compounds production.

    PubMed

    Bautista-Rosales, Pedro Ulises; Ragazzo-Sánchez, Juan Arturo; Ruiz-Montañez, Gabriela; Ortiz-Basurto, Rosa Isela; Luna-Solano, Guadalupe; Calderón-Santoyo, Montserrat

    2014-01-01

    Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (<6°GL) with potential to be produced at an industrial scale was obtained. Alcoholic fermentations were performed at 28°C, 200 rpm, and noncontrolled pH. The synergistic effect on the aromatic compounds production during fermentation in mixed culture was compared with those obtained by monoculture and physic mixture of spirits produced in monoculture. The aromatic composition was determined by HS-SPME-GC. The differences in aromatic profile principally rely on the proportions in aromatic compounds and not on the number of those compounds. The multivariance analysis, principal component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains.

  11. High nitrate removal from synthetic wastewater with the mixed bacterial culture.

    PubMed

    Foglar, Lucija; Briski, Felicita; Sipos, Laszlo; Vuković, Marija

    2005-05-01

    The applicability of the mixed bacterial culture, originated from two-stage anaerobic-aerobic industrial yeasts production wastewater treatment plant for high rate denitrification processes was investigated. After acclimation to nitrate, the dominant strains were Pseudomonas and Paracoccus sp. Complete denitrification with low accumulation of nitrite-N (0.1 mg/l) was found in synthetic wastewater, obeying a zero-order reaction with respect to nitrate and a first-order reaction with respect to biomass concentration. Denitrification was then monitored in the continuous-flow stirred reactor at different hydraulic retention time, HRT (62-28 h) in order to achieve the optimal HRT. Nitrate was completely removed during following 45 days, at 25 degrees C with HRT, which we reduced from 62 to 28 h. Yet still, at 28 h HRT, high average specific denitrification rate of 142 mg NO3- -N/g VSS h was obtained. PMID:15627558

  12. Production of cellulases and hemicellulases by an anaerobic mixed culture from lignocellulosic biomass.

    PubMed

    Tabassum, R; Rajoka, M I; Malik, K A

    1990-03-01

    A comparison of different habitats, biogas plant, rumen fluid and sewage sludge, for cellulolytic organisms indicated sewage studge was the best source. Enrichment cultura gave a mixed culture which exhibited CMCase activity as well as extracellular Avicelase, xylanase, β-glucosidase, β-xylosidase activities and cell-bound β-glucosidase, and β-xylosidase production in a synthetic medium with eleven different cellulosic and lignocellulosic substrates. The activity of extracellular β-glucosidase and β-xylosidase production was significantly higher than endogenous activities. Hemicellulases were induced better than cellulases. The anzyme system was stable under aerobic conditions. Of the different lignocellulosic substrates, kallar grass was the best inducer of extracellular enzymes.

  13. Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery.

    PubMed

    Samorì, Chiara; Abbondanzi, Federica; Galletti, Paola; Giorgini, Loris; Mazzocchetti, Laura; Torri, Cristian; Tagliavini, Emilio

    2015-01-01

    Polyhydroxyalkanoates (PHAs) can be extracted from mixed microbial cultures (MMCs) by means of dimethyl carbonate (DMC) or combination of DMC and sodium hypochlorite (NaClO). The protocol based on DMC, a green solvent never used before for the extraction of PHAs from MMC, allows an overall polymer recovery of 63%; also the purity and the molecular weight of the recovered polymers are good (98% and 1.2 MDa, respectively). The use of NaClO pretreatment before DMC extraction increases the overall PHA recovery (82%) but lowers the mean molecular weight to 0.6-0.2 MDa. A double extraction with DMC results to be the method of choice for the recovery of high quality PHAs from attractive but challenging MMCs.

  14. Kinetic analysis of high-concentration isopropanol biodegradation by a solvent-tolerant mixed microbial culture.

    PubMed

    Bustard, Mark T; Meeyoo, Vissanu; Wright, Phillip C

    2002-06-20

    The ability of a previously enriched microbial population to utilize isopropanol (IPA) as the sole carbon source within a minimal salts medium is studied. The advantage of prior enrichment procedures for the improvement of IPA biodegradation performance is demonstrated for an IPA concentration of up to 24 g L(-1). Results showing the interrelationship between temperature and substrate utilization and inhibition levels at temperatures of between 2 degrees C and 45 degrees C are examined. Models of inhibition based on enzyme kinetics are assessed via nonlinear analysis, in order to accurately represent the growth kinetics of this solvent-tolerant mixed culture. The model that best describes the data is the Levenspiel substrate inhibition model, which can predict the maximum substrate level above which growth is completely limited. This is the first report of IPA treatment of up to 24 g L(-1) by an aerobic solvent-tolerant population. PMID:11992536

  15. Kinetic analysis of high-concentration isopropanol biodegradation by a solvent-tolerant mixed microbial culture.

    PubMed

    Bustard, Mark T; Meeyoo, Vissanu; Wright, Phillip C

    2002-06-20

    The ability of a previously enriched microbial population to utilize isopropanol (IPA) as the sole carbon source within a minimal salts medium is studied. The advantage of prior enrichment procedures for the improvement of IPA biodegradation performance is demonstrated for an IPA concentration of up to 24 g L(-1). Results showing the interrelationship between temperature and substrate utilization and inhibition levels at temperatures of between 2 degrees C and 45 degrees C are examined. Models of inhibition based on enzyme kinetics are assessed via nonlinear analysis, in order to accurately represent the growth kinetics of this solvent-tolerant mixed culture. The model that best describes the data is the Levenspiel substrate inhibition model, which can predict the maximum substrate level above which growth is completely limited. This is the first report of IPA treatment of up to 24 g L(-1) by an aerobic solvent-tolerant population.

  16. Butyric acid fermentation of sodium hydroxide pretreated rice straw with undefined mixed culture.

    PubMed

    Ai, Binling; Li, Jianzheng; Chi, Xue; Meng, Jia; Liu, Chong; Shi, En

    2014-05-01

    This study describes an alternative mixed culture fermentation technology to anaerobically convert lignocellulosic biomass into butyric acid, a valuable product with wide application, without supplementary cellulolytic enzymes. Rice straw was soaked in 1% NaOH solution to increase digestibility. Among the tested pretreatment conditions, soaking rice straw at 50°C for 72 h removed ~66% of the lignin, but retained ~84% of the cellulose and ~71% of the hemicellulose. By using an undefined cellulose-degrading butyrate-producing microbial community as butyric acid producer in batch fermentation, about 6 g/l of butyric acid was produced from the pretreated rice straw, which accounted for ~76% of the total volatile fatty acids. In the repeated-batch operation, the butyric acid production declined batch by batch, which was most possibly caused by the shift of microbial community structure monitored by denaturing gradient gel electrophoresis. In this study, batch operation was observed to be more suitable for butyric acid production.

  17. Saccharomyces cerevisiae Mixed Culture of Blackberry (Rubus ulmifolius L.) Juice: Synergism in the Aroma Compounds Production

    PubMed Central

    Ragazzo-Sánchez, Juan Arturo; Ortiz-Basurto, Rosa Isela; Luna-Solano, Guadalupe; Calderón-Santoyo, Montserrat

    2014-01-01

    Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (<6°GL) with potential to be produced at an industrial scale was obtained. Alcoholic fermentations were performed at 28°C, 200 rpm, and noncontrolled pH. The synergistic effect on the aromatic compounds production during fermentation in mixed culture was compared with those obtained by monoculture and physic mixture of spirits produced in monoculture. The aromatic composition was determined by HS-SPME-GC. The differences in aromatic profile principally rely on the proportions in aromatic compounds and not on the number of those compounds. The multivariance analysis, principal component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains. PMID:25506606

  18. Generalized Additive Mixed-Models for Pharmacology Using Integrated Discrete Multiple Organ Co-Culture

    PubMed Central

    Ingersoll, Thomas; Cole, Stephanie; Madren-Whalley, Janna; Booker, Lamont; Dorsey, Russell; Li, Albert; Salem, Harry

    2016-01-01

    Integrated Discrete Multiple Organ Co-culture (IDMOC) is emerging as an in-vitro alternative to in-vivo animal models for pharmacology studies. IDMOC allows dose-response relationships to be investigated at the tissue and organoid levels, yet, these relationships often exhibit responses that are far more complex than the binary responses often measured in whole animals. To accommodate departure from binary endpoints, IDMOC requires an expansion of analytic techniques beyond simple linear probit and logistic models familiar in toxicology. IDMOC dose-responses may be measured at continuous scales, exhibit significant non-linearity such as local maxima or minima, and may include non-independent measures. Generalized additive mixed-modeling (GAMM) provides an alternative description of dose-response that relaxes assumptions of independence and linearity. We compared GAMMs to traditional linear models for describing dose-response in IDMOC pharmacology studies. PMID:27110941

  19. Coupling limonene formation and oxyfunctionalization by mixed-culture resting cell fermentation.

    PubMed

    Willrodt, Christian; Hoschek, Anna; Bühler, Bruno; Schmid, Andreas; Julsing, Mattijs K

    2015-09-01

    Metabolic engineering strategies mark a milestone for the fermentative production of bulk and fine chemicals. Yet, toxic products and volatile reaction intermediates with low solubilities remain challenging. Prominent examples are artificial multistep pathways like the production of perillyl acetate (POHAc) from glucose via limonene. For POHAc, these limitations can be overcome by mixed-culture fermentations. A limonene biosynthesis pathway and cytochrome P450 153A6 (CYP153A6) as regioselective hydroxylase are used in two distinct recombinant E. coli. POHAc formation from glucose in one recombinant cell was hindered by ineffective coupling of limonene synthesis and low rates of oxyfunctionalization. The optimization of P450 gene expression led to the formation of 6.20 ± 0.06 mg gcdw (-1) POHAc in a biphasic batch cultivation with glucose as sole carbon and energy source. Increasing the spatial proximity between limonene synthase and CYP153A6 by a genetic fusion of both enzymes changed the molar limonene/POHAc ratio from 3.2 to 1.6. Spatial separation of limonene biosynthesis from its oxyfunctionalization improved POHAc concentration 3.3-fold to 21.7 mg L(-1) as compared to a biphasic fermentation. Mixed-cultures of E. coli BL21 (DE3) containing the limonene biosynthesis pathway and E. coli MG1655 harboring either CYP153A6, or alternatively a cymene monooxygenase, showed POHAc formation rates of 0.06 or 0.11 U gcdw (-1) , respectively. This concept provides a novel framework for fermentative syntheses involving toxic, volatile, or barely soluble compounds or pathway intermediates.

  20. Experimental and mathematical model of the interactions in the mixed culture of links in the “producer-consumer” cycle

    NASA Astrophysics Data System (ADS)

    Pisman, T. I.

    2009-07-01

    The paper presents a experimental and mathematical model of interactions between invertebrates (the ciliates Paramecium caudatum and the rotifers Brachionus plicatilis) in the "producer-consumer" aquatic biotic cycle with spatially separated components. The model describes the dynamics of the mixed culture of ciliates and rotifers in the "consumer" component, feeding on the mixed algal culture of the "producer" component. It has been found that metabolites of the algae Scenedesmus produce an adverse effect on the reproduction of the ciliates P. caudatum. Taking into account this effect, the results of investigation of the mathematical model were in qualitative agreement with the experimental results. In the "producer-consumer" biotic cycle it was shown that coexistence is impossible in the mixed culture of invertebrates of the "consumer" component. The ciliates P. caudatum are driven out by the rotifers B. plicatilis.

  1. Biodesulfurization of model compounds and de-asphalted bunker oil by mixed culture.

    PubMed

    Jiang, Xia; Yang, Senlin; Li, Wangling

    2014-01-01

    In this study, complicated model sulfur compounds in bunker oil and de-asphalted bunker oil were biodesulfurized in a batch process by microbial consortium enriched from oil sludge. Dibenzothiophene (DBT) and benzo[b]naphtho[1,2-d]thiophene (BNT1) were selected as model sulfur compounds. The results show that the mixed culture was able to grow by utilizing DBT and BNT1 as the sole sulfur source, while the cell density was higher using DBT than BNT1 as the sulfur source. GC-MS analysis of their desulfurized metabolites indicates that both DBT and BNT1 could be desulfurized through the sulfur-specific degradation pathway with the selective cleavage of carbon-sulfur bonds. When DBT and BNT1 coexisted, the biodesulfurization efficiency of BNT1 decreased significantly as the DBT concentrations increased (>0.1 mmol/L). BNT1 desulfurization efficiency also decreased along with the increase of 2-hydroxybiphenyl as the end product of DBT desulfurization. For real bunker oil, only 2.8 % of sulfur was removed without de-asphalting after 7 days of biotreatment. After de-asphalting, the biodesulfurization efficiency was significantly improved (26.2-36.5 %), which is mainly attributed to fully mixing of the oil and water due to the decreased viscosity of bunker oil. PMID:24046256

  2. Fatty acids production from hydrogen and carbon dioxide by mixed culture in the membrane biofilm reactor.

    PubMed

    Zhang, Fang; Ding, Jing; Zhang, Yan; Chen, Man; Ding, Zhao-Wei; van Loosdrecht, Mark C M; Zeng, Raymond J

    2013-10-15

    Gasification of waste to syngas (H2/CO2) is seen as a promising route to a circular economy. Biological conversion of the gaseous compounds into a liquid fuel or chemical, preferably medium chain fatty acids (caproate and caprylate) is an attractive concept. This study for the first time demonstrated in-situ production of medium chain fatty acids from H2 and CO2 in a hollow-fiber membrane biofilm reactor by mixed microbial culture. The hydrogen was for 100% utilized within the biofilms attached on the outer surface of the hollow-fiber membrane. The obtained concentrations of acetate, butyrate, caproate and caprylate were 7.4, 1.8, 0.98 and 0.42 g/L, respectively. The biomass specific production rate of caproate (31.4 mmol-C/(L day g-biomass)) was similar to literature reports for suspended cell cultures while for caprylate the rate (19.1 mmol-C/(L day g-biomass)) was more than 6 times higher. Microbial community analysis showed the biofilms were dominated by Clostridium spp., such as Clostridium ljungdahlii and Clostridium kluyveri. This study demonstrates a potential technology for syngas fermentation in the hollow-fiber membrane biofilm reactors.

  3. Optimization of polyhydroxybutyrate production by mixed cultures submitted to aerobic dynamic feeding conditions.

    PubMed

    Serafim, Luísa S; Lemos, Paulo C; Oliveira, Rui; Reis, Maria A M

    2004-07-20

    Activated sludge submitted to aerobic dynamic feeding conditions showed a good and stable capacity to store polyhydroxybutyrate (PHB). The system, working for 2 years, selected a microbial population with a high PHB storage capacity. The influence of carbon and nitrogen concentrations on the PHB accumulation yield was studied in a range of 15-180 Cmmol/l for acetate and 0-2.8 Nmmol/l for ammonia. Low ammonia concentrations favored PHB accumulation. The maximum PHB content, 67.5%, was obtained for 180 Cmmol/l of acetate supplied in one pulse. However, such high substrate concentration proved to be inhibitory for the storage mechanism, causing a slowdown of the specific PHB storage rate. In order to avoid substrate inhibition, 180 Cmmol/l of acetate was supplied in different ways: continuously fed and in three pulses of 60 Cmmol/l each. In both cases the specific PHB storage rate increased and the PHB content obtained were 56.2% and 78.5%, respectively. The latter value of PHB content is similar to that obtained by pure cultures and was never reported for mixed cultures. Addition of acetate by pulses controlled by the oxygen concentration was kept for 16 days, the PHB content being always above 70% of cell dry weight.

  4. Lactic acid production from potato peel waste by anaerobic sequencing batch fermentation using undefined mixed culture.

    PubMed

    Liang, Shaobo; McDonald, Armando G; Coats, Erik R

    2015-11-01

    Lactic acid (LA) is a necessary industrial feedstock for producing the bioplastic, polylactic acid (PLA), which is currently produced by pure culture fermentation of food carbohydrates. This work presents an alternative to produce LA from potato peel waste (PPW) by anaerobic fermentation in a sequencing batch reactor (SBR) inoculated with undefined mixed culture from a municipal wastewater treatment plant. A statistical design of experiments approach was employed using set of 0.8L SBRs using gelatinized PPW at a solids content range from 30 to 50 g L(-1), solids retention time of 2-4 days for yield and productivity optimization. The maximum LA production yield of 0.25 g g(-1) PPW and highest productivity of 125 mg g(-1) d(-1) were achieved. A scale-up SBR trial using neat gelatinized PPW (at 80 g L(-1) solids content) at the 3 L scale was employed and the highest LA yield of 0.14 g g(-1) PPW and a productivity of 138 mg g(-1) d(-1) were achieved with a 1 d SRT.

  5. 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

  6. Lactic acid production from potato peel waste by anaerobic sequencing batch fermentation using undefined mixed culture.

    PubMed

    Liang, Shaobo; McDonald, Armando G; Coats, Erik R

    2015-11-01

    Lactic acid (LA) is a necessary industrial feedstock for producing the bioplastic, polylactic acid (PLA), which is currently produced by pure culture fermentation of food carbohydrates. This work presents an alternative to produce LA from potato peel waste (PPW) by anaerobic fermentation in a sequencing batch reactor (SBR) inoculated with undefined mixed culture from a municipal wastewater treatment plant. A statistical design of experiments approach was employed using set of 0.8L SBRs using gelatinized PPW at a solids content range from 30 to 50 g L(-1), solids retention time of 2-4 days for yield and productivity optimization. The maximum LA production yield of 0.25 g g(-1) PPW and highest productivity of 125 mg g(-1) d(-1) were achieved. A scale-up SBR trial using neat gelatinized PPW (at 80 g L(-1) solids content) at the 3 L scale was employed and the highest LA yield of 0.14 g g(-1) PPW and a productivity of 138 mg g(-1) d(-1) were achieved with a 1 d SRT. PMID:25708409

  7. PHA production by mixed cultures: a way to valorize wastes from pulp industry.

    PubMed

    Queirós, Diogo; Rossetti, Simona; Serafim, Luísa S

    2014-04-01

    In this work, hardwood spent sulfite liquor (HSSL), a complex feedstock originating from the pulp industry, was tested for the first time as a substrate for polyhydroxyalkanoate (PHA) production by a mixed microbial culture (MMC) under aerobic dynamic feeding (ADF) conditions. A sequencing batch reactor (SBR) fed with HSSL was operated for 67days and the selected MMC reached a maximum PHA content of 67.6%. The MMC demonstrated a differential utilization of the carbon sources present in HSSL. Acetic acid was fully consumed, while xylose and lignosulphonates were partially consumed (30% and 14%, respectively). The selected culture was characterized by Fluorescence in Situ Hybridization (FISH). Bacteria belonging to the three main classes were identified: Alpha- (72.7±4.0%), Beta- (11.1±0.37%) and Gammaproteobacteria (10.3±0.3%). Within Alphaproteobacteria, a small amount of Paracoccus (4.2±0.51%) and Defluvicoccus related to Tetrad Forming Organisms (9.0±0.28%) were detected.

  8. Co-metabolic degradation of diazo dye- reactive blue 160 by enriched mixed cultures BDN.

    PubMed

    Balapure, Kshama H; Jain, Kunal; Chattaraj, Sananda; Bhatt, Nikhil S; Madamwar, Datta

    2014-08-30

    Mixed cultures BDN (BDN) proficient in decolourizing diazo dye-reactive blue 160 (RB160) consist of eight bacterial strains, was developed through culture enrichment method from soil samples contaminated with anthropogenic activities. The synthrophic interactions of BDN have led to complete decolourization and degradation of RB160 (100mg/L) within 4h along with co-metabolism of yeast extract (0.5%) in minimal medium. BDN microaerophilicaly decolourized even 1500mg/L of RB160 under high saline conditions (20g/L NaCl) at 37°C and pH 7.0. BDN exhibited broad substrate specificity and decolourized 27 structurally different dyes. The reductase enzymes symmetrically cleaved RB160 and oxidative enzymes further metabolised the degraded products and five different intermediates were identified using FTIR, (1)HNMR and GC-MS. The phytotoxicity assay confirmed that intact RB160 was more toxic than dye degraded intermediates. The BDN was able to colonize and decolourized RB160 in soil model system in presence of indigenous miocroflora as well as in sterile soil without any amendment of additional nutrients, which signifies it useful and potential application in bioremediation. PMID:25043700

  9. Characterization of microbial compositions in a thermophilic chemostat of mixed culture fermentation.

    PubMed

    Zhang, Fang; Yang, Jing-Hua; Dai, Kun; Chen, Yun; Li, Qiu-Rong; Gao, Fa-Ming; Zeng, Raymond J

    2016-02-01

    The microbial community compositions of a chemostat enriched in a thermophilic (55 °C) mixed culture fermentation (MCF) for hydrogen production under different operational conditions were revealed in this work by integrating denaturing gradient gel electrophoresis (DGGE), Illumina Miseq high-throughput sequencing, and 16S rRNA clone library sequencing. The results showed that the community structure of the enriched cultures was relatively simple. Clones close to the genera of Thermoanaerobacter and/or Bacillus mainly dominated the bacteria. And homoacetogens and archaea were washed out and not detected even by Illumina Miseq high-throughput sequencing which supported the benefit for hydrogen production. On the other hand, the results revealed that the metabolic shift was clearly associated with the change of dominated bacterial groups. The effects of hydrogen partial pressure (PH2) and pH from 4.0 to 5.5 on the microbial compositions were not notable and Thermoanaerobacter was dominant, thus, the metabolites were also not changed. While Bacillus, Thermoanaerobacter and Propionispora hippei dominated the bacteria communities at neutral pH, or Bacillus and Thermoanaerobacter dominated at high influent glucose concentrations, consequently the main metabolites shifted to acetate, ethanol, propionate, or lactate. Thereby, the effect of microbial composition on the metabolite distribution and shift shall be considered when modeling thermophilic MCF in the future. PMID:26563549

  10. Reductive dechlorination of tetrachloroethene by a mixed bacterial culture growing on ethyl lactate.

    PubMed

    Jayaraj, Jayashree; Rockne, Karl J; Makkar, Randhir S

    2004-01-01

    Chloroethenes like tetrachloroethene (PCE) are the most prevalent groundwater contaminants in the USA. Their presence as nonaqueous phase liquids (NAPLs) makes remediation difficult. Among options for NAPL cleanup, co-solvent injection has demonstrated success. However, the process has the potential to leave considerable residue of the co-solvent as well as residual chloroethene. Our rationale in this study was to examine whether this residual solvent could be a potential electron donor for the remediation of the residual chloroethene. We hypothesized that ethyl lactate, a "green" solvent, could serve both as a NAPL extraction solvent and an electron donor for reductive dechlorination of residual chloroethene. We examined whether a mixed culture known to degrade PCE with lactate could also grow on ethyl lactate and whether it could stimulate PCE dechlorination. Biomass growth and PCE dechlorination were observed by protein and chloride production, respectively, in the culture; with a specific dechlorination rate of 50 150 microg (mg cell d)(-1). Ethyl lactate abiotically breaks down to ethanol and lactate, the latter being a rich source of hydrogen fo reductive dechlorination. The results demonstrate that ethyl lactate may be promising for in situ bioremediation following NAPL extraction.

  11. Increased diazinon hydrolysis to 2-isopropyl-6-methyl-4-pyrimidinol in liquid medium by a specific Streptomyces mixed culture.

    PubMed

    Briceño, G; Schalchli, H; Rubilar, O; Tortella, G R; Mutis, A; Benimeli, C S; Palma, G; Diez, M C

    2016-08-01

    Actinobacteria identified as Streptomyces spp. were evaluated for their ability to remove diazinon as the only carbon source from a liquid medium. Single cultures of Streptomyces strains were exposed to diazinon at a concentration of 50 mg L(-1). After 96 h incubation, six of the eight cultures grew and five strains showed an increase in their total protein concentrations and changes in their protein profile. Up to 32% of the diazinon was removed by the single Streptomyces cultures. A compatibility assay showed that the different Streptomyces species were not antagonistic. Twenty-six mixed cultures were then prepared. Diazinon removal was increased when mixed cultures were used, and maximum diazinon removal of 62% was observed when the Streptomyces spp. strains AC5, AC9, GA11 and ISP13 were mixed; this was defined as the selected mixed culture (SMC). Diazinon removal was positively influenced by the addition of glucose into the liquid medium. Our study showed a diazinon degradation rate of 0.025 h(-1), half-life of 28 h(-1) and 2-isopropyl-6-methyl-4-pyrimidinol (IMHP) production of 0.143 mg L h(-1). Rapid diazinon hydrolysis to IMHP was associated with a decrease in the pH of the medium as a consequence of microbial glucose metabolism and organic acid exudation. Moreover, the SMC of Streptomyces was able to remove IMHP. This work constitutes a new, if not the only, report on diazinon degradation by mixed cultures of Streptomyces spp. Given the high levels of diazinon removal, the SMC formed by four Streptomyces strains has the potential to be used to treat the diazinon present in environmental matrices. PMID:27176942

  12. Increased diazinon hydrolysis to 2-isopropyl-6-methyl-4-pyrimidinol in liquid medium by a specific Streptomyces mixed culture.

    PubMed

    Briceño, G; Schalchli, H; Rubilar, O; Tortella, G R; Mutis, A; Benimeli, C S; Palma, G; Diez, M C

    2016-08-01

    Actinobacteria identified as Streptomyces spp. were evaluated for their ability to remove diazinon as the only carbon source from a liquid medium. Single cultures of Streptomyces strains were exposed to diazinon at a concentration of 50 mg L(-1). After 96 h incubation, six of the eight cultures grew and five strains showed an increase in their total protein concentrations and changes in their protein profile. Up to 32% of the diazinon was removed by the single Streptomyces cultures. A compatibility assay showed that the different Streptomyces species were not antagonistic. Twenty-six mixed cultures were then prepared. Diazinon removal was increased when mixed cultures were used, and maximum diazinon removal of 62% was observed when the Streptomyces spp. strains AC5, AC9, GA11 and ISP13 were mixed; this was defined as the selected mixed culture (SMC). Diazinon removal was positively influenced by the addition of glucose into the liquid medium. Our study showed a diazinon degradation rate of 0.025 h(-1), half-life of 28 h(-1) and 2-isopropyl-6-methyl-4-pyrimidinol (IMHP) production of 0.143 mg L h(-1). Rapid diazinon hydrolysis to IMHP was associated with a decrease in the pH of the medium as a consequence of microbial glucose metabolism and organic acid exudation. Moreover, the SMC of Streptomyces was able to remove IMHP. This work constitutes a new, if not the only, report on diazinon degradation by mixed cultures of Streptomyces spp. Given the high levels of diazinon removal, the SMC formed by four Streptomyces strains has the potential to be used to treat the diazinon present in environmental matrices.

  13. Transformation yields of chlorinated ethenes by a methanotrophic mixed culture expressing particulate methane monooxygenase.

    PubMed Central

    Anderson, J E; McCarty, P L

    1997-01-01

    Transformation yields for the aerobic cometabolic degradation of five chlorinated ethenes were determined by using a methanotrophic mixed culture expressing particulate methane monooxygenase (pMMO). Transformation yields (expressed as moles of chlorinated ethene degraded per mole of methane consumed) were 0.57, 0.25, 0.058, 0.0019, and 0.00022 for trans-1,2-dichloroethylene (t-DCE), vinyl chloride (VC), cis-1,2-dichloroethylene (c-DCE), trichloroethylene (TCE), and 1,1-dichloroethylene (1,1-DCE), respectively. Degradation of t-DCE and VC was observed only in the presence of formate or methane, sources of reducing energy necessary for cometabolism. The t-DCE and VC transformation yields represented 35 and 15%, respectively, of the theoretical maximum yields, based on reducing-energy availability from methane dissimilation to carbon dioxide, exclusive of all other processes that require reducing energy. The yields for t-DCE and VC were 20 times greater than the yields reported by others for cells expressing soluble methane monooxygenase (sMMO). Transformation yields for c-DCE, TCE, and 1,1-DCE were similar to or less than those for cultures expressing sMMO. Although methanotrophic biotreatment systems have typically been designed to incorporate cultures expressing sMMO, these results suggest that pMMO expression may be highly advantageous for degradation of t-DCE or VC. It may also be much easier to maintain pMMO expression in treatment systems, because pMMO is expressed by all methanotrophs whereas sMMO is expressed only by type II methanotrophs under copper-limited conditions. PMID:9023946

  14. Denitrification with epsilon-caprolactam by acclimated mixed culture and by pure culture of bacteria isolated from polyacrylonitrile fibre manufactured wastewater treatment system.

    PubMed

    Lee, C M; Wang, C C

    2004-01-01

    The aim of this study is to isolate denitrifying bacteria utilizing epsilon-caprolactam as the substrate, from a polyacrylonitrile fibre manufactured wastewater treatment system. The aim is also to compare the performance of PAN (polyacrylonitrile) mixed bacteria cultures acclimated to epsilon-caprolactam and isolated pure strain for treating different initial epsilon-caprolactam concentrations from synthetic wastewater under anoxic conditions. The result showed that the PAN mixed bacteria cultures acclimated to epsilon-caprolactam could utilize 1538.5 mg/l of epsilon-caprolactam as a substrate for denitrification. Sufficient time and about 2200 mg/l of nitrate were necessary for the complete epsilon-caprolactam removal. Paracoccus thiophilus was isolated from the polyacrylonitrile fibre manufactured wastewater treatment system and it could utilize 1722.5 mg/l of epsilon-caprolactam as a substrate for denitrification. About 3500 mg/l of nitrate was necessary for the complete removal of epsilon-caprolactam. When the initial epsilon-caprolactam concentration was below 784.3 mg/l, the removal efficiency of epsilon-caprolactam by Paracoccus thiophilus was better than that for the PAN mixed bacteria cultures. The growth of Paracoccus thiophilus was better. However, when the initial epsilon-caprolactam concentration was as high as 1445.8 mg/l, both the epsilon-caprolactam removal efficiency by Paracoccus thiophilus and Paracoccus thiophilus specific growth rate were similar to the PAN mixed bacteria cultures. PMID:15137443

  15. Existence of glia mitigated ketamine-induced neurotoxicity in neuron-glia mixed cultures of neonatal rat cortex and the glia-mediated protective effect of 2-PMPA.

    PubMed

    Zuo, Daiying; Wang, Chengna; Li, Zengqiang; Lin, Li; Duan, Zhenfang; Qi, Huan; Li, Lin; Sun, Feng; Wu, Yingliang

    2014-09-01

    The present study compared ketamine-induced neurotoxicity in the neuron-glia mixed cultures and neuronal cultures and further explored the neuroprotective effect of the NAAG peptidase inhibitor 2-(phosphonomethyl) pentanedioic acid (2-PMPA). Firstly, Rosenfeld's staining and immunofluorescence staining of microtubule-associated protein 2 (MAP2) and glial fibrillary acidic protein (GFAP) were used to address the difference of morphology in the mixed cultures and neuronal cultures. Our results showed that neurons and astrocytes grew in good conditions. The ratio of neurons and astrocytes in the mixed cultures was around 1:1, and the purity of neurons in the neuronal cultures is 91.3%. Furthermore, ketamine was used to test the hypothesis that the presence of a higher proportion of glia in the mixed cultures would be protective against ketamine-induced neurotoxicity in the mixed cultures compared with neuronal cultures. The results showed that ketamine-induced morphological changes, cell viability decrease and lactate dehydrogenase (LDH) levels increase were significantly mitigated in neuron-glia mixed cultures compared with neuronal cultures. Furthermore, 2-PMPA was included to further explore efficient protective drug for ketamine-induced neurotoxicity. Our results showed that 2-PMPA reduced ketamine-induced decrease of cell viability and increase of LDH levels in the mixed cultures but not in the neuronal cultures. Further morphological changes of neurons and astrocytes also indicated that 2-PMPA could improve ketamine damaged neurons in the mixed cultures instead of neuronal cultures. These results indicate that glia protect neurons from ketamine-induced neurotoxicity. These data further suggest that glia mediate the neuroprotective effect of 2-PMPA and 2-PMPA has the potential to treat ketamine-induced neurotoxicity in vivo. Delineating the mechanisms underlying the communication between neurons and glia and the neuroprotective effects of 2-PMPA in the mixed

  16. Polyhydroxyalkanoates production with mixed microbial cultures: from culture selection to polymer recovery in a high-rate continuous process.

    PubMed

    Villano, Marianna; Valentino, Francesco; Barbetta, Andrea; Martino, Lucrezia; Scandola, Mariastella; Majone, Mauro

    2014-06-25

    Polyhydroxyalkanoates (PHA) production with mixed microbial cultures (MMC) has been investigated by means of a sequential process involving three different stages, consisting of a lab-scale sequencing batch reactor for MMC selection, a PHA accumulation reactor and a polymer extraction reactor. All stages were performed under continuous operation for at least 4 months to check the overall process robustness as well as the related variability of polymer composition and properties. By operating both biological stages at high organic loads (8.5 and 29.1 gCOD/Ld, respectively) with a synthetic mixture of acetic and propionic acid, it was possible to continuously produce PHA at 1.43 g/Ld with stable performance (overall, the storage yield was 0.18 COD/COD). To identify the optimal operating conditions of the extraction reactor, two digestion solutions have been tested, NaOH (1m) and NaClO (5% active Cl2). The latter resulted in the best performance both in terms of yield of polymer recovery (around 100%, w/w) and purity (more than 90% of PHA content in the residual solids, on a weight basis). In spite of the stable operating conditions and performance, a large variation was observed for the HV content, ranging between 4 and 20 (%, w/w) for daily samples after accumulation and between 9 and 13 (%, w/w) for weekly average samples after extraction and lyophilization. The molecular weight of the produced polymer ranged between 3.4 × 10(5) and 5.4 × 10(5)g/mol with a large polydispersity index. By contrast, TGA and DSC analysis showed that the thermal polymer behavior did not substantially change over time, although it was strongly affected by the extraction agent used (NaClO or NaOH).

  17. Evaluation of Mixed Probiotic Starter Cultures Isolated from Kimchi on Physicochemical and Functional Properties, and Volatile Compounds of Fermented Hams

    PubMed Central

    Yoo, Seung Seok

    2016-01-01

    The objective of this study was to investigate the effects of mixed starter cultures isolated from kimchi on physicochemical properties, functionality and flavors of fermented ham. Physicochemical properties, microbial counts, shear force, cholesterol contents and volatile compounds of fermented ham were investigated during processing (curing and ripening time). Curing process for 7 d increased saltiness, however, decreased hunter color values (L, a, and b values). Ripening process for 21 d increased most parameters, such as saltiness, color values, weight loss, shear force and cholesterol content due to the drying process. The mixed starter culture had higher lactic acid bacteria than the commercial one. While eight volatile compounds were identified from fermented hams during curing process, total fiftyeight volatile compounds were identified from fermented hams during ripening process. The main volatile compounds were alcohols, esters and furans. However, no differences in volatile compounds were observed between two batches. Fermented hams (batch B) manufactured with probiotic starter culture (LPP) had higher sensory score in texture, color and overall acceptability than counterparts (batch A), while the opposite trend was observed in flavor. Therefore, mixed probiotic starter culture isolated from kimchi might be used as a starter culture to be able to replace with commercial starter culture (LK-30 plus) for the manufacture of fermented ham. PMID:27499673

  18. Evaluation of Mixed Probiotic Starter Cultures Isolated from Kimchi on Physicochemical and Functional Properties, and Volatile Compounds of Fermented Hams.

    PubMed

    Kim, Young Joo; Park, Sung Yong; Lee, Hong Chul; Yoo, Seung Seok; Oh, Sejong; Kim, Kwang Hyun; Chin, Koo Bok

    2016-01-01

    The objective of this study was to investigate the effects of mixed starter cultures isolated from kimchi on physicochemical properties, functionality and flavors of fermented ham. Physicochemical properties, microbial counts, shear force, cholesterol contents and volatile compounds of fermented ham were investigated during processing (curing and ripening time). Curing process for 7 d increased saltiness, however, decreased hunter color values (L, a, and b values). Ripening process for 21 d increased most parameters, such as saltiness, color values, weight loss, shear force and cholesterol content due to the drying process. The mixed starter culture had higher lactic acid bacteria than the commercial one. While eight volatile compounds were identified from fermented hams during curing process, total fiftyeight volatile compounds were identified from fermented hams during ripening process. The main volatile compounds were alcohols, esters and furans. However, no differences in volatile compounds were observed between two batches. Fermented hams (batch B) manufactured with probiotic starter culture (LPP) had higher sensory score in texture, color and overall acceptability than counterparts (batch A), while the opposite trend was observed in flavor. Therefore, mixed probiotic starter culture isolated from kimchi might be used as a starter culture to be able to replace with commercial starter culture (LK-30 plus) for the manufacture of fermented ham. PMID:27499673

  19. Mixed feeds of glycerol and methanol can improve the performance of Pichia pastoris cultures: A quantitative study based on concentration gradients in transient continuous cultures.

    PubMed

    Jungo, Carmen; Marison, Ian; von Stockar, Urs

    2007-03-10

    Transient continuous cultures constitute a means to speed up strain characterization, by avoiding the need for many time-consuming steady-state experiments. In this study, mixed substrate growth on glycerol and methanol of a Pichia pastoris strain expressing and secreting recombinant avidin was characterized quantitatively by performing a nutrient gradient with linear increase of the methanol fraction in the feed medium from 0.5 to 0.93 C-mol C-mol(-1) at a dilution rate of 0.06 h(-1). The influence of the methanol fraction in the feed medium on recombinant avidin productivity and on specific alcohol oxidase activity were also examined. Results showed that, compared with cultures on methanol as sole carbon source, the specific recombinant avidin production rate was the same provided the methanol fraction in the feed medium was higher than 0.6 C-mol C-mol(-1). The volumetric avidin production rate was even 1.1-fold higher with a methanol fraction in the feed medium of 0.62 C-mol C-mol(-1) as a result of the higher biomass yield on mixed substrate growth compared with methanol alone. Moreover, since heat production and oxygen uptake rates are lower during mixed substrate growth on glycerol and methanol, mixed substrate cultures present technical advantages for the performance of high cell density P. pastoris cultures. Results obtained in a high cell density fed-batch culture with a mixed feed of 0.65 C-mol C-mol(-1) methanol and 0.35 C-mol C-mol(-1) glycerol were in agreement with results obtained during the transient nutrient gradient.

  20. To a cultural perspective of mixed reality events: a case study of event overflow in operas and concerts in mixed reality

    NASA Astrophysics Data System (ADS)

    Lucas, Jean-François; Cornish, Tracy; Margolis, Todd

    2012-12-01

    Mixed reality defines the sharing of a space-time between the real and the virtual world. The definition of this concept is further extended when virtual worlds such as Second Life® (SL) are included. Through cultural events such as concerts and operas, we will see that the main goal of these kinds of projects is not simply to offer a video and audio broadcast of these events in the digital dimension. The current challenge is to create interactions between the individuals who are in different shared spaces. By studying the unfolding of these events in its various phases-before, during, and after-we examine the culture of the event. We question how the culture of the event can be transposed in a mixed reality display, and how this kind of event can affect people on both sides of the "membrane" made by the technical configuration. Beyond the alignments and adjustments that we can see between the different individuals involved in these events, we examine more broadly the changes and mutations of the culture of the event in this specific configuration.

  1. Reconstituted yogurt from yogurt cultured milk powder mix has better overall characteristics than reconstituted yogurt from commercial yogurt powder.

    PubMed

    Song, Lijie; Aryana, Kayanush J

    2014-10-01

    For manufacture of commercial yogurt powder, yogurt has to go through a drying process, which substantially lowers the yogurt culture counts, so the potential health benefits of the yogurt culture bacteria are reduced. Also, upon reconstitution, commercial yogurt powder does not taste like yogurt and has an off-flavor. The objective was to study the microbial, physicochemical, and sensory characteristics of reconstituted yogurt from yogurt cultured milk powder (YCMP) mix and reconstituted yogurt from commercial yogurt powder (CYP). The CYP reconstituted yogurt was the control and YCMP mix reconstituted yogurt was the treatment. Microbial and physicochemical characteristics of the CYP reconstituted yogurt and YCMP mix reconstituted yogurt were analyzed daily for the first week and then weekly for a period of 8 wk. Sensory consumer testing of CYP reconstituted yogurt and YCMP mix reconstituted yogurt was conducted with 100 consumers. At 56 d, YCMP mix reconstituted yogurt had 5 log cfu/mL higher counts of Streptococcus thermophilus than the control (CYP reconstituted yogurt). Also, Lactobacillus bulgaricus counts of YCMP mix reconstituted yogurt were 6.55 log cfu/mL at 28 d and were 5.35 log cfu/mL at 56 d, whereas the CYP reconstituted yogurt from 28 d onwards had a count of <10 cfu/mL. The YCMP mix reconstituted yogurt also had significantly higher apparent viscosity and sensory scores for appearance, color, aroma, taste, thickness, overall liking, consumer acceptability, and purchase intent than CYP reconstituted yogurt. Overall, YCMP mix reconstituted yogurt had more desirable characteristics than CYP reconstituted yogurt.

  2. Workforce Education and Development Curriculum Responsiveness to Culturally and Internationally Diverse Graduate Students: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Ferdinand, Debra

    2009-01-01

    This descriptive study used a mixed methods design and sought to examine students' perceptions on workforce education and development (WED) curriculum responsiveness to culturally and internationally diverse graduate students at a Midwestern university on four dimensions: "teaching strategies (to include delivery)," "curriculum inclusiveness,"…

  3. Degradation of soil cyanide by single and mixed cultures of Pseudomonas stutzeri and Bacillus subtilis.

    PubMed

    Nwokoro, Ogbonnaya; Dibua, Marie Esther Uju

    2014-03-01

    The aim of this investigation was to study whether certain bacteria could be used for cyanide degradation in soil. The bacteria Pseudomonas stutzeri and Bacillus subtilis were selected based on their good growth in a minimal medium containing 0.8 mg mL-1 potassium cyanide (KCN). In this study we tested their ability to reduce cyanide levels in a medium containing 1.5 mg mL-1 of KCN. Although both microorganisms reduced cyanide levels, Pseudomonas stutzeri was the more effective test organism. Later on, the selected cultures were grown, diluted and their various cell concentrations were used individually and in combination to test their ability of cyanide degradation in soil samples collected around a cassava processing mill. Bacillus subtilis caused degradation of soil cyanide from 0.218 mg g-1 soil immediately with an inoculum concentration of 0.1 (OD600nm) to 0.072 mg g-1 soil after 10 days with an inoculum concentration of 0.6 (OD600nm) implying a 66.9 % reduction. Pseudomonas stutzeri cell concentration of 0.1 (OD600nm) decreased soil cyanide from 0.218 mg g-1 soil initially to 0.061 mg g-1 soil after 10 days with an inoculum concentration of 0.6 (OD600nm) (72 % reduction). The mixed culture of the two bacteria produced the best degradation of soil cyanide from 0.218 mg g-1 soil sample with a combined inoculum concentration of 0.1 (OD600nm) initially to 0.025 mg g-1 soil with a combined inoculum concentration of 0.6 (OD600nm) after 10 days incubation resulting in an 88.5 % degradation of soil cyanide. The analysed bacteria displayed high cyanide degradation potential and may be useful for efficient decontamination of cyanide contaminated sites.

  4. Improving flavor metabolism of Saccharomyces cerevisiae by mixed culture with Bacillus licheniformis for Chinese Maotai-flavor liquor making.

    PubMed

    Meng, Xing; Wu, Qun; Wang, Li; Wang, Diqiang; Chen, Liangqiang; Xu, Yan

    2015-12-01

    Microbial interactions could impact the metabolic behavior of microbes involved in food fermentation, and therefore they are important for improving food quality. This study investigated the effect of Bacillus licheniformis, the dominant bacteria in the fermentation process of Chinese Maotai-flavor liquor, on the metabolic activity of Saccharomyces cerevisiae. Results indicated that S. cerevisiae inhibited the growth of B. licheniformis in all mixed culture systems and final viable cell count was lower than 20 cfu/mL. Although growth of S. cerevisiae was barely influenced by B. licheniformis, its metabolism was changed as initial inoculation ratio varied. The maximum ethanol productions were observed in S. cerevisiae and B. licheniformis at 10(6):10(7) and 10(6):10(8) ratios and have increased by 16.8 % compared with single culture of S. cerevisiae. According to flavor compounds, the culture ratio 10(6):10(6) showed the highest level of total concentrations of all different kinds of flavor compounds. Correlation analyses showed that 12 flavor compounds, including 4 fatty acids and their 2 corresponding esters, 1 terpene, and 5 aromatic compounds, that could only be produced by S. cerevisiae were significantly correlated with the initial inoculation amount of B. licheniformis. These metabolic changes in S. cerevisiae were not only a benefit for liquor aroma, but may also be related to its inhibition effect in mixed culture. This study could help to reveal the microbial interactions in Chinese liquor fermentation and provide guidance for optimal arrangement of mixed culture fermentation systems.

  5. The relationship between Mexican American cultural values and resilience among Mexican American college students: a mixed methods study.

    PubMed

    Morgan Consoli, Melissa L; Llamas, Jasmin D

    2013-10-01

    The current study investigated the role of cultural values in the resilience of Mexican American college students. Utilizing mixed methodology, 124 self-identified Mexican American college students were asked to complete an online survey, including a demographic questionnaire, the Resilience Scale, Mexican American Cultural Values Scale, and 2 open-ended questions concerning overcoming adversity and cultural values. As hypothesized, Mexican American traditional cultural values (Familismo, Respeto, Religiosidad, and Traditional Gender Roles) predicted resilience, with Familismo accounting for the majority of the variance. Consensual qualitative research (Hill, Thompson, & Nutt Williams, 1997) was used to identify emergent domains and themes within the open-ended question responses. Traditional Mexican American Value themes included Familismo, Ethnic Identity, Religiosidad, Perseverance, and Respeto. Results highlight the important role that certain Mexican American cultural values play in providing strength for overcoming adversities.

  6. Transferability of Trypanosoma cruzi from mixed human host infection to Triatoma infestans and from insects to axenic culture.

    PubMed

    Ortiz, Sylvia; Zulantay, Inés; Apt, Werner; Saavedra, Miguel; Solari, Aldo

    2015-02-01

    The etiologic agent of Chagas disease is Trypanosoma cruzi, a protozoan whose life cycle involves obligatory passage through vertebrate and invertebrate hosts in a series of stages. The aim of this study was to explore the transferability of mixed discrete typing units (DTUs) of T. cruzi present in chronic chagasic patients when passed through an invertebrate host during xenodiagnosis (XD) and then when transferred to axenic cultures to obtain T. cruzi isolates. DTUs of T. cruzi present in these two hosts and axenic cultures were identified by kDNA PCR amplification and subsequent hybridization with DTU-specific probes. Mixtures of Tc I, Tc II, Tc V and Tc VI DTUs were detected in blood samples. However as a result of XD and axenic cultures it was possible to identify mostly Tc V. We conclude that the transferability of an isolate of T.cruzi derived from mixed DTUs present in human blood depends upon the starved invertebrate host used for xenodiagnosis.

  7. High-purity propionate production from glycerol in mixed culture fermentation.

    PubMed

    Chen, Yun; Wang, Ting; Shen, Nan; Zhang, Fang; Zeng, Raymond J

    2016-11-01

    High-purity propionate production from glycerol in mixed culture fermentation (MCF) induced by high ammonium concentration was investigated. Fed-batch experiments revealed that higher ammonium concentration (>2.9g/L) had simultaneous negative effects on acetate and propionate degradation. Propionate production and yield was up to 22.6g/L and 0.45g COD/g COD glycerol, respectively, with a purity of 96%. Sequential batch experiments demonstrated that the yields of propionate were 0.3±0.05, 0.32±0.01, and 0.34±0.03g COD/g COD at a glycerol concentration of 2.78, 4.38, and 5.56g/L, respectively, and the purity of propionate was 91-100%. Microbial community analysis showed that the phylum Firmicutes dominated the bacterial community at different glycerol concentrations. However, the Methanosaeta population decreased from 46% to 6% when glycerol concentration increased from 2.78 to 5.56g/L, resulting in lower acetate degradation rate. Thus, the present study might provide an alternative option for the production of propionate from glycerol via MCF. PMID:27544916

  8. Use of mixed culture bacteria for photofermentive hydrogen of dark fermentation effluent.

    PubMed

    Tawfik, Ahmed; El-Bery, Haitham; Kumari, Sheena; Bux, Faizal

    2014-09-01

    Hydrogen production (HP) from dark fermentation effluent of starch wastewater via vertical tubular photo-bioreactor was investigated. The reactor was inoculated with mixed culture of bacteria and operated at light intensity of 190 W/m(2). Hydraulic retention time (HRT) and organic loading rate (OLR) was varied between 0.9 to 4.0 h and 3.2 to 16 g COD/l.d., respectively. Increasing the HRT from 0.9 to 2.5 h, significantly (P<0.05) increased HP from 1±0.04 to 3.05±0.19 l/d, respectively. However, minimal increase in HP occurred when increasing the HRT up to 4.0 h. The HP remained unaffected when increasing the OLR from 3.2 to 6.4 g COD/l.d. Further increase in the OLR up to 8.2 and 16 g COD/l.d., resulted in a drop in HP i.e. 0.96 and 0.19 l/d, respectively. Microbial community analysis of the reactor samples showed the presence and dominance of hydrogen producing purple non-sulfur phototrophic (PNS) bacterium, Rhodopseudomonas palustris in the reactor. PMID:24768414

  9. Inhibitory effects of butyrate on biological hydrogen production with mixed anaerobic cultures.

    PubMed

    Zheng, Xian-Jun; Yu, Han-Qing

    2005-01-01

    In this study batch experiments were conducted to investigate the inhibitory effects of butyrate addition on hydrogen production from glucose by using anaerobic mixed cultures. Experimental results showed that addition of butyrate at 4.18 and 6.27 g/l only slightly inhibited hydrogen production, and addition of butyrate at 8.36-12.54 g/l imposed a moderate inhibitory effect on hydrogen production. At addition of 25.08 g/l, butyrate had a strong inhibitory influence on substrate degradation and hydrogen production. The distribution of the volatile fatty acids produced from the acidogeneisis of glucose was significantly influenced by the addition of butyrate. The inhibition of butyrate addition on hydrogen production was described well by a non-competitive and non-linear inhibition model, with the maximum hydrogen production rate of 59.3 ml/g-SS/h, critical added butyrate concentration of 25.08 g/l, and inhibition degree of 0.323, respectively. The C(I,50) values (the butyrate concentration at which bioactivity is reduced by 50%) for hydrogen production rate and yield were estimated as 19.39 and 20.78 g/l of added butyrate, respectively.

  10. Bioelectricity production from microbial fuel cell using mixed bacterial culture isolated from distillery wastewater.

    PubMed

    Samsudeen, N; Radhakrishnan, T K; Matheswaran, Manickam

    2015-11-01

    The effect of various system parameters such as wastewater Chemical Oxygen Demand (COD) concentration, pH, conductivity, membrane size and thickness on efficient energy production using mixed isolated culture from the distillery wastewater in the MFC was studied. The power density increased with increase in the anolyte pH from 6 to 8. The peak power density and COD removal efficiency was observed as 63.8±0.65 mW/m(2) and 63.5±1.5% at pH 8, respectively. The MFC performance increased with increasing COD concentration (800-3200 mg/l), conductivity (1.1-9.7 mS/cm) and membrane area (8-24 cm(2)). The MFC operating with wastewater COD concentration of 3200 mg/l and its conductivity of 9.7 mS/cm produced the highest power density of 202±6 mW/m(2) with a corresponding current density of 412±12 mA/m(2). The results showed that the efficient electricity generation and simultaneous treatment of distillery wastewater can be attained in the MFC.

  11. Effects of repetitive low-pressure explosive blast on primary neurons and mixed cultures.

    PubMed

    Zander, Nicole E; Piehler, Thuvan; Banton, Rohan; Benjamin, Richard

    2016-09-01

    Repetitive mild traumatic brain injury represents a considerable health concern, particularly for athletes and military personnel. For blast-induced brain injury, threshold shock-impulse levels required to induce such injuries and cumulative effects with single and/or multiple exposures are not well characterized. Currently, there is no established in vitro experimental model with blast pressure waves generated by live explosives. This study presents results of primary neurons and mixed cultures subjected to our unique in vitro indoor experimental platform that uses real military explosive charges to probe the effects of primary explosive blast at the cellular level. The effects of the blast on membrane permeability, generation of reactive oxygen species (ROS), uptake of sodium ions, intracellular calcium, and release of glutamate were probed 2 and 24 hr postblast. Significant changes in membrane permeability and sodium uptake among the sham, single-blast-injured, and triple-blast-injured samples were observed. A significant increase in ROS and glutamate release was observed for the triple-blast-injured samples compared with the sham. Changes in intracellular calcium were not significant. These results suggest that blast exposure disrupts the integrity of the plasma membrane, leading to the upset of ion homeostasis, formation of ROS, and glutamate release. Published 2016. †This article is a U.S. Government work and is in the public domain in the USA.

  12. Chemical characterization and anaerobic biodegradability of hydrothermal liquefaction aqueous products from mixed-culture wastewater algae.

    PubMed

    Tommaso, Giovana; Chen, Wan-Ting; Li, Peng; Schideman, Lance; Zhang, Yuanhui

    2015-02-01

    This study examined the chemical characteristics and the anaerobic degradability of the aqueous product from hydrothermal liquefaction (HTL-ap) from the conversion of mixed-culture algal biomass grown in a wastewater treatment system. The effects of the HTL reaction times from 0 to 1.5 h, and reaction temperatures from 260 °C to 320 °C on the anaerobic degradability of the HTL-ap were quantified using biomethane potential assays. Comparing chemical oxygen demand data for HTL-ap from different operating conditions, indicated that organic matter may partition from organic phase to aqueous phase at 320 °C. Moderate lag phase and the highest cumulative methane production were observed when HTL-ap was obtained at 320 °C. The longest lag phase and the smallest production rate were observed in the process fed with HTL-ap obtained at 300 °C. Nevertheless, after overcoming adaptation issues, this HTL-ap led to the second highest accumulated specific methane production. Acetogenesis was identified as a possible rate-limiting pathway.

  13. Oxygen suppresses light-driven anodic current generation by a mixed phototrophic culture.

    PubMed

    Darus, Libertus; Ledezma, Pablo; Keller, Jürg; Freguia, Stefano

    2014-12-01

    This paper describes the detrimental effect of photosynthetically evolved oxygen on anodic current generation in the presence of riboflavin upon illumination of a mixed phototrophic culture enriched from a freshwater pond at +0.6 V vs standard hydrogen electrode. In the presence of riboflavin, the phototrophic biomass in the anodic compartment produced an electrical current in response to light/dark cycles (12 h/12 h) over 12 months of operation, generating a maximum current density of 17.5 mA x m(-2) during the dark phase, whereas a much lower current of approximately 2 mA x m(-2) was generated during illumination. We found that the low current generation under light exposure was caused by high rates of reoxidation of reduced riboflavin by oxygen produced during photosynthesis. Quantification of biomass by fluorescence in situ hybridization images suggested that green algae were predominant in both the anode-based biofilm (55.1%) and the anolyte suspension (87.9%) with the remaining biovolume accounted for by bacteria. Genus-level sequencing analysis revealed that bacteria were dominated by cyanobacterium Leptolyngbia (∼35%), while the prevailing algae were Dictyosphaerium, Coelastrum, and Auxenochlorella. This study offers a key comprehension of mediator sensitivity to reoxidation by dissolved oxygen for improvement of microbial solar cell performance.

  14. Inoculation of paperboard mill sludge versus mixed culture bacteria for hydrogen production from paperboard mill wastewater.

    PubMed

    Farghaly, Ahmed; Tawfik, Ahmed; Danial, Amal

    2016-02-01

    A comparative evaluation of paperboard mill sludge (PMS) versus mixed culture bacteria (MCB) as inoculum for hydrogen production from paperboard mill wastewater (PMW) was investigated. The experiments were conducted at different initial cultivation pHs, inoculums to substrate ratios (ISRs gVS/gCOD), and hydraulic retention times (HRTs). The peak hydrogen yield (HY) of 5.29 ± 0.16 and 1.22 ± 0.11 mmol/gCODinitial was occurred at pH = 5 for MCB and PMS, respectively. At pH of 5, the HY and COD removal achieved the highest values of 2.26 ± 0.14 mmol/gCODinitial and 86 ± 1.6% at ISR = 6 for MCB, and 2.38 ± 0.25 mmol/gCODinitial and 60.4 ± 2.5% at ISRs = 3 for PMS. The maximum hydrogen production rate was 93.75 ± 8.9 mmol/day at HRT = 9.6 h from continuous upflow anaerobic reactor inoculated with MCB. Meanwhile, the 16S ribosomal RNA (rRNA) gene fragments indicated a dominance of a novel hydrogen-producing bacterium of Stenotrophomonas maltophilia for PMS microbial community. On the other hand, Escherichia fergusonii and Enterobacter hormaechei were the predominant species for MCB.

  15. A practical approach to biosurfactant production using nonaseptic fermentation of mixed cultures

    SciTech Connect

    Ghurye, G.L.; Vipulanandan, C.; Willson, R.C. )

    1994-08-20

    Non-aseptic production of biosurfactant from molasses by a mixed culture was investigated in stirred batch reactors. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), and emulsification capacity (EC). Biosurfactant production was directly correlated with biomass production, and was improved by pH control and addition of yeast extract. Centrifugation of the whole broth increased emulsifying capacity and reduced surface tension. Acidification of the whole broth increased the emulsification capacity but reduced the apparent biosurfactant concentration (CMD), without affecting the surface tension. The emulsification capacity of the cell-free broth was equivalent to that of a 100 mg/L solution of sodium dodecyl sulfate. The emulsification capacity of the whole broth and cell-free broth were reduced by about 50% at and above NaCl concentrations of 100 mM. Preliminary characterization suggests that the biosurfactant activity is primarily associated with one or more protease-sensitive species, released from cells in larger quantities after more vigorous centrifugation.

  16. Mixed Wastewater Coupled with CO2 for Microalgae Culturing and Nutrient Removal

    PubMed Central

    Yao, Lili; Shi, Jianye; Miao, Xiaoling

    2015-01-01

    Biomass, nutrient removal capacity, lipid productivity and morphological changes of Chlorella sorokiniana and Desmodesmus communis were investigated in mixed wastewaters with different CO2 concentrations. Under optimal condition, which was 1:3 ratio of swine wastewater to second treated municipal wastewater with 5% CO2, the maximum biomass concentrations were 1.22 g L-1 and 0.84 g L-1 for C. sorokiniana and D. communis, respectively. Almost all of the ammonia and phosphorus were removed, the removal rates of total nitrogen were 88.05% for C. sorokiniana and 83.18% for D. communis. Lipid content reached 17.04% for C. sorokiniana and 20.37% for D. communis after 10 days culture. CO2 aeration increased intracellular particle numbers of both microalgae and made D. communis tend to be solitary. The research suggested the aeration of CO2 improve the tolerance of microalgae to high concentration of NH4-N, and nutrient excess stress could induce lipid accumulation of microalgae. PMID:26418261

  17. Direct 5S rRNA assay for monitoring mixed-culture bioprocesses

    SciTech Connect

    Stoner, D.L.; Bulmer, D.K.; Ward, T.E.

    1996-06-01

    This study demonstrates the efficacy of a direct 5S rRNA assay for the characterization of mixed microbial populations by using as an example the bacteria associated with acidic mining environments. The direct 5S rRNA assay described herein represents a nonselective, direct molecular method for monitoring and characterizing the predominant, metabolically active members of a microbial population. The foundation of the assay is high-resolution denaturing gradient gel electrophoresis in denaturing gradient gel electrophoresis (DGGE), which is used to separate 5S rRNA species during electrophoresis in denaturing gradient gels. With mixtures of RNA extracted from laboratory cultures, the upper practical limit for detection in the current experimental system has been estimated to be greater than 15 different species. With this method, the resolution was demonstrated to be effective at least to the species level. The strength of this approach was demonstrated by the ability to discriminate between Thiobacillus ferrooxidans ATCC 19859 and Thiobacillus thiooxidans ATCC 8085, two very closely related species. Migration patterns for the 5S rRNA from members of the genus Thiobacillus were readily distinguishable from those of the general Acidiphilium and Leptospirillum. In conclusion, the 5S rRNA assay represents a powerful method by which the structure of a microbial population within acidic environments can be assessed. 40 refs., 12 figs., 1 tab.

  18. Effects of repetitive low-pressure explosive blast on primary neurons and mixed cultures.

    PubMed

    Zander, Nicole E; Piehler, Thuvan; Banton, Rohan; Benjamin, Richard

    2016-09-01

    Repetitive mild traumatic brain injury represents a considerable health concern, particularly for athletes and military personnel. For blast-induced brain injury, threshold shock-impulse levels required to induce such injuries and cumulative effects with single and/or multiple exposures are not well characterized. Currently, there is no established in vitro experimental model with blast pressure waves generated by live explosives. This study presents results of primary neurons and mixed cultures subjected to our unique in vitro indoor experimental platform that uses real military explosive charges to probe the effects of primary explosive blast at the cellular level. The effects of the blast on membrane permeability, generation of reactive oxygen species (ROS), uptake of sodium ions, intracellular calcium, and release of glutamate were probed 2 and 24 hr postblast. Significant changes in membrane permeability and sodium uptake among the sham, single-blast-injured, and triple-blast-injured samples were observed. A significant increase in ROS and glutamate release was observed for the triple-blast-injured samples compared with the sham. Changes in intracellular calcium were not significant. These results suggest that blast exposure disrupts the integrity of the plasma membrane, leading to the upset of ion homeostasis, formation of ROS, and glutamate release. Published 2016. †This article is a U.S. Government work and is in the public domain in the USA. PMID:27317559

  19. Mixed Wastewater Coupled with CO2 for Microalgae Culturing and Nutrient Removal.

    PubMed

    Yao, Lili; Shi, Jianye; Miao, Xiaoling

    2015-01-01

    Biomass, nutrient removal capacity, lipid productivity and morphological changes of Chlorella sorokiniana and Desmodesmus communis were investigated in mixed wastewaters with different CO2 concentrations. Under optimal condition, which was 1:3 ratio of swine wastewater to second treated municipal wastewater with 5% CO2, the maximum biomass concentrations were 1.22 g L-1 and 0.84 g L-1 for C. sorokiniana and D. communis, respectively. Almost all of the ammonia and phosphorus were removed, the removal rates of total nitrogen were 88.05% for C. sorokiniana and 83.18% for D. communis. Lipid content reached 17.04% for C. sorokiniana and 20.37% for D. communis after 10 days culture. CO2 aeration increased intracellular particle numbers of both microalgae and made D. communis tend to be solitary. The research suggested the aeration of CO2 improve the tolerance of microalgae to high concentration of NH4-N, and nutrient excess stress could induce lipid accumulation of microalgae.

  20. Dynamic metabolic modelling of volatile fatty acids conversion to polyhydroxyalkanoates by a mixed microbial culture.

    PubMed

    Pardelha, Filipa; Albuquerque, Maria G E; Reis, Maria A M; Oliveira, Rui; Dias, João M L

    2014-06-25

    In this work, we present a dynamic metabolic model that describes the uptake of complex mixtures of volatile fatty acids (VFA) and respective conversion into PHA by mixed microbial cultures (MMC). This model builds upon a previously published flux balance analysis model [1] that identified the minimization of TCA cycle activity as the key metabolic objective to predict PHA storage fluxes and respective composition. The model was calibrated either with experimental data of PHA production from fermented sugar cane molasses or from synthetic mixtures of VFA. All PHA production experiments were performed using a MMC selected with fermented sugar cane molasses under feast and famine regimen. The model was able to capture the process dynamics denoted by an excellent fit between experimental and computed time profiles of concentrations with the regression coefficients always above 0.92. The introduced VFA uptake regulatory factor reflects the decrease of acetyl-CoA and propionyl-CoA available to TCA cycle in conformity with the hypothesis that the minimization of TCA cycle is a key metabolic objective for MMC subjected to feast and famine regimen for the maximization of PHA production.

  1. Characterization of polyhydroxyalkanoates synthesized from microbial mixed cultures and of their nanobiocomposites with bacterial cellulose nanowhiskers.

    PubMed

    Martínez-Sanz, Marta; Villano, Marianna; Oliveira, Catarina; Albuquerque, Maria G E; Majone, Mauro; Reis, Maria; Lopez-Rubio, Amparo; Lagaron, Jose M

    2014-06-25

    The present work reports on the production and characterization of polyhydroxyalkanoates (PHAs) with different valerate contents, which were synthesized from microbial mixed cultures, and the subsequent development of nanocomposites incorporating bacterial cellulose nanowhiskers (BCNW) via solution casting processing. The characterization of the pure biopolyesters showed that the properties of PHAs may be strongly modified by varying the valerate ratio in the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer, as expected. Increasing the valerate content was seen to greatly decrease the melting temperature and enthalpy of the material, as well as its rigidity and stiffness, resulting in a more ductile behaviour. Additionally, the higher valerate PHA displayed higher permeability to water and oxygen and higher moisture sensitivity. Subsequently, BCNW were incorporated into both PHA grades, achieving a high level of dispersion for a 1 wt.-% loading, whereas some agglomeration took place for 3 wt.-% BCNW. As evidenced by DSC analyses, BCNW presented a nucleating effect on the PHA matrices. BCNW also increased the thermal stability of the polymeric matrices when properly dispersed due to strong matrix-filler interactions. Barrier properties were seen to depend on relative humidity and improved at low nanofiller loadings and low relative humidity.

  2. A mixed culture of endophytic fungi increases production of antifungal polyketides.

    PubMed

    Chagas, Fernanda O; Dias, Luís G; Pupo, Mônica T

    2013-10-01

    Secondary metabolites produced by endophytic microorganisms can provide benefits to host plants, such as stimulating growth and enhancing the plant's resistance toward biotic and abiotic factors. During its life, a host plant may be inhabited by many species of endophytes within a restrictive environment. This condition can stimulate secondary metabolite production that improves microbial competition and may consequently affect both the neighboring microorganisms and the host plant. The interactions between the endophytes that co-habit the same host plant have been studied. However, the effect of these interactions on the host plant has remained neglected. When using mixed microbial cultures, we found that the endophytic fungus Alternaria tenuissima significantly increased the production of some polyketides, including antifungal stemphyperylenol in response to the endophytic Nigrospora sphaerica. Biological activity assays revealed that stemphyperylenol can cause cytotoxic effects against N. sphaerica, although no phytotoxicity was observed in the host plant Smallanthus sonchifolius, even at concentrations much higher than those toxic to the fungus. The polyketides produced by A. tenuissima may be important for the ecological relationships between endophyte-endophyte and endophytes-host plants in the natural environment.

  3. Polyhydroxyalkanoates (PHAs) production from fermented cheese whey by using a mixed microbial culture.

    PubMed

    Colombo, Bianca; Pepè Sciarria, Tommy; Reis, Maria; Scaglia, Barbara; Adani, Fabrizio

    2016-10-01

    Two fermented cheese wheys (FCW), FCW1 composed of lactic, acetic and butyric acids in the proportion of 58/16/26 (% CODOrganic Acid (OA)) and FCW2 composed of acetic, propionic, butyric, lactic and valeric acids in the proportion of 58/19/13/6/4 (% CODOA) were used to produce polyhydroxyalkanoates (PHAs) by using a pre-selected mixed microbial culture (MMC). PHA accumulation gave for fermented FCW1 a PHA yield (Ytot) of 0.24±0.02mgCODPHAmgCODSolubleSubstrate(SS)(-1) and a total PHA production, referred to the substrate used, of 60gPHAkgcheesewheyTotalSolids(TS)(-1). For fermented FCW2 results were: PHA yield (Ytot) of 0.42±0.03mgCODPHAmgCODSS(-1) and PHA from a substrate of 70gPHAkgcheesewheyTS(-1). Qualitatively, PHAs from FCW1 was made up exclusively of 3-hydroxybutyrate (HB), while those obtained from FCW2 were composed of 40% of 3-hydroxyvalerate (HV) and 60% of HB.

  4. Transformation of trinitrotoluene to triaminotoluene by mixed cultures incubated under methanogenic conditions

    SciTech Connect

    Hwang, P.; Chow, T.; Adrian, N.R.

    2000-04-01

    2,4,6-Trinitrotoluene (TNT) is an explosive widely used by the military. Although it is no longer manufactured in the US, large amounts of wastewater are generated annually from load, assembly, packing, and demilitarization operations. Granular-activated carbon adsorption is the standard technology for treating wastewater containing TNT and maintaining discharges within the limits established under the National Pollutant Discharge Elimination System. Studies evaluating biological treatment of pink water with an anaerobic fluidized-bed, granular-activated carbon bioreactor have been promising, but the fate of TNT is unknown. The authors investigated the anaerobic transformation of TNT by biofilm microorganisms obtained from a wastewater treatment plant receiving explosive manufacturing wastewater. The TNT was transformed to a mixture of 2-amino-4,6-dinitrotoluene; 4-amino-2,6-dinitrotoluene; 2,4-diamino-6-nitrotoluene; and 2,6-diamino-4-nitrotoluene before culminating in the formation of triaminotoluene (TAT). Triaminotoluene was susceptible to further degradation under anaerobic conditions, but its fate was not determined. Methane formation was inhibited but resumed after the depletion of the diaminonitrotoluene isomers. These studies demonstrate near stoichiometric formation of TAT from TNT and the transformation of 2-amino-4,6-dinitrotoluene to 2,4-diamino-6-nitrotoluene and 2,6-diamino-4-nitrotoluene by a mixed culture incubated under methanogenic conditions. This evidence indicates TAT is also a likely end-product of TNT biodegradation in the anaerobic fluidized fed bioreactor.

  5. Noncytotoxic T cell clones obtained from a human mixed leukocyte culture.

    PubMed

    Chu, M H; Wee, S L; Bach, F H

    1990-02-01

    Peripheral blood mononuclear cells from a DQW-1 homozygous individual were cocultured with irradiated lymphoblastoid cell line from a DQW-1 homozygous unrelated donor bearing BW35-DW1 haplotype. From T cell cloning of primary and twice-stimulated mixed leukocyte cultures (MLC), 7 and 11 T cell clones were obtained respectively. None of the 18 clones showed specific cytotoxic activity against the alloantigen of the stimulator cell as well as natural killer (NK)-like activity against K562 cells. However, most T cell clones from both primary and re-stimulated MLC demonstrated moderate cytotoxic activity in lectin-dependent cell-mediated cytolysis (LDCC) assay. Screening assay for cell-mediated lympholysis (CML) performed on growing microcultures obtained from restimulated MLC cloning confirmed the non-cytotoxic status of these T cell clones by showing that 41 out of 44 growing microcultures were not cytotoxic against the stimulator cell; the other 3 clones lyzed the target cell mildly. The cells from all 5 T cell clones detected for indirect fluorescence expressed CD3 and CD4 surface markers. Taken together, the results suggested that proliferation-regulating T cell subsets or factor(s) may be generated during the course of MLCs under the present responder-stimulator combination, and may suppress the development of alloreactive cytotoxic T cells and NK-like cells. PMID:2144231

  6. Differential alloreactivity at SLA-DR and -DQ matching in two-way mixed lymphocyte culture.

    PubMed

    Hosokawa-Kanai, Tomoko; Tanioka, Yoshikuni; Tanigawa, Manabu; Matsumoto, Yasunobu; Ueda, Susumu; Onodera, Takashi; Matsumoto, Yoshitsugu

    2002-02-01

    The major histocompatibility complex (MHC) class II molecules are heterodimeric cell surface glycoproteins important for antigen presentation to CD4+ T lymphocytes. Class II molecules of the pig MHC, termed SLA, identified so far include DR and DQ. Thus far, functional differences between products of different loci in SLalpha class II have not been well characterized. For detailed research on this issue, SLalpha-DRbeta1 and -DQbeta typings were newly developed by restriction fragment length polymorphism (RFLP) of the reverse transcriptase-polymerase chain reaction (RT-PCR) products. Using this method, several RFLP types were chosen from 13 CSK miniature pigs, and alloreactivities in two-way mixed lymphocyte culture (MLC) derived from these pigs were examined by cell proliferation assay using flow cytometry. The responses in MLC varied according to the degree of phenotype difference. In MLC from individuals of the same RFLP type in both SLA-DRbeta1 and -DQbeta, the proliferative responses showed slight reaction indicating that they were not so stimulated by each other. On the other hand, for the RFLP type-mismatching combination, the responses were strong indicating that they recognized each others alloantigens. The reactivity of only the DQbeta mismatching combination was as strong as those of only the DRbeta1 mismatching combination. These data indicate the important role of the DQ as well as DR molecule on alloreactivity in MLC.

  7. Polyhydroxyalkanoates (PHAs) production from fermented cheese whey by using a mixed microbial culture.

    PubMed

    Colombo, Bianca; Pepè Sciarria, Tommy; Reis, Maria; Scaglia, Barbara; Adani, Fabrizio

    2016-10-01

    Two fermented cheese wheys (FCW), FCW1 composed of lactic, acetic and butyric acids in the proportion of 58/16/26 (% CODOrganic Acid (OA)) and FCW2 composed of acetic, propionic, butyric, lactic and valeric acids in the proportion of 58/19/13/6/4 (% CODOA) were used to produce polyhydroxyalkanoates (PHAs) by using a pre-selected mixed microbial culture (MMC). PHA accumulation gave for fermented FCW1 a PHA yield (Ytot) of 0.24±0.02mgCODPHAmgCODSolubleSubstrate(SS)(-1) and a total PHA production, referred to the substrate used, of 60gPHAkgcheesewheyTotalSolids(TS)(-1). For fermented FCW2 results were: PHA yield (Ytot) of 0.42±0.03mgCODPHAmgCODSS(-1) and PHA from a substrate of 70gPHAkgcheesewheyTS(-1). Qualitatively, PHAs from FCW1 was made up exclusively of 3-hydroxybutyrate (HB), while those obtained from FCW2 were composed of 40% of 3-hydroxyvalerate (HV) and 60% of HB. PMID:27420156

  8. Competition for hydrogen within a chlorinated solvent dehalogenating anaerobic mixed culture

    SciTech Connect

    Yang, Y.; McCarty, P.L.

    1998-11-15

    Use of an appropriate hydrogen level is necessary to favor dehalogenation of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), over other hydrogen using processes. This study examined the competition between dehalogenators and other microorganisms occurring in a benzoate-acclimated dehalogenating methanogenic mixed culture. Results show that the dehalogenators competed best against methanogens and homoacetogens when the hydrogen level was maintained between 2 and 11 nM. The 2 nM hydrogen concentration represents the lower threshold value found here for cis-1,2-dichloroethene (cis-DCE) dehalogenation. The usefulness of this hydrogen range was further confirmed with both batch-fed and continuously-fed reactors. In batch studies, three times more ethene was produced from dehalogenation of cis-DCE using propionate than benzoate as electron donor, while benzoate produced three times more methane than propionate. A three times greater hydrogen utilization efficiency for dehalogenation was obtained with a CSTR than with batch reactors when benzoate was used as substrate because a constant hydrogen concentration in the appropriate range could be maintained with the CSTR. These results suggest different approaches that might be used to favor dehalogenators in competition with other microorganisms.

  9. Direct 5S rRNA Assay for Monitoring Mixed-Culture Bioprocesses

    PubMed Central

    Stoner, D. L.; Browning, C. K.; Bulmer, D. K.; Ward, T. E.; MacDonell, M. T.

    1996-01-01

    This study demonstrates the efficacy of a direct 5S rRNA assay for the characterization of mixed microbial populations by using as an example the bacteria associated with acidic mining environments. The direct 5S rRNA assay described herein represents a nonselective, direct molecular method for monitoring and characterizing the predominant, metabolically active members of a microbial population. The foundation of the assay is high-resolution denaturing gradient gel electrophoresis (DGGE), which is used to separate 5S rRNA species extracted from collected biomass. Separation is based on the unique migration behavior of each 5S rRNA species during electrophoresis in denaturing gradient gels. With mixtures of RNA extracted from laboratory cultures, the upper practical limit for detection in the current experimental system has been estimated to be greater than 15 different species. With this method, the resolution was demonstrated to be effective at least to the species level. The strength of this approach was demonstrated by the ability to discriminate between Thiobacillus ferrooxidans ATCC 19859 and Thiobacillus thiooxidans ATCC 8085, two very closely related species. Migration patterns for the 5S rRNA from members of the genus Thiobacillus were readily distinguishable from those of the genera Acidiphilium and Leptospirillum. In conclusion, the 5S rRNA assay represents a powerful method by which the structure of a microbial population within acidic environments can be assessed. PMID:16535333

  10. Stoichiometric control of live cell mixing to enable fluidically-encoded co-culture models in perfused microbioreactor arrays.

    PubMed

    Occhetta, P; Glass, N; Otte, E; Rasponi, M; Cooper-White, J J

    2016-02-01

    In vivo, tissues are maintained and repaired through interactions between the present (different) cell types, which communicate with each other through both the secretion of paracrine factors and direct cell-cell contacts. In order to investigate and better understand this dynamic, complex interplay among diverse cell populations, we must develop new in vitro co-culture strategies that enable us to recapitulate such native tissue complexity. In this work, a microfluidic mixer based on a staggered herringbone design was computationally designed and experimentally validated that features the ability to mix large, non-diffusive particles (i.e. live cells) in a programmed manner. This is the first time that the herringbone mixer concept has been shown to effectively mix particles of the size range applicable to live cells. The cell mixer allowed for sequentially mixing of two cell types to generate reverse linear concentration co-culture patterns. Once validated, the mixer was integrated into a perfused microbioreactor array as an upstream module to deliver mixed cells to five downstream culture units, each consisting of ten serially-connected circular microculture chambers. This novel cell mixer microbioreactor array (CM-MBA) platform was validated through the establishment of spatio-temporally tunable osteogenic co-culture models, investigating the role of pre-osteoblastic cells (SAOS2) on human mesenchymal stem cells (hMSCs) commitment to an osteogenic endpoint. An increase on expression of alkaline phosphatase in sequential (downstream) chambers, consistent with the initial linear distribution of SAOS2, suggests not only osteoblastic cell-driven hMSCs induction towards the osteogenic phenotype, but also the importance of paracrine signaling. In conclusion, the cell mixer microbioreactor array combines the ability to rapidly establish cell co-culture models in a high-throughput, programmable fashion, with the additional advantage of maintaining cells in culture

  11. Oxygen Limited Bioreactors System For Nitrogen Removal Using Immobilized Mix Culture

    NASA Astrophysics Data System (ADS)

    Pathak, B. K.; Sumino, T.; Saiki, Y.; Kazama, F.

    2005-12-01

    Recently nutrients concentrations especially nitrogen in natural water is alarming in the world wide. Most of the effort is being done on the removal of high concentration of nitrogen especially from the wastewater treatment plants. The removal efficiency is targeted in all considering the effluent discharge standard set by the national environment agency. In many cases, it does not meet the required standard and receiving water is being polluted. Eutrophication in natural water bodies has been reported even if the nitrogen concentration is low and self purification of natural systems itself is not sufficient to remove the nitrogen due to complex phenomenon. In order to recover the pristine water environment, it is very essential to explore bioreactor systems for natural water systems using immobilized mix culture. Microorganism were entrapped in Polyethylene glycol (PEG) prepolymer gel and cut into 3mm cubic immobilized pellets. Four laboratory scale micro bio-reactors having 0.1 L volumes were packed with immobilized pellets with 50% compact ratio. RUN1, RUN2, RUN3 and RUN4 were packed with immobilized pellets from reservoirs sediments, activated sludge (AS), mixed of AS, AG and biodegradable plastic and anaerobic granules (AG) respectively. Water from Shiokawa Reservoirs was feed to all reactors with supplemental ammonia and nitrite nitrogen as specified in the results and discussions. The reactors were operated dark incubated room in continuous flow mode with hydraulic retention time of 12 hours under oxygen limiting condition. Ammonium, nitrate nitrite nitrogen and total organic carbon (TOC) concentrations were measured as described in APWA and AWWA (1998). Laboratory scale four bioreactors containing different combination of immobilized cell were monitored for 218 days. Influent NH4+-N and NO2--N concentration were 2.27±0.43 and 2.05±0.41 mg/l respectively. Average dissolved oxygen concentration and pH in the reactors were 0.40-2.5 mg/l and pH 6

  12. [Effects of mono- and mixed culture on the grain yield and water use efficiency of two winter wheat cultivars].

    PubMed

    Liu, Lin; Li, Feng-min; Xu, Bing-cheng; Ma, Shou-chen; Liu, Wen-zhao

    2008-01-01

    Taking two winter wheat (Triticum aestivum L.) cultivars Changwu 135 and Pingliang 40 commonly cultivated in the semi-arid area on Loess Plateau as test materials, and by the method of ecological replacement, a 2-year field experiment was conducted to study the effects of mono- and mixed culture on the grain yield and water use efficiency of the cultivars. The results showed that under mono-culture, Pingliang 40 had a much higher unit area root biomass (367.60 g x m(-2)) than Changwu 135 (297.31 g x m(-2)), and a more uniform root distribution (i.e., a better root type for water absorption), but its grain yield and water use efficiency were lower than Changwu 135. Under mixed culture, the population root biomass of Pingliang 40 and Changwu 135 was 13.36 g * m(-2) and 8.50 g x m(-2) higher than that under mono-culture, respectively, suggesting that mixed population could absorb the water in deeper soil layers, and had higher total unit area biomass, which in turn increased the water use efficiency. Comparing with Pingliang 40, Changwu 135 allocated more dry matter to its productive organ, leading to its higher grain yield, harvest index, and water use efficiency. PMID:18419078

  13. Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) by mixed culture fermentation.

    PubMed

    Kongjan, Prawit; Min, Booki; Angelidaki, Irini

    2009-03-01

    Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) was investigated in batch and continuous-mode operation. Biohydrogen was successfully produced from xylose by repeated batch cultivations with mixed culture received from a biohydrogen reactor treating household solid wastes at 70 degrees C. The highest hydrogen yield of 1.62+/-0.02 mol-H2/mol-xylose(consumed) was obtained at initial xylose concentration of 0.5 g/L with synthetic medium amended with 1g/L of yeast extract. Lower hydrogen yield was achieved at initial xylose concentration higher than 2g/L. Addition of yeast extract in the cultivation medium resulted in significant improvement of hydrogen yield. The main metabolic products during xylose fermentation were acetate, ethanol, and lactate. The specific growth rates were able to fit the experimental points relatively well with Haldane equation assuming substrate inhibition, and the following kinetic parameters were obtained: the maximum specific growth rate (mu(max)) was 0.17 h(-1), the half-saturation constant (K(s)) was 0.75g/L, and inhibition constant (K(i)) was 3.72 g/L of xylose. Intermittent N2 sparging could enhance hydrogen production when high hydrogen partial pressure (> 0.14 atm) was present in the headspace of the batch reactors. Biohydrogen could be successfully produced in continuously stirred reactor (CSTR) operated at 72-h hydraulic retention time (HRT) with 1g/L of xylose as substrate at 70 degrees C. The hydrogen production yield achieved in the CSTR was 1.36+/-0.03 mol-H2/mol-xylose(sonsumed), and the production rate was 62+/-2 ml/d x L(reactor). The hydrogen content in the methane-free mixed gas was approximately 31+/-1%, and the rest was carbon dioxide. The main intermediate by-products from the effluent were acetate, formate, and ethanol at 4.25+/-0.10, 3.01+/-0.11, and 2.59+/-0.16 mM, respectively.

  14. The conversion of BTEX compounds by single and defined mixed cultures to medium-chain-length polyhydroxyalkanoate.

    PubMed

    Nikodinovic, Jasmina; Kenny, Shane T; Babu, Ramesh P; Woods, Trevor; Blau, Werner J; O'Connor, Kevin E

    2008-09-01

    Here, we report the use of petrochemical aromatic hydrocarbons as a feedstock for the biotechnological conversion into valuable biodegradable plastic polymers--polyhydroxyalkanoates (PHAs). We assessed the ability of the known Pseudomonas putida species that are able to utilize benzene, toluene, ethylbenzene, p-xylene (BTEX) compounds as a sole carbon and energy source for their ability to produce PHA from the single substrates. P. putida F1 is able to accumulate medium-chain-length (mcl) PHA when supplied with toluene, benzene, or ethylbenzene. P. putida mt-2 accumulates mcl-PHA when supplied with toluene or p-xylene. The highest level of PHA accumulated by cultures in shake flask was 26% cell dry weight for P. putida mt-2 supplied with p-xylene. A synthetic mixture of benzene, toluene, ethylbenzene, p-xylene, and styrene (BTEXS) which mimics the aromatic fraction of mixed plastic pyrolysis oil was supplied to a defined mixed culture of P. putida F1, mt-2, and CA-3 in the shake flasks and fermentation experiments. PHA was accumulated to 24% and to 36% of the cell dry weight of the shake flask and fermentation grown cultures respectively. In addition a three-fold higher cell density was achieved with the mixed culture grown in the bioreactor compared to shake flask experiments. A run in the 5-l fermentor resulted in the utilization of 59.6 g (67.5 ml) of the BTEXS mixture and the production of 6 g of mcl-PHA. The monomer composition of PHA accumulated by the mixed culture was the same as that accumulated by single strains supplied with single substrates with 3-hydroxydecanoic acid occurring as the predominant monomer. The purified polymer was partially crystalline with an average molecular weight of 86.9 kDa. It has a thermal degradation temperature of 350 degrees C and a glass transition temperature of -48.5 degrees C.

  15. Multi-enzyme production by pure and mixed cultures of Saccharomyces and non-Saccharomyces yeasts during wine fermentation.

    PubMed

    Maturano, Y Paola; Rodríguez Assaf, Leticia A; Toro, M Eugenia; Nally, M Cristina; Vallejo, Martha; Castellanos de Figueroa, Lucía I; Combina, Mariana; Vazquez, Fabio

    2012-04-01

    Saccharomyces and non-Saccharomyces yeasts release enzymes that are able to transform neutral compounds of grape berries into active aromatic compounds, a process that enhances the sensory attributes of wines. So far, there exists only little information about enzymatic activity in mixed cultures of Saccharomyces and non-Saccharomyces during grape must fermentations. The aim of the present work was to determine the ability of yeasts to produce extracellular enzymes of enological relevance (β-glucosidases, pectinases, proteases, amylases or xylanases) in pure and mixed Saccharomyces/non-Saccharomyces cultures during fermentation. Pure and mixed cultures of Saccharomyces cerevisiae BSc562, Hanseniaspora vinae BHv438 and Torulaspora delbrueckii BTd259 were assayed: 1% S. cerevisiae/99% H. vinae, 10% S. cerevisiae/90% H. vinae, 1% S. cerevisiae/99% T. delbrueckii and 10% S. cerevisiae/90% T. delbrueckii. Microvinifications were carried out with fresh must without pressing from Vitis vinifera L. c.v. Pedro Jiménez, an autochthonous variety from Argentina. Non-Saccharomyces species survived during 15-18days (BTd259) or until the end of the fermentation (BHv438) and influenced enzymatic profiles of mixed cultures. The results suggest that high concentrations of sugars did not affect enzymatic activity. β-Glucosidase and pectinase activities seemed to be adversely affected by an increase in ethanol: activity diminished with increasing fermentation time. Throughout the fermentation, Saccharomyces and non-Saccharomyces isolates assayed produced a broad range of enzymes of enological interest that catalyze hydrolysis of polymers present in grape juice. Vinifications carried out by a pure or mixed culture of BTd259 (99% of T. delbrueckii) showed the highest production of all enzymes assayed except for β-glucosidase. In mixed cultures, S. cerevisiae outgrew H. vinae, and T. delbrueckii was only detected until halfway the fermentation process. Nevertheless, their secreted

  16. Therapeutic effect of lung mixed culture-derived epithelial cells on lung fibrosis.

    PubMed

    Tanaka, Kensuke; Fujita, Tetsuo; Umezawa, Hiroki; Namiki, Kana; Yoshioka, Kento; Hagihara, Masahiko; Sudo, Tatsuhiko; Kimura, Sadao; Tatsumi, Koichiro; Kasuya, Yoshitoshi

    2014-11-01

    Cell-based therapy is recognized as one of potential therapeutic options for lung fibrosis. However, preparing stem/progenitor cells is complicated and not always efficient. Here, we show easily prepared cell populations having therapeutic capacity for lung inflammatory disease that are named as 'lung mixed culture-derived epithelial cells' (LMDECs). LMDECs expressed surfactant protein (SP)-C and gave rise to type I alveolar epithelial cells (AECs) in vitro and in vivo that partly satisfied type II AEC-like characteristics. An intratracheal delivery of not HEK 293 cells but LMDECs to the lung ameliorated bleomycin (BLM)-induced lung injury. A comprehensive analysis of bronchoalveolar fluid by western blot array revealed that LMDEC engraftment could improve the microenvironment in the BLM-instilled lung in association with stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 signaling axis. SDF-1 enhanced both migration activity and differentiating efficiency of LMDECs. Further classification of LMDECs by flow cytometric study showed that a major population of LMDECs (LMDEC(Maj), 84% of total LMDECs) was simultaneously SP-C(+), CD44(+), CD45(+), and hematopoietic cell lineage(+) and that LMDECs included bronchioalveolar stem cells (BASCs) showing SP-C(+)Clara cell secretory protein(+)stem cell antigen (Sca)1(+) as a small population (1.8% of total LMDECs). CD44(+)-sorted LMDEC(Maj) and Sca1(+)-sorted LMDECs equally ameliorated fibrosis induced by BLM like LMDECs did. However, infiltrated neutrophils were observed in Sca1(+)-sorted LMDEC-treated alveoli that was not typical in LMDEC(Maj)- or LMDEC-treated alveoli. These findings suggest that the protective effect of LMDECs against BLM-induced lung injury depends greatly on that of LMDEC(Maj). Furthermore, the cells expressing both alveolar epithelial and hematopoietic cell lineage markers (SP-C(+)CD45(+)) that have characteristics corresponding to LMDEC(Maj) were observed in the alveoli of lung and

  17. Public perceptions of health risks from polluted coastal bathing waters: a mixed methodological analysis using cultural theory.

    PubMed

    Langford, I H; Georgiou, S; Bateman, I J; Day, R J; Turner, R K

    2000-10-01

    This article explores public perceptions of, and attitudes toward, possible health risks from polluted coastal bathing waters in the United Kingdom. Cultural theory is applied in the present analysis, using a mixed methodology of quantitative analysis from interviews and qualitative interpretation of focus group discussions to provide insights into how different cultural solidarities view a number of issues. These include risks to health; attitudes toward regulation; public consultation and information provision; and trust, blame, and accountability applied to different stakeholders in the bathing-water-quality debate. The results show that individuals' standpoints can be represented on a number of dimensions, consistent with cultural theory, including perceptions of power and authority, beliefs in the efficacy of collective action, and acceptance or rejection of incremental change as opposed to radical solutions. The discussion focuses both on methodological and substantive issues related to the use of cultural theory as a research tool, and on policy recommendations arising from this research.

  18. Molecular Biomarker-Based Biokinetic Modeling of a PCE-Dechlorinating and Methanogenic Mixed Culture

    SciTech Connect

    Heavner, Gretchen L. W.; Rowe, Annette R.; Mansfeldt, Cresten B.; Pan, Ju Khuan; Gossett, James M.; Richardson, Ruth E.

    2013-04-16

    Bioremediation of chlorinated ethenes via anaerobic reductive dechlorination relies upon the activity of specific microbial population-most notably Dehalococcoides (DHC) strains. In the lab and field Dehalococcoides grow most robustly in mixed communities which usually contain both fermenters and methanogens. Recently, researchers have been developing quantitative molecular biomarkers to aid in field site diagnostics and it is hoped that these biomarkers could aid in the modeling of anaerobic reductive dechlorination. A comprehensive biokinetic model of a community containing Dehalococcoides mccartyi (formerly D. ethenogenes) was updated to describe continuously fed reactors with specific biomass levels based on quantitative PCR (qPCR)-based population data (DNA and RNA). The model was calibrated and validated with subsets of chemical and molecular biological data from various continuous feed experiments (n = 24) with different loading rates of the electron acceptor (1.5 to 482 μeeq/L-h), types of electron acceptor (PCE, TCE, cis-DCE) and electron donor to electron acceptor ratios. The resulting model predicted the sum of dechlorination products vinyl chloride (VC) and ethene (ETH) well. However, VC alone was under-predicted and ETH was over predicted. Consequently, competitive inhibition among chlorinated ethenes was examined and then added to the model. Additionally, as 16S rRNA gene copy numbers did not provide accurate model fits in all cases, we examined whether an improved fit could be obtained if mRNA levels for key functional enzymes could be used to infer respiration rates. The resulting empirically derived mRNA “adjustment factors” were added to the model for both DHC and the main methanogen in the culture (a Methanosaeta species) to provide a more nuanced prediction of activity. Results of this study suggest that at higher feeding rates competitive inhibition is important and mRNA provides a more accurate indicator of a population’s instantaneous

  19. Modeling of anaerobic formate kinetics in mixed biofilm culture using dynamic membrane mass spectrometric measurement

    SciTech Connect

    Dornseiffer, P.; Meyer, B.; Heinzle, E.

    1995-02-05

    Anaerobic wastewater treatment is an attractive alternative to aerobic treatment because of lower operating costs, less sludge production, energy recovery (biogas), and control of odor emission in necessarily contained systems. The dynamics of the anaerobic conversion of formate in a microbial mixed culture taken from an anaerobic fluidized bed reactor was studied using a new stirred micro reactor equipped with a membrane mass spectrometer. The microreactor with a toroidally shaped bottom and pitched blade turbine and a cylindrical flow guide was thermostated and additionally equipped with a pH electrode and pH control. During fed-batch experiments using formate, the dissolved gases (methane, hydrogen, and carbon dioxide), as well as the acid consumption rates for pH control were monitored continuously. Initially and at the end of each experiment, organic acids were analyzed using ion chromatography (IC). It was found that about 50% of the formate was converted to methane via hydrogen and carbon dioxide, 40% gave methane either directly or via acetate. This was calculated from experiments using H{sup 13}CO{sub 3}{sup {minus}} pulses and measurement of {sup 12}CH{sub 4} and {sup 13}CH{sub 4} production rates. About 10% of the formate was converted to lactate, acetate, and propionate, thereby increasing the measured CO{sub 2}/CH{sub 4} production ratio. The nondissociated formic acid was shown to be rate determining. From the relatively high K{sub s} value of 2.5 mmol m{sup {minus}3}, it was concluded that formate cannot play an important role in electron transfer. During dynamic feeding of formate, hydrogen concentration always increased to a maximum before decreasing again. This peak was found to be very discriminative during modeling. From the various models set up, only those with two-stage degradation and double Monrod kinetics, both for CO{sub 2} and hydrogen, were able to describe the experimental data adequately.

  20. Molecular biomarker-based biokinetic modeling of a PCE-dechlorinating and methanogenic mixed culture.

    PubMed

    Heavner, Gretchen L W; Rowe, Annette R; Mansfeldt, Cresten B; Pan, Ju Khuan; Gossett, James M; Richardson, Ruth E

    2013-04-16

    Bioremediation of chlorinated ethenes via anaerobic reductive dechlorination relies upon the activity of specific microbial populations--most notably Dehalococcoides (DHC) strains. In the lab and field Dehalococcoides grow most robustly in mixed communities which usually contain both fermenters and methanogens. Recently, researchers have been developing quantitative molecular biomarkers to aid in field site diagnostics and it is hoped that these biomarkers could aid in the modeling of anaerobic reductive dechlorination. A comprehensive biokinetic model of a community containing Dehalococcoides mccartyi (formerly D. ethenogenes) was updated to describe continuously fed reactors with specific biomass levels based on quantitative PCR (qPCR)-based population data (DNA and RNA). The model was calibrated and validated with subsets of chemical and molecular biological data from various continuous feed experiments (n = 24) with different loading rates of the electron acceptor (1.5 to 482 μeeq/L-h), types of electron acceptor (PCE, TCE, cis-DCE) and electron donor to electron acceptor ratios. The resulting model predicted the sum of dechlorination products vinyl chloride (VC) and ethene (ETH) well. However, VC alone was under-predicted and ETH was over predicted. Consequently, competitive inhibition among chlorinated ethenes was examined and then added to the model. Additionally, as 16S rRNA gene copy numbers did not provide accurate model fits in all cases, we examined whether an improved fit could be obtained if mRNA levels for key functional enzymes could be used to infer respiration rates. The resulting empirically derived mRNA "adjustment factors" were added to the model for both DHC and the main methanogen in the culture (a Methanosaeta species) to provide a more nuanced prediction of activity. Results of this study suggest that at higher feeding rates competitive inhibition is important and mRNA provides a more accurate indicator of a population's instantaneous

  1. Predator-Specific Enrichment of Actinobacteria from a Cosmopolitan Freshwater Clade in Mixed Continuous Culture

    PubMed Central

    Pernthaler, Jakob; Posch, Thomas; S̆imek, Karel; Vrba, Jaroslav; Pernthaler, Annelie; Glöckner, Frank Oliver; Nübel, Ulrich; Psenner, Roland; Amann, Rudolf

    2001-01-01

    We investigated whether individual populations of freshwater bacteria in mixed experimental communities may exhibit specific responses to the presence of different bacterivorous protists. In two successive experiments, a two-stage continuous cultivation system was inoculated with nonaxenic batch cultures of the cryptophyte Cryptomonas sp. Algal exudates provided the sole source of organic carbon for growth of the accompanying microflora. The dynamics of several 16S rRNA-defined bacterial populations were followed in the experimental communities. Although the composition and stability of the two microbial communities differed, numerous members of the first assemblage could again be detected during the second experiment. The introduction of a size-selectively feeding mixotrophic nanoflagellate (Ochromonas sp.) always resulted in an immediate bloom of a single phylotype population of members of the class Actinobacteria (Ac1). These bacteria were phylogenetically affiliated with an uncultured lineage of gram-positive bacteria that have been found in freshwater habitats only. The Ac1 cells were close to the average size of freshwater bacterioplankton and significantly smaller than any of the other experimental community members. In contrast, no increase of the Ac1 population was observed in vessels exposed to the bacterivorous ciliate Cyclidium glaucoma. However, when the Ochromonas sp. was added after the establishment of C. glaucoma, the proportion of population Ac1 within the microbial community rapidly increased. Populations of a beta proteobacterial phylotype related to an Aquabacterium sp. decreased relative to the total bacterial communities following the addition of either predator, albeit to different extents. The community structure of pelagic microbial assemblages can therefore be influenced by the taxonomic composition of the predator community. PMID:11319094

  2. Predator-specific enrichment of actinobacteria from a cosmopolitan freshwater clade in mixed continuous culture.

    PubMed

    Pernthaler, J; Posch, T; Simek, K; Vrba, J; Pernthaler, A; Glöckner, F O; Nübel, U; Psenner, R; Amann, R

    2001-05-01

    We investigated whether individual populations of freshwater bacteria in mixed experimental communities may exhibit specific responses to the presence of different bacterivorous protists. In two successive experiments, a two-stage continuous cultivation system was inoculated with nonaxenic batch cultures of the cryptophyte Cryptomonas sp. Algal exudates provided the sole source of organic carbon for growth of the accompanying microflora. The dynamics of several 16S rRNA-defined bacterial populations were followed in the experimental communities. Although the composition and stability of the two microbial communities differed, numerous members of the first assemblage could again be detected during the second experiment. The introduction of a size-selectively feeding mixotrophic nanoflagellate (Ochromonas sp.) always resulted in an immediate bloom of a single phylotype population of members of the class Actinobacteria (Ac1). These bacteria were phylogenetically affiliated with an uncultured lineage of gram-positive bacteria that have been found in freshwater habitats only. The Ac1 cells were close to the average size of freshwater bacterioplankton and significantly smaller than any of the other experimental community members. In contrast, no increase of the Ac1 population was observed in vessels exposed to the bacterivorous ciliate Cyclidium glaucoma. However, when the Ochromonas sp. was added after the establishment of C. glaucoma, the proportion of population Ac1 within the microbial community rapidly increased. Populations of a beta proteobacterial phylotype related to an Aquabacterium sp. decreased relative to the total bacterial communities following the addition of either predator, albeit to different extents. The community structure of pelagic microbial assemblages can therefore be influenced by the taxonomic composition of the predator community.

  3. Molecular biomarker-based biokinetic modeling of a PCE-dechlorinating and methanogenic mixed culture.

    PubMed

    Heavner, Gretchen L W; Rowe, Annette R; Mansfeldt, Cresten B; Pan, Ju Khuan; Gossett, James M; Richardson, Ruth E

    2013-04-16

    Bioremediation of chlorinated ethenes via anaerobic reductive dechlorination relies upon the activity of specific microbial populations--most notably Dehalococcoides (DHC) strains. In the lab and field Dehalococcoides grow most robustly in mixed communities which usually contain both fermenters and methanogens. Recently, researchers have been developing quantitative molecular biomarkers to aid in field site diagnostics and it is hoped that these biomarkers could aid in the modeling of anaerobic reductive dechlorination. A comprehensive biokinetic model of a community containing Dehalococcoides mccartyi (formerly D. ethenogenes) was updated to describe continuously fed reactors with specific biomass levels based on quantitative PCR (qPCR)-based population data (DNA and RNA). The model was calibrated and validated with subsets of chemical and molecular biological data from various continuous feed experiments (n = 24) with different loading rates of the electron acceptor (1.5 to 482 μeeq/L-h), types of electron acceptor (PCE, TCE, cis-DCE) and electron donor to electron acceptor ratios. The resulting model predicted the sum of dechlorination products vinyl chloride (VC) and ethene (ETH) well. However, VC alone was under-predicted and ETH was over predicted. Consequently, competitive inhibition among chlorinated ethenes was examined and then added to the model. Additionally, as 16S rRNA gene copy numbers did not provide accurate model fits in all cases, we examined whether an improved fit could be obtained if mRNA levels for key functional enzymes could be used to infer respiration rates. The resulting empirically derived mRNA "adjustment factors" were added to the model for both DHC and the main methanogen in the culture (a Methanosaeta species) to provide a more nuanced prediction of activity. Results of this study suggest that at higher feeding rates competitive inhibition is important and mRNA provides a more accurate indicator of a population's instantaneous

  4. Photometabolic production of hydrogen from organic substrates by free and immobilized mixed cultures of rhodospirillum rubrum and klebsiella pneumoniae

    SciTech Connect

    Weetall, H.H.; Sharma, B.P.; Detar, C.C.

    1981-03-01

    A culture of R. rubrum cells apparently contaminated with K. pneumoniae were immobilized by entrapment in agar. This system was used as a model for hydrogen production by photometabolic means. Observed results indicated that the contaminant exerted a major influence on the observed results. This preparation, when immobilized and used in a specifically designed reactor with glucose substrate, showed operational half-lives of approximately 1000 hr. The feasibility of using this ''mixed'' culture for producing hydrogen from acid hydrolyzed cellulose and wood sawdust was also examined. 5 refs.

  5. Fine bubble mixing (FBM) culture of E. coli: a highly cost-effective middle scale-size culture system.

    PubMed

    Yasumitsu, Hidetaro; Tajima, Hitoshi; Isobe, Masaharu; Kutsuna, Sinsuke; Kawsar, Sarkar M A; Fujii, Yuki; Kanaly, Robert A; Ozeki, Yasuhiro; Yokota, Eriko

    2013-02-01

    A highly cost-effective and easy-to-assemble cultivation system suitable for middle scale-size culturing of bacterial cells is described. In the culture, from a flat-shaped air-stone with large surface area, fine bubbles are generated with a low-cost air pump available in an aquarium fish shop, and cell-agitation and oxygen supply are efficiently conducted by fine bubbles simultaneously. Growth properties of the cells and their saturation density are comparable to those in a conventional culture system. The expression of recombinant protein was revealed to be similar to conventional methods. The system does not require any expensive machines or equipments. In addition, all equipments except plastic flat-shaped airstone are reusable after sterilization. Due to the low cost, the ease to use and multiple cultivations at once, our system may enable to find better culture conditions, to scale-up with ease and to perform timesaving efficient protein production. PMID:22894161

  6. Biochemical Study of Mixed Culture Prototype in a Closed Ecological System

    NASA Technical Reports Server (NTRS)

    Tischer, R. G.

    1960-01-01

    Since June 1, 1960, the date of initiation of this research project, efforts have been directed toward studying cultural and fermentation patterns and the methodology of pure culture isolation of prototype microorganisms to be employed in closed ecological systems.

  7. Finding Balance in a Mix of Culture: Appreciation of Diversity through Multicultural Music Education

    ERIC Educational Resources Information Center

    Nethsinghe, Rohan

    2012-01-01

    This study explores the understandings of cultural diversity as enacted in multicultural music education and is located in Victoria, which is identified as the most culturally diverse state in Australia with a population that comes from various countries and speaks many languages. This cultural diversity is reflected in the schools. This…

  8. Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

    PubMed Central

    Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

    2014-01-01

    The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 ± 0.06, 1.0 ± 0.13 and 0.4 ± 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation. PMID:24920064

  9. Controlled mixed culture fermentation: a new perspective on the use of non-Saccharomyces yeasts in winemaking.

    PubMed

    Ciani, Maurizio; Comitini, Francesca; Mannazzu, Ilaria; Domizio, Paola

    2010-03-01

    Mixed fermentations using controlled inoculation of Saccharomyces cerevisiae starter cultures and non-Saccharomyces yeasts represent a feasible way towards improving the complexity and enhancing the particular and specific characteristics of wines. The profusion of selected starter cultures has allowed the more widespread use of inoculated fermentations, with consequent improvements to the control of the fermentation process, and the use of new biotechnological processes in winemaking. Over the last few years, as a consequence of the re-evaluation of the role of non-Saccharomyces yeasts in winemaking, there have been several studies that have evaluated the use of controlled mixed fermentations using Saccharomyces and different non-Saccharomyces yeast species from the wine environment. The combined use of different species often results in unpredictable compounds and/or different levels of fermentation products being produced, which can affect both the chemical and the aromatic composition of wines. Moreover, possible synergistic interactions between different yeasts might provide a tool for the implementation of new fermentation technologies. Thus, knowledge of the Saccharomyces and non-Saccharomyces wine yeast interactions during wine fermentation needs to be improved. To reach this goal, further investigations into the genetic and physiological background of such non-Saccharomyces wine yeasts are needed, so as to apply '-omics' approaches to mixed culture fermentations.

  10. Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

    2014-06-01

    The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 +/- 0.06, 1.0 +/- 0.13 and 0.4 +/- 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.

  11. Development of a mixed mode adsorption process for the direct product sequestration of an extracellular protease from microbial batch cultures.

    PubMed

    Hamilton, G E; Luechau, F; Burton, S C; Lyddiatt, A

    2000-04-28

    Direct product sequestration of extracellular proteins from microbial batch cultures can be achieved by continuous or intermittent broth recycle through an external extractive loop. Here, we describe the development of a fluidisable, mixed mode adsorbent, designed to tolerate increasing ionic strength (synonymous with extended productive batch cultures). This facilitated operations for the integrated recovery of an extracellular acid protease from cultures of Yarrowia lipolytica. Mixed mode adsorbents were prepared using chemistries containing hydrophobic and ionic groups. Matrix hydrophobicity and titration ranges were matched to the requirements of integrated protease adsorption. A single expanded bed was able to service the productive phase of growth without recourse to the pH adjustment of the broth previously required for ion exchange adsorption. This resulted in increased yields of product, accompanied by further increases in enzyme specific activity. A step change from pH 4.5 to 2.6, across the isoelectric point of the protease, enabled high resolution fixed bed elution induced by electrostatic repulsion. The generic application of mixed mode chemistries, which combine the physical robustness of ion-exchange ligands in sanitisation and sterilisation procedures with a selectivity, which approaches that of affinity interactions, is discussed.

  12. Cell-to-cell contact and antimicrobial peptides play a combined role in the death of Lachanchea thermotolerans during mixed-culture alcoholic fermentation with Saccharomyces cerevisiae.

    PubMed

    Kemsawasd, Varongsiri; Branco, Patrícia; Almeida, Maria Gabriela; Caldeira, Jorge; Albergaria, Helena; Arneborg, Nils

    2015-07-01

    The roles of cell-to-cell contact and antimicrobial peptides in the early death of Lachanchea thermotolerans CBS2803 during anaerobic, mixed-culture fermentations with Saccharomyces cerevisiae S101 were investigated using a commercially available, double-compartment fermentation system separated by cellulose membranes with different pore sizes, i.e. 1000 kDa for mixed- and single-culture fermentations, and 1000 and 3.5-5 kDa for compartmentalized-culture fermentations. SDS-PAGE and gel filtration chromatography were used to determine an antimicrobial peptidic fraction in the fermentations. Our results showed comparable amounts of the antimicrobial peptidic fraction in the inner compartments of the mixed-culture and 1000 kDa compartmentalized-culture fermentations containing L. thermotolerans after 4 days of fermentation, but a lower death rate of L. thermotolerans in the 1000 kDa compartmentalized-culture fermentation than in the mixed-culture fermentation. Furthermore, L. thermotolerans died off even more slowly in the 3.5-5 kDa than in the 1000 kDa compartmentalized-culture fermentation, which coincided with the presence of less of the antimicrobial peptidic fraction in the inner compartment of that fermentation than of the 1000 kDa compartmentalized-culture fermentation. Taken together, these results indicate that the death of L. thermotolerans in mixed cultures with S. cerevisiae is caused by a combination of cell-to-cell contact and antimicrobial peptides.

  13. Fermentative capabilities and volatile compounds produced by Kloeckera/Hanseniaspora and Saccharomyces yeast strains in pure and mixed cultures during Agave tequilana juice fermentation.

    PubMed

    González-Robles, Ivonne Wendolyne; Estarrón-Espinosa, Mirna; Díaz-Montaño, Dulce María

    2015-09-01

    The fermentative and aromatic capabilities of Kloeckera africana/Hanseniaspora vineae K1, K. apiculata/H. uvarum K2, and Saccharomyces cerevisiae S1 and S2 were studied in pure and mixed culture fermentations using Agave tequila juice as the culture medium. In pure and mixed cultures, Kloeckera/Hanseniaspora strains showed limited growth and sugar consumption, as well as low ethanol yield and productivity, compared to S. cerevisiae, which yielded more biomass, ethanol and viable cell concentrations. In pure and mixed cultures, S. cerevisiae presented a similar behaviour reaching high biomass production, completely consuming the sugar, leading to high ethanol production. Furthermore, the presence of S. cerevisiae strains in the mixed cultures promoted the production of higher alcohols, acetaldehyde and ethyl esters, whereas Kloeckera/Hanseniaspora strains stimulated the production of ethyl acetate and 2-phenyl ethyl acetate compounds.

  14. Fermentative capabilities and volatile compounds produced by Kloeckera/Hanseniaspora and Saccharomyces yeast strains in pure and mixed cultures during Agave tequilana juice fermentation.

    PubMed

    González-Robles, Ivonne Wendolyne; Estarrón-Espinosa, Mirna; Díaz-Montaño, Dulce María

    2015-09-01

    The fermentative and aromatic capabilities of Kloeckera africana/Hanseniaspora vineae K1, K. apiculata/H. uvarum K2, and Saccharomyces cerevisiae S1 and S2 were studied in pure and mixed culture fermentations using Agave tequila juice as the culture medium. In pure and mixed cultures, Kloeckera/Hanseniaspora strains showed limited growth and sugar consumption, as well as low ethanol yield and productivity, compared to S. cerevisiae, which yielded more biomass, ethanol and viable cell concentrations. In pure and mixed cultures, S. cerevisiae presented a similar behaviour reaching high biomass production, completely consuming the sugar, leading to high ethanol production. Furthermore, the presence of S. cerevisiae strains in the mixed cultures promoted the production of higher alcohols, acetaldehyde and ethyl esters, whereas Kloeckera/Hanseniaspora strains stimulated the production of ethyl acetate and 2-phenyl ethyl acetate compounds. PMID:26108494

  15. Financial abuse in elderly Korean immigrants: mixed analysis of the role of culture on perception and help-seeking intention.

    PubMed

    Lee, Hee Yun; Eaton, Charissa K

    2009-07-01

    This study aims to evaluate how elderly Korean immigrants perceive and respond to a hypothetical incident of financial abuse on the basis of their cultural background. By using a quota sampling strategy, 124 elderly Korean immigrants were recruited. A mixed-method approach was employed to explore the role of culture on elderly immigrants' view of financial abuse and the construct of independent and interdependent self-construal was adopted to theoretically guide the study. Mixed-method analysis confirmed considerable influence of culture, particularly in responding to the abusive situation. Although the vast majority of the elders (92%) perceived financial abuse as elder mistreatment, only two-thirds (64%) intended to seek help. Five major themes for not seeking help were produced. These are: (a) issues related to family problems, (b) tolerance of the abuse, (c) shame, (d) victim blame, and (e) mistrust toward third party intervention. A series of binary logistic regressions revealed (a) a lower likelihood of seeking formal types of help with those who had higher level of adherence to traditional values and (b) the profile of vulnerable elderly Koreans who are at higher risk of being financially abused: male and less educated. This article also discusses implications for social work practice and elder mistreatment policy, particularly focusing on how to work with elderly Korean immigrants who are vulnerable to this problem and who tend to use collectivistic cultural values in responding to financial abuse.

  16. Cellulose decomposition and associated nitrogen fixation by mixed cultures of Cellulomonas gelida and Azospirillum species or Bacillus macerans

    SciTech Connect

    Halsall, D.M.; Gibson, A.H.

    1985-10-01

    Mixed cultures of Cellulomonas gelida plus Azospirillum lipoferum or Azospirillum brasilense and C. gelida plus Bacillus macerans were shown to degrade cellulose and straw and to utilize the energy-yielding products to fix atmospheric nitrogen. This cooperative process was followed over 30 days in sand-based cultures in which the breakdown of 20% of the cellulose and 28 to 30% of the straw resulted in the fixation of 12 to 14.6 mg of N per g of cellulose and 17 to 19 mg of N per g of straw consumed. Cellulomonas species have certain advantages over aerobic cellulose-degrading fungi in being able to degrade cellulose at oxygen concentrations as low as 1% O/sub 2/ (vol/vol) which would allow a close association between cellulose-degrading and microaerobic diazotrophic microorganisms. Cultures inoculated with initially different proportions of A. brasilense and C. gelida all reached a stable ratio of approximately 1 Azospirillum/3 Cellulomonas cells.

  17. Three-dimensional culture of a mixed mullerian tumor of the ovary: expression of in vivo characteristics

    NASA Technical Reports Server (NTRS)

    Goodwin, T. J.; Prewett, T. L.; Spaulding, G. F.; Becker, J. L.

    1997-01-01

    The Rotating-Wall Vessel (RWV) is a novel in vitro cell culture system used to successfully culture a cell line derived from a heterologous mixed mullerian tumor cell of the ovary. Although the original tumor was comprised of both epithelial and mesodermal components, long-term culture in conventional flasks established a cell line from this tumor with homogeneous epitheliallike growth characteristics (1). Cells from Passage 36 were seeded into a Rotating-Wall Vessel containing Cytodex-3 microcarrier beads. Scanning electron micrographs of tumor cells cultured for 32 d in the RWV showed the presence of heterogeneous cell populations organized into three-dimensional tissuelike architecture. Immunocytochemical analysis confirmed the cellular heterogeneity, as demonstrated by expression of both epithelial and mesenchymal antigens. Reverse transcription polymerase chain reaction amplification demonstrated the presence of mRNA for cellular oncogenes HER-2/neu, H-ras, K-ras, and tumor suppressor p53. Thus, there are two advantages to propagation of tissue in the RWV culture system:(a) tissue diversification representing populations present in the original tumor, and (b) the three-dimensional freedom to organize tissues morphologically akin to those observed in vivo. These data indicate that the RWV culture system is suitable for generating large quantities of ovarian tumor cells in vitro that are amenable to immunocytochemical, oncogenic, morphologic characteristics demonstrated in vivo.

  18. Mixed culture models for predicting intestinal microbial interactions between Escherichia coli and Lactobacillus in the presence of probiotic Bacillus subtilis.

    PubMed

    Yang, J J; Niu, C C; Guo, X H

    2015-01-01

    Bacillus has been proposed as a probiotic due to its in vivo effectiveness in the gastrointestinal tract through antimicrobial activities. The present study investigates the effects of Lactobacillus alone or in the presence of Bacillus subtilis MA139 on the inhibition of pathogenic Escherichia coli K88. Mixed cultures were used to predict the possible interactions among these bacteria within the intestinal tract of animals. B. subtilis MA139 was first assayed for its inhibition against E. coli K88 both under shaking and static culture conditions. A co-culture assay was employed under static conditions to test the inhibitory effects of Lactobacillus reuteri on E. coli K88, with or without addition of B. subtilis MA139. The results showed that B. subtilis MA139 had marked inhibition against E. coli K88 under shaking conditions and weak inhibition under static conditions. Lactobacillus alone as well as in combination with B. subtilis MA139 spores exerted strong inhibition against E. coli K88 under static conditions. However, the inhibition by Lactobacillus in combination with B. subilis spores was much higher than that by Lactobacillus alone (P<0.01). B. subtilis MA139 significantly decreased the pH and oxidation-reduction potential values of the co-culture broth compared to that of Lactobacillus alone (P<0.05). The viability of Lactobacillus increased when co-cultured with B. subtilis MA139 because of significantly higher Lactobacillus counts and lower pH values in the broth (P<0.05). The role of Bacillus in the mixed culture models suggests that Bacillus may produce beneficial effects by increasing the viability of lactobacilli and subsequently inhibiting the growth of pathogenic E. coli. Therefore, the combination of Bacillus and Lactobacillus species as a probiotic is recommended. PMID:26259891

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

    PubMed

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

    2015-09-01

    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

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

    PubMed

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

    2015-09-01

    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.

  1. Survival and synergistic growth of mixed cultures of bifidobacteria and lactobacilli combined with prebiotic oligosaccharides in a gastrointestinal tract simulator

    PubMed Central

    Adamberg, Signe; Sumeri, Ingrid; Uusna, Riin; Ambalam, Padma; Kondepudi, Kanthi Kiran; Adamberg, Kaarel; Wadström, Torkel; Ljungh, Åsa

    2014-01-01

    Background Probiotics, especially in combination with non-digestible oligosaccharides, may balance the gut microflora while multistrain preparations may express an improved functionality over single strain cultures. In vitro gastrointestinal models enable to test survival and growth dynamics of mixed strain probiotics in a controlled, replicable manner. Methods The robustness and compatibility of multistrain probiotics composed of bifidobacteria and lactobacilli combined with mixed prebiotics (galacto-, fructo- and xylo-oligosaccharides or galactooligosaccharides and soluble starch) were studied using a dynamic gastrointestinal tract simulator (GITS). The exposure to acid and bile of the upper gastrointestinal tract was followed by dilution with a continuous decrease of the dilution rate (de-celerostat) to simulate the descending nutrient availability of the large intestine. The bacterial numbers and metabolic products were analyzed and the growth parameters determined. Results The most acid- and bile-resistant strains were Lactobacillus plantarum F44 and L. paracasei F8. Bifidobacterium breve 46 had the highest specific growth rate and, although sensitive to bile exposure, recovered during the dilution phase in most experiments. B. breve 46, L. plantarum F44, and L. paracasei F8 were selected as the most promising strains for further studies. Conclusions De-celerostat cultivation can be applied to study the mixed bacterial cultures under defined conditions of decreasing nutrient availability to select a compatible set of strains. PMID:25045346

  2. Aerobic degradation of methyl tert-butyl ether in a closed symbiotic system containing a mixed culture of Chlorella ellipsoidea and Methylibium petroleiphilum PM1.

    PubMed

    Zhong, Weihong; Li, Yixiao; Sun, Kedan; Jin, Jing; Li, Xuanzhen; Zhang, Fuming; Chen, Jianmeng

    2011-01-30

    The contamination of groundwater by methyl tert-butyl ether (MTBE) is one of the most serious environmental problems around the world. MTBE degradation in a closed algal-bacterial symbiotic system, containing a mixed culture of Methylibium petroleiphilum PM1 and Chlorella ellipsoidea, was investigated. The algal-bacterial symbiotic system showed increased MTBE degradation. The MTBE-degradation rate in the mixed culture (8.808 ± 0.007 mg l(-1) d(-1)) was higher than that in the pure bacterial culture (5.664 ± 0.017 mg l(-1) d(-1)). The level of dissolved oxygen was also higher in the mixed culture than that in the pure bacterial culture. However, the improved efficiency of MTBE degradation was not in proportional to the biomass of the alga. The optimal ratio of initial cell population of bacteria to algae was 100:1. An immobilized culture of mixed bacteria and algae also showed higher MTBE degradation rate than the immobilized pure bacterial culture. A mixed culture with algae and PM1 immobilized separately in different gel beads showed higher degradation rate (8.496 ± 0.636 mg l(-1) d(-1)) than that obtained with algae and PM1 immobilized in the same gel beads (5.424 ± 0.010 mg l(-1) d(-1)).

  3. Biohydrogen production from rotten orange with immobilized mixed culture: Effect of immobilization media for various composition of substrates

    NASA Astrophysics Data System (ADS)

    Damayanti, Astrilia; Sarto, Syamsiah, Siti; Sediawan, Wahyudi B.

    2015-12-01

    Enriched-immobilized mixed culture was utilized to produce biohydrogen in mesophilic condition under anaerobic condition using rotten orange as substrate. The process was conducted in batch reactors for 100 hours. Microbial cultures from three different sources were subject to a series of enrichment and immobilized in two different types of media, i.e. calcium alginate (CA, 2%) and mixture of alginate and activated carbon (CAC, 1:1). The performance of immobilized culture in each media was tested for biohydrogen production using four different substrate compositions, namely orange meat (OM), orange meat added with peel (OMP), orange meat added with limonene (OML), and mixture of orange meat and peel added with limonene (OMPL). The results show that, with immobilized culture in CA, the variation of substrate composition gave significant effect on the production of biohydrogen. The highest production of biohydrogen was detected for substrate containing only orange meet, i.e. 2.5%, which was about 3-5 times higher than biohydrogen production from other compositions of substrate. The use of immobilized culture in CAC in general has increased the hydrogen production by 2-7 times depending on the composition of substrate, i.e. 5.4%, 4.8%, 5.1%, and 4.4% for OM, OMP, OML, and OMPL, respectively. The addition of activated carbon has eliminated the effect of inhibitory compounds in the substrate. The major soluble metabolites were acetic acid, propionic acid, and butyric acid.

  4. Biohydrogen production from rotten orange with immobilized mixed culture: Effect of immobilization media for various composition of substrates

    SciTech Connect

    Damayanti, Astrilia; Sarto,; Syamsiah, Siti; Sediawan, Wahyudi B.

    2015-12-29

    Enriched–immobilized mixed culture was utilized to produce biohydrogen in mesophilic condition under anaerobic condition using rotten orange as substrate. The process was conducted in batch reactors for 100 hours. Microbial cultures from three different sources were subject to a series of enrichment and immobilized in two different types of media, i.e. calcium alginate (CA, 2%) and mixture of alginate and activated carbon (CAC, 1:1). The performance of immobilized culture in each media was tested for biohydrogen production using four different substrate compositions, namely orange meat (OM), orange meat added with peel (OMP), orange meat added with limonene (OML), and mixture of orange meat and peel added with limonene (OMPL). The results show that, with immobilized culture in CA, the variation of substrate composition gave significant effect on the production of biohydrogen. The highest production of biohydrogen was detected for substrate containing only orange meet, i.e. 2.5%, which was about 3-5 times higher than biohydrogen production from other compositions of substrate. The use of immobilized culture in CAC in general has increased the hydrogen production by 2-7 times depending on the composition of substrate, i.e. 5.4%, 4.8%, 5.1%, and 4.4% for OM, OMP, OML, and OMPL, respectively. The addition of activated carbon has eliminated the effect of inhibitory compounds in the substrate. The major soluble metabolites were acetic acid, propionic acid, and butyric acid.

  5. Bioethanol production from mixed sugars by Scheffersomyces stipitis free and immobilized cells, and co-cultures with Saccharomyces cerevisiae.

    PubMed

    De Bari, Isabella; De Canio, Paola; Cuna, Daniela; Liuzzi, Federico; Capece, Angela; Romano, Patrizia

    2013-09-25

    Bioethanol can be produced from several biomasses including lignocellulosic materials. Besides 6-carbon sugars that represent the prevalent carbohydrates, some of these feedstocks contain significant amounts of 5-carbon sugars. One common limit of the major part of the xylose-fermenting yeasts is the diauxic shift between the uptake of glucose and xylose during the fermentation of mixed syrups. Thus, optimized fermentation strategies are required. In this paper the ability of Scheffersomyces stipitis strain NRRLY-11544 to ferment mixed syrups with a total sugar concentration in the range 40-80 g/L was investigated by using mono cultures, co-cultures with Saccharomyces cerevisiae strain Bakers Yeast Type II and single cultures immobilized in silica-hydrogel films. The experimental design for the fermentations with immobilized cells included the process analysis in function of two parameters: the fraction of the gel in the broth and the concentration of the cells loaded in the gel. Furthermore, for each total sugars level, the fermentative course of S. stipitis was analyzed at several glucose-to xylose ratios. The results indicated that the use of S. stipitis and S. cerevisiae in free co-cultures ensured faster processes than single cultures of S. stipitis either free or immobilized. However, the rapid production of ethanol by S. cerevisiae inhibited S. stipitis and caused a stuck of the process. Immobilization of S. stipitis in silica-hydrogel increased the relative consumption rate of xylose-to-glucose by 2-6 times depending on the composition of the fermentation medium. Furthermore the films performances appeared stable over three weeks of continuous operations. However, on the whole, the final process yields obtained with the immobilized cells were not meaningfully different from that of the free cells. This was probably due to concurrent fermentations operated by the cells released in the broth. Optimization of the carrier characteristics could improve the

  6. Characterization of carbon-sulfur bond cleavage by axenic and mixed cultures of Rhodococcus rhodochrous IGTS8

    SciTech Connect

    Kayser, K.J.; Bielaga, B.A.; Jackowski, K.; Oduson, O.; Kilbane, J. II

    1992-12-31

    Growth assays reveal that Rhodococcus rhodochrous IGTS8 can utilize a wide range of organosulfur compounds as the sole source of sulfur. Compounds that are utilized include thiophenes, sulfides, disulfides, mercaptans, sulfoxides, and sulfones. None of the organosulfur compounds tested can serve as a carbon source. A convenient spectrophotometric assay (Gibbs assay) based on the chromogenic reaction of 2,6-dichloroquinone-4-chloroimide with aromatic hydroxyl groups was developed and used in conjunction with GC/MS analysis to examine the kinetics of carbon-sulfur bond cleavage by axenic and mixed cell cultures of Rhodococcus rhodochrous IGTS8. The desulfurization trait is expressed at uniform levels during the mid-exponential phase, reaches a maximum during idiophase, and then declines in stationary-phase cells. Desulfurization rates for dibenzothiophene (DBT) range from 8 to 15 {mu}M of DBT/10{sup 12} cells/hour. Mixtures of genetically marked Rhodococcus rhodochrous IGTS8 and an organisms incapable of cleaning carbon-sulfur bonds in relevant test compounds, Enterobacter cloacae, were prepared in ratios that varied over six orders of magnitude. Growth studies revealed that Enterobacter cloacae was able to gain access to sulfur liberated from organosulfur compounds by IGTS8; however, cell-to-cell contact was required. These data also indicate that the desulfurization activity of IGTS8 cells in mixed cultures may be as much as 200-fold higher than in axenic cultures.

  7. Sedimentation of mixed cultures using natural coagulants for the treatment of effluents generated in terrestrial fuel distribution terminals.

    PubMed

    Vieira, R B; Vieira, P A; Cardoso, S L; Ribeiro, E J; Cardoso, V L

    2012-09-15

    This study evaluated the use of natural coagulants (Moringa oleifera and chitosan) under different conditions with a mixed culture (C1 mixed culture). This culture was used for the biodegradation of hydrocarbons present in the effluent from fuel distribution terminals contaminated with diesel oil and gasoline. The biodegradation was evaluated by two central composite design (CCD) experiments: the first with varying concentrations of Moringa oleifera (MO), drying temperatures (TE) and seed drying times (TI); the second with varying concentrations of chitosan and the hydrochloric acid in which chitosan had been solubilized. The responses monitored in the CCD experiments included the sludge volume index (SVI), the turbidity removal (TR) and the specific rate of oxygen uptake (SOUR). Subsequently, the biodegradation was monitored in a sequencing batch reactor (SBR) under the optimal conditions obtained for each CCD experiment. The results indicated that the best coagulant was chitosan solubilized in 0.25 N HCl at a concentration of 50mg/L. Within five cycles with chitosan as a coagulant, the total organic carbon (TOC) removal increased from 77±1.0% to 82±0.5%, the volatile suspended solids (VSS) increased from 1.4±0.3 to 2.25±0.3 g/L and the total petroleum hydrocarbon (TPH) removal increased from 75±1.0% to 81±0.5%.

  8. Sedimentation of mixed cultures using natural coagulants for the treatment of effluents generated in terrestrial fuel distribution terminals.

    PubMed

    Vieira, R B; Vieira, P A; Cardoso, S L; Ribeiro, E J; Cardoso, V L

    2012-09-15

    This study evaluated the use of natural coagulants (Moringa oleifera and chitosan) under different conditions with a mixed culture (C1 mixed culture). This culture was used for the biodegradation of hydrocarbons present in the effluent from fuel distribution terminals contaminated with diesel oil and gasoline. The biodegradation was evaluated by two central composite design (CCD) experiments: the first with varying concentrations of Moringa oleifera (MO), drying temperatures (TE) and seed drying times (TI); the second with varying concentrations of chitosan and the hydrochloric acid in which chitosan had been solubilized. The responses monitored in the CCD experiments included the sludge volume index (SVI), the turbidity removal (TR) and the specific rate of oxygen uptake (SOUR). Subsequently, the biodegradation was monitored in a sequencing batch reactor (SBR) under the optimal conditions obtained for each CCD experiment. The results indicated that the best coagulant was chitosan solubilized in 0.25 N HCl at a concentration of 50mg/L. Within five cycles with chitosan as a coagulant, the total organic carbon (TOC) removal increased from 77±1.0% to 82±0.5%, the volatile suspended solids (VSS) increased from 1.4±0.3 to 2.25±0.3 g/L and the total petroleum hydrocarbon (TPH) removal increased from 75±1.0% to 81±0.5%. PMID:22795394

  9. Human-mouse mixed lymphocyte cultures. II. Partial separation of functionally distinct populations on discontinuous albumin gradients.

    PubMed Central

    Boylston, A W; Anderson, R L

    1979-01-01

    Human-mouse mixed lymphocyte cultures (MLC) develop stable, strain-specific responses directed towards antigens determined by the mouse major histocompatibility complex (MHC). By restimulation in vitro a two- to four-fold increase in total cell numbers can be achieved. Sensitized cells can be fractionated on discontinuous BSA gradients to produce fractions with predominantly proliferative or cytotoxic activity towards the intiating antigens. Mixing experiments show that fractionation of biological activity is the result of fractination of specifically sensitized effector cells rather than fractionation of inhibitory or collaborative elements. Since biological activities or can be separated on the basis of physical properties into distinct cell populations these experiments support the idea that these functions are the properties of distinct subclasses of human T lymphocyte. Xenogeneic MLC coupled to physical separation measures is a useful approach to the study of antigen-specific human T lymphocytes. PMID:155651

  10. Human-mouse mixed lymphocyte cultures. II. Partial separation of functionally distinct populations on discontinuous albumin gradients.

    PubMed

    Boylston, A W; Anderson, R L

    1979-02-01

    Human-mouse mixed lymphocyte cultures (MLC) develop stable, strain-specific responses directed towards antigens determined by the mouse major histocompatibility complex (MHC). By restimulation in vitro a two- to four-fold increase in total cell numbers can be achieved. Sensitized cells can be fractionated on discontinuous BSA gradients to produce fractions with predominantly proliferative or cytotoxic activity towards the intiating antigens. Mixing experiments show that fractionation of biological activity is the result of fractination of specifically sensitized effector cells rather than fractionation of inhibitory or collaborative elements. Since biological activities or can be separated on the basis of physical properties into distinct cell populations these experiments support the idea that these functions are the properties of distinct subclasses of human T lymphocyte. Xenogeneic MLC coupled to physical separation measures is a useful approach to the study of antigen-specific human T lymphocytes.

  11. Development of quantitative PCR and metagenomics-based approaches for strain quantification of a defined mixed-strain starter culture.

    PubMed

    Johansen, Pernille; Vindeløv, Jannik; Arneborg, Nils; Brockmann, Elke

    2014-05-01

    Although the strain composition of mixed cultures may hugely affect production of various fermented foods, such as e.g. cheese, tools for investigating it have so far been limited. In this study, two new approaches for quantification of seven Lactococcus lactis subsp. cremoris strains (S1-S7) in a defined mixed-strain starter culture were developed and verified. By mapping NGS reads from 47 sequenced L. lactis strains to de novo assembly contigs of the seven strains, two strain-specific sequence regions (SEQ1 and SEQ2) were identified for each strain for qPCR primer design (A1 and A2). The qPCR assays amplified their strain-specific sequence region target efficiently. Additionally, high reproducibility was obtained in a validation sample containing equal amounts of the seven strains, and assay-to-assay coefficients of variance (CVs) for six (i.e. S1, S2, S4-S7) of the seven strains correlated to the inter-plate CVs. Hence, at least for six strains, the qPCR assay design approach was successful. The metagenomics-based approach quantified the seven strains based on average coverage of SEQ1 and SEQ2 by mapping sequencing reads from the validation sample to the strain-specific sequence regions. Average coverages of the SEQ1 and SEQ2 in the metagenomics data showed CVs of ≤17.3% for six strains (i.e. S1-S4, S6, S7). Thus, the metagenomics-based quantification approach was considered successful for six strains, regardless of the strain-specific sequence region used. When comparing qPCR- and metagenomics-based quantifications of the validation sample, the identified strain-specific sequence regions were considered suitable and applicable for quantification at a strain level of defined mixed-strain starter cultures.

  12. Cultural Socialization in Families with Adopted Korean Adolescents: A Mixed-Method, Multi-Informant Study.

    PubMed

    Kim, Oh Myo; Reichwald, Reed; Lee, Richard M

    2012-11-01

    Transracial, transnational families understand and transmit cultural socialization messages in ways that differ from same-race families. This study explored the ways in which transracial, transnational adoptive families discuss race and ethnicity and how these family discussions compared to self-reports from adoptive parents and adolescents regarding the level of parental engagement in cultural socialization. Of the thirty families with at least one adolescent-aged child (60% female, average age 17.8 years) who was adopted from South Korea, nine families acknowledged racial and ethnic differences, six families rejected racial and ethnic differences, and fifteen families held a discrepancy of views. Parents also reported significantly greater engagement in cultural socialization than adolescents' reports of parental engagement. However, only adolescent self-reports of parental engagement in cultural socialization matched the qualitative coding of family conversations. PMID:24235782

  13. Cultural Socialization in Families with Adopted Korean Adolescents: A Mixed-Method, Multi-Informant Study

    PubMed Central

    Kim, Oh Myo; Reichwald, Reed; Lee, Richard M.

    2012-01-01

    Transracial, transnational families understand and transmit cultural socialization messages in ways that differ from same-race families. This study explored the ways in which transracial, transnational adoptive families discuss race and ethnicity and how these family discussions compared to self-reports from adoptive parents and adolescents regarding the level of parental engagement in cultural socialization. Of the thirty families with at least one adolescent-aged child (60% female, average age 17.8 years) who was adopted from South Korea, nine families acknowledged racial and ethnic differences, six families rejected racial and ethnic differences, and fifteen families held a discrepancy of views. Parents also reported significantly greater engagement in cultural socialization than adolescents’ reports of parental engagement. However, only adolescent self-reports of parental engagement in cultural socialization matched the qualitative coding of family conversations. PMID:24235782

  14. Role of methanogenic and sulfate-reducing bacteria in the reductive dechlorination of tetrachloroethylene in mixed culture

    SciTech Connect

    Cabirol, N.; Perrier, J.; Jacob, F.

    1996-05-01

    Tetrachloroethylene (perchloroethylene, PCE) is widely used in many industries and particularly as a degreasing and dry-cleaning solvent. It is commonly found as a groundwater contaminant and because of its carcinogenic properties is considered a pollutant, which must be eliminated by proper treatment. This research examines the role of a mixed culture in PCE dechlorination at high concentration from an ecological point of view. The respective role of sulfate-reducing and methaogenic bacteria in tetrachloroethylene cechlorination is studied. 19 refs., 5 figs., 2 tabs.

  15. Study of the rice straw biodegradation in mixed culture of Trichoderma viride and Aspergillus niger by GC-MS and FTIR.

    PubMed

    Chen, Yaoning; Huang, Jingxia; Li, Yuanping; Zeng, Guangming; Zhang, Jiachao; Huang, Aizhi; Zhang, Jie; Ma, Shuang; Tan, Xuebin; Xu, Wei; Zhou, Wei

    2015-07-01

    This study was conducted to investigate the biodegradation ability of the mixed culture of Trichoderma viride and Aspergillus niger through the study of the organic matter extracted from rice straw and the lignocellulose structure by using gas chromatography-mass spectrometer (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The results of the GC-MS showed that the mixed culture possessed shorter alkane (heptane) at the end of the incubation and more kinds of organic matter (except the alkanes, 29 kinds of organic matter were detected) than the pure cultures. It could be deduced that the organic matter could indicate the degradation degree of the lignocellulose to some extent. Moreover, pinene was detected in the mixed culture on days 5 and 10, which might represent the antagonistic relationship between T. viride and A. niger. The analysis of FTIR spectrums which indirectly verified the GC-MS results showed that the mixed culture possessed a better degradation of rice straw compared with the pure culture. Therefore, the methods used in this research could be considered as effective ones to investigate the lignocellulose degradation mechanism in mixed culture. PMID:25639249

  16. Comparison of different mixed cultures for bio-hydrogen production from ground wheat starch by combined dark and light fermentation.

    PubMed

    Ozmihci, Serpil; Kargi, Fikret

    2010-04-01

    Composition of the mixed culture was varied in combined dark-light fermentation of wheat powder starch in order to improve hydrogen gas formation rate and yield. Heat-treated anaerobic sludge and pure culture of Clostridium beijerinckii (DSMZ 791T) were combined with two different light fermentation bacteria of Rhodobacter sphaeroides (RS-NRRL and RS-RV) in order to select a more suitable mixture resulting in high hydrogen yield and formation rate. A combination of the anaerobic sludge and RS-NRRL yielded the highest cumulative hydrogen (CHF = 140 ml), the highest yield (0.36 mol H2 mol(-1) glucose) and specific hydrogen formation rate (2.5 ml H2 g(-1) biomass h(-1)). During dark fermentation (70 h) hydrogen was produced simultaneously by the dark and light fermentation bacteria using glucose from hydrolyzed starch. However, only light fermentation bacteria produced hydrogen from VFA's derived from dark fermentation after a long adaptation period.

  17. Chemically-defined medium for growth and differentiation of mixed epithelial and connective tissues in organ culture.

    PubMed

    Hodges, G M; Melcher, A H

    1976-06-01

    The effect on tissue differentiation and growth in vitro of certain of the factors implicated in collagen synthesis (ascorbic acid, alpha-ketoglutarate and oxygen) and the influence of hydrocortisone was studied using organ cultures of fetal mouse mandible as a mixed epithelial and connective tissue system. Using serum-free Waymouth's MB 752/1 chemically-defined medium, addition of high levels of ascorbic acid (300mug per ml), hydrocortisone (1mug per ml) and oxygen (95%) enhanced differentiation in a number of tissues, in particular skin and appendages, tooth germs and bone, while osteoid and dentine production were noticeable promoted. It is suggested that an essential aspect of media design for organ culture involves the incorporaation of collagen-promoting factors to the in vitro enviornment particularly with regard to the controlling role implicated for collagen in a variety of biological processess.

  18. Formation of Short-Chain Fatty Acids from H2 and CO2 by a Mixed Culture of Bacteria

    PubMed Central

    Goldberg, I.; Cooney, C. L.

    1981-01-01

    The biological utilization of CO2 and H2 for the formation of short-chain fatty acids was studied by using a mixed culture of bacteria. Optimization of a medium was carried out in continuous culture to identify limiting factors which controlled growth and production of organic acids. The optimal pH for growth and acid production was 7.0 at 37°C; the maximal cell concentration obtained was 5.9 g of cells per liter (dry weight), and the maximal amount of volatile acids formed was 4.7 g/liter, with acetic acid as the predominant acid. With the optimized medium, it was found that the rate of transfer of hydrogen or carbon dioxide, or both, from gas to liquid was the limiting factor which controlled growth and production of acids. PMID:16345680

  19. Mixed lymphocyte cultures can predict TCR Vbeta repertoires of T cells infiltrating kidney transplants during acute rejection episodes.

    PubMed

    Paraoan, Marius T; Bakran, Ali; Hammad, Abdul; Sells, Robert A; Christmas, Stephen E

    2005-12-27

    Alloreactive T cell populations can show skewing of T-cell antigen receptor (TCR) Vbeta gene usage. The aims of the experiments were to compare in vivo and in vitro T cell alloresponses against donor alloantigens for TCR Vbeta gene usage. T-cell cultures from renal biopsies taken during acute rejection and pretransplant mixed lymphocyte cultures (MLC) were established from five renal transplant patients. TCR Vbeta gene usage, assessed with Vbeta family specific antibodies, showed that up to five different Vbeta families were significantly expanded. In four of five cases, there was close concordance between Vbeta families expanded from the biopsy and in MLC. T-cell clones from one renal biopsy were specific for the mismatched donor alloantigen and showed similar TCR Vbeta gene usage to the original T-cell line. The results show very similar patterns of TCR Vbeta gene usage in alloreactive T cells generated ex vivo or in vitro.

  20. The Role of Leadership and Culture in Creating Meaningful Assessment: A Mixed Methods Case Study

    ERIC Educational Resources Information Center

    Guetterman, Timothy C.; Mitchell, Nancy

    2016-01-01

    With increased demands for institutional accountability and improved student learning, involvement in assessment has become a fundamental role of higher education faculty (Rhodes, 2010). However, faculty members and administrators often question whether assessment efforts do indeed improve student learning (Hutchings, 2010). This mixed methods…

  1. The Politics of Culture: Understanding Local Political Resistance to Detracking in Racially Mixed Schools.

    ERIC Educational Resources Information Center

    Wells, Amy Stuart; Serna, Irene

    1996-01-01

    A 3-year study of 10 racially mixed schools implementing detracking shows how elite parents undermine the reforms by threatening flight, co-opting those educators who have power and authority, obtaining support of the "not-quite elite," and using bribes. (SK)

  2. Biofilm formation and interspecies interactions in mixed cultures of thermo-acidophilic archaea Acidianus spp. and Sulfolobus metallicus.

    PubMed

    Castro, Camila; Zhang, Ruiyong; Liu, Jing; Bellenberg, Sören; Neu, Thomas R; Donati, Edgardo; Sand, Wolfgang; Vera, Mario

    2016-09-01

    The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482(T) and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures.

  3. The effects of concentration-dependent morphology of self-assembling RADA16 nanoscaffolds on mixed retinal cultures

    NASA Astrophysics Data System (ADS)

    Ho, Dominic; Fitzgerald, Melinda; Bartlett, Carole A.; Zdyrko, Bogdan; Luzinov, Igor A.; Dunlop, Sarah A.; Swaminathan Iyer, K.

    2011-03-01

    RADA16 self-assembling peptide nanofiber scaffolds (SAPNSs) have been shown to have positive effects on neural regeneration following injury to the central nervous system in vivo, but mechanisms are unclear. Here we show that RADA16 SAPNSs form scaffolds of increasing fiber density with increasing peptide concentration which in turn has a concentration-dependent effect on neurons and astrocytes in mixed retinal cultures. Importantly, we report that the final nanoscale fiber architecture is an important factor to consider in designing scaffolds to promote regeneration in the central nervous system.RADA16 self-assembling peptide nanofiber scaffolds (SAPNSs) have been shown to have positive effects on neural regeneration following injury to the central nervous system in vivo, but mechanisms are unclear. Here we show that RADA16 SAPNSs form scaffolds of increasing fiber density with increasing peptide concentration which in turn has a concentration-dependent effect on neurons and astrocytes in mixed retinal cultures. Importantly, we report that the final nanoscale fiber architecture is an important factor to consider in designing scaffolds to promote regeneration in the central nervous system. Electronic supplementary information (ESI) available: Detailed experimental procedures, additional SEM data and AFM analysis. See DOI: 10.1039/c0nr00666a

  4. Biofilm formation and interspecies interactions in mixed cultures of thermo-acidophilic archaea Acidianus spp. and Sulfolobus metallicus.

    PubMed

    Castro, Camila; Zhang, Ruiyong; Liu, Jing; Bellenberg, Sören; Neu, Thomas R; Donati, Edgardo; Sand, Wolfgang; Vera, Mario

    2016-09-01

    The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482(T) and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures. PMID:27388200

  5. Nonpathogenic Entamoeba dispar quickly outgrows pathogenic Entamoeba histolytica in mixed xenic cultures.

    PubMed

    Pysova, I; Tumova, P; Tolarova, V; Nohynkova, E

    2009-04-01

    Entamoeba histolytica and Entamoeba dispar are two microscopically indistinguishable amoebae living in the human colon. The former is a pathogen, whereas the latter is a nonpathogenic commensal. Using a model system of in vitro cocultures and PCR detection of the Entamoeba species, we found that the nonpathogenic species can rapidly outgrow the pathogen in xenic cultures.

  6. Cultural Border Crossing in Three Urban Classrooms: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Roopnarine, Rupnarain

    2016-01-01

    This study examined the effects of the instruction of four youth cultural border crossing behaviors: flexibility, being at ease, playfulness, and citizenship as an intervention aimed at helping students to transition across three borders, student to student, student to science, and student to teacher. The research involved 12 ninth- and 10th-grade…

  7. Adaptation of a mixed culture of acidophiles for a tank biooxidation of refractory gold concentrates containing a high concentration of arsenic.

    PubMed

    Hong, Jeongsik; Silva, Rene A; Park, Jeonghyun; Lee, Eunseong; Park, Jayhyun; Kim, Hyunjung

    2016-05-01

    We adapted a mixed culture of acidophiles to high arsenic concentrations to confirm the possibility of achieving more than 70% biooxidation of refractory gold concentrates containing high arsenic (As) concentration. The biooxidation process was applied to refractory gold concentrates containing approximately 139.67 g/kg of total As in a stirred tank reactor using an adapted mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The percentage of the biooxidation process was analyzed based on the total As removal efficiency. The As removal was monitored by inductively coupled plasma (ICP) analysis, conducted every 24 h. The results obtained with the adapted culture were compared with the percentage of biooxidation obtained with a non-adapted mixed culture of A. ferrooxidans and A. thiooxidans, and with their respective pure cultures. The percentages of biooxidation obtained during 358 h of reaction were 72.20%, 38.20%, 27.70%, and 11.45% for adapted culture, non-adapted culture, and pure cultures of A. thiooxidans and A. ferrooxidans, respectively. The adapted culture showed a peak maximum percentage of biooxidation of 77% at 120 h of reaction, confirming that it is possible to obtain biooxidation percentages over 70% in gold concentrates containing high As concentrations.

  8. Adaptation of a mixed culture of acidophiles for a tank biooxidation of refractory gold concentrates containing a high concentration of arsenic.

    PubMed

    Hong, Jeongsik; Silva, Rene A; Park, Jeonghyun; Lee, Eunseong; Park, Jayhyun; Kim, Hyunjung

    2016-05-01

    We adapted a mixed culture of acidophiles to high arsenic concentrations to confirm the possibility of achieving more than 70% biooxidation of refractory gold concentrates containing high arsenic (As) concentration. The biooxidation process was applied to refractory gold concentrates containing approximately 139.67 g/kg of total As in a stirred tank reactor using an adapted mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The percentage of the biooxidation process was analyzed based on the total As removal efficiency. The As removal was monitored by inductively coupled plasma (ICP) analysis, conducted every 24 h. The results obtained with the adapted culture were compared with the percentage of biooxidation obtained with a non-adapted mixed culture of A. ferrooxidans and A. thiooxidans, and with their respective pure cultures. The percentages of biooxidation obtained during 358 h of reaction were 72.20%, 38.20%, 27.70%, and 11.45% for adapted culture, non-adapted culture, and pure cultures of A. thiooxidans and A. ferrooxidans, respectively. The adapted culture showed a peak maximum percentage of biooxidation of 77% at 120 h of reaction, confirming that it is possible to obtain biooxidation percentages over 70% in gold concentrates containing high As concentrations. PMID:26481159

  9. Selective enrichment media bias the types of Salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths.

    PubMed

    Gorski, Lisa

    2012-01-01

    For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the pathogen the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown in one set of standard enrichment media to see if culture bias patterns emerged. Nineteen strains representing four serogroups and ten serotypes were compared in four-strain mixtures in Salmonella-only and in cattle fecal culture enrichment backgrounds using Salmonella enrichment media. One or more strain(s) emerged as dominant in each mixture. No serotype was most fit, but strains of serogroups C2 and E were more likely to dominate enrichment culture mixtures than strains of serogroups B or C1. Different versions of Rappaport-Vassiliadis (RV) medium gave different patterns of strain dominance in both Salmonella-only and fecal enrichment culture backgrounds. The fittest strains belonged to serogroups C1, C2, and E, and included strains of S. Infantis, S. Thompson S. Newport, S. 6,8:d:-, and S. Give. Strains of serogroup B, which included serotypes often seen in outbreaks such as S. Typhimurium, S. Saintpaul, and S. Schwarzengrund were less likely to emerge as dominant strains in the mixtures when using standard RV as part of the enrichment. Using a more nutrient-rich version of RV as part of the protocol led to a different pattern of strains emerging, however some were still present in very low numbers in the resulting population. These results indicate that outbreak investigations of food and/or other environmental samples should include multiple enrichment protocols to ensure isolation of target strains of Salmonella.

  10. Model-based data evaluation of polyhydroxybutyrate producing mixed microbial cultures in aerobic sequencing batch and fed-batch reactors.

    PubMed

    Johnson, Katja; Kleerebezem, Robbert; van Loosdrecht, Mark C M

    2009-09-01

    The production of polyhydroxyalkanoates (PHAs) with mixed microbial cultures is a promising approach for the sustainable production of bioplastics. Usually a two-step process is employed consisting of (i) the enrichment of a PHA producing mixed culture in a sequencing batch reactor (SBR) and (ii) the subsequent PHA production in a fed-batch reactor. Both reactors are highly dynamic systems, particularly if the SBR is working at low sludge residence times (SRTs) or if growth is (partly) permitted in fed-batch systems. Under these conditions the concentrations of substrate, PHA and biomass change rapidly, complicating the identification of biomass specific conversion rates as required for process characterization. We developed a structured approach for the evaluation of such SBR and fed-batch experiments consisting of five steps: (1) Measurement of a sufficiently large set of parameters including off-gas concentrations, (2) Corrections of measurements for effects of sampling and addition of liquids (pH control, substrate), (3) Calculation of oxygen uptake and carbon dioxide evolution rates, the latter including inorganic carbon dissolved in the liquid phase, (4) Balancing of the measured conversions, (5) Evaluation of the measurements by means of a metabolic model. This approach has been successfully applied to a large number of data sets. Steps 1-4 ensured that data sets of high quality were obtained. Step 5 allowed to find the best estimates for all conversions and biomass specific rates for the measured data sets, while complying with material balances. Conversions of the substrate acetate, the nitrogen source ammonia and of the storage polymer PHA (here polyhydroxybutyrate (PHB)) were described very accurately by the model. Modeled off-gas conversions often deviated somewhat from measured conversions, which might be partly due to an inaccurate model stoichiometry. Nonetheless, the described approach proved to be a very useful tool for the evaluation and

  11. Cultural border crossing in three urban classrooms: A mixed methods study

    NASA Astrophysics Data System (ADS)

    Roopnarine, Rupnarain

    This study examined the effects of the instruction of four youth cultural border crossing behaviors: flexibility, being at ease, playfulness, and citizenship as an intervention aimed at helping students to transition across three borders, student to student, student to science, and student to teacher. The research involved 12 ninth- and 10th-grade students in a large urban school district in three diverse classrooms, A, B, and C. Four students in each classroom volunteered for the study. The students in Groups A and B were in 9th grade Living Environment and students in Group B were in 10th grade chemistry. These students participated in this instructional intervention for three months. The study was conducted using both quantitative and qualitative methods based on participant observations, interviews, and questionnaire. The result indicated that there was no significant effect of the cultural border crossing instructions on the students' interactions across the three borders examined. However, the instructions helped Group A and Group B to be more flexible but not group C. Also, the instructions helped Group A to be more playful and at ease but not Group B and C. The instructions also helped Group A to show more citizenship but not Group B and C. In addition, there was no difference between the pretest and posttest cultural bother crossing behavior. Moreover, qualitative data analysis showed that the participants were more flexible, at ease, and playful among peers than across student to teacher and student to science borders. Also, the use of citizenship in the three groups showed no effect on the participants' interaction with peers. Although, the findings showed no effect of cultural border crossing instructions on students' interactions, it is suggested that we continue to find ways to help students feel more comfortable in science.

  12. Thrombin-induced activation of astrocytes in mixed rat hippocampal cultures is inhibited by soluble thrombomodulin.

    PubMed

    Niego, Be'eri; Samson, Andre L; Petersen, Karl-Uwe; Medcalf, Robert L

    2011-03-24

    Thrombin, a serine protease known for its role in coagulation, also induces a variety of protease activated receptor (PAR)-mediated responses in the central nervous system that contribute to many brain pathologies. Since the proteolytic specificity of thrombin is uniquely controlled by thrombomodulin (TM), we investigated the mechanisms by which thrombin and a recombinant soluble form of human TM (Solulin, INN: sothrombomodulin alpha; rhsTM) could influence rat hippocampal cultures. Treatment of hippocampal cultures with thrombin for up to 48h resulted in a significant morphological rearrangement with the formation of expansive cell-free areas (CFAs) and a reduction in cell viability; both effects were blocked by rhsTM. Treatment with the selective PAR-1 agonist, TRAP (SFLLRN) caused the formation of CFAs, suggesting that CFA formation involved PAR-1 signaling. Astrocytes prepared from PAR-1(-/-) mice also had an attenuated CFA response to thrombin. Thrombin-induced CFA formation was a consequence of cell movement and substantial changes in cell morphology, rather than due to cell detachment. Immunocytochemical and functional analyses revealed that the thrombin-sensitive cells within these hippocampal cultures were astrocytes. The effects of thrombin on CFA development were mediated by astrocyte-specific release of intracellular calcium and signalling through ERK1/2. rhsTM was able to attenuate thrombin-induced ERK1/2 phosphorylation. Finally, astrocytes were shown to maintain thrombin-sensitivity following neuronal depletion with NMDA, a result which was confirmed with pure astrocyte cultures. Hence thrombin mediates PAR-1-induced activation of hippocampal astrocytes, but not neurons, in a process that can be modulated by rhsTM. PMID:21241677

  13. Cell-wall proteinases PrtS and PrtB have a different role in Streptococcus thermophilus/Lactobacillus bulgaricus mixed cultures in milk.

    PubMed

    Courtin, P; Monnet, V; Rul, F

    2002-11-01

    The manufacture of yoghurt relies on the simultaneous utilization of two starters: Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus). A protocooperation usually takes place between the two species, which often results in enhanced milk acidification and aroma formation compared to pure cultures. Cell-wall proteinases of Lactococcus lactis and lactobacilli have been shown to be essential to growth in milk in pure cultures. In this study, the role of proteinases PrtS from S. thermophilus and PrtB from Lb. bulgaricus in bacterial growth in milk was evaluated; a negative mutant for the prtS gene of S. thermophilus CNRZ 385 was constructed for this purpose. Pure cultures of S. thermophilus CNRZ 385 and its PrtS-negative mutant were made in milk as well as mixed cultures of S. thermophilus and Lb. bulgaricus: S. thermophilus CNRZ 385 or its PrtS-negative mutant was associated with several strains of Lb. bulgaricus, including a PrtB-negative strain. The pH and growth of bacterial populations of the resulting mixed cultures were followed, and the Lactobacillus strain was found to influence both the extent of the benefit of Lb. bulgaricus/S. thermophilus association on milk acidification and the magnitude of S. thermophilus population dominance at the end of fermentation. In all mixed cultures, the sequential growth of S. thermophilus then of Lb. bulgarius and finally of both bacteria was observed. Although proteinase PrtS was essential to S. thermophilus growth in milk in pure culture, it had no effect on bacterial growth and thus on the final pH of mixed cultures in the presence of PrtB. In contrast, proteinase PrtB was necessary for the growth of S. thermophilus, and its absence resulted in a higher final pH. From these results, a model of growth of both bacteria in mixed cultures in milk is proposed.

  14. Mixed, short rotation culture of red alder and black cottonwood: growth, coppicing, nitrogen fixation, and allelopathy

    SciTech Connect

    Heilman, P.; Stettler, R.F.

    1985-01-01

    Alnus rubra seedlings were grown in a 1:1 mixture at a spacing of 1.2 x 1.2 m with 28 Populus clones (25 clones pf P. trichocarpa, 2 of P. deltoides x P. trichocarpa, and one P. deltoides x P. nigra) in a study established in W. Washington in March 1979. Trees were harvested at 4 yr old. At harvest, average heights were: pure Populus, 10.2 m; Populus in the mixed stand 11.0 m; and alder 8.4 m. Most Populus sprouted satisfactorily after harvest (6.6 shoots/plant when pure, 7.6 shoots/plant in the mixture), but alder sprouted poorly (3.6 shoots/plant). Above-ground biomass at harvest was 15.9 t/ha p.a. for the mixture and 16.7 t/ha p.a. for pure Populus, although the mixture had been more productive at 2 yr. Nitrogenase activity (nitrogen fixation as measured by acetylene reduction) of alder declines in the 4th season; competition was the most important factor influencing this decline. Soil N content had no effect on fixation. A pot study showed that ground Populus leaf and litter material inhibited the growth of red alder seedlings, although soil collected from Populus plots had no effect. Results indicated that allelopathy is probably a minor factor under field conditions, at most, and that growing mixed stands may, on balance, be beneficial. 20 references.

  15. Development of a floating photobioreactor with internal partitions for efficient utilization of ocean wave into improved mass transfer and algal culture mixing.

    PubMed

    Kim, Z-Hun; Park, Hanwool; Hong, Seong-Joo; Lim, Sang-Min; Lee, Choul-Gyun

    2016-05-01

    Culturing microalgae in the ocean has potentials that may reduce the production cost and provide an option for an economic biofuel production from microalgae. The ocean holds great potentials for mass microalgal cultivation with its high specific heat, mixing energy from waves, and large cultivable area. Suitable photobioreactors (PBRs) that are capable of integrating marine energy into the culture systems need to be developed for the successful ocean cultivation. In this study, prototype floating PBRs were designed and constructed using transparent low-density polyethylene film for microalgal culture in the ocean. To improve the mixing efficiency, various types of internal partitions were introduced within PBRs. Three different types of internal partitions were evaluated for their effects on the mixing efficiency in terms of mass transfer (k(L)a) and mixing time in the PBRs. The partition type with the best mixing efficiency was selected, and the number of partitions was varied from one to three for investigation of its effect on mixing efficiency. When the number of partitions is increased, mass transfer increased in proportion to the number of partitions. However, mixing time was not directly related to the number of partitions. When a green microalga, Tetraselmis sp. was cultivated using PBRs with the selected partition under semi-continuous mode in the ocean, biomass and fatty acid productivities in the PBRs were increased by up to 50 % and 44% at high initial cell density, respectively, compared to non-partitioned ones. The results of internally partitioned PBRs demonstrated potentials for culturing microalgae by efficiently utilizing ocean wave energy into culture mixing in the ocean.

  16. Development of a floating photobioreactor with internal partitions for efficient utilization of ocean wave into improved mass transfer and algal culture mixing.

    PubMed

    Kim, Z-Hun; Park, Hanwool; Hong, Seong-Joo; Lim, Sang-Min; Lee, Choul-Gyun

    2016-05-01

    Culturing microalgae in the ocean has potentials that may reduce the production cost and provide an option for an economic biofuel production from microalgae. The ocean holds great potentials for mass microalgal cultivation with its high specific heat, mixing energy from waves, and large cultivable area. Suitable photobioreactors (PBRs) that are capable of integrating marine energy into the culture systems need to be developed for the successful ocean cultivation. In this study, prototype floating PBRs were designed and constructed using transparent low-density polyethylene film for microalgal culture in the ocean. To improve the mixing efficiency, various types of internal partitions were introduced within PBRs. Three different types of internal partitions were evaluated for their effects on the mixing efficiency in terms of mass transfer (k(L)a) and mixing time in the PBRs. The partition type with the best mixing efficiency was selected, and the number of partitions was varied from one to three for investigation of its effect on mixing efficiency. When the number of partitions is increased, mass transfer increased in proportion to the number of partitions. However, mixing time was not directly related to the number of partitions. When a green microalga, Tetraselmis sp. was cultivated using PBRs with the selected partition under semi-continuous mode in the ocean, biomass and fatty acid productivities in the PBRs were increased by up to 50 % and 44% at high initial cell density, respectively, compared to non-partitioned ones. The results of internally partitioned PBRs demonstrated potentials for culturing microalgae by efficiently utilizing ocean wave energy into culture mixing in the ocean. PMID:26857371

  17. Do furanic and phenolic compounds of lignocellulosic and algae biomass hydrolyzate inhibit anaerobic mixed cultures? A comprehensive review.

    PubMed

    Monlau, F; Sambusiti, C; Barakat, A; Quéméneur, M; Trably, E; Steyer, J-P; Carrère, H

    2014-01-01

    Nowadays there is a growing interest on the use of both lignocellulosic and algae biomass to produce biofuels (i.e. biohydrogen, ethanol and methane), as future alternatives to fossil fuels. In this purpose, thermal and thermo-chemical pretreatments have been widely investigated to overcome the natural physico-chemical barriers of such biomass and to enhance biofuel production from lignocellulosic residues and, more recently, marine biomass (i.e. macro and microalgae). However, the pretreatment technologies lead not only to the conversion of carbohydrate polymers (ie cellulose, hemicelluloses, starch, agar) to soluble monomeric sugar (ie glucose, xylose, arabinose, galactose), but also the generation of various by-products (i.e. furfural and 5-HMF). In the case of lignocellulosic residues, part of the lignin can also be degraded in lignin derived by-products, mainly composed of phenolic compounds. Although the negative impact of such by-products on ethanol production has been widely described in literature, studies on their impact on biohydrogen and methane production operated with mixed cultures are still very limited. This review aims to summarise and discuss literature data on the impact of pre-treatment by-products on H2-producing dark fermentation and anaerobic digestion processes when using mixed cultures as inoculum. As a summary, furanic (5-HMF, furfural) and phenolic compounds were found to be stronger inhibitors of the microbial dark fermentation than the full anaerobic digestion process. Such observations can be explained by differences in process parameters: anaerobic digestion is performed with more complex mixed cultures, lower substrate/inoculum and by-products/inoculum ratios and longer batch incubation times than dark fermentation. Finally, it has been reported that, during dark fermentation process, the presence of by-products could lead to a metabolic shift from H2-producing pathways (i.e. acetate and butyrate) to non-H2-producing pathways (i

  18. Reductive Dechlorination of Carbon Tetrachloride by Tetrachloroethene and Trichloroethene Respiring Anaerobic Mixed Cultures

    NASA Astrophysics Data System (ADS)

    Vickstrom, K. E.; Azizian, M.; Semprini, L.

    2015-12-01

    Carbon tetrachloride (CT) is a toxic and recalcitrant groundwater contaminant with the potential to form a broad range of transformation products. Of the possible biochemical pathways through which CT can be degraded, reductive dehalogenation to less chlorinated compounds and mineralization to carbon dioxide (CO2) appear to be the most frequently utilized pathways by anaerobic organisms. Results will be presented from batch experiments of CT degradation by the Evanite (EV), Victoria Strain (VS) and Point Mugu (PM) anaerobic dechlorinating cultures. The cultures are grown in chemostats and are capable of transforming tetrachloroethene (PCE) or trichloroethene (TCE) to ethene by halorespiration via reductive dehalogenase enzymes. For the batch CT transformation tests, the cells along with supernatant were harvested from chemostats fed PCE or TCE, but never CT. The batch reactors were initially fed 0.0085 mM CT and an excess of formate (EV and VS) or lactate (PM) as electron donor. Transformation of CT was 100% with about 20% converted to chloroform (CF) and undetected products. Multiple additions of CT showed a slowing of pseudo first-order CT transformation rates across all cultures. Batch reactors were then established and fed 0.085 mM CT with an excess of electron donor in order to better quantify the reductive pathway. CT was transformed to CF and dichloromethane (DCM), with trace amounts of chloromethane (CM) detected. Between 60-90% of the mass added to the system was accounted for, showing that the majority of the carbon tetrachloride present is being reductively dehalogenated. Results from batch reactors that were poisoned using sodium azide, and from reactors not provided electron donor will be presented to distinguish between biotic and abiotic reactions. Furthermore, results from reactors prepared with acetylene (a potent, reversible inhibitor of reductive dehalogenases (1)) will be presented as a means of identifying the enzymes involved in the

  19. Comparison of fecal culture and Danish Mix-ELISA for determination of Salmonella enterica subsp. enterica prevalence in growing swine.

    PubMed

    Funk, J A; Harris, I T; Davies, P R

    2005-04-25

    In the USA, control of food-borne salmonellosis associated with meat consumption has been predominantly focused at slaughter and processing. It is expected that standards at slaughter and processing will become more stringent, creating pressure to reduce prevalence of Salmonella-positive food animals through on-farm interventions. The aim of this study was to compare traditional fecal culture and the Danish Mix-ELISA (DME) for determination of Salmonella prevalence pre-harvest in swine. In Trial 1, five cohorts of individually identified pigs were longitudinally sampled during the growing period to compare the kinetics of prevalence as estimated by fecal culture and the DME. In Trial 2, the correlation between fecal prevalence and seroprevalence was estimated pre-marketing in 49 groups of pigs. In Trial 1, fecal prevalence and seroprevalence showed similar kinetics, with a tendency of a higher OD% cut-off to more closely approximate fecal prevalence. In Trial 2, correlations between fecal culture and the DME were 0.40, 0.36, 0.43, and 0.43 (p<0.001) for OD% cut-offs > or =10, 20, 30, and 40, respectively. Based on these results, a higher OD% cut-off would be recommended if more approximate estimation of fecal prevalence is desired and longitudinal sampling would be suggested for evaluating the impact of on-farm interventions for Salmonella reduction whether utilizing fecal culture or the DME. Further evaluation of the impact of Salmonella serovar present on farms on seroprevalence and the relationship of on-farm seroprevalence with food safety risk are needed prior to utilizing the DME for pre-harvest Salmonella diagnostics in the US swine herd.

  20. Comparison of fecal culture and Danish Mix-ELISA for determination of Salmonella enterica subsp. enterica prevalence in growing swine.

    PubMed

    Funk, J A; Harris, I T; Davies, P R

    2005-04-25

    In the USA, control of food-borne salmonellosis associated with meat consumption has been predominantly focused at slaughter and processing. It is expected that standards at slaughter and processing will become more stringent, creating pressure to reduce prevalence of Salmonella-positive food animals through on-farm interventions. The aim of this study was to compare traditional fecal culture and the Danish Mix-ELISA (DME) for determination of Salmonella prevalence pre-harvest in swine. In Trial 1, five cohorts of individually identified pigs were longitudinally sampled during the growing period to compare the kinetics of prevalence as estimated by fecal culture and the DME. In Trial 2, the correlation between fecal prevalence and seroprevalence was estimated pre-marketing in 49 groups of pigs. In Trial 1, fecal prevalence and seroprevalence showed similar kinetics, with a tendency of a higher OD% cut-off to more closely approximate fecal prevalence. In Trial 2, correlations between fecal culture and the DME were 0.40, 0.36, 0.43, and 0.43 (p<0.001) for OD% cut-offs > or =10, 20, 30, and 40, respectively. Based on these results, a higher OD% cut-off would be recommended if more approximate estimation of fecal prevalence is desired and longitudinal sampling would be suggested for evaluating the impact of on-farm interventions for Salmonella reduction whether utilizing fecal culture or the DME. Further evaluation of the impact of Salmonella serovar present on farms on seroprevalence and the relationship of on-farm seroprevalence with food safety risk are needed prior to utilizing the DME for pre-harvest Salmonella diagnostics in the US swine herd. PMID:15795083

  1. Stratification and mixing in the Limfjorden in relation to mussel culture

    NASA Astrophysics Data System (ADS)

    Wiles, Philip J.; van Duren, Luca A.; Häse, Clivia; Larsen, Jens; Simpson, John H.

    2006-04-01

    The physical regime of Limfjorden in northern Denmark has been investigated with the aim of defining its role in controlling the food supply to a community of benthic filter feeders, which is dominated by commercially valuable mussels. A two-week campaign of hydrodynamic observations at different spatial scales was undertaken in May/June 2003 as part of an interdisciplinary study. The results reveal that the water column in Limfjorden switches periodically between stratified and mixed conditions in response to meteorological forcing. During calm periods, stratification develops in response to solar heating. This stratifying tendency is opposed principally by wind stirring indirectly through wave motions. Due to the low velocities, there is very little generation of turbulence due to shear stresses at the bed. The mussels appear to have a subtle effect on turbulence levels very close to the bed, but in this system the effect of mussels on the hydrodynamics of the whole water column is limited. A reduced physics model of the competition between these processes has been developed, which incorporates the effects of waves and of shallow water on the absorption of solar radiation. When forced by observed data for wave activity and surface heating, the model simulates the principal features of the observed evolution of water column stability. Stratification is usually detrimental to mussel growth, as it limits access of mussels to food in the upper water layers. However, if mussels are capable of depleting the whole water column under fully mixed conditions, brief periods of stratification could theoretically act as a temporary refuge for phytoplankton, allowing the population to recover. The ultimate effect of this hydrodynamic switching of the system needs further assessment.

  2. Nitroxides as anti-biofilm compounds for the treatment of Pseudomonas aeruginosa and mixed-culture biofilms.

    PubMed

    Alexander, Stefanie-Ann; Kyi, Caroline; Schiesser, Carl H

    2015-04-28

    A series of 23 nitroxides () was tested for biofilm modulatory activity using a crystal violet staining technique. 3-(Dodecane-1-thiyl)-4-(hydroxymethyl)-2,2,5,5-tetramethyl-1-pyrrolinoxyl () was found to significantly suppress biofilm formation and elicit dispersal events in both Pseudomonas aeruginosa and mixed-culture biofilms. Twitching and swarming motilities were enhanced by nitroxide , leaving the planktonic-specific swimming motility unaffected and suggesting that the mechanism of -mediated biofilm modulation is linked to the hyperactivation of surface-associated cell motilities. Preliminary structure-activity relationship studies identify the dodecanethiyl chain, hydroxymethyl substituent and the free radical moiety to be structural features pertinent to the anti-biofilm activity of .

  3. Why and How Do Nursing Homes Implement Culture Change Practices? Insights from Qualitative Interviews in a Mixed Methods Study

    PubMed Central

    Shield, Renée R.; Looze, Jessica; Tyler, Denise; Lepore, Michael; Miller, Susan C.

    2015-01-01

    Objective To understand the process of instituting culture change (CC) practices in nursing homes (NHs). Methods NH Directors of Nursing (DONs) and Administrators (NHAs) at 4,149 United States NHs were surveyed about CC practices. Follow-up interviews with 64 NHAs were conducted and analyzed by a multidisciplinary team which reconciled interpretations recorded in an audit trail. Results The themes include: 1) Reasons for implementing CC practices vary; 2) NH approaches to implementing CC practices are diverse; 3) NHs consider resident mix in deciding to implement practices; 4) NHAs note benefits and few implementation costs of implementing CC practices; 5) Implementation of changes is challenging and strategies for change are tailored to the challenges encountered; 6) Education and communication efforts are vital ways to institute change; and 7) NHA and other staff leadership is key to implementing changes. Discussion Diverse strategies and leadership skills appear to help NHs implement reform practices, including CC innovations. PMID:24652888

  4. Optimization of critical factors to enhance polyhydroxyalkanoates (PHA) synthesis by mixed culture using Taguchi design of experimental methodology.

    PubMed

    Venkata Mohan, S; Venkateswar Reddy, M

    2013-01-01

    Optimizing different factors is crucial for enhancement of mixed culture bioplastics (polyhydroxyalkanoates (PHA)) production. Design of experimental (DOE) methodology using Taguchi orthogonal array (OA) was applied to evaluate the influence and specific function of eight important factors (iron, glucose concentration, VFA concentration, VFA composition, nitrogen concentration, phosphorous concentration, pH, and microenvironment) on the bioplastics production. Three levels of factor (2(1) × 3(7)) variation were considered with symbolic arrays of experimental matrix [L(18)-18 experimental trails]. All the factors were assigned with three levels except iron concentration (2(1)). Among all the factors, microenvironment influenced bioplastics production substantially (contributing 81%), followed by pH (11%) and glucose concentration (2.5%). Validation experiments were performed with the obtained optimum conditions which resulted in improved PHA production. Good substrate degradation (as COD) of 68% was registered during PHA production. Dehydrogenase and phosphatase enzymatic activities were monitored during process operation. PMID:23201522

  5. Metabolic model for acetate uptake by a mixed culture of phosphate- and glycogen-accumulating organisms under anaerobic conditions.

    PubMed

    Yagci, Nevin; Artan, Nazik; Cokgör, Emine Ubay; Randall, Clifford W; Orhon, Derin

    2003-11-01

    This paper proposes a new metabolic model for acetate uptake by a mixed culture of phosphate- and glycogen-accumulating organisms (PAOs and GAOs) under anaerobic conditions. The model uses variable overall stoichiometry based on the assumption that PAOs may have the ability of using the glyoxylate pathway to produce the required reducing power for polyhydroxyalkonate (PHA) synthesis. The proposed model was tested and verified by experimental results. A sequencing batch reactor system was operated for enhanced biological phosphorus removal (EBPR) with acetate as the sole carbon source at different influent acetate/phosphate ratios. The resulting experimental data supported the validity of the proposed model, indicating the presence of GAOs for all tested HAc/P ratios, especially under P-limiting conditions. Strong agreement is observed between experimental values and model predictions for all model components, namely, PHB production, PHA composition, glycogen utilization, and P release.

  6. Production of polyhydroxyalkanoates from fermented sugar cane molasses by a mixed culture enriched in glycogen accumulating organisms.

    PubMed

    Bengtsson, Simon; Pisco, Ana R; Reis, Maria A M; Lemos, Paulo C

    2010-02-01

    Batch production of polyhydroxyalkanoates (PHAs) under aerobic conditions by an open mixed culture enriched in glycogen accumulating organisms (GAOs) with fermented sugar cane molasses as substrate was studied. The produced polymers contained five types of monomers, namely 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylbutyrate (3H2MB), 3-hydroxy-2-methylvalerate (3H2MV) and the medium chain length monomer 3-hydroxyhexanoate (3HHx). With fermented molasses as substrate, PHA was produced under concurrent consumption of stored glycogen with yields of 0.47-0.66 C-mol PHA per C-mol of total carbon substrate and with rates up to 0.65 C-mol/C-molX h. In order to investigate the role of glycogen during aerobic PHA accumulation in GAOs, synthetic single volatile fatty acids (VFAs) were used as substrates and it was found that the fate of glycogen was dependent on the type of VFA being consumed. Aerobic PHA accumulation occurred under concurrent glycogen consumption with acetate as substrate and under minor concurrent glycogen production with propionate as substrate. With butyrate and valerate as substrates, PHA accumulation occurred with the glycogen pool unaffected. The composition of the PHA was dependent on the VFA composition of the fermented molasses and was 56-70 mol-% 3HB, 13-43 mol-% 3HV, 1-23 mol-% 3HHx and 0-2 mol-% 3H2MB and 3H2MV. The high polymer yields and production rates suggest that enrichment of GAOs can be a fruitful strategy for mixed culture production of PHA from waste substrates.

  7. Kinetics of nitrate and sulfate removal using a mixed microbial culture with or without limited-oxygen fed.

    PubMed

    Xu, Xi-Jun; Chen, Chuan; Wang, Ai-Jie; Guo, Hong-Liang; Yuan, Ye; Lee, Duu-Jong; Ren, Nan-Qi

    2014-07-01

    The biological degradation of nitrate and sulfate was investigated using a mixed microbial culture and lactate as the carbon source, with or without limited-oxygen fed. It was found that sulfate reduction was slightly inhibited by nitrate, since after nitrate depletion the sulfate reduction rate increased from 0.37 mg SO4 (2-)/mg VSS d to 0.71 mg SO4 (2-)/mg VSS d, and the maximum rate of sulfate reduction in the presence of nitrate corresponded to 56 % of the non-inhibited sulfate reduction rate determined after nitrate depleted. However, simultaneous but not sequential reduction of both oxy-anions was observed in this study, unlike some literature reports in which sulfate reduction starts only after depletion of nitrate, and this case might be due to the fact that lactate was always kept above the limiting conditions. At limited oxygen, the inhibited effect on sulfate reduction by nitrate was relieved, and the sulfate reduction rate seemed relatively higher than that obtained without limited-oxygen fed, whereas kept almost constant (0.86-0.89 mg SO4 (2-)/mg VSS d) cross the six ROS states. In contrast, nitrate reduction rates decreased substantially with the increase in the initial limited-oxygen fed, showing an inhibited effect on nitrate reduction by oxygen. Kinetic parameters determined for the mixed microbial culture showed that the maximum specific sulfate utilization rate obtained (0.098 ± 0.022 mg SO4 (2-)/(mg VSS h)) was similar to the reported typical value (0.1 mg SO4 (2-)/(mg VSS h)), also indicating a moderate inhibited effect by nitrate.

  8. [An experimental study and a mathematical model of interactions in mixed culture of invertebrates and algae in the "producer-consumer" aquatic biotic cycle].

    PubMed

    Pis'man, T I; Bogdanova, O N

    2004-01-01

    An experimental investigation was carried out, and a mathematical model of interaction between invertebrates (infusoria Paramecium caudatum and rotifera Brachionus plicatilis) and algae (Chlorella vulgaris and Scenedesmus quadricauda) in the "producer-consumer" aquatic biotic cycle with spatially divided links was constructed. The model describes the dynamics of a mixed culture of infusoria and rotifera in the "consumer" link, when they consume a mixed culture of algae coming from the "producer" link. A negative influence of products of algae Scenedesmus metabolism upon the reproduction of infusoria P. caudatum was revealed. Taking this into account, a qualitative coincidence of the results of mathematical modeling with experimental data was obtained. It was shown that the co-existence of mixed algae culture in the "producer" link with invertebrates in the "consumer" link in the "producer-consumer" aquatic biotic cycle is impossible because of the displacement of infusoria P. caudatum by rotifera Brachionus plicatilis. PMID:15612555

  9. Responses of neotropical mangrove seedlings grown in monoculture and mixed culture under treatments of hydroperiod and salinity

    USGS Publications Warehouse

    Cardona-Olarte, P.; Twilley, R.R.; Krauss, K.W.; Rivera-Monroy, V.

    2006-01-01

    We investigated the combined effects of salinity and hydroperiod on seedlings of Rhizophora mangle and Laguncularia racemosa grown under experimental conditions of monoculture and mixed culture by using a simulated tidal system. The objective was to test hypotheses relative to species interactions to either tidal or permanent flooding at salinities of 10 or 40 g/l. Four-month-old seedlings were experimentally manipulated under these environmental conditions in two types of species interactions: (1) seedlings of the same species were grown separately in containers from September 2000 to August 2001 to evaluate intraspecific response and (2) seedlings of each species were mixed in containers to evaluate interspecific, competitive responses from August 2002 to April 2003. Overall, L. racemosa was strongly sensitive to treatment combinations while R. mangle showed little effect. Most plant responses of L. racemosa were affected by both salinity and hydroperiod, with hydroperiod inducing more effects than salinity. Compared to R. mangle, L. racemosa in all treatment combinations had higher relative growth rate, leaf area ratio, specific leaf area, stem elongation, total length of branches, net primary production, and stem height. Rhizophora mangle had higher biomass allocation to roots. Species growth differentiation was more pronounced at low salinity, with few species differences at high salinity under permanent flooding. These results suggest that under low to mild stress by hydroperiod and salinity, L. racemosa exhibits responses that favor its competitive dominance over R. mangle. This advantage, however, is strongly reduced as stress from salinity and hydroperiod increase. ?? Springer 2006.

  10. The formal-informal patient payment mix in European countries. Governance, economics, culture or all of these?

    PubMed

    Tambor, Marzena; Pavlova, Milena; Golinowska, Stanisława; Sowada, Christoph; Groot, Wim

    2013-12-01

    Cost-sharing for health care is high on the policy agenda in many European countries that struggle with deficits in their public budget. However, such policy often meets with public opposition, which might delay or even prevent its implementation. Increased reliance on patient payments may also have adverse equity effects, especially in countries where informal patient payments are widespread. The factors which might influence the presence of both, formal and informal payments can be found in economic, governance and cultural differences between countries. The aim of this paper is to review the formal-informal payment mix in Europe and to outline factors associated with this mix. We use quantitative analyses of macro-data for 35 European countries and a qualitative description of selected country experiences. The results suggest that the presence of obligatory cost-sharing for health care services is associated with governance factors, while informal patient payments are a multi-cause phenomenon. A consensus-based policy, supported by evidence and stakeholders' engagement, might contribute to a more sustainable patient payment policy. In some European countries, the implementation of cost-sharing requires policy actions to reduce other patient payment obligations, including measures to eliminate informal payments.

  11. Monophyletic group of unclassified γ-Proteobacteria dominates in mixed culture biofilm of high-performing oxygen reducing biocathode.

    PubMed

    Rothballer, Michael; Picot, Matthieu; Sieper, Tina; Arends, Jan B A; Schmid, Michael; Hartmann, Anton; Boon, Nico; Buisman, Cees J N; Barrière, Frédéric; Strik, David P B T B

    2015-12-01

    Several mixed microbial communities have been reported to show robust bioelectrocatalysis of oxygen reduction over time at applicable operation conditions. However, clarification of electron transfer mechanism(s) and identification of essential micro-organisms have not been realised. Therefore, the objective of this study was to shape oxygen reducing biocathodes with different microbial communities by means of surface modification using the electrochemical reduction of two different diazonium salts in order to discuss the relation of microbial composition and performance. The resulting oxygen reducing mixed culture biocathodes had complex bacterial biofilms variable in size and shape as observed by confocal and electron microscopy. Sequence analysis of ribosomal 16S rDNA revealed a putative correlation between the abundance of certain microbiota and biocathode performance. The best performing biocathode developed on the unmodified graphite electrode and reached a high current density for oxygen reducing biocathodes at neutral pH (0.9 A/m(2)). This correlated with the highest domination (60.7%) of a monophyletic group of unclassified γ-Proteobacteria. These results corroborate earlier reports by other groups, however, higher current densities and higher presence of these unclassified bacteria were observed in this work. Therefore, members of this group are likely key-players for highly performing oxygen reducing biocathodes.

  12. Type II pneumocytes in mixed cell culture of human lung: a light and electron microscopic study.

    PubMed Central

    Bingle, L; Bull, T B; Fox, B; Guz, A; Richards, R J; Tetley, T D

    1990-01-01

    Alveolar Type II epithelial cells dedifferentiate rapidly in vitro. Studies with animal tissue suggest that cell-cell and extracellular matrix-cell interactions are important in the retention of Type II cell morphology in vitro. Thus, in this study with human tissue, alveolar Type II cells, alveolar macrophages, and spindle cells were prepared from the same sample of lung (obtained following lobectomy for cancer, n = 3), cocultured on glass cover slips or tissue culture plastic, and studied by light microscopy with scanning (SEM) and transmission (TEM) electron microscopy for 8 days. The primary cell isolates contained approximately 45% Type II cells; the remainder were macrophages or unidentifiable cells. Clusters, made up of a single layer of cuboidal Type II cells around a central core of connective tissue (largely collagen and some elastic tissue), formed above a monolayer of spindle cells. The Type II cells were morphologically similar to those seen in vivo. The cells were still cuboidal at 8 days but had lost their lamellar bodies, which were released into the medium via the apical surface. The clusters increased in size with time (area, microns 2: day 1, 29(5-143) x 10(2); day 8, 63(10-311) x 10(2); mean(range); p less than 0.02) without changing in number per culture, suggesting Type II cell proliferation. This may have been due to factors produced by the other cells and adherence to the extracellular matrix (ECM); (free collagen fibers, present in the original preparation, spindle cells, and/or Type II cells could be responsible for presence of ECM). We propose this as a useful model for the study of human Type II epithelial cells in vitro. Images FIGURE 1. a FIGURE 1. b FIGURE 1. c FIGURE 1. d FIGURE 1. e FIGURE 1. f FIGURE 2. a FIGURE 2. b FIGURE 2. c FIGURE 2. d FIGURE 2. e FIGURE 2. f FIGURE 2. g FIGURE 3. PMID:2384069

  13. Effective remediation of fish processing waste using mixed culture biofilms capable of simultaneous nitrification and denitrification.

    PubMed

    Markande, Anoop R; Kapagunta, Chandrika; Patil, Pooja S; Nayak, Binaya B

    2016-09-01

    Fish processing waste water causes pollution and eutrophication of water bodies when released untreated. Use of bacteria capable of simultaneous nitrification and denitrification (SND) as biofilms on carriers in a moving bed bioreactor (MBBR) is a popular approach but seldom used for fish processing waste water remediation. Here, we studied the variations in biofilm formation and application activities by isolates Lysinibacillus sp. HT13, Alcaligenes sp. HT15 and Proteus sp. HT37 previously reported by us. While HT13 and HT15 formed significantly higher biofilms in polystyrene microtitre plates than on carriers, HT37 exhibited highest on carriers. A consortium of the three selected bacteria grown as biofilm on MBBR carriers exhibited better remediation of ammonia (200-600 ppm and 50 mM) than the individual isolates on carriers. The mixed biofilm set on the carriers was used for nitrogenous waste removal from fish processing waste water in 2 and 20 L setups. The total nitrogen estimated by elemental analysis showed complete remediation from 250 ppm in both 2 and 20 L waste water systems within 48 h. The usual toxic nitrogenous components-ammonia, nitrite and nitrate were also remediated efficiently. PMID:27213464

  14. Simultaneous production and separation of biohydrogen in mixed culture systems by continuous dark fermentation.

    PubMed

    Ramírez-Morales, Juan E; Tapia-Venegas, Estela; Toledo-Alarcón, Javiera; Ruiz-Filippi, Gonzalo

    2015-01-01

    Hydrogen production by dark fermentation is one promising technology. However, there are challenges in improving the performance and efficiency of the process. The important factors that must be considered to obtain a suitable process are the source of the inoculum and its pre-treatment, types of substrates, the reactor configurations and the hydrogen partial pressure. Furthermore, to obtain high-quality hydrogen, it is necessary to integrate an effective separation procedure that is compatible with the intrinsic characteristics of a biological process. Recent studies have suggested that a stable and robust process could be established if there was an effective selection of a mixed microbial consortium with metabolic pathways directly targeted to high hydrogen yields. Additionally, the integration of membrane technology for the extraction and separation of the hydrogen produced has advantages for the upgrading step, because this technology could play an important role in reducing the negative effect of the hydrogen partial pressure. Using this technology, it has been possible to implement a production-purification system, the 'hydrogen-extractive membrane bioreactor'. This configuration has great potential for direct applications, such as fuel cells, but studies of new membrane materials, module designs and reactor configurations are required to achieve higher separation efficiencies.

  15. Community perspectives: mixed-methods investigation of culture, stress, resilience, and health.

    PubMed

    Abdou, Cleopatra M; Schetter, Christine Dunkel; Jones, Felica; Roubinov, Danielle; Tsai, Sid; Jones, Loretta; Lu, Michael; Hobel, Calvin

    2010-01-01

    Despite well-documented ethnic and socioeconomic disparities, our understanding of child, maternal and family health is based disproportionately on White middle-class populations in the United States. The National Institute of Child Health and Human Development funded the Community Child Health Network (CCHN) in 2004, a partnership of five academic institutions and community organizations, to collaborate in the design and conduct of a study to foster new understandings of these disparities. Reported here are findings from a pilot study conducted at one site to inform CCHN regarding community views of stress, coping resources, family and health. Mixed-methods (qualitative and quantitative) interviews were conducted with 54 adult participants recruited from public healthcare clinics to obtain both their self-reports and their reports of their communities' perspectives. Findings include the pervasiveness of experiences of racism and gender differences in support seeking and coping behavior. There was little recognition of some common health conditions, such as low birth weight and preterm birth, which disproportionately affect poor and minority communities. Many indicators of strength and resilience in individuals, families, and the communities at large emerged in these interviews. Communities were described as valuing achievement and upward mobility. Participants also indicated an intuitive understanding of effective parenting and of the roles of nature (genetics) and nurture (environment and behavior) in determining child health. The results inform intervention and stress research in underrepresented communities.

  16. Microbial reduction and precipitation of vanadium (V) in groundwater by immobilized mixed anaerobic culture.

    PubMed

    Zhang, Baogang; Hao, Liting; Tian, Caixing; Yuan, Songhu; Feng, Chuanping; Ni, Jinren; Borthwick, Alistair G L

    2015-09-01

    Vanadium is an important contaminant impacted by natural and industrial activities. Vanadium (V) reduction efficiency as high as 87.0% was achieved by employing immobilized mixed anaerobic sludge as inoculated seed within 12h operation, while V(IV) was the main reduction product which precipitated instantly. Increasing initial V(V) concentration resulted in the decrease of V(V) removal efficiency, while this index increased first and then decreased with the increase of initial COD concentration, pH and conductivity. High-throughput 16S rRNA gene pyrosequencing analysis indicated the decreased microbial diversity. V(V) reduction was realized through dissimilatory reduction process by significantly enhanced Lactococcus and Enterobacter with oxidation of lactic and acetic acids from fermentative microorganisms such as the enriched Paludibacter and the newly appeared Acetobacterium, Oscillibacter. This study is helpful to detect new functional species for V(V) reduction and constitutes a step ahead in developing in situ bioremediations of vanadium contamination.

  17. Mixed culture biofilms of Salmonella Typhimurium and cultivable indigenous microorganisms on lettuce show enhanced resistance of their sessile cells to cold oxygen plasma.

    PubMed

    Jahid, Iqbal Kabir; Han, Noori; Zhang, Cheng-Yi; Ha, Sang-Do

    2015-04-01

    Control of foodborne pathogens in fresh produce is crucial for food safety, and numerous Salmonella Typhimurium (ST) outbreaks have been reported already. The present study was done to assess effectiveness of cold oxygen plasma (COP) against biofilms of ST mixed with cultivable indigenous microorganisms (CIM). ST and CIM were grown at 15 °C as monocultures and mixed cultures for planktonic state, biofilm on stainless steel, and lettuce leaves. Thereafter, the samples were treated with COP and surviving populations were counted using plate counting methods. Biofilms and stomatal colonization were examined using field emission scanning electron microscopy (FESEM) and food quality was assessed after treatment. Mixed cultures of ST and CIM showed an antagonistic interaction on lettuce but not on SS or in planktonic state. Mixed cultures showed significantly (p < 0.05) greater resistance to COP compared to monoculture biofilms on lettuce but not on SS or planktonic state. Shift from smooth to rugose colony type was found for planktonic and for biofilms on SS but not on lettuce for ST. Mixed culture biofilms colonized stomata on the inside as demonstrated by FESEM. Although, lettuce quality was not affected by COP, this technology has to be optimized for further development of the successful inactivation of complex multispecies biofilm structures presented by real food environment.

  18. Flux balance analysis of mixed microbial cultures: application to the production of polyhydroxyalkanoates from complex mixtures of volatile fatty acids.

    PubMed

    Pardelha, Filipa; Albuquerque, Maria G E; Reis, Maria A M; Dias, João M L; Oliveira, Rui

    2012-12-31

    Fermented agro-industrial wastes are potential low cost substrates for polyhydroxyalkanoates (PHA) production by mixed microbial cultures (MMC). The use of complex substrates has however profound implications in the PHA metabolism. In this paper we investigate PHA accumulation using a lumped metabolic model that describes PHA storage from arbitrary mixtures of volatile fatty acids (VFA). Experiments were conducted using synthetic and complex VFA mixtures obtained from the fermentation of sugar cane molasses. Metabolic flux analysis (MFA) and flux balance analysis (FBA) were performed at different stages of culture enrichment in order to investigate the effect of VFA composition and time of enrichment in PHA storage efficiency. Substrate uptake and PHA storage fluxes increased over enrichment time by 70% and 73%, respectively. MFA calculations show that higher PHA storage fluxes are associated to an increase in the uptake of VFA with even number of carbon atoms and a more effective synthesis of hydroxyvalerate (HV) precursors from VFA with odd number of carbons. Furthermore, FBA shows that the key metabolic objective of a MMC subjected to the feast and famine regimen is the minimization of the tricarboxylic acid cycle fluxes. The PHA flux and biopolymer composition (hydroxybutyrate (HB): HV) could be accurately predicted in several independent experiments.

  19. Critical analysis of hydrogen production from mixed culture fermentation under thermophilic condition (60 °C).

    PubMed

    Zheng, Hang; Zeng, Raymond J; O'Sullivan, Cathryn; Clarke, William P

    2016-06-01

    Bio-hydrogen production from mixed culture fermentation (MCF) of glucose was studied by conducting a comprehensive product measurement and detailed mass balance analysis of their contributions to the final H2 yield. The culture used in this study was enriched on glucose at 60 °C through a sequential batch operation consisting of daily glucose feeds, headspace purging and medium replacement every third day in serum bottles for over 2 years. 2-Bromoethanesulfonate (BES) was only required during the first three 3-day cycles to permanently eliminate methanogenic activity. Daily glucose feeds were fully consumed within 24 h, with a persistent H2 yield of 2.7 ± 0.1 mol H2/mol glucose, even when H2 was allowed to accumulate over the 3-day cycle. The measured H2 production exceeded by 14 % the theoretical production of H2 associated with the fermentation products, dominated by acetate and butyrate. Follow-up experiments using acetate with a (13)C-labelled methyl group showed that the excess H2 production was not due to acetate oxidation. Chemical formula analysis of the biomass showed a more reduced form of C5H11.8O2.1N1.1 suggesting that the biomass formation may even consume produced H2 from fermentation. PMID:27052381

  20. Concomitant biohydrogen and poly-β-hydroxybutyrate production from dark fermentation effluents by adapted Rhodobacter sphaeroides and mixed photofermentative cultures.

    PubMed

    Ghimire, Anish; Valentino, Serena; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-10-01

    This work aimed at investigating concomitant production of biohydrogen and poly-β-hydroxybutyrate (PHB) by photofermentation (PF) using dark fermentation effluents (DFE). An adapted culture of Rhodobacter sphaeroides AV1b (pH 6.5, 24±2°C) achieved H2 and PHB yields of 256 (±2) NmLH2/g Chemical Oxygen Demand (COD) and 273.8mgPHB/gCOD (32.5±3% of the dry cells weight (DCW)), respectively. When a diluted (1:2) DFE medium was applied to the adapted pure and mixed photofermentative culture, the respective H2 yields were 164.0 (±12) and 71.3 (±6) NmLH2/gCOD and the PHB yields were 212.1 (±105.2) and 50.7 (±2.7) mgPHB/gCOD added, corresponding to 24 (±0.7) and 6.3 (±0) % DCW, respectively. The concomitant H2 and PHB production from the PF process gave a good DFE post treatment achieving up to 80% COD removal from the initial DFE.

  1. Direct surfactin-gramicidin S antagonism supports detoxification in mixed producer cultures of Bacillus subtilis and Aneurinibacillus migulanus.

    PubMed

    Rautenbach, Marina; Eyéghé-Bickong, Hans André; Vlok, Nicolas Maré; Stander, Marietjie; de Beer, Abré

    2012-12-01

    Antibiotic production as a defence mechanism is a characteristic of a wide variety of organisms. In natural evolutionary adaptation, cellular events such as sporulation, biofilm formation and resistance to antibiotics enable some micro-organisms to survive environmental and antibiotic stress conditions. The two antimicrobial cyclic peptides in this study, gramicidin S (GS) from Aneurinibacillus migulanus and the lipopeptide surfactin (Srf) from Bacillus subtilis, have been shown to affect both membrane and intercellular components of target organisms. Many functions, other than that of antimicrobial activity, have been assigned to Srf. We present evidence that an additional function may exist for Srf, namely that of a detoxifying agent that protects its producer from the lytic activity of GS. We observed that Srf producers were more resistant to GS and could be co-cultured with the GS producer. Furthermore, exogenous Srf antagonized the activity of GS against both Srf-producing and non-producing bacterial strains. A molecular interaction between the anionic Srf and the cationic GS was observed with circular dichroism and electrospray MS. Our results indicate that the formation of an inactive complex between GS and Srf supports resistance towards GS, with the anionic Srf forming a chemical barrier to protect its producer. This direct detoxification combined with the induction of protective stress responses in B. subtilis by Srf confers resistance toward GS from A. migulanus and allows survival in mixed cultures.

  2. Development of bioelectrocatalytic activity stimulates mixed-culture reduction of glycerol in a bioelectrochemical system

    PubMed Central

    Zhou, Mi; Freguia, Stefano; Dennis, Paul G; Keller, Jürg; Rabaey, Korneel

    2015-01-01

    In a microbial bioelectrochemical system (BES), organic substrate such as glycerol can be reductively converted to 1,3-propanediol (1,3-PDO) by a mixed population biofilm growing on the cathode. Here, we show that 1,3-PDO yields positively correlated to the electrons supplied, increasing from 0.27 ± 0.13 to 0.57 ± 0.09 mol PDO mol−1 glycerol when the cathodic current switched from 1 A m−2 to 10 A m−2. Electrochemical measurements with linear sweep voltammetry (LSV) demonstrated that the biofilm was bioelectrocatalytically active and that the cathodic current was greatly enhanced only in the presence of both biofilm and glycerol, with an onset potential of −0.46 V. This indicates that glycerol or its degradation products effectively served as cathodic electron acceptor. During long-term operation (> 150 days), however, the yield decreased gradually to 0.13 ± 0.02 mol PDO mol−1 glycerol, and the current–product correlation disappeared. The onset potentials for cathodic current decreased to −0.58 V in the LSV tests at this stage, irrespective of the presence or absence of glycerol, with electrons from the cathode almost exclusively used for hydrogen evolution (accounted for 99.9% and 89.5% of the electrons transferred at glycerol and glycerol-free conditions respectively). Community analysis evidenced a decreasing relative abundance of Citrobacter in the biofilm, indicating a community succession leading to cathode independent processes relative to the glycerol. It is thus shown here that in processes where substrate conversion can occur independently of the electrode, electroactive microorganisms can be outcompeted and effectively disconnected from the substrate. PMID:25817314

  3. Essential oils have different effects on human pathogenic and commensal bacteria in mixed faecal fermentations compared with pure cultures.

    PubMed

    Thapa, Dinesh; Louis, Petra; Losa, Riccardo; Zweifel, Béatrice; Wallace, R John

    2015-02-01

    A static batch culture system inoculated with human faeces was used to determine the influence of essential oil compounds (EOCs) on mixed faecal microbiota. Bacteria were quantified using quantitative PCR of 16S rRNA genes. Incubation for 24 h of diluted faeces from six individuals caused enrichment of Bifidobacterium spp., but proportions of other major groups were unaffected. Thymol and geraniol at 500 p.p.m. suppressed total bacteria, resulting in minimal fermentation. Thymol at 100 p.p.m. had no effect, nor did eugenol or nerolidol at 100 or 500 p.p.m. except for a slight suppression of Eubacterium hallii. Methyl isoeugenol at 100 or 500 p.p.m. suppressed the growth of total bacteria, accompanied by a large fall in the molar proportion of propionate formed. The relative abundance of Faecalibacterium prausnitzii was unaffected except with thymol at 500 p.p.m. The ability of EOCs to control numbers of the pathogen Clostridium difficile was investigated in a separate experiment, in which the faecal suspensions were amended by the addition of pure culture of C. difficile. Numbers of C. difficile were suppressed by thymol and methyl isoeugenol at 500 p.p.m. and to a lesser extent at 100 p.p.m. Eugenol and geraniol gave rather similar suppression of C. difficile numbers at both 100 and 500 p.p.m. Nerolidol had no significant effect. It was concluded from these and previous pure-culture experiments that thymol and geraniol at around 100 p.p.m. could be effective in suppressing pathogens in the small intestine, with no concern for beneficial commensal colonic bacteria in the distal gut. PMID:25500493

  4. Essential oils have different effects on human pathogenic and commensal bacteria in mixed faecal fermentations compared with pure cultures.

    PubMed

    Thapa, Dinesh; Louis, Petra; Losa, Riccardo; Zweifel, Béatrice; Wallace, R John

    2015-02-01

    A static batch culture system inoculated with human faeces was used to determine the influence of essential oil compounds (EOCs) on mixed faecal microbiota. Bacteria were quantified using quantitative PCR of 16S rRNA genes. Incubation for 24 h of diluted faeces from six individuals caused enrichment of Bifidobacterium spp., but proportions of other major groups were unaffected. Thymol and geraniol at 500 p.p.m. suppressed total bacteria, resulting in minimal fermentation. Thymol at 100 p.p.m. had no effect, nor did eugenol or nerolidol at 100 or 500 p.p.m. except for a slight suppression of Eubacterium hallii. Methyl isoeugenol at 100 or 500 p.p.m. suppressed the growth of total bacteria, accompanied by a large fall in the molar proportion of propionate formed. The relative abundance of Faecalibacterium prausnitzii was unaffected except with thymol at 500 p.p.m. The ability of EOCs to control numbers of the pathogen Clostridium difficile was investigated in a separate experiment, in which the faecal suspensions were amended by the addition of pure culture of C. difficile. Numbers of C. difficile were suppressed by thymol and methyl isoeugenol at 500 p.p.m. and to a lesser extent at 100 p.p.m. Eugenol and geraniol gave rather similar suppression of C. difficile numbers at both 100 and 500 p.p.m. Nerolidol had no significant effect. It was concluded from these and previous pure-culture experiments that thymol and geraniol at around 100 p.p.m. could be effective in suppressing pathogens in the small intestine, with no concern for beneficial commensal colonic bacteria in the distal gut.

  5. Shear and mixing effects on cells in agitated microcarrier tissue culture reactors

    NASA Technical Reports Server (NTRS)

    Cherry, Robert S.; Papoutsakis, E. Terry

    1987-01-01

    Tissue cells are known to be sensitive to mechanical stresses imposed on them by agitation in bioreactors. The amount of agitation provided in a microcarrier or suspension bioreactor should be only enough to provide effective homogeneity. Three distinct flow regions can be identified in the reactor: bulk turbulent flow, bulk laminar flow and boundary-layer flows. Possible mechanisms of cell damage are examined by analyzing the motion of microcarriers or free cells relative to the surrounding fluid, to each other and to moving or stationary solid surfaces. The primary mechanisms of cell damage appear to result from: (1) direct interaction between microcarriers and turbulent eddies; (2) collisions between microcarriers in turbulent flow; and (3) collisions against the impeller or other stationary surfaces. If the smallest eddies of turbulent flow are of the same size as the microcarrier beads, they may cause high shear stresses on the cells. Eddies the size of the average interbead spacing may cause bead-bead collisions which damage cells. The severity of the collisions increases when the eddies are also of the same size as the beads. Impeller collisions occur when beads cannot avoid the impeller leading edge as it advances through the liquid. The implications of the results of this analysis on the design and operation of tissue culture reactors are discussed.

  6. Cultural responses to pain in UK children of primary school age: a mixed-methods study.

    PubMed

    Azize, Pary M; Endacott, Ruth; Cattani, Allegra; Humphreys, Ann

    2014-06-01

    Pain-measurement tools are often criticized for not addressing the influence of culture and ethnicity on pain. This study examined how children who speak English as a primary or additional language discuss pain. Two methods were used in six focus group interviews with 34 children aged 4-7 years: (i) use of drawings from the Pediatric Pain Inventory to capture the language used by children to describe pain; and (ii) observation of the children's placing of pain drawings on red/amber/green paper to denote perceived severity of pain. The findings demonstrated that children with English as an additional language used less elaborate language when talking about pain, but tended to talk about the pictures prior to deciding where they should be placed. For these children, there was a positive significant relationship between language, age, and length of stay in the UK. The children's placement of pain drawings varied according to language background, sex, and age. The findings emphasize the need for sufficient time to assess pain adequately in children who do not speak English as a first language.

  7. Teachers' and School Counselors' Perceptions of Their Cultural Competence in Working with Newly Arrived Latino Immigrant Students: A Mixed Methods Research Study

    ERIC Educational Resources Information Center

    Guardiola Castillo, Irma V.

    2014-01-01

    The purpose of this study was to explore teachers' and school counselors' perceptions of their cultural competence in working with newly arrived Latino immigrant students by using a mixed instrument with closed-ended and open-ended items. Multicultural Counseling Competencies (MCC) served as the theoretical framework for this study (Sue,…

  8. Striving and Thriving in a Foreign Culture: A Mixed Method Approach on Adult International Students' Experience in U.S.A.

    ERIC Educational Resources Information Center

    Chen, Dianbing; Yang, Xinxiao

    2014-01-01

    In this mixed method study, we examined the experience of a sample of international students in four American universities to identify the factors that might enhance their ability in surviving and thriving in a foreign country within the context of university internationalization. The research explored the concepts of cultural values, behaviors,…

  9. Comparative evaluation of fermentative hydrogen production using Enterobacter cloacae and mixed culture: effect of Pd (II) ion and phytogenic palladium nanoparticles.

    PubMed

    Mohanraj, Sundaresan; Anbalagan, Krishnasamy; Kodhaiyolii, Shanmugam; Pugalenthi, Velan

    2014-12-20

    Palladium nanoparticles (PdNPs) were synthesized from PdCl2 using Coriandrum sativum leaf extract. The transmission electron microscopy (TEM) images confirm that the formation of PdNPs was mainly spherical in shape, with an average size of 87 nm. The influence of the PdCl2 and synthesized PdNPs on fermentative hydrogen production from glucose using Enterobacter cloacae and mixed culture was evaluated. In PdCl2 supplemented experiments, the hydrogen yields of E. cloacae and mixed culture were 1.39 ± 0.07 and 2.11 ± 0.11 mol H2/mol glucose, respectively, with 5.0 mg/L of PdCl2. The resulting hydrogen yield (P < 0.05) was lower than that of the control experiment (without supplementation), due to the soluble metabolites shift. However, the highest hydrogen yields of E. cloacae and mixed culture were 1.48 ± 0.04 and 2.48 ± 0.09 mol H2/mol glucose, respectively at 5.0 mg/L of PdNPs supplementation. The enhancement of biohydrogen production using mixed culture was significantly higher than that of E. cloacae as the same concentration of PdNPs. PMID:25456058

  10. Effect of supplementing orchardgrass herbage with a total mixed ration or flaxseed fermentation profile and bacterial protein synthesis in continuous culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A 4-unit dual-flow continuous culture fermentor system was used to evaluate the effects of herbage, a total mixed ration (TMR) and flaxseed on nutrient digestibility and microbial N synthesis. Treatments were randomly assigned to fermentors in a 4 x 4 Latin square design. Each fermentor was fed a to...

  11. Biodegradation of Low-Density Polyethylene (LDPE) by Mixed Culture of Lysinibacillus xylanilyticus and Aspergillus niger in Soil

    PubMed Central

    Esmaeili, Atefeh; Pourbabaee, Ahmad Ali; Alikhani, Hossein Ali; Shabani, Farzin; Esmaeili, Ensieh

    2013-01-01

    In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source. PMID:24086254

  12. Biodegradation of low-density polyethylene (LDPE) by mixed culture of Lysinibacillus xylanilyticus and Aspergillus niger in soil.

    PubMed

    Esmaeili, Atefeh; Pourbabaee, Ahmad Ali; Alikhani, Hossein Ali; Shabani, Farzin; Esmaeili, Ensieh

    2013-01-01

    In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source.

  13. Biohydrogen production in granular up-flow anaerobic sludge blanket (UASB) reactors with mixed cultures under hyper-thermophilic temperature (70 degrees C).

    PubMed

    Kotsopoulos, Thomas A; Zeng, Raymond J; Angelidaki, Irini

    2006-06-01

    Hyper-thermophilic hydrogen production without methane was demonstrated for the first time in granular up-flow anaerobic sludge blanket (UASB) system fed with glucose using mixed cultures. The maximum hydrogen yield in this study was 2.47 +/- 0.15 mol H2/mol glucose. This high yield has never been previously reported in mixed culture systems and it was likely due to more favorable thermodynamic conditions at hyper-thermophilic temperatures. Different start-up strategies (bromoethanosulfonate (BES) addition and flow recycle) were evaluated. BES addition during start-up prevented the establishment of methanogenic cultures in granules. Flow recycle was important to achieve higher hydrogen yield through enriching better hydrogen-producing organisms and reduced the start-up period as well. This study indicated UASB system was a promising system for hydrogen production.

  14. Using carbon dioxide to maintain an elevated oleaginous microalga concentration in mixed-culture photo-bioreactors.

    PubMed

    Giannetto, Michael J; Retotar, Allison; Rismani-Yazdi, Hamid; Peccia, Jordan

    2015-06-01

    Microbial contamination of growth reactors is a major concern for microalgal biofuel production. In this study, the oleaginous, CO2-tolerant microalga Scenedesmus dimorphus was combined with a wastewater-derived microbial community and grown in replicated sequencing batch photobioreactors. The reactors were sparged with either ambient air or 20% v/v CO2. In the initial growth cycles, air and the 20% CO2 reactors were similar in terms of growth and microbial community structure. Beyond the fourth growth cycle, however, the ambient air reactors had larger decreases in cell density and growth rate, and increases in species richness and non-algal microorganisms compared to the 20% CO2 reactors. Both qPCR and rDNA sequence analyses demonstrated a greater loss in S. dimorphus enrichment in the ambient-air reactors compared to the 20% CO2 reactors. These results demonstrate that environmental parameters can be used to delay the adverse impacts of microbial contamination in open, mixed-culture microalgae bioreactors.

  15. Using carbon dioxide to maintain an elevated oleaginous microalga concentration in mixed-culture photo-bioreactors.

    PubMed

    Giannetto, Michael J; Retotar, Allison; Rismani-Yazdi, Hamid; Peccia, Jordan

    2015-06-01

    Microbial contamination of growth reactors is a major concern for microalgal biofuel production. In this study, the oleaginous, CO2-tolerant microalga Scenedesmus dimorphus was combined with a wastewater-derived microbial community and grown in replicated sequencing batch photobioreactors. The reactors were sparged with either ambient air or 20% v/v CO2. In the initial growth cycles, air and the 20% CO2 reactors were similar in terms of growth and microbial community structure. Beyond the fourth growth cycle, however, the ambient air reactors had larger decreases in cell density and growth rate, and increases in species richness and non-algal microorganisms compared to the 20% CO2 reactors. Both qPCR and rDNA sequence analyses demonstrated a greater loss in S. dimorphus enrichment in the ambient-air reactors compared to the 20% CO2 reactors. These results demonstrate that environmental parameters can be used to delay the adverse impacts of microbial contamination in open, mixed-culture microalgae bioreactors. PMID:25768421

  16. Mitigation of soil N2O emission by inoculation with a mixed culture of indigenous Bradyrhizobium diazoefficiens

    PubMed Central

    Akiyama, Hiroko; Hoshino, Yuko Takada; Itakura, Manabu; Shimomura, Yumi; Wang, Yong; Yamamoto, Akinori; Tago, Kanako; Nakajima, Yasuhiro; Minamisawa, Kiwamu; Hayatsu, Masahito

    2016-01-01

    Agricultural soil is the largest source of nitrous oxide (N2O), a greenhouse gas. Soybean is an important leguminous crop worldwide. Soybean hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) in root nodules. In soybean ecosystems, N2O emissions often increase during decomposition of the root nodules. Our previous study showed that N2O reductase can be used to mitigate N2O emission from soybean fields during nodule decomposition by inoculation with nosZ++ strains [mutants with increased N2O reductase (N2OR) activity] of Bradyrhizobium diazoefficiens. Here, we show that N2O emission can be reduced at the field scale by inoculation with a mixed culture of indigenous nosZ+ strains of B. diazoefficiens USDA110 group isolated from Japanese agricultural fields. Our results also suggested that nodule nitrogen is the main source of N2O production during nodule decomposition. Isolating nosZ+ strains from local soybean fields would be more applicable and feasible for many soybean-producing countries than generating mutants. PMID:27633524

  17. Towards Effective and Socio-Culturally Appropriate Sanitation and Hygiene Interventions in the Philippines: A Mixed Method Approach

    PubMed Central

    Pfadenhauer, Lisa Maria; Rehfuess, Eva

    2015-01-01

    Inadequate water, sanitation and hygiene (WASH) represent an important health burden in the Philippines. The non-governmental organisation Fit for School intends to complement its handwashing programme in schools with sanitation interventions. The objectives of this mixed-method study therefore were to describe WASH practices and their impact on childhood diarrhoea in the Philippines, and to examine socio-cultural and environmental factors underlying defecation and anal cleansing practices in Northern Mindanao. We quantified the effect of WASH practices on diarrhoea through logistic regression models, using the Philippine Demographic and Health Survey 2008. When adjusting for non-modifiable factors, susceptibility and socioeconomic factors, WASH factors failed to show a statistically significant effect. Focus group discussions were held with women in urban and rural Northern Mindanao, and findings analysed using thematic analysis. Defecation and anal cleansing behaviours were constrained by the physical environment, particularly the lack of clean, safe, comfortable and private facilities. Individual determinants of behaviour were influenced by habit and motivations such as disgust, with some evidence of planned behaviour. Where available, water was the preferred material for anal cleansing. This study combines nationally-representative quantitative data with local in-depth qualitative insights, constituting critical formative research in the development of effective and appropriate interventions. PMID:25664699

  18. Use of mixed infections to study cell invasion and intracellular proliferation of Salmonella enterica in eukaryotic cell cultures.

    PubMed

    Segura, Ignacio; Casadesús, Josep; Ramos-Morales, Francisco

    2004-01-01

    Epithelial cell lines are widely used as an in vitro model to study cell invasion by Salmonella. In turn, phagocytic cell lines are used to study Salmonella intracellular survival and proliferation. We describe a novel method, derived from the classical mixed infection procedure, to quantify invasion and proliferation defects in Salmonella enterica serovar Typhimurium. A eukaryotic cell culture is infected with two strains (e.g., a mutant and the wild-type). After infection, bacterial cells that remain extracellular are eliminated with gentamicin. At the end of the trial, intracellular bacteria are recovered and plated. Colonies from each strain are then counted for the calculation of a competitive index. Strain discrimination can be achieved either with antibiotic resistance markers or using plasmids encoding color markers (e.g., fluorescent proteins). Because both strains are exposed to the same conditions throughout the process, the procedure decreases the variability between independent trials and allows a direct measurement of the impairment of the mutant in invasion or intracellular proliferation.

  19. Identification of auditory neurons by retrograde labelling for patch-clamp recordings in a mixed culture of chick brainstem.

    PubMed

    Wirth, Marcus J; Kuenzel, Thomas; Luksch, Harald; Wagner, Hermann

    2008-03-30

    We present a method to identify specific sub-populations of auditory neurons in a mixed primary cell culture of the chicken brainstem, allowing the study of individual neurons with a known identity in vitro. To label specific afferent cell types, we injected retrograde tracers (dextrans coupled to fluorescent dyes) into either the mid-line or the superior olivary nuclei (SON) of the isolated chicken brainstem in vitro. Mid-line injections resulted in stable labelling of neurons of the nucleus magnocellularis (NM), whereas injections into the SON retrogradely labelled neurons of the nucleus laminaris (NL). The fluorescent label survives the dissociation procedure and is detectable for at least 1 week in vitro. Only about 0.1% of all cells in vitro are pre-labelled. The auditory identity of the pre-labelled neurons was confirmed with calretinin immunocytochemistry and electrophysiological recordings, where the cells had typical firing patterns of auditory brainstem neurons. In the future, this method can be combined with single cell PCR to match nuclear origin, firing patterns and the expression of functional molecules in vitro.

  20. Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: Sudan Black B versus Nile Blue A staining.

    PubMed

    Mesquita, Daniela P; Amaral, A Luís; Leal, Cristiano; Oehmen, Adrian; Reis, Maria A M; Ferreira, Eugénio C

    2015-03-20

    Polyhydroxyalkanoates (PHA) can be produced and intracellularly accumulated as inclusions by mixed microbial cultures (MMC) for bioplastic production and in enhanced biological phosphorus removal (EBPR) systems. Classical methods for PHA quantification use a digestion step prior to chromatography analysis, rendering them labor intensive and time-consuming. The present work investigates the use of two quantitative image analysis (QIA) procedures specifically developed for PHA inclusions identification and quantification. MMC obtained from an EBPR system were visualized by bright-field and fluorescence microscopy for PHA inclusions detection, upon Sudan Black B (SBB) and Nile Blue A (NBA) staining, respectively. The captured color images were processed by QIA techniques and the image analysis data were further treated using multivariate statistical analysis. Partial least squares (PLS) regression coefficients of 0.90 and 0.86 were obtained between QIA parameters and PHA concentrations using SBB and NBA, respectively. It was found that both staining procedures might be seen as alternative methodologies to classical PHA determination.

  1. Towards effective and socio-culturally appropriate sanitation and hygiene interventions in the Philippines: a mixed method approach.

    PubMed

    Pfadenhauer, Lisa Maria; Rehfuess, Eva

    2015-02-05

    Inadequate water, sanitation and hygiene (WASH) represent an important health burden in the Philippines. The non-governmental organisation Fit for School intends to complement its handwashing programme in schools with sanitation interventions. The objectives of this mixed-method study therefore were to describe WASH practices and their impact on childhood diarrhoea in the Philippines, and to examine socio-cultural and environmental factors underlying defecation and anal cleansing practices in Northern Mindanao. We quantified the effect of WASH practices on diarrhoea through logistic regression models, using the Philippine Demographic and Health Survey 2008. When adjusting for non-modifiable factors, susceptibility and socioeconomic factors, WASH factors failed to show a statistically significant effect. Focus group discussions were held with women in urban and rural Northern Mindanao, and findings analysed using thematic analysis. Defecation and anal cleansing behaviours were constrained by the physical environment, particularly the lack of clean, safe, comfortable and private facilities. Individual determinants of behaviour were influenced by habit and motivations such as disgust, with some evidence of planned behaviour. Where available, water was the preferred material for anal cleansing. This study combines nationally-representative quantitative data with local in-depth qualitative insights, constituting critical formative research in the development of effective and appropriate interventions.

  2. Mitigation of soil N2O emission by inoculation with a mixed culture of indigenous Bradyrhizobium diazoefficiens.

    PubMed

    Akiyama, Hiroko; Hoshino, Yuko Takada; Itakura, Manabu; Shimomura, Yumi; Wang, Yong; Yamamoto, Akinori; Tago, Kanako; Nakajima, Yasuhiro; Minamisawa, Kiwamu; Hayatsu, Masahito

    2016-01-01

    Agricultural soil is the largest source of nitrous oxide (N2O), a greenhouse gas. Soybean is an important leguminous crop worldwide. Soybean hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) in root nodules. In soybean ecosystems, N2O emissions often increase during decomposition of the root nodules. Our previous study showed that N2O reductase can be used to mitigate N2O emission from soybean fields during nodule decomposition by inoculation with nosZ++ strains [mutants with increased N2O reductase (N2OR) activity] of Bradyrhizobium diazoefficiens. Here, we show that N2O emission can be reduced at the field scale by inoculation with a mixed culture of indigenous nosZ+ strains of B. diazoefficiens USDA110 group isolated from Japanese agricultural fields. Our results also suggested that nodule nitrogen is the main source of N2O production during nodule decomposition. Isolating nosZ+ strains from local soybean fields would be more applicable and feasible for many soybean-producing countries than generating mutants. PMID:27633524

  3. The chemostat study of metabolic distribution in extreme-thermophilic (70°C) mixed culture fermentation.

    PubMed

    Zhang, Fang; Chen, Yun; Dai, Kun; Zeng, Raymond J

    2014-12-01

    The effects of pH, hydrogen partial pressure (PH2), and influent glucose concentration on the metabolic distribution in chemostat were investigated in this work in extreme-thermophilic mixed culture fermentation (MCF) process. The results showed that acetate, ethanol, and hydrogen were the main metabolites. A shift of ethanol to acetate and hydrogen was observed as pH increasing from 4.0 to 7.0 or PH2 decreasing from 0.64 to 0.05 atm. The maximum hydrogen yield was 3.16 ± 0.16 mol/mol glucose at PH2 0.05 atm. Lactate was only accumulated at low pH or high influent glucose concentration, while others such as butyrate and formate were rather low. Thermodynamic analysis illustrated that a mixture of acetate, ethanol, and/or lactate was essential for hydrogen production in extreme-thermophilic MCF. The hydrogen-producing rate was also calculated, and the maximum value was 2.2 ± 0.1 L/(L-reactor/day) at PH2 0.05 atm. Except hydrogen, other metabolites, such as liquid fatty acids and biofuels, could also be the producing targets in extreme-thermophilic MCF.

  4. A modified metabolic model for mixed culture fermentation with energy conserving electron bifurcation reaction and metabolite transport energy.

    PubMed

    Zhang, Fang; Zhang, Yan; Chen, Man; van Loosdrecht, Mark C M; Zeng, Raymond J

    2013-07-01

    A modified metabolic model for mixed culture fermentation (MCF) is proposed with the consideration of an energy conserving electron bifurcation reaction and the transport energy of metabolites. The production of H2 related to NADH/NAD(+) and Fdred/Fdox is proposed to be divided in three processes in view of energy conserving electron bifurcation reaction. This assumption could fine-tune the intracellular redox balance and regulate the distribution of metabolites. With respect to metabolite transport energy, the proton motive force is considered to be constant, while the transport rate coefficient is proposed to be proportional to the octanol-water partition coefficient. The modeling results for a glucose fermentation in a continuous stirred tank reactor show that the metabolite distribution is consistent with the literature: (1) acetate, butyrate, and ethanol are main products at acidic pH, while the production shifts to acetate and propionate at neutral and alkali pH; (2) the main products acetate, ethanol, and butyrate shift to ethanol at higher glucose concentration; (3) the changes for acetate and butyrate are following an increasing hydrogen partial pressure. The findings demonstrate that our modified model is more realistic than previous proposed model concepts. It also indicates that inclusion of an energy conserving electron bifurcation reaction and metabolite transport energy for MCF is sound in the viewpoint of biochemistry and physiology.

  5. Biodegradation kinetics and interactions of styrene and ethylbenzene as single and dual substrates for a mixed bacterial culture.

    PubMed

    Hazrati, Hossein; Shayegan, Jalal; Seyedi, Seyed Mojtaba

    2015-01-01

    This study examined biodegradation kinetics of styrene and ethylbenzene as representatives of alkenylbenzenes and mono-alkylbenzenes, respectively. The compounds were studied independently and as binary mixtures using a series of aerobic batch degradation experiments introduced by acclimatized mix culture. Initial concentration of styrene and ethylbenzene in the liquid phase vacillated from 0 to 220 mg/l. The Andrew model was applied for the biodegradation of individual substrates and the estimated constants of the equation for styrene and ethylbenzene were μmax = 0.1581, 0.2090 (1/h), KS =25.91, 37.77 (mg/L), KI =13.15, 62.62 (mg/L), respectively. The accomplished parameters from single substrate degradation tests were used to predict possible interaction factors achieved from dual substrate experiments. The Sum Kinetics with Interaction Parameters (SKIP) model and the purely competitive enzyme kinetics model were employed to evaluate any interactions. The SKIP model was found to accurately describe these interactions. Moreover, it was revealed that ethylbenzene plays an influential role on styrene consumption (e.g. IE,S = 1.64) compared to styrene which has insignificant inhibitory effect on ethylbenzene usage (e.g. IS,E =0.4) . The active site differences for styrene and ethylbenzene biodegradation and the pathway variations for biodegradation are among the major potential reasons for failure of the estimation that occurred in purely competitive kinetics model. This study is the first to calculate the interactions between styrene and ethylbenzene.

  6. Segregated flux balance analysis constrained by population structure/function data: the case of PHA production by mixed microbial cultures.

    PubMed

    Pardelha, F; Albuquerque, M G E; Carvalho, G; Reis, M A M; Dias, J M L; Oliveira, R

    2013-08-01

    In this study we developed a segregated flux balance analysis (FBA) method to calculate metabolic flux distributions of the individual populations present in a mixed microbial culture (MMC). Population specific flux data constraints were derived from the raw data typically obtained by the fluorescence in situ hybridization (FISH) and microautoradiography (MAR)-FISH techniques. This method was applied to study the metabolic heterogeneity of a MMC that produces polyhydroxyalkanoates (PHA) from fermented sugar cane molasses. Three populations were identified by FISH, namely Paracoccus sp., Thauera sp., and Azoarcus sp. The segregated FBA method predicts a flux distribution for each of the identified populations. The method is shown to predict with high accuracy the average PHA storage flux and the respective monomeric composition for 16 independent experiments. Moreover, flux predictions by segregated FBA were slightly better than those obtained by nonsegregated FBA, and also highly concordant with metabolic flux analysis (MFA) estimated fluxes. The segregated FBA method can be of high value to assess metabolic heterogeneity in MMC systems and to derive more efficient eco-engineering strategies. For the case of PHA-producing MMC considered in this work, it becomes apparent that the PHA average monomeric composition might be controlled not only by the volatile fatty acids (VFA) feeding profile but also by the population composition present in the MMC. PMID:23475571

  7. Hydrothermal liquefaction of mixed-culture algal biomass from wastewater treatment system into bio-crude oil.

    PubMed

    Chen, Wan-Ting; Zhang, Yuanhui; Zhang, Jixiang; Yu, Guo; Schideman, Lance C; Zhang, Peng; Minarick, Mitchell

    2014-01-01

    In this study, a mixed-culture algal biomass harvested from a functioning wastewater treatment system (AW) was hydrothermally converted into bio-crude oils. The highest bio-crude oil yield (49% of volatile matter) and the highest energy recovery were obtained at 300 °C with 1 h retention time. The highest heating value of the bio-crude oil was 33.3 MJ/kg, produced at 320 °C and 1h retention time. Thermogravimetric analysis showed approximately 60% of the bio-crude oils were distilled in the range of 200-550 °C; and the solid residue might be suitable for use in asphalt. GC-MS results indicated that the bio-crude oil contained hydrocarbons and fatty acids, while the aqueous product was rich in organic acids and cyclic amines. The nitrogen recovery (NR) in the bio-crude oil ranged from 8.41% to 16.8%, which was lower than the typical range of 25%-53% from previous studies. PMID:24287452

  8. Extended mixed-culture biofilms (MCB) model to describe integrated fixed film/activated sludge (IFAS) process behaviour.

    PubMed

    Albizuri, J; van Loosdrecht, M C M; Larrea, L

    2009-01-01

    This paper presents how, in a calibration process, different assumptions regarding the standard Mixed-Culture Biofilms (MCB) model were able to match the average results at a continuous Johannesburg pilot plant (comprising two aerobic reactors, AE1 and AE2), but failed to match the batch test results of either the rate of endogenous carbonaceous oxygen uptake (OUR) or the rate of nitrate production (NPR). Under the first assumption, where attachment and diffusion of particulate components were not used, the OUR in the biofilm of the first aerobic reactor (AE1) was too low due to the absence of slowly biodegradable COD (X(S)) attachment flux. In a second assumption, where high diffusion and attachment coefficients were used, the NPR in the biofilm of the AE1 reactor exceeded the experimental value due to the high attachment flux used for nitrifiers (X(A)) and the low competition for space from X(S) and heterotrophic bacteria (X(H)). The only way to match all the experimental results was through the use of a higher attachment coefficient for X(S) in the first reactor (AE1), but this was considered unreasonable. Hence, an extended model was developed where a colloidal state, which interacts at the same time with the flocs and the biofilm through attachment-detachment processes, is distinguished. This model allowed the experimental results to be matched, but using the same value for the attachment coefficients of all particulate components. PMID:19955648

  9. Polyhydroxyalkanoate granules quantification in mixed microbial cultures using image analysis: Sudan Black B versus Nile Blue A staining.

    PubMed

    Mesquita, Daniela P; Amaral, A Luís; Leal, Cristiano; Oehmen, Adrian; Reis, Maria A M; Ferreira, Eugénio C

    2015-03-20

    Polyhydroxyalkanoates (PHA) can be produced and intracellularly accumulated as inclusions by mixed microbial cultures (MMC) for bioplastic production and in enhanced biological phosphorus removal (EBPR) systems. Classical methods for PHA quantification use a digestion step prior to chromatography analysis, rendering them labor intensive and time-consuming. The present work investigates the use of two quantitative image analysis (QIA) procedures specifically developed for PHA inclusions identification and quantification. MMC obtained from an EBPR system were visualized by bright-field and fluorescence microscopy for PHA inclusions detection, upon Sudan Black B (SBB) and Nile Blue A (NBA) staining, respectively. The captured color images were processed by QIA techniques and the image analysis data were further treated using multivariate statistical analysis. Partial least squares (PLS) regression coefficients of 0.90 and 0.86 were obtained between QIA parameters and PHA concentrations using SBB and NBA, respectively. It was found that both staining procedures might be seen as alternative methodologies to classical PHA determination. PMID:25732579

  10. Mixed culture of oleaginous yeast Rhodotorula glutinis and microalga Chlorella vulgaris for lipid production from industrial wastes and its use as biodiesel feedstock.

    PubMed

    Cheirsilp, Benjamas; Suwannarat, Warangkana; Niyomdecha, Rujira

    2011-07-01

    A mixed culture of oleaginous yeast Rhodotorula glutinis and microalga Chlorella vulgaris was performed to enhance lipid production from industrial wastes. These included effluent from seafood processing plant and molasses from sugar cane plant. In the mixed culture, the yeast grew faster and the lipid production was higher than that in the pure cultures. This could be because microalga acted as an oxygen generator for yeast, while yeast provided CO(2) to microalga and both carried out the production of lipids. The optimal conditions for lipid production by the mixed culture were as follows: ratio of yeast to microalga at 1:1; initial pH at 5.0; molasses concentration at 1%; shaking speed at 200 rpm; and light intensity at 5.0 klux under 16:8 hours light and dark cycles. Under these conditions, the highest biomass of 4.63±0.15 g/L and lipid production of 2.88±0.16 g/L were obtained after five days of cultivation. In addition, the plant oil-like fatty acid composition of yeast and microalgal lipids suggested their high potential for use as biodiesel feedstock.

  11. Potential of Kalopanax septemlobus leaf extract in synthesis of silver nanoparticles for selective inhibition of specific bacterial strain in mixed culture.

    PubMed

    Salunke, Bipinchandra K; Sawant, Shailesh S; Kim, Beom Soo

    2014-09-01

    Silver nanoparticles (AgNPs) were synthesised using Kalopanax septemlobus plant leaf extracts. UV-visible spectrophotometric, Fourier-transform infrared, electron dispersive X-ray spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses confirmed synthesis of AgNPs. TEM micrographs revealed presence of well-dispersed AgNPs predominantly of small size and different shapes with an average particle size of 30.8 nm. Antimicrobial susceptibility tests of AgNP treatments revealed variability in sensitivity of bacteria Bacillus cereus and Saccharophagus degradans under study. Minimum inhibitory concentration (MIC) values of the AgNPs for B. cereus and S. degradans were found to be 30 and 10 μg/mL, respectively. The mixed culture of B. cereus and S. degradans treated with AgNPs at 10 μg/mL showed increase in growth with time, suggesting survival of bacteria in liquid media. The plating of mixed culture before AgNP treatment showed presence of both bacteria, but 24-h-old mixed culture treated with AgNPs at the concentration of 10 μg/mL showed presence of B. cereus colonies. SEM micrographs revealed damage to S. degradans cells but no effect on B. cereus cells after AgNP treatment. Confocal microscopic observations of AgNP-treated mixed cultures by Nile blue A staining indicated intact polyhydroxyalkanoates producing flourescent cells of B. cereus but damage and deformities in S. degradans cells. This study suggests that AgNPs can selectively inhibit growth of S. degradans and retain B. cereus at MIC of S. degradans. This report is a case study for selective inhibition of one bacteria and growth of the other in a culture using plant-synthesized silver nanoparticles. PMID:25085530

  12. Transcriptomic and metabolic responses of Staphylococcus aureus in mixed culture with Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans in milk.

    PubMed

    Zdenkova, Kamila; Alibayov, Babek; Karamonova, Ludmila; Purkrtova, Sabina; Karpiskova, Renata; Demnerova, Katerina

    2016-09-01

    Staphylococcus aureus is a major food-borne pathogen due to the production of enterotoxin and is particularly prevalent in contaminated milk and dairy products. The lactic acid bacteria (LAB) are widely used as biocontrol agents in fermented foods which can inhibit pathogenic flora. In our work, we investigated the influence of three strains of LAB (Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans) on the relative expression of three enterotoxin genes (sea, sec, sell) and eight virulence and/or regulatory genes (sarA, saeS, codY, srrA, rot, hld/RNAIII, agrA/RNAII, sigB) in two S. aureus strains (MW2 and Sa1612) in TSB and reduced-fat milk (1.5 %) at 30 °C over a 24-h period. The tested LAB and S. aureus strains proved to be mutually non-competitive or only slightly competitive during co-cultivation. In addition, under the above-mentioned conditions, differential gene expression between the S. aureus MW2 and Sa1612 strains was well documented. S. aureus growth was changed in mixed culture with LAB; however, its effect on the repression of sea and sec expression correlated with production of these virulence factors. In comparison, the presence of LAB strains generally inhibited the expression of sec, sell, sarA, seaS, agrA/RNAII and hld/RNAIII genes. The effect of LAB strains presence on the expression of sea, codY, srrA, rot and sigB genes was medium, time, LAB and S. aureus strain specific. SEA and SEC production was significantly reduced in milk compared to TSB in pure culture. After the 24-h cultivation, S. aureus MW2 and Sa1612 SEC production was 187 and 331 times lower in milk compared to TSB, respectively (0.07 and 0.39 ng/mL in milk, versus 13.1 and 129.2 ng/mL in TSB, respectively). At the same time S. aureus MW2 and Sa1612 SEA production was 77 and 68 times lower in milk compared to TSB, respectively (0.99 and 0.17 ng/mL in milk, versus 76.4 and 11.5 ng/mL in TSB, respectively). This study has revealed new insights into the

  13. Transcriptomic and metabolic responses of Staphylococcus aureus in mixed culture with Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans in milk.

    PubMed

    Zdenkova, Kamila; Alibayov, Babek; Karamonova, Ludmila; Purkrtova, Sabina; Karpiskova, Renata; Demnerova, Katerina

    2016-09-01

    Staphylococcus aureus is a major food-borne pathogen due to the production of enterotoxin and is particularly prevalent in contaminated milk and dairy products. The lactic acid bacteria (LAB) are widely used as biocontrol agents in fermented foods which can inhibit pathogenic flora. In our work, we investigated the influence of three strains of LAB (Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans) on the relative expression of three enterotoxin genes (sea, sec, sell) and eight virulence and/or regulatory genes (sarA, saeS, codY, srrA, rot, hld/RNAIII, agrA/RNAII, sigB) in two S. aureus strains (MW2 and Sa1612) in TSB and reduced-fat milk (1.5 %) at 30 °C over a 24-h period. The tested LAB and S. aureus strains proved to be mutually non-competitive or only slightly competitive during co-cultivation. In addition, under the above-mentioned conditions, differential gene expression between the S. aureus MW2 and Sa1612 strains was well documented. S. aureus growth was changed in mixed culture with LAB; however, its effect on the repression of sea and sec expression correlated with production of these virulence factors. In comparison, the presence of LAB strains generally inhibited the expression of sec, sell, sarA, seaS, agrA/RNAII and hld/RNAIII genes. The effect of LAB strains presence on the expression of sea, codY, srrA, rot and sigB genes was medium, time, LAB and S. aureus strain specific. SEA and SEC production was significantly reduced in milk compared to TSB in pure culture. After the 24-h cultivation, S. aureus MW2 and Sa1612 SEC production was 187 and 331 times lower in milk compared to TSB, respectively (0.07 and 0.39 ng/mL in milk, versus 13.1 and 129.2 ng/mL in TSB, respectively). At the same time S. aureus MW2 and Sa1612 SEA production was 77 and 68 times lower in milk compared to TSB, respectively (0.99 and 0.17 ng/mL in milk, versus 76.4 and 11.5 ng/mL in TSB, respectively). This study has revealed new insights into the

  14. Cultural epidemiology of pandemic influenza in urban and rural Pune, India: a cross-sectional, mixed-methods study

    PubMed Central

    Sundaram, Neisha; Schaetti, Christian; Purohit, Vidula; Kudale, Abhay; Weiss, Mitchell G

    2014-01-01

    Objective To identify and compare sociocultural features of pandemic influenza with reference to illness-related experience, meaning and behaviour in urban and rural areas of India. Design Cross-sectional, mixed-methods, cultural epidemiological survey with vignette-based interviews. Semistructured explanatory model interviews were used to study community ideas of the 2009 influenza pandemic. In-depth interviews elaborated respondents’ experience during the pandemic. Setting Urban and rural communities, Pune district, western India. Participants Survey of urban (n=215) and rural (n=221) residents aged between 18 and 65 years. In-depth interviews of respondents with a history of 2009 pandemic influenza (n=6). Results More urban (36.7%) than rural respondents (16.3%, p<0.001) identified the illness in the vignette as ‘swine flu’. Over half (56.7%) believed the illness would be fatal without treatment, but with treatment 96% predicted full recovery. Worry (‘tension’) about the illness was reported as more troubling than somatic symptoms. The most common perceived causes—‘exposure to a dirty environment’ and ‘cough or sneeze of an infected person’–were more prominent in the urban group. Among rural respondents, climatic conditions, drinking contaminated water, tension and cultural ideas on humoral imbalance from heat-producing or cold-producing foods were more prominent. The most widely reported home treatment was herbal remedies; more rural respondents suggested reliance on prayer, and symptom relief was more of a priority for urban respondents. Government health services were preferred in the urban communities, and rural residents relied more than urban residents on private facilities. The important preventive measures emphasised were cleanliness, wholesome lifestyle and vaccines, and more urban respondents reported the use of masks. In-depth interviews indicated treatment delays during the 2009 pandemic, especially among rural patients

  15. Synthesis of short-/medium-chain-length poly(hydroxyalkanoate) blends by mixed culture fermentation of glycerol.

    PubMed

    Ashby, Richard D; Solaiman, Daniel K Y; Foglia, Thomas A

    2005-01-01

    Glycerol was used as a substrate in the bio-production of poly(hydroxyalkanoates) (PHAs) in an effort to establish an alternative outlet for glycerol and produce value-added products. Pseudomonas oleovorans NRRL B-14682 and Pseudomonas corrugata 388 grew and synthesized poly(3-hydroxybutyrate) (P3HB) and medium-chain-length PHA (mcl-PHA) consisting primarily of 3-hydroxydecanoic acid (C(10:0); 44 +/- 2 mol %) and 3-hydroxydodecenoic acid (C(12:1); 31 +/- 2 mol %), respectively, from glycerol at concentrations up to 5% (v/v). Cellular productivity maximized at 40% for P. oleovorans in 5% (v/v) glycerol and 20% for P. corrugata in 2% (v/v) glycerol after 72 h. Increasing the glycerol media concentration from 1% to 5% (v/v) caused a 61% and 72% reduction in the molar mass (M(n)) of the P3HB and mcl-PHA polymers, respectively. Proton-NMR analysis of the glycerol-derived P3HB revealed that the M(n) decrease was the result of esterification of glycerol onto the polymer in a chain terminating position. However, no evidence of glycerol-based chain termination was present in the mcl-PHA. The growth patterns of P. oleovorans and P. corrugata on glycerol permitted their use as mixed cultures to produce natural blends of P3HB and mcl-PHA. By incorporating a staggered inoculation pattern and varying the duration of the fermentations, P3HB/mcl-PHA ratios were achieved that varied from 34:66 to 96:4. PMID:16004451

  16. Community proteomics provides functional insight into polyhydroxyalkanoate production by a mixed microbial culture cultivated on fermented dairy manure.

    PubMed

    Hanson, Andrea J; Guho, Nicholas M; Paszczynski, Andrzej J; Coats, Erik R

    2016-09-01

    Polyhydroxyalkanoates (PHAs) are bio-based, biodegradable polyesters that can be produced from organic-rich waste streams using mixed microbial cultures (MMCs). To maximize PHA production, MMCs are enriched for bacteria with a high polymer storage capacity through the application of aerobic dynamic feeding (ADF) in a sequencing batch reactor (SBR), which consequently induces a feast-famine metabolic response. Though the feast-famine response is generally understood empirically at a macro-level, the molecular level is less refined. The objective of this study was to investigate the microbial community composition and proteome profile of an enriched MMC cultivated on fermented dairy manure. The enriched MMC exhibited a feast-famine response and was capable of producing up to 40 % (wt. basis) PHA in a fed-batch reactor. High-throughput 16S rRNA gene sequencing revealed a microbial community dominated by Meganema, a known PHA-producing genus not often observed in high abundance in enrichment SBRs. The application of the proteomic methods two-dimensional electrophoresis and LC-MS/MS revealed PHA synthesis, energy generation, and protein synthesis prominently occurring during the feast phase, corroborating bulk solution variable observations and theoretical expectations. During the famine phase, nutrient transport, acyl-CoA metabolism, additional energy generation, and housekeeping functions were more pronounced, informing previously under-determined MMC functionality under famine conditions. During fed-batch PHA production, acetyl-CoA acetyltransferase and PHA granule-bound phasin proteins were in increased abundance relative to the SBR, supporting the higher PHA content observed. Collectively, the results provide unique microbial community structural and functional insight into feast-famine PHA production from waste feedstocks using MMCs. PMID:27147532

  17. Fixed-bed fermentation of rice straw and chicken manure using a mixed culture of marine mesophilic microorganisms.

    PubMed

    Agbogbo, Frank K; Holtzapple, Mark T

    2007-05-01

    A mixture of rice straw (80%) and chicken manure (20%) was pretreated and fermented to carboxylic acids by using a mixed culture of marine mesophilic microorganisms. Two sets of four fermentors, built from PVC pipes, were used for both biomass pretreatment and fermentation. Four 1L fermentors (F1-F4) were arranged in series, where liquid fermentation products were transferred from one fermentor to the other, to form a train. A liquid volume of 10mL and 15mL were transferred every four days for Trains A and B, respectively. The maximum total acid concentration for F1 in Train A was 34.2g/L and the maximum acid concentration in F2-F4 was approximately 44g/L. The maximum total acid concentration in F1 in Train B was 30.5g/L and the maximum acid concentration in F2-F4 was approximately 48g/L. The conversion in each of the fermentors in Train A varied from 0.821 to 0.879g VS digested/g VS fed and the yield was in the range 0.489-0.609g total acids/g VS fed. The conversion and yield in Train B were 0.741-0.914g VS digested/g VS fed and 0.563-0.669g total acids/g VS fed, respectively. The continuum particle distribution model (CPDM) predicted acid concentrations and retention times in the fixed-bed fermentation system with R(2) of 0.67-0.84 in Trains A and B.

  18. Biopolymer Production Kinetics of Mixed Culture Using Wastewater Sludge as a Raw Material and the Effect of Different Cations on Biopolymer Applications in Water and Wastewater Treatment.

    PubMed

    More, T T; Yan, S; Tyagi, R D; Surampalli, R Y

    2016-05-01

    Thirteen extracellular polymeric substances (EPS) producing bacterial strains were cultivated (as mixed culture) in the sterilized sludge (suspended solids of 25 g/L) and the batch fermentation was carried out. Mixed culture revealed a high specific growth rate of 0.35/hr. The EPS production rate was higher up to 24 hours, which gradually decreased with further incubation. The kinetic estimates demonstrated growth-associated EPS production. Broth EPS revealed higher flocculation activity when combined with different cations (Ca(2+), Mg(2+), Fe(3+), and Al(3+)) in river water (≥90%), municipal wastewater (≥90%), and brewery wastewater (≥80%), respectively. A low dose (5 to 40 mg/L) of trivalent cations was required to achieve higher flocculation compared to the divalent cations (50 to 250 mg/L). Flocculation performance of EPS was comparable to Magnafloc-155 (chemical polymer) and, hence, it could be used as a flocculant. PMID:27131306

  19. Biopolymer Production Kinetics of Mixed Culture Using Wastewater Sludge as a Raw Material and the Effect of Different Cations on Biopolymer Applications in Water and Wastewater Treatment.

    PubMed

    More, T T; Yan, S; Tyagi, R D; Surampalli, R Y

    2016-05-01

    Thirteen extracellular polymeric substances (EPS) producing bacterial strains were cultivated (as mixed culture) in the sterilized sludge (suspended solids of 25 g/L) and the batch fermentation was carried out. Mixed culture revealed a high specific growth rate of 0.35/hr. The EPS production rate was higher up to 24 hours, which gradually decreased with further incubation. The kinetic estimates demonstrated growth-associated EPS production. Broth EPS revealed higher flocculation activity when combined with different cations (Ca(2+), Mg(2+), Fe(3+), and Al(3+)) in river water (≥90%), municipal wastewater (≥90%), and brewery wastewater (≥80%), respectively. A low dose (5 to 40 mg/L) of trivalent cations was required to achieve higher flocculation compared to the divalent cations (50 to 250 mg/L). Flocculation performance of EPS was comparable to Magnafloc-155 (chemical polymer) and, hence, it could be used as a flocculant.

  20. Carbon dioxide reduction by mixed and pure cultures in microbial electrosynthesis using an assembly of graphite felt and stainless steel as a cathode.

    PubMed

    Bajracharya, Suman; ter Heijne, Annemiek; Dominguez Benetton, Xochitl; Vanbroekhoven, Karolien; Buisman, Cees J N; Strik, David P B T B; Pant, Deepak

    2015-11-01

    Carbon dioxide (CO2) reduction to multi-carbon compounds at the cathode using chemolithoautotrophs is an emerging application of microbial electrosynthesis (MES). In this study, CO2 reduction in MES was investigated at hydrogen evolving potentials, separately by a mixed culture and Clostridium ljungdahlii, using a graphite felt and stainless steel assembly as cathode. The mixed culture reactor produced acetate at the maximum rate of 1.3 mM d(-1), along with methane and hydrogen at -1.1 V/Ag/AgCl. Over 160 days of run-time in four fed-batches, 26% of bicarbonate was converted to acetate between day 28 and 41, whereas in the late batches, methane production prevailed. Out of 45 days of run-time in the C. ljungdahlii reactor, 2.4 mM d(-1) acetate production was achieved at -0.9 V/Ag/AgCl in Batch 1. Simultaneous product degradation occurred when the mixed culture was not selectively enriched. Hydrogen evolution is potentially the rapid way of transferring electrons to the biocatalysts for higher bioproduction rates.

  1. Nitrogen availability of grape juice limits killer yeast growth and fermentation activity during mixed-culture fermentation with sensitive commercial yeast strains.

    PubMed Central

    Medina, K; Carrau, F M; Gioia, O; Bracesco, N

    1997-01-01

    The competition between selected or commercial killer strains of type K2 and sensitive commercial strains of Saccharomyces cerevisiae was studied under various conditions in sterile grape juice fermentations. The focus of this study was the effect of yeast inoculation levels and the role of assimilable nitrogen nutrition on killer activity. A study of the consumption of free amino nitrogen (FAN) by pure and mixed cultures of killer and sensitive cells showed no differences between the profiles of nitrogen assimilation in all cases, and FAN was practically depleted in the first 2 days of fermentation. The effect of the addition of assimilable nitrogen and the size of inoculum was examined in mixed killer and sensitive strain competitions. Stuck and sluggish wine fermentations were observed to depend on nitrogen availability when the ratio of killer to sensitive cells was low (1:10 to 1:100). A relationship between the initial assimilable nitrogen content of must and the proportion of killer cells during fermentation was shown. An indirect relationship was found between inoculum size and the percentage of killer cells: a smaller inoculum resulted in a higher proportion of killer cells in grape juice fermentations. In all cases, wines obtained with pure-culture fermentations were preferred to mixed-culture fermentations by sensory analysis. The reasons why killer cells do not finish fermentation under competitive conditions with sensitive cells are discussed. PMID:9212430

  2. Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems.

    PubMed

    Pachapur, Vinayak Laxman; Kutty, Prianka; Brar, Satinder Kaur; Ramirez, Antonio Avalos

    2016-01-13

    Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H₂) production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG) as substrate. Results for heat treatment (100 °C for 15 min) showed the highest H₂ production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H₂ consuming bacteria and produced twice as much as H₂ as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L), percentage of inoculum size (InS) (1.23% to 24% v/v) along with initial pH (2.98 to 8.02) was tested using central composite design (CCD) with H₂ production as response parameter. The maximum H₂ production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011) contribution to H₂ production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H₂ production.

  3. Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems

    PubMed Central

    Pachapur, Vinayak Laxman; Kutty, Prianka; Brar, Satinder Kaur; Ramirez, Antonio Avalos

    2016-01-01

    Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H2) production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG) as substrate. Results for heat treatment (100 °C for 15 min) showed the highest H2 production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H2 consuming bacteria and produced twice as much as H2 as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L), percentage of inoculum size (InS) (1.23% to 24% v/v) along with initial pH (2.98 to 8.02) was tested using central composite design (CCD) with H2 production as response parameter. The maximum H2 production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011) contribution to H2 production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H2 production. PMID:26771607

  4. Impact of bioavailable Pb2+ on Fe2+ oxidation in the presence of a mixed culture of Acidithiobacillus ferrooxidans

    NASA Astrophysics Data System (ADS)

    Wang, H.; Yang, X.; Gong, L.; Jiang, Z.

    2009-12-01

    Numerous investigations were conducted on the effects of a variety of metals, including As, Cu, Zn, Cr on the growth of Acidithiobacillus ferrooxidans (an iron oxidizer and indigenous to acidic environment) and Fe2+ oxidation. However, less work was reported concerning the Pb2+ effect due to its quick precipitation as anglesite in SO42--rich solutions. The reported inhibiting concentrations of Pb2+ varied greatly on the oxidizing rate of ferrous in the presence of A. ferrooxidans, and the reasons remain unclear. Comparative studies were conducted between chemical and microbial oxidation of ferrous by a mixed culture of A. ferrooxidans in the presence of different concentration of Pb2+. Eh, pH and Fe2+ concentration were monitored periodically and the final precipitates were analyzed by X-ray diffraction (XRD), scanning electronic microscopy (SEM), and SEM-EDAX (Energy-dispersive X-ray spectroscopy). To check the impact of bioavailable Pb2+ on Fe2+ oxidation, initial precipitation was removed before the microbial inoculation. Our data showed that Pb2+ will exert a remarkable inhibition on microbial oxidation of ferrous when initial Pb2+ concentration reached as high as 5 g/L. However, the bioavailable Pb2+ in this case should be much lower than 5 g/L in the solution due to the precipitation of anglesite (The absolute concentration was under analysis). The threshold of Pb2+ concentrations to inhibit the microbial oxidation varies among the previous studies. This might result from the different microbial strains used or the mistaking of initial concentration as the substantial concentration of bioavailable Pb2+ after precipitation as anglesite. In contrast, Pb2+ does not show any obvious influence on chemical oxidation of ferrous. XRD spectrum of the final precipitates showed that anglesite was the only solid phase detected in chemical systems, while pure jarosite was found in the microbial systems. No lead was detected in jarosite by SEM-EDAX, inferring that Pb was

  5. Hydrodynamic characteristics and mixing behaviour of Sclerotium glucanicum culture fluids in an airlift reactor with an internal loop used for scleroglucan production.

    PubMed

    Kang, X; Wang, H; Wang, Y; Harvey, L M; McNeil, B

    2001-10-01

    The filamentous fungus, Sclerotium glucanicum NRRL 3006, was cultivated in a 0.008 m(3) airlift bioreactor with internal recirculation loop (ARL-IL) for production of the biopolymer, scleroglucan. The rheological behaviour of the culture fluid was characterised by measurement of the fluid consistency coefficient (K) and the flow behaviour index (n). Based on these measurements, the culture fluid changed from a low viscosity Newtonian system early in the process, to a viscous non-Newtonian (pseudoplastic) system. In addition, reactor hydrodynamics and mixing behaviour were characterised by measurement of whole mean gas hold-up (epsilon(g)), liquid re-circulation velocity (U(ld)) and mixing time (t(m)). Under identical process conditions, the effects of the viscosity of the culture fluid and air flow rate on epsilon(g), U(ld) and t(m) were examined and empirical correlations for epsilon(g), U(ld) and t(m) with both superficial velocity U(g) and consistency coefficient K were obtained and expressed separately. The correlations obtained are likely to describe the behaviour of real fungal culture fluids more accurately than previous correlations based on Newtonian or simulated non-Newtonian systems. PMID:11687932

  6. Culture.

    ERIC Educational Resources Information Center

    1997

    Twelve conference papers on cultural aspects of second language instruction include: "Towards True Multiculturalism: Ideas for Teachers" (Brian McVeigh); Comparing Cultures Through Critical Thinking: Development and Interpretations of Meaningful Observations" (Laurel D. Kamada); "Authority and Individualism in Japan and the USA" (Alisa Woodring);…

  7. Biological synthesis of very small silver nanoparticles by culture supernatant of Klebsiella pneumonia: The effects of visible-light irradiation and the liquid mixing process

    SciTech Connect

    Mokhtari, Narges; Daneshpajouh, Shahram; Seyedbagheri, Seyedali; Atashdehghan, Reza; Abdi, Khosro; Sarkar, Saeed; Minaian, Sara; Shahverdi, Hamid Reza; Shahverdi, Ahmad Reza

    2009-06-03

    This study has investigated different visible-light irradiation's effect on the formation of silver nanoparticles from silver nitrate using the culture supernatant of Klebsiella pneumonia. Our study shows that visible-light emission can significantly prompt the synthesis of silver nanoparticles. Also, the study experimentally investigated the liquid mixing process effect on silver nanoparticle synthesis by visible-light irradiation. This study successfully synthesized uniformly dispersed silver nanoparticles with a uniform size and shape in the range of 1-6 nm with an average size of 3 nm. Furthermore, the study investigated the mechanism of the reduction of silver ions by culture supernatant of K. pneumonia, and used X-ray diffraction to characterize silver chloride as an intermediate compound. Silver chloride was prepared synthetically and used as a substrate for the synthesis of silver nanoparticles by culture supernatant of K. pneumonia. The silver nanoparticles have been prepared from silver chloride during this investigation for the first time.

  8. Effect of a probiotic mixed culture on texture profile and sensory performance of Minas fresh cheese in comparison with the traditional products.

    PubMed

    Buriti, Flávia C A; Okazaki, Tania Y; Alegro, João H A; Saad, Susana M I

    2007-06-01

    The effect of a mixed probiotic culture on instrumental texture, and on sensorial and related properties of Minas fresh cheese during refrigerated storage was investigated. Three cheese-making trials were prepared: T1, with the traditional type O starter culture (Lactococcus lactis subsp. lactis + L. lactis subsp. cremoris), T2 with only lactic acid and T3, with lactic acid and the probiotic ABT culture (Lactobacillus acidophilus La-5 + Bifidobacterium animalis Bb-12 + Streptococcus thermophilus). Instrumental texture profile analysis and related properties were monitored during storage for up to 21 days. Lb. acidophilus and B. animalis were present in high levels throughout storage of cheeses T3, above 6 log cfu.g(-1), threshold required for probiotic activity, and stimulation of the La-5 growth was observed. Cheeses with added probiotic ABT culture, as well as those made adding lactic acid only, showed to be less brittle and with more favorable sensorial features, due to higher pH values. Results indicated that the use of probiotic ABT culture complementary to lactic acid for the purpose of substituting the type O (Lc. lactis subsp. lactis + Lc. lactis subsp. cremoris) culture, traditionally employed for Minas cheese production, is advantageous. PMID:17992983

  9. Students' Attitudes towards Culturally Mixed Groups on International Campuses: Impact of Participation in Diverse and Non-Diverse Groups

    ERIC Educational Resources Information Center

    Summers, Mark; Volet, Simone

    2008-01-01

    International campuses provide social forums to enhance students' intercultural competence, skills and confidence. Yet, despite multiple opportunities for social contact, the most typical pattern is one of minimal interaction between students from different cultural backgrounds. This study examined students' attitudes towards culturally mixed…

  10. Comparison of S9 mix and hepatocytes as external metabolizing systems in mammalian cell cultures: cytogenetic effects of 7,12-dimethylbenzanthracene and aflatoxin B1

    SciTech Connect

    Madle, E.; Tiedemann, G.; Madle, S.; Oett, A.; Kaufmann, G.

    1986-01-01

    Two external metabolizing systems, S9 mix from Aroclor-induced rat livers and freshly isolated hepatocytes, were used for activation in cultures of human lymphocytes and V79 cells. 7, 12-dimethylbenzanthracene (DMBA) and aflatoxin B1 (AFB1) were employed as indirectly acting reference mutagens. Mutagenic effects were measured by induction of sister chromatid exchange (SCE). With DMBA, SCE-inducing effects were found to be quite similar after activation by S9 mix and activation by hepatocytes. In contrast with AFB1, S9 activation led to a stronger SCE induction than hepatocyte activation in both target cells. The induction of chromosomal aberrations by AFB1 after activation by the two metabolizing systems was also analyzed in V79 cells. This experiment again revealed that AFB1 was more efficiently activated by S9 mix than by hepatocytes. The experiments have shown that the suitability of hepatocytes as an activation system is not restricted to microbial or eukaryotic point mutation assays, but that hepatocyte metabolism can also be successfully included in cytogenetic tests with short- and long-term cultures of mammalian target cells.

  11. Characterization of wheat straw-degrading anaerobic alkali-tolerant mixed cultures from soda lake sediments by molecular and cultivation techniques

    PubMed Central

    Porsch, Katharina; Wirth, Balázs; Tóth, Erika M; Schattenberg, Florian; Nikolausz, Marcell

    2015-01-01

    Alkaline pretreatment has the potential to enhance the anaerobic digestion of lignocellulosic biomass to biogas. However, the elevated pH of the substrate may require alkalitolerant microbial communities for an effective digestion. Three mixed anaerobic lignocellulolytic cultures were enriched from sediments from two soda lakes with wheat straw as substrate under alkaline (pH 9) mesophilic (37°C) and thermophilic (55°C) conditions. The gas production of the three cultures ceased after 4 to 5 weeks, and the produced gas was composed of carbon dioxide and methane. The main liquid intermediates were acetate and propionate. The physiological behavior of the cultures was stable even after several transfers. The enrichment process was also followed by molecular fingerprinting (terminal restriction fragment length polymorphism) of the bacterial 16S rRNA gene and of the mcrA/mrtA functional gene for methanogens. The main shift in the microbial community composition occurred between the sediment samples and the first enrichment, whereas the structure was stable in the following transfers. The bacterial communities mainly consisted of Sphingobacteriales, Clostridiales and Spirochaeta, but differed at genus level. Methanothermobacter and Methanosarcina genera and the order Methanomicrobiales were predominant methanogenes in the obtained cultures. Additionally, single cellulolytic microorganisms were isolated from enrichment cultures and identified as members of the alkaliphilic or alkalitolerant genera. The results show that anaerobic alkaline habitats harbor diverse microbial communities, which can degrade lignocellulose effectively and are therefore a potential resource for improving anaerobic digestion. PMID:25737100

  12. Characterization of wheat straw-degrading anaerobic alkali-tolerant mixed cultures from soda lake sediments by molecular and cultivation techniques.

    PubMed

    Porsch, Katharina; Wirth, Balázs; Tóth, Erika M; Schattenberg, Florian; Nikolausz, Marcell

    2015-09-01

    Alkaline pretreatment has the potential to enhance the anaerobic digestion of lignocellulosic biomass to biogas. However, the elevated pH of the substrate may require alkalitolerant microbial communities for an effective digestion. Three mixed anaerobic lignocellulolytic cultures were enriched from sediments from two soda lakes with wheat straw as substrate under alkaline (pH 9) mesophilic (37°C) and thermophilic (55°C) conditions. The gas production of the three cultures ceased after 4 to 5 weeks, and the produced gas was composed of carbon dioxide and methane. The main liquid intermediates were acetate and propionate. The physiological behavior of the cultures was stable even after several transfers. The enrichment process was also followed by molecular fingerprinting (terminal restriction fragment length polymorphism) of the bacterial 16S rRNA gene and of the mcrA/mrtA functional gene for methanogens. The main shift in the microbial community composition occurred between the sediment samples and the first enrichment, whereas the structure was stable in the following transfers. The bacterial communities mainly consisted of Sphingobacteriales, Clostridiales and Spirochaeta, but differed at genus level. Methanothermobacter and Methanosarcina genera and the order Methanomicrobiales were predominant methanogenes in the obtained cultures. Additionally, single cellulolytic microorganisms were isolated from enrichment cultures and identified as members of the alkaliphilic or alkalitolerant genera. The results show that anaerobic alkaline habitats harbor diverse microbial communities, which can degrade lignocellulose effectively and are therefore a potential resource for improving anaerobic digestion.

  13. Reduction of Salmonella Typhimurium by Fermentation Metabolites of Diamond V Original XPC in an In Vitro Anaerobic Mixed Chicken Cecal Culture

    PubMed Central

    Rubinelli, Peter; Roto, Stephanie; Kim, Sun Ae; Park, Si Hong; Pavlidis, Hilary O.; McIntyre, Don; Ricke, Steven C.

    2016-01-01

    Fermentation metabolites of Diamond V Original XPC™ (XPC), a biological product derived from yeast fermentation, were evaluated for their ability to reduce the Salmonella Typhimurium population using an in vitro mixed anaerobic culture system containing cecal microbiota to simulate chicken hindgut conditions. Four different samples were prepared: anaerobic mixed culture containing (1) feed only, (2) cecal only (ceca were harvested from 42 days old broiler chickens), (3) feed and cecal contents, and (4) feed, cecal contents, and 1% XPC. Two experimental conditions were investigated: Group 1, in which the cecal content was added at the same time as a S. Typhimurium marker strain and Group 2, in which the cecal content was preincubated for 24 h prior to the inoculation with the S. Typhimurium marker strain. The mixed cultures were incubated anaerobically at 37°C, and the S. Typhimurium marker strain was enumerated at 0, 24, and 48 h. Analysis of short chain fatty acids was also conducted for 24 h. In the Group 1 experiment, adding XPC did not exhibit significant reduction of S. Typhimurium. However, the presence of XPC resulted in rapid reduction of S. Typhimurium in Group 2. S. Typhimurium was reduced from 6.81 log10 CFU/ml (0 h) to 3.73 log10 CFU/ml and 1.19 log10 CFU/ml after 24 and 48 h, respectively. These levels were also 2.47 log10 and 2.72 log10 lower than the S. Typhimurium level recovered from the control culture with feed and cecal contents, but without XPC. Based on these results, it appears that the ability of XPC to reduce S. Typhimurium requires the presence of the cecal microbiota. Short chain fatty acid analysis indicated that acetate and butyrate concentrations of cultures containing XPC were twofold greater than the control cultures by 24 h of anaerobic growth. Results from the present study suggest that dietary inclusion of XPC may influence cecal microbiota fermentation and has the potential to reduce Salmonella in the cecum

  14. Reduction of Salmonella Typhimurium by Fermentation Metabolites of Diamond V Original XPC in an In Vitro Anaerobic Mixed Chicken Cecal Culture

    PubMed Central

    Rubinelli, Peter; Roto, Stephanie; Kim, Sun Ae; Park, Si Hong; Pavlidis, Hilary O.; McIntyre, Don; Ricke, Steven C.

    2016-01-01

    Fermentation metabolites of Diamond V Original XPC™ (XPC), a biological product derived from yeast fermentation, were evaluated for their ability to reduce the Salmonella Typhimurium population using an in vitro mixed anaerobic culture system containing cecal microbiota to simulate chicken hindgut conditions. Four different samples were prepared: anaerobic mixed culture containing (1) feed only, (2) cecal only (ceca were harvested from 42 days old broiler chickens), (3) feed and cecal contents, and (4) feed, cecal contents, and 1% XPC. Two experimental conditions were investigated: Group 1, in which the cecal content was added at the same time as a S. Typhimurium marker strain and Group 2, in which the cecal content was preincubated for 24 h prior to the inoculation with the S. Typhimurium marker strain. The mixed cultures were incubated anaerobically at 37°C, and the S. Typhimurium marker strain was enumerated at 0, 24, and 48 h. Analysis of short chain fatty acids was also conducted for 24 h. In the Group 1 experiment, adding XPC did not exhibit significant reduction of S. Typhimurium. However, the presence of XPC resulted in rapid reduction of S. Typhimurium in Group 2. S. Typhimurium was reduced from 6.81 log10 CFU/ml (0 h) to 3.73 log10 CFU/ml and 1.19 log10 CFU/ml after 24 and 48 h, respectively. These levels were also 2.47 log10 and 2.72 log10 lower than the S. Typhimurium level recovered from the control culture with feed and cecal contents, but without XPC. Based on these results, it appears that the ability of XPC to reduce S. Typhimurium requires the presence of the cecal microbiota. Short chain fatty acid analysis indicated that acetate and butyrate concentrations of cultures containing XPC were twofold greater than the control cultures by 24 h of anaerobic growth. Results from the present study suggest that dietary inclusion of XPC may influence cecal microbiota fermentation and has the potential to reduce Salmonella in the cecum

  15. Hyperspectral imaging for detection of non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups on spread plates of mixed cultures

    NASA Astrophysics Data System (ADS)

    Yoon, Seung Chul; Windham, William R.; Ladely, Scott; Heitschmidt, Gerald W.; Lawrence, Kurt C.; Park, Bosoon; Narang, Neelam; Cray, William C.

    2012-05-01

    We investigated the feasibility of visible and near-infrared (VNIR) hyperspectral imaging for rapid presumptive-positive screening of six representative non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) on spread plates of mixed cultures. Although the traditional culture method is still the "gold standard" for presumptive-positive pathogen screening, it is time-consuming, labor-intensive, not effective in testing large amount of food samples, and cannot completely prevent unwanted background microflora from growing together with target microorganisms on agar media. A previous study was performed using the data obtained from pure cultures individually inoculated on spot and/or spread plates in order to develop multivariate classification models differentiating each colony of the six non-O157 STEC serogroups and to optimize the models in terms of parameters. This study dealt with the validation of the trained and optimized models with a test set of new independent samples obtained from colonies on spread plates of mixed cultures. A new validation protocol appropriate to a hyperspectral imaging study for mixed cultures was developed. One imaging experiment with colonies obtained from two serial dilutions was performed. A total of six agar plates were prepared, where O45, O111 and O121 serogroups were inoculated into all six plates and each of O45, O103 and O145 serogroups was added into the mixture of the three common bacterial cultures. The number of colonies grown after 24-h incubation was 331 and the number of pixels associated with the grown colonies was 16,379. The best model found from this validation study was based on pre-processing with standard normal variate and detrending (SNVD), first derivative, spectral smoothing, and k-nearest neighbor classification (kNN, k=3) of scores in the principal component subspace spanned by 6 principal components. The independent testing results showed 95% overall

  16. Production of medium-chain volatile fatty acids by mixed ruminal microorganisms is enhanced by ethanol in co-culture with Clostridium kluyveri.

    PubMed

    Weimer, Paul J; Nerdahl, Michael; Brandl, Dane J

    2015-01-01

    Mixed bacterial communities from the rumen ferment cellulosic biomass primarily to C2-C4 volatile fatty acids, and perform only limited chain extension to produce C5 (valeric) and C6 (caproic) acids. The aim of this study was to increase production of caproate and valerate in short-term in vitro incubations. Co-culture of mixed ruminal microbes with a rumen-derived strain of the bacterium Clostridium kluyveri converted cellulosic biomass (alfalfa stems or switchgrass herbage) plus ethanol to VFA mixtures that include valeric and caproic acids as the major fermentation products over a 48-72h run time. Concentrations of caproate reached 6.1gL(-1), similar to or greater than those reported in most conventional carboxylate fermentations that employ substantially longer run times.

  17. Phytoremediation efficiency of a pcp-contaminated soil using four plant species as mono- and mixed cultures.

    PubMed

    Hechmi, Nejla; Aissa, Nadhira Ben; Abdenaceur, Hassen; Jedidi, Naceur

    2014-01-01

    Bioremediation of soil polluted by pentachlorophenol (PCP) is of great importance due to the persistence and carcinogenic properties of PCP. Phytoremediation has long been recognized as a promising approach for removal of PCP from soil. The present study was conducted to investigate the capability of four plant species; white clover, ryegrass, alfalfa, and rapeseed grown alone and in combination to remediate pentachlorophenol contaminated soil. After 60 days cultivation, white clover, raygrass, alfalfa, and rapeseed all significantly enhanced the degradation of PCP in soils. Alfalfa showed highest efficiency for the removal of PCP in single cropping flowed by rapeseed and ryegrass. Mixed cropping significantly enhanced the remediation efficiencies as compared to single cropping; about 89.84% of PCP was removed by mixed cropping of rapeseed and alfalfa, and 72.01% of PCP by mixed cropping of rape and white clover. Mixed cropping of rapeseed with alfalfa was however far better for the remediation of soil PCP than single cropping. An evaluation of soil biological activities as a monitoring mechanism for the bioremediation process of a PCP-contaminated soil was made using measurements of microbial counts and dehydrogenase activity.

  18. What Counts as the Mixed Method of Reading Instruction in Guinea? Fractures in the Global Culture of Modern Schooling.

    ERIC Educational Resources Information Center

    Anderson-Levitt, Kathryn M.

    This paper examines a case of educational innovation--the introduction of new methods for teaching reading in the Republic of Guinea, West Africa--as a reality check on the appealing but sweeping theory of John Meyer and his colleagues about the diffusion of educational ideals. The paper focuses on Guinea's official adoption of the "mixed" method…

  19. Phytoremediation efficiency of a pcp-contaminated soil using four plant species as mono- and mixed cultures.

    PubMed

    Hechmi, Nejla; Aissa, Nadhira Ben; Abdenaceur, Hassen; Jedidi, Naceur

    2014-01-01

    Bioremediation of soil polluted by pentachlorophenol (PCP) is of great importance due to the persistence and carcinogenic properties of PCP. Phytoremediation has long been recognized as a promising approach for removal of PCP from soil. The present study was conducted to investigate the capability of four plant species; white clover, ryegrass, alfalfa, and rapeseed grown alone and in combination to remediate pentachlorophenol contaminated soil. After 60 days cultivation, white clover, raygrass, alfalfa, and rapeseed all significantly enhanced the degradation of PCP in soils. Alfalfa showed highest efficiency for the removal of PCP in single cropping flowed by rapeseed and ryegrass. Mixed cropping significantly enhanced the remediation efficiencies as compared to single cropping; about 89.84% of PCP was removed by mixed cropping of rapeseed and alfalfa, and 72.01% of PCP by mixed cropping of rape and white clover. Mixed cropping of rapeseed with alfalfa was however far better for the remediation of soil PCP than single cropping. An evaluation of soil biological activities as a monitoring mechanism for the bioremediation process of a PCP-contaminated soil was made using measurements of microbial counts and dehydrogenase activity. PMID:24933915

  20. Collagen-graft mixed cellulose esters membrane maintains undifferentiated morphology and markers of potential pluripotency in feeder-free culture of induced pluripotent stem cells.

    PubMed

    Lotfalah Moradi, Sadegh; Hajishafieeha, Zahra; Nojedehi, Shahrzad; Dinarvand, Vida; Hesami Tackallou, Saeed; Roy, Ram V; Ardeshirylajimi, Abdolreza; Soleimani, Masoud

    2016-09-01

    Induced pluripotent stem cells (iPSCs) are unique and unlimited clinical sources of stem cell therapy for the regenerative medicine. Feeder layer preparation is an important step for iPSCs production, which is expensive, time-consuming and requires conversance. In the present study, we investigated the maintenance of pluripotency, and stemness of the iPSCs through feeder-free culture on a collagen-grafted Mixed Cellulose Esters membrane (MCE-COL) after three passages during twelve days. Results have demonstrated that the iPSCs cultured on MCE-COL membrane had a fine, typical undifferentiated morphology, increased proliferation rate and significant multi-lineage differentiation potential. Alkaline phosphatase (ALP) staining and pluripotency associated gene markers expression further confirmed that iPSCs cultured on the surface of MCE-COL had more ALP positive colonies and enhanced expression of Oct-4, Nanog, Sox-2 and ALP in comparison with MCE and control groups. Since MCE-COL membrane has three dimensional structure and bioactivity, it has the potential for usage in the feeder-free culture of iPSCs, and could be a suitable candidate to use as a feeder layer in stem cells preparation. PMID:27449919

  1. Grooming and cultural socialization: A mixed method study of caregiving practices in Burma (Myanmar) and the United States†

    PubMed Central

    Thein-Lemelson, Seinenu M

    2015-01-01

    Grooming behaviours are thought to be a crucial aspect of parenting and integral to the sociality of non-human mammals, but there have been few empirical studies on how grooming might be relevant to parenting and socialization processes in humans. Study 1 is a quantitative cross-cultural comparison of grooming practices in two cultural settings: an urban centre in Burma (Myanmar) and an urban centre in the United States. The study uses naturalistic video data of 57 families to analyse grooming behaviours directed at children. A broad range of ages was sampled in each culture to examine the developmental trajectory of grooming behaviours. Results indicate that significant cultural differences exist between Burma and the United States, with Burmese children being groomed by their caregivers more often than U.S. children. Results also indicate that cultural differences in grooming practices begin early and remain constant across age. An unexpected finding was that Burmese families were more variable in their behaviour than U.S. families. Study 2 attempts to explain this variability by using ethnography to describe how sociodemographic changes in Burma are leading to changes in parental values and socialization practices in the schools, but how embodied primary care in the homes appear resistant to change. PMID:25530498

  2. Grooming and cultural socialization: a mixed method study of caregiving practices in Burma (Myanmar) and the United States.

    PubMed

    Thein-Lemelson, Seinenu M

    2015-02-01

    Grooming behaviours are thought to be a crucial aspect of parenting and integral to the sociality of non-human mammals, but there have been few empirical studies on how grooming might be relevant to parenting and socialization processes in humans. Study 1 is a quantitative cross-cultural comparison of grooming practices in two cultural settings: an urban centre in Burma (Myanmar) and an urban centre in the United States. The study uses naturalistic video data of 57 families to analyse grooming behaviours directed at children. A broad range of ages was sampled in each culture to examine the developmental trajectory of grooming behaviours. Results indicate that significant cultural differences exist between Burma and the United States, with Burmese children being groomed by their caregivers more often than U.S. children. Results also indicate that cultural differences in grooming practices begin early and remain constant across age. An unexpected finding was that Burmese families were more variable in their behaviour than U.S. families. Study 2 attempts to explain this variability by using ethnography to describe how sociodemographic changes in Burma are leading to changes in parental values and socialization practices in the schools, but how embodied primary care in the homes appear resistant to change.

  3. Interaction of a mixed yeast culture in an ``autotroph-heterotroph'' system with a closed atmosphere cycle and spatially separated components

    NASA Astrophysics Data System (ADS)

    Pisman, T. I.; Somova, L. A.

    The study considers an experimental model of the "autotroph-heterotroph" system with a closed atmosphere cycle, in which the heterotrophic link is a mixed yeast population. The autotrophic link is represented by the algae Chlorella vulgaris and the heterotrophic link by the yeasts Candida utilis and Candida guilliermondii. The controls are populations of Chlorella and the same yeasts isolated from the atmosphere. It has been shown that the outcome of competition in the heterotrophic link depends on the strategy of the yeast population towards the substrate and oxygen. The C. utilis population quickly utilizes the substrate as it is an r-strategist and is less sensitive to oxygen deficiency. The C. guilliermondii population consumes low concentrations of the substrate because it is a K-strategist, but it is more sensitive to oxygen deficiency. That is why, in the "autotroph-heterotroph" system with a closed gas cycle, after a considerable amount of the substrate has been consumed, the C. guilliermondii population becomes more competitive that the C. utilis population. In the culture of yeasts, isolated from the atmosphere, the C. utilis population finds itself in more favorable conditions due to oxygen deficiency. The system with a complex heterotrophic component survive longer than a system whose heterotrophic component is represented by only one yeast species. This is explained for by the positive metabolite interaction of yeasts and a more complete utilization of the substrate by a mixed culture of yeasts featuring different strategies towards the substrate.

  4. Interaction of the mixed yeast culture in the autotroph-heterotroph system with a closed gas cycle and spatially separated components

    NASA Astrophysics Data System (ADS)

    Pisman, T.; Somova, L.

    The study considers the experimental model of the "autotroph-heterotroph" system with a closed gas cycle, in which the heterotrophic link is a mixed yeast population. The autotrophic link is represented by the algae Chlorella vulgaris and the heterotrophic link by the yeasts Candida utilis and Candida guilliermondii. The controls are separate links of Chlorella and yeasts isolated from the atmosphere. It has been shown that the outcome of the competition in the heterotrophic link depends on the strategy of the yeast population towards the substrate and oxygen. The C. utilis population quickly utilizes the substrate as it is an R-strategist and is less sensitive to oxygen deficiency. The C. guilliermondii population consumes low concentrations of the substrate because it is a K-strategist, but it is more sensitive to oxygen deficiency. That is why, in the "autotroph-heterotroph" system with a closed gas cycle, after a considerable amount of the substrate has been consumed, the C. guilliermondii population becomes more competitive that the C. utilis population. In the culture of a separate yeast link, isolated from the atmosphere, the C. utilis population finds itself in more favorable conditions due to oxygen deficiency. The system with a complex heterotrophic component exists longer than the system whose heterotrophic component is represented by one yeast species. This is accounted for by the positive metabolite interaction of yeasts and a more complete utilization of the substrate by a mixed culture of yeasts featuring different strategies towards the substrate.

  5. Structural and physiochemical characterization of rhamnolipids produced by Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa in single strain and mixed cultures.

    PubMed

    Hošková, Miriam; Ježdík, Richard; Schreiberová, Olga; Chudoba, Josef; Šír, Marek; Čejková, Alena; Masák, Jan; Jirků, Vladimír; Řezanka, Tomáš

    2015-01-10

    Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp. cultivations. Here we report rhamnolipids producing bacteria Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa that were cultivated separately and as mixed populations. The ratio and composition of rhamnolipid congeners was determined by tandem mass spectrometry with negative electrospray ionization. Mono-rhamnolipid and di-rhamnolipid homologues containing one or two saturated or monounsaturated 3-hydroxy fatty acids were found in all strains. Physiochemical characterization of rhamnolipids was evaluated by the critical micelle concentration determination, the emulsification test, oil displacement test and phenanthrene solubilization. Critical micelle concentrations of rhamnolipids produced by both single strain and mixed cultures were found to be very low (10-63 mg/l) and to correspond with saturated/unsaturated fatty acid content of rhamnolipid homologues. The rhamnolipids produced by all strains effectively emulsified crude petroleum in comparison with synthetic surfactants Tween 80 and sodium dodecyl sulfate (SDS). Good performance of phenanthrene solubilization was exhibited by rhamnolipids from E. asburiae. The single strain and co-cultures cultivations were proposed as a possible way to produce rhamnolipid mixtures with a specific composition and different physiochemical properties, which could be exploited in bioremediation of various hydrophobic contaminants.

  6. Promises and Problems of Teaching with Popular Culture: A Linguistic Ethnographic Analysis of Discourse Genre Mixing in a Literacy Lesson

    ERIC Educational Resources Information Center

    Lefstein, Adam; Snell, Julia

    2011-01-01

    This article problematises a broad consensus in favour of importing popular culture into classrooms as a means of engaging pupils, transforming interactional norms and facilitating pupil understanding. A literacy lesson in which an English primary school teacher invoked the televised talent show, "X factor", in organising the class to provide…

  7. Mixed Harvest: The Second Great Transformation in the Rural North, 1870-1930. Studies in Rural Culture.

    ERIC Educational Resources Information Center

    Barron, Hal S.

    Between 1870 and 1930, a "second great transformation" in the Northeast and Midwest was characterized by centralization of the economy, expansion of state power and professional expertise, and a rising urban consumer culture. Communities in the rural North faced a number of challenges: diminishing local control over schools and roads, the effects…

  8. Using consumer perspectives to inform the cultural adaptation of psychological treatments for depression: A mixed methods study from South Asia

    PubMed Central

    Aggarwal, Neil Krishan; Balaji, Madhumitha; Kumar, Shuba; Mohanraj, Rani; Rahman, Atif; Verdeli, Helena; Araya, Ricardo; Jordans, M.J.D.; Chowdhary, Neerja; Patel, Vikram

    2014-01-01

    Background Integrating consumer perspectives in developing and adapting psychological treatments (PTs) can enhance their acceptability in diverse cultural contexts. Objective To describe the explanatory models (EMs) of depression in South Asia with the goal of informing the content of culturally appropriate PTs for this region. Methods Two methods were used: a systematic review of published literature on the EMs of depression in South Asia; and in-depth interviews with persons with depression and family caregivers in two sites in India. Findings from both were analysed independently and then triangulated. Results There were 19 studies meeting our inclusion criteria. Interviews were conducted with 27 patients and 10 caregivers. Findings were grouped under four broad categories: illness descriptions, perceived impact, causal beliefs and self-help forms of coping. Depression was characterised predominantly by somatic complaints, stress, low mood, and negative and ruminative thoughts. Patients experienced disturbances in interpersonal relationships occupational functioning, and stigma. Negative life events, particularly relationship difficulties, were perceived as the main cause. Patients mostly engaged in distracting activities, religious practices, and received support from family and friends to cope with the illness. Limitations The primary data are entirely from India but the studies from the literature review covering South Asia are consistent with these findings. This study also does not include literature in local languages or explore how consumer perspectives change over time. Conclusions EMs can inform cultural adaptations to PTs for depression in South Asia by defining target outcomes, content for psycho-education, and culturally appropriate treatment strategies. PMID:24836093

  9. Biodegradation of beet molasses vinasse by a mixed culture of micro organisms: effect of aeration conditions and pH control.

    PubMed

    Lutosławski, Krzysztof; Ryznar-Luty, Agnieszka; Cibis, Edmund; Krzywonos, Małgorzata; Miśkiewicz, Tadeusz

    2011-01-01

    The effect of aeration conditions and pH control on the progress and efficiency of beet molasses vinasse biodegradation was investigated during four batch processes at 38 degrees C with the mixed microbial culture composed of Bifidobacterium, Lactobacillus, Lactococcus, Streptococcus, Bacillus, Rhodopseudomonas, and Saccharomyces. The four processes were carried out in a shake flask with no pH control, an aerobic bioreactor without mixing with no pH control, and a stirred-tank reactor (STR) with aeration with and without pH control, respectively. All experiments were started with an initial pH 8.0. The highest efficiency of biodegradation was achieved through the processes conducted in the STR, where betaine (an organic pollutant occurring in beet molasses in very large quantities) was completely degraded by the microorganisms. The process with no pH control carried out in the STR produced the highest reduction in the following pollution measures: organic matter expressed as chemical oxygen demand determined by the dichromatic method + theoretical COD of betaine (COD(sum), 85.5%), total organic carbon (TOC, 78.8%) and five-day biological oxygen demand (BOD5, 98.6%). The process conditions applied in the shake flask experiments, as well as those used in the aerobic bioreactor without mixing, failed to provide complete betaine assimilation. As a consequence, reduction in COD(sum), TOC and BOD5 was approximately half that obtained with STR. PMID:22432306

  10. Biodegradation of beet molasses vinasse by a mixed culture of micro organisms: effect of aeration conditions and pH control.

    PubMed

    Lutosławski, Krzysztof; Ryznar-Luty, Agnieszka; Cibis, Edmund; Krzywonos, Małgorzata; Miśkiewicz, Tadeusz

    2011-01-01

    The effect of aeration conditions and pH control on the progress and efficiency of beet molasses vinasse biodegradation was investigated during four batch processes at 38 degrees C with the mixed microbial culture composed of Bifidobacterium, Lactobacillus, Lactococcus, Streptococcus, Bacillus, Rhodopseudomonas, and Saccharomyces. The four processes were carried out in a shake flask with no pH control, an aerobic bioreactor without mixing with no pH control, and a stirred-tank reactor (STR) with aeration with and without pH control, respectively. All experiments were started with an initial pH 8.0. The highest efficiency of biodegradation was achieved through the processes conducted in the STR, where betaine (an organic pollutant occurring in beet molasses in very large quantities) was completely degraded by the microorganisms. The process with no pH control carried out in the STR produced the highest reduction in the following pollution measures: organic matter expressed as chemical oxygen demand determined by the dichromatic method + theoretical COD of betaine (COD(sum), 85.5%), total organic carbon (TOC, 78.8%) and five-day biological oxygen demand (BOD5, 98.6%). The process conditions applied in the shake flask experiments, as well as those used in the aerobic bioreactor without mixing, failed to provide complete betaine assimilation. As a consequence, reduction in COD(sum), TOC and BOD5 was approximately half that obtained with STR.

  11. Significance of the choice of tissue culture technique on the chromosomal patterns in human mixed salivary gland tumors.

    PubMed

    Mark, J; Sandros, J; Wedell, B; Stenman, G; Ekedahl, C

    1988-07-15

    Cytogenetic observations by banding methods in 56 new cases of human benign pleomorphic adenomas are reported. Thirty of the cases (series I) were studied in preparations from primary cultures established from cells growing out from mechanically dispersed tumor pieces. The remaining 26 cases (series II) were analyzed in preparations from primary cultures established from enzymatically pretreated material. The use of the latter method resulted in a decrease in the frequency of cases with a normal stemline from about 53% to about 19%. However, the general characteristics of the aberrations observed in abnormal stemlines in both series agreed well. The minor differences observed consisted of a higher frequency of recurrent t(3;8)(p21;q12) in series II and, in the same series, fewer cases showing an involvement of 8q or 12q. The present results emphasize the importance of molecular studies of, in particular, the regions 8q12, 12q13-15, and 3p21.

  12. Optimization of a biological process for treating potato chips industry wastewater using a mixed culture of Aspergillus foetidus and Aspergillus niger.

    PubMed

    Mishra, B K; Arora, Anju; Lata

    2004-08-01

    Potato chips industry wastewater was collected and analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and total carbohydrates. Two Aspergillus species, A. foetidus and A. niger, were evaluated for their ability to grow and produce biomass and reduce the organic load of the wastewater. A. foetidus MTCC 508 and A. niger ITCC 2012 were able to reduce COD by about 60% and produce biomass 2.4 and 2.85 gl(-1), respectively. Co-inoculation of both Aspergillus strains resulted in increased fungal biomass production and higher COD reduction than in individual culture at different culture pH. pH 6 was optimum for biomass production and COD reduction. Amendment of the wastewater with different N and P sources, increased the biomass production and COD reduction substantially. Under standardized conditions of pH 6 and amendment of wastewater with 0.1% KH2PO4 and 0.1% (NH4)2 SO4, a mixed culture gave 90% reduction in COD within 60 h of incubation.

  13. Evidence for cooperative mineralization of diuron by Arthrobacter sp. BS2 and Achromobacter sp. SP1 isolated from a mixed culture enriched from diuron exposed environments.

    PubMed

    Devers-Lamrani, Marion; Pesce, Stéphane; Rouard, Nadine; Martin-Laurent, Fabrice

    2014-12-01

    Diuron was found to be mineralized in buffer strip soil (BS) and in the sediments (SED) of the Morcille river in the Beaujolais vineyard repeatedly treated with this herbicide. Enrichment cultures from BS and SED samples led to the isolation of three bacterial strains transforming diuron to 3,4-dichloroaniline (3,4-DCA) its aniline derivative. 16S rRNA sequencing revealed that they belonged to the genus Arthrobacter (99% of similarity to Arthrobacter globiformis strain K01-01) and were designated as Arthrobacter sp. BS1, BS2 and SED1. Diuron-degrading potential characterized by sequencing of the puhA gene, characterizing the diuron-degradaing potential, revealed 99% similarity to A. globiformis strain D47 puhA gene isolated a decade ago in the UK. These isolates were also able to use chlorotoluron for their growth. Although able to degrade linuron and monolinuron to related aniline derivatives they were not growing on them. Enrichment cultures led to the isolation of a strain from the sediments entirely degrading 3,4-DCA. 16S rRNA sequence analysis showed that it was affiliated to the genus Achromobacter (99% of similarity to Achromobacter sp. CH1) and was designated as Achromobacter sp. SP1. The dcaQ gene encoding enzyme responsible for the transformation of 3,4-DCA to chlorocatechol was found in SP1 with 99% similarity to that of Comamonas testosteroni WDL7. This isolate also used for its growth a range of anilines (3-chloro-4-methyl-aniline, 4-isopropylaniline, 4-chloroaniline, 3-chloroaniline, 4-bromoaniline). The mixed culture composed of BS2 and SP1 strains entirely mineralizes (14)C-diuron to (14)CO2. Diuron-mineralization observed in the enrichment culture could result from the metabolic cooperation between these two populations. PMID:25061887

  14. Unraveling the Physiological Roles of the Cyanobacterium Geitlerinema sp. BBD and Other Black Band Disease Community Members through Genomic Analysis of a Mixed Culture

    PubMed Central

    Den Uyl, Paul A.; Richardson, Laurie L.; Jain, Sunit

    2016-01-01

    Black band disease (BBD) is a cyanobacterial-dominated polymicrobial mat that propagates on and migrates across coral surfaces, necrotizing coral tissue. Culture-based laboratory studies have investigated cyanobacteria and heterotrophic bacteria isolated from BBD, but the metabolic potential of various BBD microbial community members and interactions between them remain poorly understood. Here we report genomic insights into the physiological and metabolic potential of the BBD-associated cyanobacterium Geitlerinema sp. BBD 1991 and six associated bacteria that were also present in the non-axenic culture. The essentially complete genome of Geitlerinema sp. BBD 1991 contains a sulfide quinone oxidoreductase gene for oxidation of sulfide, suggesting a mechanism for tolerating the sulfidic conditions of BBD mats. Although the operon for biosynthesis of the cyanotoxin microcystin was surprisingly absent, potential relics were identified. Genomic evidence for mixed-acid fermentation indicates a strategy for energy metabolism under the anaerobic conditions present in BBD during darkness. Fermentation products may supply carbon to BBD heterotrophic bacteria. Among the six associated bacteria in the culture, two are closely related to organisms found in culture-independent studies of diseased corals. Their metabolic pathways for carbon and sulfur cycling, energy metabolism, and mechanisms for resisting coral defenses suggest adaptations to the coral surface environment and biogeochemical roles within the BBD mat. Polysulfide reductases were identified in a Flammeovirgaceae genome (Bacteroidetes) and the sox pathway for sulfur oxidation was found in the genome of a Rhodospirillales bacterium (Alphaproteobacteria), revealing mechanisms for sulfur cycling, which influences virulence of BBD. Each genomic bin possessed a pathway for conserving energy from glycerol degradation, reflecting adaptations to the glycerol-rich coral environment. The presence of genes for detoxification

  15. Unraveling the Physiological Roles of the Cyanobacterium Geitlerinema sp. BBD and Other Black Band Disease Community Members through Genomic Analysis of a Mixed Culture.

    PubMed

    Den Uyl, Paul A; Richardson, Laurie L; Jain, Sunit; Dick, Gregory J

    2016-01-01

    Black band disease (BBD) is a cyanobacterial-dominated polymicrobial mat that propagates on and migrates across coral surfaces, necrotizing coral tissue. Culture-based laboratory studies have investigated cyanobacteria and heterotrophic bacteria isolated from BBD, but the metabolic potential of various BBD microbial community members and interactions between them remain poorly understood. Here we report genomic insights into the physiological and metabolic potential of the BBD-associated cyanobacterium Geitlerinema sp. BBD 1991 and six associated bacteria that were also present in the non-axenic culture. The essentially complete genome of Geitlerinema sp. BBD 1991 contains a sulfide quinone oxidoreductase gene for oxidation of sulfide, suggesting a mechanism for tolerating the sulfidic conditions of BBD mats. Although the operon for biosynthesis of the cyanotoxin microcystin was surprisingly absent, potential relics were identified. Genomic evidence for mixed-acid fermentation indicates a strategy for energy metabolism under the anaerobic conditions present in BBD during darkness. Fermentation products may supply carbon to BBD heterotrophic bacteria. Among the six associated bacteria in the culture, two are closely related to organisms found in culture-independent studies of diseased corals. Their metabolic pathways for carbon and sulfur cycling, energy metabolism, and mechanisms for resisting coral defenses suggest adaptations to the coral surface environment and biogeochemical roles within the BBD mat. Polysulfide reductases were identified in a Flammeovirgaceae genome (Bacteroidetes) and the sox pathway for sulfur oxidation was found in the genome of a Rhodospirillales bacterium (Alphaproteobacteria), revealing mechanisms for sulfur cycling, which influences virulence of BBD. Each genomic bin possessed a pathway for conserving energy from glycerol degradation, reflecting adaptations to the glycerol-rich coral environment. The presence of genes for detoxification

  16. Fate of β-hexachlorocyclohexane in the mixed microbial cultures (MMCs) three-stage polyhydroxyalkanoates (PHA) production process from cheese whey.

    PubMed

    Valentino, Francesco; Riccardi, Carmela; Campanari, Sabrina; Pomata, Donatella; Majone, Mauro

    2015-09-01

    This work aimed to study the fate and effect of β-hexachlorocyclohexane (β-HCH) during several steps of PHA production and purification, by using an artificially contaminated cheese whey (CW) as the feedstock. Most of β-HCH (around 90%) was adsorbed on CW solids and it was removed after the acidogenic fermentation step, when residual CW solids are separated along with anaerobic biomass from the liquid-phase. Purification steps also contributed strongly to the removal of residual β-HCH; overall, the PHA production process removed about 99.9% of initial β-HCH content. Moreover, it has been shown that β-HCH has neither detrimental effect on acidogenic fermentation nor on PHA accumulation, that were performed by using unacclimated mixed microbial cultures. PMID:26048084

  17. Fate of β-hexachlorocyclohexane in the mixed microbial cultures (MMCs) three-stage polyhydroxyalkanoates (PHA) production process from cheese whey.

    PubMed

    Valentino, Francesco; Riccardi, Carmela; Campanari, Sabrina; Pomata, Donatella; Majone, Mauro

    2015-09-01

    This work aimed to study the fate and effect of β-hexachlorocyclohexane (β-HCH) during several steps of PHA production and purification, by using an artificially contaminated cheese whey (CW) as the feedstock. Most of β-HCH (around 90%) was adsorbed on CW solids and it was removed after the acidogenic fermentation step, when residual CW solids are separated along with anaerobic biomass from the liquid-phase. Purification steps also contributed strongly to the removal of residual β-HCH; overall, the PHA production process removed about 99.9% of initial β-HCH content. Moreover, it has been shown that β-HCH has neither detrimental effect on acidogenic fermentation nor on PHA accumulation, that were performed by using unacclimated mixed microbial cultures.

  18. Treatment and electricity harvesting from sulfate/sulfide-containing wastewaters using microbial fuel cell with enriched sulfate-reducing mixed culture.

    PubMed

    Lee, Duu-Jong; Lee, Chin-Yu; Chang, Jo-Shu

    2012-12-01

    Anaerobic treatment of sulfate-laden wastewaters can produce excess sulfide, which is corrosive to pipelines and is toxic to incorporated microorganisms. This work started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture as anodic biofilms and applied the so yielded MFC for treating sulfate or sulfide-laden wastewaters. The sulfate-reducing bacteria in anodic biofilm effectively reduced sulfate to sulfide, which was then used by neighboring anode respiring bacteria (ARB) as electron donor for electricity production. The presence of organic carbons enhanced MFC performance since the biofilm ARB were mixotrophs that need organic carbon to grow. The present device introduces a route for treating sulfate laden wastewaters with electricity harvesting.

  19. Enrichment and properties of an anaerobic mixed culture reductively dechlorinating 1,2,3-trichlorobenzene to 1,3-dichlorobenzene

    SciTech Connect

    Holliger, C.; Schraa, G.; Stams, A.J.M.; Zehnder, A.J.B. )

    1992-05-01

    Hexachlorobenzene (HCB), pentachlorobenzene (QCB), all three isomers of tetrachlorobenzene (TeCB), 1,2,3-trichlorobenzene (1,2,3-TCB), and 1,2,4-TCB were reductively dechlorinated by enrichment cultures in the presence of lactate, glucose, ethanol, or isopropanol as the electron donor. The enrichment cultures originated from percolation columns filled with Rhine River sediment in which dechlorination of TCBs and dichlorobenzenes (DCBs) occurred. A stable consortium obtained by transfer on lactate as the energy and carbon source in the presence of 1,2,3-TCB dechlorinated this isomer stoichiometrically to 1,3-DCB. Dechlorinating activity could only be maintained when an electron donor was added. Lactate, ethanol, and hydrogen appeared to be the best substrates. Optimal temperature and pH for dechlorination were 30 C and 7.2, respectively. The specificity of the enrichment on lactate and 1,2,3-TCB was tested after approximately 60 transfers (after 2.5 years). HCB and QCB were stoichiometrically dechlorinated to 1,3,5-TCB and minor amounts of 1,2,4-TCB. 1,3,5-TCB was the sole product formed from 1,2,3,5-TeCB, while 1,2,3,4-TeCB and 1,2,4,5-TeCB were converted to 1,2,4-TCB. 1,2,4-TCB, 1,3,5-TCB, and the three isomers of DCB were not dechlorinated during 4 weeks of incubation. For further enrichment of the 1,2,3-TCB-dechlorinating bacteria, a two-liquid-phase (hexadecane-water) system was used with hydrogen as the electron donor and 1,2,3-TCB or CO[sub 2] as the electron acceptor. Methanogens and acetogens were the major substrate-competing (H[sub 2]-CO[sub 2]) microorganisms in the two-liquid-phase system.

  20. Effect of dilution rate and methanol-glycerol mixed feeding on heterologous Rhizopus oryzae lipase production with Pichia pastoris Mut(+) phenotype in continuous culture.

    PubMed

    Canales, Christian; Altamirano, Claudia; Berrios, Julio

    2015-01-01

    The induction using substrate mixtures is an operational strategy for improving the productivity of heterologous protein production with Pichia pastoris. Glycerol as a cosubstrate allows for growth at a higher specific growth rate, but also has been reported to be repressor of the expression from the AOX1 promoter. Thus, further insights about the effects of glycerol are required for designing the induction stage with mixed substrates. The production of Rhizopus oryzae lipase (ROL) was used as a model system to investigate the application of methanol-glycerol feeding mixtures in fast metabolizing methanol phenotype. Cultures were performed in a simple chemostat system and the response surface methodology was used for the evaluation of both dilution rate and methanol-glycerol feeding composition as experimental factors. Our results indicate that productivity and yield of ROL are strongly affected by dilution rate, with no interaction effect between the involved factors. Productivity showed the highest value around 0.04-0.06 h(-1) , while ROL yield decreased along the whole dilution rate range evaluated (0.03-0.1 h(-1) ). Compared to production level achieved with methanol-only feeding, the highest specific productivity was similar in mixed feeding (0.9 UA g-biomass(-1) h(-1) ), but volumetric productivity was 70% higher. Kinetic analysis showed that these results are explained by the effects of dilution rate on specific methanol uptake rate, instead of a repressor effect caused by glycerol feeding. It is concluded that despite the effect of dilution rate on ROL yield, mixed feeding strategy is a proper process option to be applied to P. pastoris Mut(+) phenotype for heterologous protein production.

  1. Specific inhibitors for identifying pathways for methane production from carbon monoxide by a nonadapted anaerobic mixed culture.

    PubMed

    Navarro, Silvia Sancho; Cimpoia, Ruxandra; Bruant, Guillaume; Guiot, Serge R

    2014-06-01

    Specific inhibitors such as 2-bromoethanesulfonate (BES) and vancomycin were employed in activity batch tests to decipher metabolic pathways that are preferentially used by a mixed anaerobic consortium (sludge from an anaerobic digester) to transform carbon monoxide (CO) into methane (CH4). We first evaluated the inhibitory effect of both BES and vancomycin on the microbial community, as well as the efficiency and stability of vancomycin at 35 °C, over time. The activity tests with CO2-H2, CO, glucose, acetate, formate, propionate, butyrate, methanol, and ethanol showed that vancomycin does not inhibit some Gram-negative bacteria, and 50 mmol/L BES effectively blocks CH4 production in the sludge. However, when sludge was incubated with propionate, butyrate, methanol, or ethanol as the sole energy and carbon source, methanogenesis was only partially inhibited by BES. Separate tests showed that 0.07 mmol/L vancomycin is enough to maintain its inhibitory efficiency and stability in the population for at least 32 days at 35 °C. Using the inhibitors above, it was demonstrated that CO conversion to CH4 is an indirect, 2-step process, in which the CO is converted first to acetate and subsequently to CH4. PMID:24896194

  2. Dynamic model-based analysis of furfural and HMF detoxification by pure and mixed batch cultures of S. cerevisiae and S. stipitis.

    PubMed

    Hanly, Timothy J; Henson, Michael A

    2014-02-01

    Inhibitory compounds that result from biomass hydrolysis are an obstacle to the efficient production of second-generation biofuels. Fermentative microorganisms can reduce compounds such as furfural and 5-hydroxymethyl furfural (HMF), but detoxification is accompanied by reduced growth rates and ethanol yields. In this study, we assess the effects of these furan aldehydes on pure and mixed yeast cultures consisting of a respiratory deficient mutant of Saccharomyces cerevisiae and wild-type Scheffersomyces stipitis using dynamic flux balance analysis. Uptake kinetics and stoichiometric equations for the intracellular reduction reactions associated with each inhibitor were added to genome-scale metabolic reconstructions of the two yeasts. Further modification of the S. cerevisiae metabolic network was necessary to satisfactorily predict the amount of acetate synthesized during HMF reduction. Inhibitory terms that captured the adverse effects of the furan aldehydes and their corresponding alcohols on cell growth and ethanol production were added to attain qualitative agreement with batch experiments conducted for model development and validation. When the two yeasts were co-cultured in the presence of the furan aldehydes, inoculums that reduced the synthesis of highly toxic acetate produced by S. cerevisiae yielded the highest ethanol productivities. The model described here can be used to generate optimal fermentation strategies for the simultaneous detoxification and fermentation of lignocellulosic hydrolysates by S. cerevisiae and/or S. stipitis.

  3. A Fast and Practical Yeast Transformation Method Mediated by Escherichia coli Based on a Trans-Kingdom Conjugal Transfer System: Just Mix Two Cultures and Wait One Hour.

    PubMed

    Moriguchi, Kazuki; Yamamoto, Shinji; Ohmine, Yuta; Suzuki, Katsunori

    2016-01-01

    Trans-kingdom conjugation is a phenomenon by which DNA is transferred into a eukaryotic cell by a bacterial conjugal transfer system. Improvement in this method to facilitate the rapid co-cultivation of donor bacterial and recipient eukaryotic cell cultures could make it the simplest transformation method, requiring neither isolation of vector DNA nor preparation of competent recipient cells. To evaluate this potential advantage of trans-kingdom conjugation, we examined this simple transformation method using vector combinations, helper plasmids, and recipient Saccharomyces cerevisiae strains. Mixing donor Escherichia coli and recipient S. cerevisiae overnight cultures (50 μL each) consistently yielded on the order of 10(1) transformants using the popular experimental strain BY4742 derived from S288c and a shuttle vector for trans-kingdom conjugation. Transformation efficiency increased to the order of 10(2) using a high receptivity trans-kingdom conjugation strain. In addition, either increasing the amount of donor cells or pretreating the recipient cells with thiols such as dithiothreitol improved the transformation efficiency by one order of magnitude. This simple trans-kingdom conjugation-mediated transformation method could be used as a practical yeast transformation method upon enrichment of available vectors and donor E. coli strains.

  4. Effects of mixing low amounts of orange peel (Citrus reticulata) with hydrocarbon-contaminated soil in solid culture to promote remediation.

    PubMed

    Roldán-Martín, A; Esparza-García, F; Calva-Calva, G; Rodríguez-Vázquez, R

    2006-01-01

    The effect of mixing low amounts of orange peel (Citrus reticulata) with a soil contaminated with hydrocarbons (58,000 mg kg(-1) soil) for promoting the soil remediation in solid culture was studied. The experimental design was established in solid culture at soil/orange (Citrus reticulata) peel ratios of 100:0, 98:2, 96:4, 94:6 and 92:8, at 30% humidity and a C:N:P ratio of 100:10:1, for 15, 60 and 90 days, respectively. The total petroleum hydrocarbons (TPHs) decreased significantly (69%) after 15 days in the treatment with a soil to orange peel ratio of 92:8. Furthermore, in this treatment bacterial counts increased from 17 to 20 ln CFU (2.6 x 10(6) to 5 x 10(8)), while the fungal count was 11 ln CFU (6.5 x 10(4)) at initial and final time of treatment. An increase in microbial respiration activity and TPH removal (69%) was observed at other soil/orange peel ratios after 60 days when moisture content and nutrients were adjusted; however, N and P were not consumed at a great extent. PMID:17018419

  5. Novel pH control strategy for efficient production of optically active l-lactic acid from kitchen refuse using a mixed culture system.

    PubMed

    Tashiro, Yukihiro; Inokuchi, Shota; Poudel, Pramod; Okugawa, Yuki; Miyamoto, Hirokuni; Miayamoto, Hisashi; Sakai, Kenji

    2016-09-01

    Uninvestigated control factors of meta-fermentation, the fermentative production of pure chemicals and fuels in a mixed culture system, were examined for production of optically pure l-lactic acid (LA) from food waste. In meta-fermentations by pH swing control, l-LA production with 100% optical purity (OPl-LA) was achieved even using unsterilized model kitchen refuse medium with preferential proliferation of l-LA-producing Bacillus coagulans, a minor member in the seed, whereas agitation decreased OPl-LA drastically. pH constant control shortened the fermentation time but decreased OPl-LA and LA selectivity (SLA) by stimulating growth of heterofermentative Bacillus thermoamylovorans. Deliberately switching from pH swing control to constant control exhibited the best performance for l-LA production: maximum accumulation, 39.2gL(-1); OPl-LA, 100%; SLA, 96.6%; productivity, 1.09gL(-1)h(-1). These results present a novel pH control strategy for efficient l-LA production in meta-fermentation based on a concept different from that of pure culture systems. PMID:27233097

  6. A Fast and Practical Yeast Transformation Method Mediated by Escherichia coli Based on a Trans-Kingdom Conjugal Transfer System: Just Mix Two Cultures and Wait One Hour.

    PubMed

    Moriguchi, Kazuki; Yamamoto, Shinji; Ohmine, Yuta; Suzuki, Katsunori

    2016-01-01

    Trans-kingdom conjugation is a phenomenon by which DNA is transferred into a eukaryotic cell by a bacterial conjugal transfer system. Improvement in this method to facilitate the rapid co-cultivation of donor bacterial and recipient eukaryotic cell cultures could make it the simplest transformation method, requiring neither isolation of vector DNA nor preparation of competent recipient cells. To evaluate this potential advantage of trans-kingdom conjugation, we examined this simple transformation method using vector combinations, helper plasmids, and recipient Saccharomyces cerevisiae strains. Mixing donor Escherichia coli and recipient S. cerevisiae overnight cultures (50 μL each) consistently yielded on the order of 10(1) transformants using the popular experimental strain BY4742 derived from S288c and a shuttle vector for trans-kingdom conjugation. Transformation efficiency increased to the order of 10(2) using a high receptivity trans-kingdom conjugation strain. In addition, either increasing the amount of donor cells or pretreating the recipient cells with thiols such as dithiothreitol improved the transformation efficiency by one order of magnitude. This simple trans-kingdom conjugation-mediated transformation method could be used as a practical yeast transformation method upon enrichment of available vectors and donor E. coli strains. PMID:26849654

  7. Novel pH control strategy for efficient production of optically active l-lactic acid from kitchen refuse using a mixed culture system.

    PubMed

    Tashiro, Yukihiro; Inokuchi, Shota; Poudel, Pramod; Okugawa, Yuki; Miyamoto, Hirokuni; Miayamoto, Hisashi; Sakai, Kenji

    2016-09-01

    Uninvestigated control factors of meta-fermentation, the fermentative production of pure chemicals and fuels in a mixed culture system, were examined for production of optically pure l-lactic acid (LA) from food waste. In meta-fermentations by pH swing control, l-LA production with 100% optical purity (OPl-LA) was achieved even using unsterilized model kitchen refuse medium with preferential proliferation of l-LA-producing Bacillus coagulans, a minor member in the seed, whereas agitation decreased OPl-LA drastically. pH constant control shortened the fermentation time but decreased OPl-LA and LA selectivity (SLA) by stimulating growth of heterofermentative Bacillus thermoamylovorans. Deliberately switching from pH swing control to constant control exhibited the best performance for l-LA production: maximum accumulation, 39.2gL(-1); OPl-LA, 100%; SLA, 96.6%; productivity, 1.09gL(-1)h(-1). These results present a novel pH control strategy for efficient l-LA production in meta-fermentation based on a concept different from that of pure culture systems.

  8. Effect of adsorbants on in vitro biohydrogenation of 22:6n-3 by mixed cultures of rumen microorganisms.

    PubMed

    Escobar, M; Vlaeminck, B; Jeyanathan, J; Thanh, L P; Shingfield, K J; Wallace, R J; Fievez, V

    2016-09-01

    Studies on microbial biohydrogenation of fatty acids in the rumen are of importance as this process lowers the availability of nutritionally beneficial unsaturated fatty acids for incorporation into meat and milk but also might result in the accumulation of biologically active intermediates. The impact was studied of adsorption of 22:6n-3 (DHA) to particulate material on its disappearance during 24 h in vitro batch incubations with rumen inoculum. Four adsorbants were used in two doses (1 and 5 mg/ml of mucin, gum arabic, bentonite or silicic acid). In addition, the distribution of 22:6n-3 in the pellet and supernatant of diluted rumen fluid was measured. Bentonite and silicic acid did not alter the distribution of 22:6n-3 between pellet and supernatant nor increased the disappearance of 22:6n-3 during the incubation. Both mucin and gum arabic increased the recovery of 22:6n-3 in the supernatant, indicating that these compounds lowered the adsorption of the fatty acid to ruminal particles. This was associated with an increased disappearance of 22:6n-3, when initial 22:6n-3 was 0.06 or 0.10 mg/ml, and an increased formation of 22:0, when initial 22:6n-3 was 0.02 mg/ml, during the 24 h batch culture experiment. Addition of gum arabic to pure cultures of Butyrivibrio fibrisolvens or Butyrivibrio proteoclasticus did not negate the inhibitory effect of 22:6n-3 on growth. As both mucin and gum arabic provide fermentable substrate for ruminal bacteria, an additional experiment was performed in which mucin and gum arabic were replaced by equal amounts of starch, cellulose or xylan. No differences in disappearance of 22:6n-3 were observed, suggesting that the stimulatory effect of mucin and gum arabic on disappearance of 22:6n-3 most probably is not due to provision of an alternative site of adsorption but related to stimulation of bacterial growth. A relatively high proportion of 22:6n-3 can be reduced to 22:0 provided the initial concentration is low.

  9. Effect of adsorbants on in vitro biohydrogenation of 22:6n-3 by mixed cultures of rumen microorganisms.

    PubMed

    Escobar, M; Vlaeminck, B; Jeyanathan, J; Thanh, L P; Shingfield, K J; Wallace, R J; Fievez, V

    2016-09-01

    Studies on microbial biohydrogenation of fatty acids in the rumen are of importance as this process lowers the availability of nutritionally beneficial unsaturated fatty acids for incorporation into meat and milk but also might result in the accumulation of biologically active intermediates. The impact was studied of adsorption of 22:6n-3 (DHA) to particulate material on its disappearance during 24 h in vitro batch incubations with rumen inoculum. Four adsorbants were used in two doses (1 and 5 mg/ml of mucin, gum arabic, bentonite or silicic acid). In addition, the distribution of 22:6n-3 in the pellet and supernatant of diluted rumen fluid was measured. Bentonite and silicic acid did not alter the distribution of 22:6n-3 between pellet and supernatant nor increased the disappearance of 22:6n-3 during the incubation. Both mucin and gum arabic increased the recovery of 22:6n-3 in the supernatant, indicating that these compounds lowered the adsorption of the fatty acid to ruminal particles. This was associated with an increased disappearance of 22:6n-3, when initial 22:6n-3 was 0.06 or 0.10 mg/ml, and an increased formation of 22:0, when initial 22:6n-3 was 0.02 mg/ml, during the 24 h batch culture experiment. Addition of gum arabic to pure cultures of Butyrivibrio fibrisolvens or Butyrivibrio proteoclasticus did not negate the inhibitory effect of 22:6n-3 on growth. As both mucin and gum arabic provide fermentable substrate for ruminal bacteria, an additional experiment was performed in which mucin and gum arabic were replaced by equal amounts of starch, cellulose or xylan. No differences in disappearance of 22:6n-3 were observed, suggesting that the stimulatory effect of mucin and gum arabic on disappearance of 22:6n-3 most probably is not due to provision of an alternative site of adsorption but related to stimulation of bacterial growth. A relatively high proportion of 22:6n-3 can be reduced to 22:0 provided the initial concentration is low. PMID:26965186

  10. Social, Cultural, and Environmental Challenges Faced by Children on Antiretroviral Therapy in Zimbabwe: a Mixed-Method Study

    PubMed Central

    Macherera, Margaret; Moyo, Lindani; Ncube, Mkhanyiseli; Gumbi, Angella

    2012-01-01

    Objectives Despite the advent of antiretroviral therapy (ART), many children, particularly in the rural communities of Zimbabwe, remain vulnerable. The purpose of this study was to determine the factors and challenges facing children on antiretroviral therapy (ART) in Brunapeg area of Mangwe District, Zimbabwe. Methods A mixed-method approach involving interviewer-guided focus group discussions and piloted semi-structured questionnaires was utilized to collect data from different key population groups. The data obtained were analyzed through content coding procedures based on a set of predetermined themes of interest. Results A number of challenges emerged as barriers to the success of antiretroviral therapy for children. Primary care givers were less informed about HIV and AIDS issues for people having direct impact on the success of antiretroviral therapy in children whilst some were found to be taking the antiretroviral drugs meant for the children. It also emerged that some primary care givers were either too young or too old to care for the children while others had failed to disclose to the children why they frequently visited the Opportunistic Infections (OI) clinic. Most primary care givers were not the biological parents of the affected children. Other challenges included inadequate access to health services, inadequate food and nutrition and lack of access to clean water, good hygiene and sanitation. The lack of community support and stigma and discrimination affected their school attendance and hospital visits. All these factors contributed to non-adherence to antiretroviral drugs. Conclusions and Public Health Implications Children on ART in rural communities in Zimbabwe remain severely compromised and have unique problems that need multi-intervention strategies both at policy and programmatic levels. Effective mitigating measures must be fully established and implemented in rural communities of developing countries in the fight for universal

  11. Growth of mono- and mixed cultures of Nannochloropsis salina and Phaeodactylum tricornutum on struvite as a nutrient source.

    PubMed

    Davis, Ryan W; Siccardi, Anthony J; Huysman, Nathan D; Wyatt, Nicholas B; Hewson, John C; Lane, Todd W

    2015-12-01

    The suitability of crude and purified struvite (MgNH4PO4), a major precipitate in wastewater streams, was investigated for renewable replacement of conventional nitrogen and phosphate resources for cultivation of microalgae. Bovine effluent wastewater stone, the source of crude struvite, was characterized for soluble N/P, trace metals, and biochemical components and compared to the purified mineral. Cultivation trials using struvite as a major nutrient source were conducted using two microalgae production strains, Nannochloropsis salina and Phaeodactylum tricornutum, in both lab and outdoor pilot-scale raceways in a variety of seasonal conditions. Both crude and purified struvite-based media were found to result in biomass productivities at least as high as established media formulations (maximum outdoor co-culture yield ∼20±4gAFDW/m(2)/day). Analysis of nutrient uptake by the alga suggest that struvite provides increased nutrient utilization efficiency, and that crude struvite satisfies the trace metals requirement and results in increased pigment productivity for both microalgae strains. PMID:26433155

  12. Asian couples in negotiation: a mixed-method observational study of cultural variations across five Asian regions.

    PubMed

    Lee, Wai-Yung; Nakamura, Shin-Ichi; Chung, Moon Ja; Chun, Young Ju; Fu, Meng; Liang, Shu-Chuan; Liu, Cui-Lian

    2013-09-01

    The purpose of this study was to explore variations in how contemporary couples from five different Asian regions negotiate disagreements. Video recordings of 50 couples (10 each from Japan, Korea, Mainland China, Taiwan, and Hong Kong) discussing unresolved disagreements provided raw data for quantitative and qualitative analyses. First, teams of coders from each region used a common protocol to make quantitative ratings of content themes and interaction patterns for couples from their own region. An interregional panel of investigators then performed in-depth qualitative reviews for half of these cases, noting cultural differences not only in observed patterns of couple behavior but also in their own perceptions of these patterns. Both quantitative and qualitative analyses revealed clear regional differences on dimensions such as overt negativity, demand-withdraw interaction, and collaboration. The qualitative results also provided a richer, more nuanced view of other (e.g., gender-linked) conflict management patterns that the quantitative analyses did not capture. Inconsistencies between qualitative and quantitative data and between the qualitative observations of investigators from different regions were most pronounced for couples from Korea and Japan, whose conflict styles were subtler and less direct than those of couples from the other regions. PMID:24033245

  13. Influence of cobalt concentration on vitamin B12 production and fermentation of mixed ruminal microorganisms grown in continuous culture flow-through fermentors.

    PubMed

    Tiffany, M E; Fellner, V; Spears, J W

    2006-03-01

    An experiment was conducted to determine the effects of dietary concentrations of Co on vitamin B12 production and fermentation of mixed ruminal microbes grown in continuous culture fermentors. Four fermentors were fed 14 g of DM/d. The DM consisted of a corn and cottonseed hull-based diet with Co supplemented as CoCO3. Dietary treatments were 1) control (containing 0.05 mg of Co/kg of DM), 2) 0.05 mg of supplemental Co/kg of DM, 3) 0.10 mg of supplemental Co/kg of DM, and 4) 1.0 mg of supplemental Co/kg of DM. After a 3-d adjustment period, fermentors were sampled over a 3-d sampling period. This process was repeated 2 additional times for a total of 3 runs. Ruminal fluid vitamin B12 concentrations were affected by Co supplementation (P < 0.01), and there was a treatment x day interaction (P < 0.01). By sampling d 3, cultures fed the basal diet supplemented with 0.10 mg of Co/kg had greater (P < 0.05) vitamin B12 concentrations than those supplemented with 0.05 mg of Co/kg of DM, and increasing supplemental Co from 0.10 to 1.0 mg/kg of DM increased (P < 0.01) ruminal fluid vitamin B12 concentration. Ruminal fluid succinate also was affected (P < 0.10) by a treatment x day interaction. Cobalt supplementation to the control diet greatly decreased (P < 0.05) succinate in ruminal cultures on sampling d 3 but not on d 1 or 2. Molar proportions of acetate, propionate, and isobutyrate, and acetate:propionate were not affected by the addition of supplemental Co to the basal diet. However, molar proportions of butyrate, valerate, and isovalerate increased (P < 0.05) in response to supplemental Co. The majority of long-chain fatty acids observed in this study were not affected by Co supplementation. However, percentages of C18:0 fatty acids in ruminal cultures tended (P < 0.10) to be greater for Co-supplemented diets relative to the control. Methane, ammonia, and pH were not greatly affected by Co supplementation. The results indicate that a total (diet plus supplemental

  14. Polyhydroxyalkanoate (PHA) storage within a mixed-culture biomass with simultaneous growth as a function of accumulation substrate nitrogen and phosphorus levels.

    PubMed

    Valentino, Francesco; Karabegovic, Lamija; Majone, Mauro; Morgan-Sagastume, Fernando; Werker, Alan

    2015-06-15

    The response of a mixed-microbial-culture (MMC) biomass for PHA accumulation was evaluated over a range of relative nitrogen (N) and phosphorus (P) availabilities with respect to the supply of either complex (fermented whey permeate - FWP) or simpler (acetic acid) organic feedstocks. Fed-batch feed-on-demand PHA accumulation experiments were conducted where the feed N/COD and P/COD ratios were varied ranging from conditions of nutrient starvation to excess. A feast-famine enrichment (activated sludge) biomass, produced in a pilot-scale aerobic sequencing batch reactor on FWP and with a long history of stable PHA accumulation performance, was used for all the experiments as reference material. FWP with N/COD ratios of (2, 5, 15, 70 mg/g all with P/COD = 8 mg/g) as well as simulated FWP with nutrient starvation (N/COD = P/COD = 0) conditions were applied. For the acetic acid accumulations, nutrient starvation as well as N/COD variations (2.5, 5, 50 mg/g all with P/COD = 9 mg/g) and P/COD variations (0.5, 2, 9, 15 mg/g all with N/COD = 10 mg/g) were evaluated. An optimal range of combined N and P limitation with N/COD from 2 to 15 mg/g and P/COD from 0.5 to 3 mg/g was considered to offer consistent improvement of productivity over the case of nutrient starvation. Productivity increased due to active biomass growth of the PHA storing biomass without observed risk for a growth response overtaking PHA storage activity. PHA production with respect to the initial active biomass was significantly higher even in cases of excess nutrient additions when compared to the cases of nutrient starvation. The 24-h PHA productivities were enhanced as much as 4-fold from a base value of 1.35 g-PHA per gram initial active biomass with respect nutrient starvation feedstock. With or without nutrient loading the biomass consistently accumulated similar and significant PHA (nominally 60% g-PHA/g-VSS). Based on results from replicate experiments some variability in the extant biomass maximum

  15. Polyhydroxyalkanoate (PHA) storage within a mixed-culture biomass with simultaneous growth as a function of accumulation substrate nitrogen and phosphorus levels.

    PubMed

    Valentino, Francesco; Karabegovic, Lamija; Majone, Mauro; Morgan-Sagastume, Fernando; Werker, Alan

    2015-06-15

    The response of a mixed-microbial-culture (MMC) biomass for PHA accumulation was evaluated over a range of relative nitrogen (N) and phosphorus (P) availabilities with respect to the supply of either complex (fermented whey permeate - FWP) or simpler (acetic acid) organic feedstocks. Fed-batch feed-on-demand PHA accumulation experiments were conducted where the feed N/COD and P/COD ratios were varied ranging from conditions of nutrient starvation to excess. A feast-famine enrichment (activated sludge) biomass, produced in a pilot-scale aerobic sequencing batch reactor on FWP and with a long history of stable PHA accumulation performance, was used for all the experiments as reference material. FWP with N/COD ratios of (2, 5, 15, 70 mg/g all with P/COD = 8 mg/g) as well as simulated FWP with nutrient starvation (N/COD = P/COD = 0) conditions were applied. For the acetic acid accumulations, nutrient starvation as well as N/COD variations (2.5, 5, 50 mg/g all with P/COD = 9 mg/g) and P/COD variations (0.5, 2, 9, 15 mg/g all with N/COD = 10 mg/g) were evaluated. An optimal range of combined N and P limitation with N/COD from 2 to 15 mg/g and P/COD from 0.5 to 3 mg/g was considered to offer consistent improvement of productivity over the case of nutrient starvation. Productivity increased due to active biomass growth of the PHA storing biomass without observed risk for a growth response overtaking PHA storage activity. PHA production with respect to the initial active biomass was significantly higher even in cases of excess nutrient additions when compared to the cases of nutrient starvation. The 24-h PHA productivities were enhanced as much as 4-fold from a base value of 1.35 g-PHA per gram initial active biomass with respect nutrient starvation feedstock. With or without nutrient loading the biomass consistently accumulated similar and significant PHA (nominally 60% g-PHA/g-VSS). Based on results from replicate experiments some variability in the extant biomass maximum

  16. [System construction of early warning for ecological security at cultural and natural heritage mixed sites and its application: a case study of Wuyishan Scenery District].

    PubMed

    You, Wei-Bin; He, Dong-Jin; Qin, De-Hua; Ji, Zhi-Rong; Wu, Li-Yun; Yu, Jian-An; Chen, Bing-Rong; Tan, Yong

    2014-05-01

    This paper proposed a new concept of ecological security for protection by a comprehensive analysis of the contents and standards of world heritage sites. A frame concept model named "Pressure-State-Control" for early warning of ecological security at world heritage mixed sites was constructed and evaluation indicators of this frame were also selected. Wuyishan Scenery District was chosen for a case study, which has been severely disturbed by natural and artificial factors. Based on the frame model of "Pressure-State-Control" and by employing extension analysis, the matter-element model was established to assess the ecological security status of this cultural and natural world heritage mixed site. The results showed that the accuracy of ecological security early warning reached 84%. Early warning rank was I level (no alert status) in 1997 and 2009, but that in 2009 had a higher possibility to convert into II level. Likewise, the early-warning indices of sensitive ranks were different between 1997 and 2009. Population density, population growth rate, area index for tea garden, cultivated land owned per capita, level of drought, and investment for ecological and environmental construction were the main limiting factors to hinder the development of ecological security from 2009 to future. In general, the status of Wuyishan Scenery District ecological security was relatively good and considered as no alert level, while risk conditions also existed in terms of a few early-warning indicators. We still need to pay more attention to serious alert indicators and adopt effective prevention and control measures to maintain a good ecological security status of this heritage site.

  17. Microbial bio-based plastics from olive-mill wastewater: Generation and properties of polyhydroxyalkanoates from mixed cultures in a two-stage pilot scale system.

    PubMed

    Ntaikou, I; Valencia Peroni, C; Kourmentza, C; Ilieva, V I; Morelli, A; Chiellini, E; Lyberatos, G

    2014-10-20

    The operational efficiency of a two stage pilot scale system for polyhydroxyalkanoates (PHAs) production from three phase olive oil mill wastewater (OMW) was investigated in this study. A mixed anaerobic, acidogenic culture derived from a municipal wastewater treatment plant, was used in the first stage, aiming to the acidification of OMW. The effluent of the first bioreactor that was operated in continuous mode, was collected in a sedimentation tank in which partial removal of the suspended solids was taking place, and was then forwarded to an aerobic reactor, operated in sequential batch mode under nutrient limitation. In the second stage an enriched culture of Pseudomonas sp. was used as initial inoculum for the production of PHAs from the acidified waste. Clarification of the acidified waste, using aluminium sulphate which causes flocculation and precipitation of solids, was also performed, and its effect on the composition of the acidified waste as well as on the yields and properties of PHAs was investigated. It was shown that clarification had no significant qualitative or quantitative effect on the primary carbon sources, i.e. short chain fatty acids and residual sugars, but only on the values of total suspended solids and total chemical oxygen demand of the acidified waste. The type and thermal characteristics of the produced PHAs were also similar for both types of feed. However the clarification of the waste seemed to have a positive impact on final PHAs yield, measured as gPHAs/100g of VSS, which reached up to 25%. Analysis of the final products via nuclear magnetic resonance spectroscopy revealed the existence of 3-hydroxybutyrate (3HB) and 3-hydroxyoctanoate (HO) units, leading to the conclusion that the polymer could be either a blend of P3HB and P3HO homopolymers or/and the 3HB-co-3HO co-polymer, an unusual polymer occurring in nature with advanced properties.

  18. Socioeconomic, cultural and behavioural features of prior and anticipated influenza vaccine uptake in urban and rural Pune district, India: a mixed-methods case study

    PubMed Central

    Kudale, Abhay; Purohit, Vidula Shridhar; Sundaram, Neisha; Schaetti, Christian; Weiss, Mitchell G

    2013-01-01

    Introduction Ensuring production capacity of efficacious vaccines for pandemic preparedness alone may not be sufficient for effective influenza control. Community willingness to accept the vaccine is also critical. Population acceptance must therefore be recognised as a major determinant of vaccine effectiveness, and the social, cultural and economic determinants of population acceptance require study for effective policy and action. Pune is a focus of pandemic influenza in India. The experience of the 2009/2010 pandemic in Pune, capacity for vaccine production and experience with vaccine use provide a unique opportunity to address key questions about an effective vaccine intervention strategy for influenza control in India. This study will examine the socioeconomic, cultural and behavioural determinants of anticipated acceptance of influenza vaccines among the urban and rural populations of Pune district. Additionally, community ideas about seasonal influenza and its distinction from pandemic influenza will be investigated. Proposed research also considers the influence of health professionals, policy makers and media professionals on the awareness, preference and use of influenza vaccines. Methods and analysis This is a mixed-methods study including urban and rural community surveys, in-depth interviews with health professionals, case studies at two hospitals where suspected influenza cases were referred during the pandemic and in-depth interviews with media professionals and public health policy makers. Ethics and dissemination This protocol was approved by the ethics review committees of the Maharashtra Association of Anthropological Sciences and the WHO, and by the Ethics Commission of Basel, Switzerland. The proposed research will provide a better understanding of communication and education needs for vaccine action for influenza control in India and other low-income and middle-income countries. The findings and the approach for health social science research

  19. Effect of Feeding a Mixed Microbial Culture Fortified with Trace Minerals on the Performance and Carcass Characteristics of Late-fattening Hanwoo Steers: A Field Study.

    PubMed

    Kwak, W S; Kim, Y I; Lee, S M; Lee, Y H; Choi, D Y

    2015-11-01

    This study was conducted to determine the effects of feeding a trace minerals-fortified microbial culture (TMC) on the performance and carcass characteristics of late-fattening Hanwoo steers. A mixture of microbes (0.6% [v/w] of Enterobacter sp., Bacillus sp., Lactobacillus sp., and Saccharomyces sp.) was cultured with 99% feedstuff for ensiling and 0.4% trace minerals (zinc, selenium, copper, and cobalt). Sixteen late-fattening steers (mean age, 21.8 months) were allocated to two diets: a control diet (concentrate mix and rice straw) and a treated diet (control diet+3.3% TMC). At a mean age of 31.1 months, all the steers were slaughtered. The addition of TMC to the diet did not affect the average daily weight gain of the late fattening steers, compared with that of control steers. Moreover, consuming the TMC-supplemented diet did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, consumption of a TMC-supplemented diet increased the concentrations of zinc, selenium, and sulfur (p<0.05) in the longissimus muscle. With respect to amino acids, animals consuming TMC showed increased (p<0.05) concentrations of lysine, leucine, and valine among essential amino acids and a decreased (p<0.05) concentration of proline among non-essential amino acids. In conclusion, the consumption of a TMC-supplemented diet during the late-fattening period elevated the concentrations of certain trace minerals and essential amino acids in the longissimus muscle, without any deleterious effects on performance and other carcass characteristics of Hanwoo steers. PMID:26580283

  20. Effect of Feeding a Mixed Microbial Culture Fortified with Trace Minerals on the Performance and Carcass Characteristics of Late-fattening Hanwoo Steers: A Field Study

    PubMed Central

    Kwak, W. S.; Kim, Y. I.; Lee, S. M.; Lee, Y. H.; Choi, D. Y.

    2015-01-01

    This study was conducted to determine the effects of feeding a trace minerals-fortified microbial culture (TMC) on the performance and carcass characteristics of late-fattening Hanwoo steers. A mixture of microbes (0.6% [v/w] of Enterobacter sp., Bacillus sp., Lactobacillus sp., and Saccharomyces sp.) was cultured with 99% feedstuff for ensiling and 0.4% trace minerals (zinc, selenium, copper, and cobalt). Sixteen late-fattening steers (mean age, 21.8 months) were allocated to two diets: a control diet (concentrate mix and rice straw) and a treated diet (control diet+3.3% TMC). At a mean age of 31.1 months, all the steers were slaughtered. The addition of TMC to the diet did not affect the average daily weight gain of the late fattening steers, compared with that of control steers. Moreover, consuming the TMC-supplemented diet did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, consumption of a TMC-supplemented diet increased the concentrations of zinc, selenium, and sulfur (p<0.05) in the longissimus muscle. With respect to amino acids, animals consuming TMC showed increased (p<0.05) concentrations of lysine, leucine, and valine among essential amino acids and a decreased (p<0.05) concentration of proline among non-essential amino acids. In conclusion, the consumption of a TMC-supplemented diet during the late-fattening period elevated the concentrations of certain trace minerals and essential amino acids in the longissimus muscle, without any deleterious effects on performance and other carcass characteristics of Hanwoo steers. PMID:26580283

  1. Comparative analysis of the chemical composition of mixed and pure cultures of green algae and their decomposed residues by C nuclear magnetic resonance spectroscopy.

    PubMed

    Zelibor, J L; Romankiw, L; Hatcher, P G; Colwell, R R

    1988-04-01

    It is known that macromolecular organic matter in aquatic environments, i.e., humic substances, is highly aliphatic. These aliphatic macromolecules, predominantly paraffinic in structure, are prevalent in marine and lacustrine sediments and are believed to originate from algae or bacteria. A comparative study of mixed and pure cultures of green algae and their decomposed residues was performed by using solid-state C nuclear magnetic resonance spectroscopy as the primary analytical method. Results obtained in this study confirm the presence of components that are chemically refractory and that are defined as alghumin and hydrolyzed alghumin. These were detected in heterogeneous, homogeneous, and axenic biomasses composed of several genera of Chlorophyta. Although the chemical composition of algal biomass varied with culture conditions, the chemical structure of the alghumin and hydrolyzed alghumin, demonstrated by C nuclear magnetic resonance spectroscopy appeared to be constant for members of the Chlorophyta examined in this study. The alghumin was dominated by carbohydrate-carbon, with minor amounts of amide or carboxyl carbon and paraffinic carbon, the latter surviving strong hydrolysis by 6 N HCI (hydrolyzed alghumin). Bacterial decomposition of heterogeneous algal biomass labeled with C was conducted under both aerobic and anaerobic conditions to determine chemical structure and stability of the refractory material. The refractory fraction ranged from 33% in aerobic to 44% in anaerobic cultures. The refractory fraction recovered from either aerobic or anaerobic degradation comprised 40% alghumin, which represented an enrichment by 10% relative to the proportion of alghumin derived from whole cells of algae. The paraffinic component in the hydrolyzed alghumin of whole algal cells was found to be 1.8% and increased to 5.1 and 6.9% after aerobic and anaerobic bacterial degradation, respectively. It is concluded that members of the Chlorophyta contain a common

  2. Effects of carbon sources on the enrichment of halophilic polyhydroxyalkanoate-storing mixed microbial culture in an aerobic dynamic feeding process

    PubMed Central

    Cui, You-Wei; Zhang, Hong-Yu; Lu, Peng-Fei; Peng, Yong-Zhen

    2016-01-01

    Microbial polyhydroxyalkanoate (PHA) production serves as a substitute for petroleum-based plastics. Enriching mixed microbial cultures (MMCs) with the capacity to store PHA is a key precursor for low-cost PHA production. This study investigated the impact of carbon types on enrichment outcomes. Three MMCs were separately fed by acetate sodium, glucose, and starch as an enriching carbon source, and were exposed to long-term aerobic dynamic feeding (ADF) periods. The PHA production capacity, kinetics and stoichiometry of the enrichments, the PHA composition, and the microbial diversity and community composition were explored to determine carbon and enrichment correlations. After 350-cycle enriching periods under feast-famine (F-F) regimes, the MMCs enriched by acetate sodium and glucose contained a maximum PHA content of 64.7% and 60.5% cell dry weight (CDW). The starch-enriched MMC only had 27.3% CDW of PHA. High-throughput sequencing revealed that non-PHA bacteria survived alongside PHA storing bacteria, even under severe F-F selective pressure. Genus of Pseudomonas and Stappia were the possible PHA accumulating bacteria in acetate-enriched MMC. Genus of Oceanicella, Piscicoccus and Vibrio were found as PHA accumulating bacteria in glucose-enriched MMC. Vibrio genus was the only PHA accumulating bacteria in starch-enriched MMC. The community diversity and composition were regulated by the substrate types. PMID:27485896

  3. The response of phosphine-resistant lesser grain borer Rhyzopertha dominica and rice weevil Sitophilus oryzae in mixed-age cultures to varying concentrations of phosphine.

    PubMed

    Rajendran, Somiahnadar; Gunasekaran, Nagamuthu

    2002-03-01

    The response of Rhyzopertha dominica and Sitophilus oryzae (both phosphine-resistant) in mixed-age cultures to phosphine at fixed concentration-time products (CT) of 10,500 to 168,000 microliters litre 1 h (ppm h) with either constant, rising or falling concentrations for 7 days was studied at 27 (+/- 2) degrees C. At lower CT products, rising concentrations of phosphine led to significantly fewer survivors of R dominica and S oryzae. Conversely, exposure to falling concentrations of phosphine resulted in significantly more survivors. The influence of changing concentrations of phosphine was more pronounced in S oryzae than in R dominica. In the latter, at the lower CT products of 21,000 and 42,000 microliters-1 h, the adult stage proved to be most tolerant, contrary to the accepted belief that the egg or pupal stage are always more tolerant to phosphine. The results indicate that application of phosphine in rising concentrations is more effective than in constant or falling concentrations.

  4. Influence of the Endogenous Storage Lipid Poly-β-Hydroxybutyrate on the Reducing Power Availability during Cometabolism of Trichloroethylene and Naphthalene by Resting Methanotrophic Mixed Cultures

    PubMed Central

    Henrysson, Tomas; McCarty, Perry L.

    1993-01-01

    The role of the storage lipid poly-β-hydroxybutyrate (PHB) in trichloroethylene transformation by methanotrophic mixed cultures was investigated. Naphthalene oxidation rates were used to assay for soluble methane monooxygenase activity. The PHB content of methanotrophic cells grown in reactors varied diurnally as well as from day to day. A positive correlation between the amount of PHB in the cells and the naphthalene oxidation rate as well as between PHB and the trichloroethylene transformation rate and capacity was found. Addition of β-hydroxybutyrate increased the naphthalene oxidation rates significantly. PHB content in cells could be manipulated by incubation at different methane-to-nitrogen ratios. A positive correlation between the naphthalene oxidation rate and the PHB content after these incubations could be seen. Both the PHB content and the naphthalene oxidation rates decreased with time in resting methanotrophic cells exposed to oxygen. However, this decrease in the naphthalene oxidation rate cannot be explained by the decrease in the PHB content alone. Probably a deactivation of the methane monooxygenase itself is also involved. PMID:16348940

  5. Comparison of Different Strategies for Selection/Adaptation of Mixed Microbial Cultures Able to Ferment Crude Glycerol Derived from Second-Generation Biodiesel.

    PubMed

    Varrone, C; Heggeset, T M B; Le, S B; Haugen, T; Markussen, S; Skiadas, I V; Gavala, H N

    2015-01-01

    Objective of this study was the selection and adaptation of mixed microbial cultures (MMCs), able to ferment crude glycerol generated from animal fat-based biodiesel and produce building-blocks and green chemicals. Various adaptation strategies have been investigated for the enrichment of suitable and stable MMC, trying to overcome inhibition problems and enhance substrate degradation efficiency, as well as generation of soluble fermentation products. Repeated transfers in small batches and fed-batch conditions have been applied, comparing the use of different inoculum, growth media, and Kinetic Control. The adaptation of activated sludge inoculum was performed successfully and continued unhindered for several months. The best results showed a substrate degradation efficiency of almost 100% (about 10 g/L glycerol in 21 h) and different dominant metabolic products were obtained, depending on the selection strategy (mainly 1,3-propanediol, ethanol, or butyrate). On the other hand, anaerobic sludge exhibited inactivation after a few transfers. To circumvent this problem, fed-batch mode was used as an alternative adaptation strategy, which led to effective substrate degradation and high 1,3-propanediol and butyrate production. Changes in microbial composition were monitored by means of Next Generation Sequencing, revealing a dominance of glycerol consuming species, such as Clostridium, Klebsiella, and Escherichia.

  6. Comparison of Different Strategies for Selection/Adaptation of Mixed Microbial Cultures Able to Ferment Crude Glycerol Derived from Second-Generation Biodiesel

    PubMed Central

    Varrone, C.; Heggeset, T. M. B.; Le, S. B.; Haugen, T.; Markussen, S.; Skiadas, I. V.; Gavala, H. N.

    2015-01-01

    Objective of this study was the selection and adaptation of mixed microbial cultures (MMCs), able to ferment crude glycerol generated from animal fat-based biodiesel and produce building-blocks and green chemicals. Various adaptation strategies have been investigated for the enrichment of suitable and stable MMC, trying to overcome inhibition problems and enhance substrate degradation efficiency, as well as generation of soluble fermentation products. Repeated transfers in small batches and fed-batch conditions have been applied, comparing the use of different inoculum, growth media, and Kinetic Control. The adaptation of activated sludge inoculum was performed successfully and continued unhindered for several months. The best results showed a substrate degradation efficiency of almost 100% (about 10 g/L glycerol in 21 h) and different dominant metabolic products were obtained, depending on the selection strategy (mainly 1,3-propanediol, ethanol, or butyrate). On the other hand, anaerobic sludge exhibited inactivation after a few transfers. To circumvent this problem, fed-batch mode was used as an alternative adaptation strategy, which led to effective substrate degradation and high 1,3-propanediol and butyrate production. Changes in microbial composition were monitored by means of Next Generation Sequencing, revealing a dominance of glycerol consuming species, such as Clostridium, Klebsiella, and Escherichia. PMID:26509171

  7. Effects of carbon sources on the enrichment of halophilic polyhydroxyalkanoate-storing mixed microbial culture in an aerobic dynamic feeding process

    NASA Astrophysics Data System (ADS)

    Cui, You-Wei; Zhang, Hong-Yu; Lu, Peng-Fei; Peng, Yong-Zhen

    2016-08-01

    Microbial polyhydroxyalkanoate (PHA) production serves as a substitute for petroleum-based plastics. Enriching mixed microbial cultures (MMCs) with the capacity to store PHA is a key precursor for low-cost PHA production. This study investigated the impact of carbon types on enrichment outcomes. Three MMCs were separately fed by acetate sodium, glucose, and starch as an enriching carbon source, and were exposed to long-term aerobic dynamic feeding (ADF) periods. The PHA production capacity, kinetics and stoichiometry of the enrichments, the PHA composition, and the microbial diversity and community composition were explored to determine carbon and enrichment correlations. After 350-cycle enriching periods under feast-famine (F-F) regimes, the MMCs enriched by acetate sodium and glucose contained a maximum PHA content of 64.7% and 60.5% cell dry weight (CDW). The starch-enriched MMC only had 27.3% CDW of PHA. High-throughput sequencing revealed that non-PHA bacteria survived alongside PHA storing bacteria, even under severe F-F selective pressure. Genus of Pseudomonas and Stappia were the possible PHA accumulating bacteria in acetate-enriched MMC. Genus of Oceanicella, Piscicoccus and Vibrio were found as PHA accumulating bacteria in glucose-enriched MMC. Vibrio genus was the only PHA accumulating bacteria in starch-enriched MMC. The community diversity and composition were regulated by the substrate types.

  8. Evaluating the efficiency of a mixed culture biofilm for the treatment of black liquor and molasses in a mediator-less microbial fuel cell.

    PubMed

    Ali, Naeem; Yousaf, Sameen; Anam, Maira; Bangash, Zain; Maleeha, Sehrish

    2016-11-01

    A microbial fuel cell (MFC) is an emerging environment-friendly technology to recover the useful energy available in waste by using microorganisms as catalyst. In this study, double chamber mediator-less MFCs separated by proton exchange membrane (PEM; Nafion) were constructed to determine the efficiency of mixed culture in using complex substrates (molasses and black liquor). It was found that activated sludge can serve as efficient source of electricigens for biofilm development on an anode. Power density of 2.425 W/m² was generated from molasses with chemical oxygen demand (COD) removal efficiency of 67% as compared to power density of 3.55 W/m² produced from black liquor along with COD removal efficiency of 78%. Moreover, it was demonstrated that surface area of PEM has a significant effect on power generation. An almost 5- to 8-fold increase in voltage was observed as the size of PEM was increased from 6.5 to 25 cm².

  9. Effects of carbon sources on the enrichment of halophilic polyhydroxyalkanoate-storing mixed microbial culture in an aerobic dynamic feeding process.

    PubMed

    Cui, You-Wei; Zhang, Hong-Yu; Lu, Peng-Fei; Peng, Yong-Zhen

    2016-01-01

    Microbial polyhydroxyalkanoate (PHA) production serves as a substitute for petroleum-based plastics. Enriching mixed microbial cultures (MMCs) with the capacity to store PHA is a key precursor for low-cost PHA production. This study investigated the impact of carbon types on enrichment outcomes. Three MMCs were separately fed by acetate sodium, glucose, and starch as an enriching carbon source, and were exposed to long-term aerobic dynamic feeding (ADF) periods. The PHA production capacity, kinetics and stoichiometry of the enrichments, the PHA composition, and the microbial diversity and community composition were explored to determine carbon and enrichment correlations. After 350-cycle enriching periods under feast-famine (F-F) regimes, the MMCs enriched by acetate sodium and glucose contained a maximum PHA content of 64.7% and 60.5% cell dry weight (CDW). The starch-enriched MMC only had 27.3% CDW of PHA. High-throughput sequencing revealed that non-PHA bacteria survived alongside PHA storing bacteria, even under severe F-F selective pressure. Genus of Pseudomonas and Stappia were the possible PHA accumulating bacteria in acetate-enriched MMC. Genus of Oceanicella, Piscicoccus and Vibrio were found as PHA accumulating bacteria in glucose-enriched MMC. Vibrio genus was the only PHA accumulating bacteria in starch-enriched MMC. The community diversity and composition were regulated by the substrate types. PMID:27485896

  10. Effects of enzyme supplementation of a total mixed ration on microbial fermentation in continuous culture, maintained at high and low pH.

    PubMed

    Colombatto, D; Hervás, G; Yang, W Z; Beauchemin, K A

    2003-10-01

    A dual-flow continuous culture system was used to investigate the effects of pH and addition of an enzyme mixture to a total mixed ration (TMR) on fermentation, nutrient digestion, and microbial protein synthesis. A 4 x 4 Latin square design with a factorial arrangement of treatments was used, with four 9-d periods consisting of 6 d for adaptation and 3 d for measurements. Treatments were as follows: 1) high pH with control TMR, 2) high pH with TMR treated with enzyme, 3) low pH with control TMR, and 4) low pH with TMR treated with enzyme. Ranges of pH were 6.0 to 6.6 and 5.4 to 6.0 for high and low, respectively. Fermenters were fed twice daily a TMR consisting of 30% alfalfa hay, 30% corn silage, and 40% rolled corn (DM basis). The silage was milled fresh and the TMR was fed to the fermenters in fresh form (64% DM). The enzyme mixture was a commercial product of almost exclusive protease activity; it was applied daily to the fresh TMR and stored at 4 degrees C for at least 12 h before feeding. Degradability of OM, NDF, ADF, and cellulose was decreased (P < 0.05) by low pH. Hemicellulose and protein degradation were not affected by pH. Enzyme addition increased (P < 0.01) NDF degradability (by 43% and 25% at high and low pH, respectively), largely as a result of an increase in hemicellulose degradation (by 79% and 51% at high and low pH, respectively). This improvement was supported by an increase (P < 0.05) in the xylanase and cellulase activities in the liquid phase of the fermenter contents. Total VFA were decreased (P < 0.05) by low pH, but were not affected by enzyme addition. Total bacterial numbers were increased (P < 0.03) at low pH and tended (P < 0.13) to increase with enzyme addition. Cellulolytic bacteria in effluent fluid were decreased (P < 0.02) at low pH but were unaffected by enzyme addition. Despite a large increase (P < 0.001) in protease activity, protein degradation was only numerically increased by enzyme addition. Microbial protein synthesis

  11. Role of fluid mixing and fault-related sulfide in the origin of the Ray Point uranium district, south Texas.

    USGS Publications Warehouse

    Goldhaber, M.B.; Reynolds, R.L.; Rye, R.O.

    1983-01-01

    The Lamprecht and Felder deposits are two of many roll-type uranium deposits hosted by the Miocene Oakville sandstone in the Ray Point district, Live Oak County, S Texas. Both deposits show similar patterns of geochemical zonation and distribution of authigenic iron disulphide minerals, and both appear to be genetically related to the nearby Oakville fault. Distribution of U, Mo and Se are typical of roll-type deposits. Sulphur isotope data indicate four stages of FeS2 mineral formation. Geochemical data suggest that the host sandstone near the Oakville fault is the site of a complex zone of mixing between fault-derived saline brines and oxygenated meteoric water. Conditions were thus provided in this zone for the proliferation of sulphate-reducing bacteria that in turn gave rise to the ore mineralization. A detailed discussion of the geological evolution of these deposits is presented.-J.E.S.

  12. Measurement tools and process indicators of patient safety culture in primary care. A mixed methods study by the LINNEAUS collaboration on patient safety in primary care

    PubMed Central

    Parker, Dianne; Wensing, Michel; Esmail, Aneez; Valderas, Jose M

    2015-01-01

    ABSTRACT Background: There is little guidance available to healthcare practitioners about what tools they might use to assess the patient safety culture. Objective: To identify useful tools for assessing patient safety culture in primary care organizations in Europe; to identify those aspects of performance that should be assessed when investigating the relationship between safety culture and performance in primary care. Methods: Two consensus-based studies were carried out, in which subject matter experts and primary healthcare professionals from several EU states rated (a) the applicability to their healthcare system of several existing safety culture assessment tools and (b) the appropriateness and usefulness of a range of potential indicators of a positive patient safety culture to primary care settings. The safety culture tools were field-tested in four countries to ascertain any challenges and issues arising when used in primary care. Results: The two existing tools that received the most favourable ratings were the Manchester patient safety framework (MaPsAF primary care version) and the Agency for healthcare research and quality survey (medical office version). Several potential safety culture process indicators were identified. The one that emerged as offering the best combination of appropriateness and usefulness related to the collection of data on adverse patient events. Conclusion: Two tools, one quantitative and one qualitative, were identified as applicable and useful in assessing patient safety culture in primary care settings in Europe. Safety culture indicators in primary care should focus on the processes rather than the outcomes of care. PMID:26339832

  13. Addition of potassium carbonate to continuous cultures of mixed ruminal bacteria shifts volatile fatty acids and daily production of biohydrogenation intermediates.

    PubMed

    Jenkins, T C; Bridges, W C; Harrison, J H; Young, K M

    2014-02-01

    A recent study reported a 0.4 percentage unit increase in milk fat of lactating dairy cattle when dietary K was increased from 1.2 to 2% with potassium carbonate. Because milk fat yield has been associated with ruminal production of certain conjugated linoleic acid (CLA) isomers, 2 studies were conducted to determine if increasing potassium carbonate in the rumen would alter patterns of fermentation and biohydrogenation. In experiment 1, 5 dual-flow continuous fermenters were injected just before each feeding with a 10% (wt/wt) stock potassium carbonate solution to provide the equivalent of 1.1 (K1), 2.2 (K2), and 3.3 (K3) % of diet dry matter (DM) as added K. One of the remaining fermenters received no K (K0) and the last fermenter (NaOH) was injected with adequate NaOH stock solution (10%, wt/wt) to match the pH observed for the K3 treatment. For experiment 2, 6 dual-flow continuous fermenters were used to evaluate 6 treatments arranged in a 2 × 3 factorial to examine 2 levels of soybean oil (0 and 3.64% of diet DM) and added K at 0, 1.6, and 3.3% of diet DM. In both experiments, fermenters were fed 55 to 57 g of DM/d of a typical dairy diet consisting of 1:1 forage (10% alfalfa hay and 90% corn silage) to concentrate mix in 2 equal portions at 0800 and 1630 h, and fed the respective diets for 10-d periods. Potassium carbonate addition increased pH in both experiments. Acetate:propionate ratio and pH in experiment 1 increased linearly for K0 to K3. Acetate:propionate ratio was lower for NaOH compared with K3 but the pH was the same. The trans-11 18:1 and cis-9,trans-11 CLA production rates (mg/d) increased linearly from K0 to K3, but K3 and NaOH did not differ. Production of trans-10 18:1 decreased and that of trans-10,cis-12 tended to decrease from K0 to K3, but production of trans-10,cis-12 CLA remained high for NaOH. Addition of K to the cultures in experiment 2 decreased propionate and increased acetate and acetate:propionate ratio for the 0% fat diet but

  14. Integrating Mixed Method Data in Psychological Research: Combining Q Methodology and Questionnaires in a Study Investigating Cultural and Psychological Influences on Adolescent Sexual Behavior

    ERIC Educational Resources Information Center

    Franz, Anke; Worrell, Marcia; Vögele, Claus

    2013-01-01

    In recent years, combining quantitative and qualitative research methods in the same study has become increasingly acceptable in both applied and academic psychological research. However, a difficulty for many mixed methods researchers is how to integrate findings consistently. The value of using a coherent framework throughout the research…

  15. Anaerobic thermophilic culture system

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A mixed culture system of the newly discovered microorganism Thermoanaerobacter ethanolicus ATCC31550 and the microorganism Clostridium thermocellum ATCC31549 is described. In a mixed nutrient culture medium that contains cellulose, these microorganisms have been coupled and cultivated to efficiently ferment cellulose to produce recoverable quantities of ethanol under anaerobic, thermophilic conditions.

  16. Characterization of the Community Structure of a Dechlorinating Mixed Culture and Comparisons of Gene Expression in Planktonic and Biofloc-Associated “Dehalococcoides” and Methanospirillum Species▿ †

    PubMed Central

    Rowe, Annette R.; Lazar, Brendan J.; Morris, Robert M.; Richardson, Ruth E.

    2008-01-01

    This study sought to characterize bacterial and archaeal populations in a perchloroethene- and butyrate-fed enrichment culture containing hydrogen-consuming “Dehalococcoides ethenogenes” strain 195 and a Methanospirillum hungatei strain. Phylogenetic characterization of this microbial community was done via 16S rRNA gene clone library and gradient gel electrophoresis analyses. Fluorescence in situ hybridization was used to quantify populations of “Dehalococcoides” and Archaea and to examine the colocalization of these two groups within culture bioflocs. A technique for enrichment of planktonic and biofloc-associated biomass was developed and used to assess differences in population distribution and gene expression patterns following provision of substrate. On a per-milliliter-of-culture basis, most D. ethenogenes genes (the hydrogenase gene hupL; the highly expressed gene for an oxidoreductase of unknown function, fdhA; the RNA polymerase subunit gene rpoB; and the 16S rRNA gene) showed no statistical difference in expression between planktonic and biofloc enrichments at either time point studied (1 to 2 and 6 h postfeeding). Normalization of transcripts to ribosome (16S rRNA) levels supported that planktonic and biofloc-associated D. ethenogenes had similar gene expression profiles, with one notable exception; planktonic D. ethenogenes showed higher expression of tceA relative to biofloc-associated cells at 6 h postfeeding. These trends were compared to those for the hydrogen-consuming methanogen in the culture, M. hungatei. The vast majority of M. hungatei cells, ribosomes (16S rRNA), and transcripts of the hydrogenase gene mvrD and the housekeeping gene rpoE were observed in the biofloc enrichments. This suggests that, unlike the comparable activity of D. ethenogenes from both enrichments, planktonic M. hungatei is responsible for only a small fraction of the hydrogenotrophic methanogenesis in this culture. PMID:18776027

  17. Characterization of the community structure of a dechlorinating mixed culture and comparisons of gene expression in planktonic and biofloc-associated "Dehalococcoides" and Methanospirillum species.

    PubMed

    Rowe, Annette R; Lazar, Brendan J; Morris, Robert M; Richardson, Ruth E

    2008-11-01

    This study sought to characterize bacterial and archaeal populations in a perchloroethene- and butyrate-fed enrichment culture containing hydrogen-consuming "Dehalococcoides ethenogenes" strain 195 and a Methanospirillum hungatei strain. Phylogenetic characterization of this microbial community was done via 16S rRNA gene clone library and gradient gel electrophoresis analyses. Fluorescence in situ hybridization was used to quantify populations of "Dehalococcoides" and Archaea and to examine the colocalization of these two groups within culture bioflocs. A technique for enrichment of planktonic and biofloc-associated biomass was developed and used to assess differences in population distribution and gene expression patterns following provision of substrate. On a per-milliliter-of-culture basis, most D. ethenogenes genes (the hydrogenase gene hupL; the highly expressed gene for an oxidoreductase of unknown function, fdhA; the RNA polymerase subunit gene rpoB; and the 16S rRNA gene) showed no statistical difference in expression between planktonic and biofloc enrichments at either time point studied (1 to 2 and 6 h postfeeding). Normalization of transcripts to ribosome (16S rRNA) levels supported that planktonic and biofloc-associated D. ethenogenes had similar gene expression profiles, with one notable exception; planktonic D. ethenogenes showed higher expression of tceA relative to biofloc-associated cells at 6 h postfeeding. These trends were compared to those for the hydrogen-consuming methanogen in the culture, M. hungatei. The vast majority of M. hungatei cells, ribosomes (16S rRNA), and transcripts of the hydrogenase gene mvrD and the housekeeping gene rpoE were observed in the biofloc enrichments. This suggests that, unlike the comparable activity of D. ethenogenes from both enrichments, planktonic M. hungatei is responsible for only a small fraction of the hydrogenotrophic methanogenesis in this culture. PMID:18776027

  18. Occurrence and activity of sulphate reducing bacteria in aerobic activated sludge systems.

    PubMed

    van den Brand, T P H; Roest, K; Chen, G H; Brdjanovic, D; van Loosdrecht, M C M

    2015-03-01

    In the sewage or wastewater treatment plant, biological sulphate reduction can occur spontaneously or be applied beneficially for its treatment. The results of this study can be applied to control SRB in the sewage and WWTP. Therefore, population diversity analyses of SRB for nine activated sludge wastewater treatment plants (WWTP) in the Netherlands and the effect of long-term (months) oxygen exposures on the SRB activity were carried out. T-RFLP and clone sequencing analyses of winter and summer samples revealed that (1) all WWTP have a similar SRB population, (2) there is no seasonal impact (10-20 °C) on the SRB population present in the WWTP and (3) Desulfobacter postgatei, Desulfovibrio desulfuricans and Desulfovibrio intestinalis were the most common and dominant SRB species observed in these samples, and origin from the sewage. Short term activity tests demonstrated that SRB were not active in the aerobic WWTP, but while flushed with N2-gas SRB became slightly active after 3 h. In a laboratory reactor at a dissolved oxygen concentration of <2 %, sulphate reduction occurred and 89 % COD removal was achieved. SRB grew in granules, in order to protect themselves for oxygen exposures. SRB are naturally present in aerobic WWTP, which is due to the formation of granules. PMID:25649202

  19. Biohydrogen production based on the evaluation of kinetic parameters of a mixed microbial culture using glucose and fruit-vegetable waste as feedstocks.

    PubMed

    Garcia-Peña, E I; Canul-Chan, M; Chairez, I; Salgado-Manjarez, E; Aranda-Barradas, J

    2013-09-01

    Hydrogen (H2) production from the organic fraction of solid waste such as fruit and vegetable waste (FVW) is a novel and feasible energy technology. Continuous application of this process would allow for the simultaneous treatment of organic residues and energy production. In this study, batch experiments were conducted using glucose as substrate, and data of H2 production obtained were successfully adjusted by a logistic model. The kinetic parameters (μ max = 0.101 h(-1), K s = 2.56 g/L) of an H2-producing microbial culture determined by the Monod and Haldane-Andrews growth models were used to establish the continuous culture conditions. This strategy led to a productive steady state in continuous culture. Once the steady state was reached in the continuous reactor, a maximum H2 production of 700 mL was attained. The feasibility of producing H2 from the FVW obtained from a local market in Mexico City was also evaluated using batch conditions. The effect of the initial FVW concentration on the H2 production and waste organic material degradation was determined. The highest H2 production rate (1.7 mmol/day), the highest cumulative H2 volume (310 mL), and 25 % chemical oxygen demand (COD) removal were obtained with an initial substrate (FVW) concentration of 37 g COD/L. The lowest H2 production rates were obtained with relatively low initial substrate concentrations of 5 and 11 g COD/L. The H2 production rates with FVW were also characterized by the logistic model. Similar cumulative H2 production was obtained when glucose and FVW were used as substrates.

  20. Population dynamics in mixed cultures of Neochloris oleoabundans and native microalgae from water of a polluted river and isolation of a diatom consortium for the production of lipid rich biomass.

    PubMed

    Olguín, Eugenia Judith; Mendoza, Anilú; González-Portela, Ricardo E; Novelo, Eberto

    2013-09-25

    The production of biodiesel utilizing microalgae has driven innovation worldwide, especially trying to overcome the current economic and technological limitations of the whole process. Within these efforts, the use of wastewater to cultivate oleaginous microalgae or the use of dual-purpose microalgae-bacteria-based systems that treat wastewater and produce oleaginous microalgae have become an attractive alternative. The aim of this work was to evaluate the population dynamics which occurred in mixed cultures of Neochloris oleoabundans with other native microalgae, in mixtures of a synthetic medium (BBM) and water of an urban polluted river. The effect of temperature, nutrient availability and the microscopic monitoring of the population dynamics in such mixed cultures were carried out. Furthermore, the isolation of the predominant consortium of diatoms and the evaluation of its kinetics of growth and its capacity for removal of pollutants was also performed. Results indicated that such green microalgae only predominated in mixtures containing 80% or 60% of the synthetic medium. In mixtures containing a volume of the polluted river higher than 40%, other microalgae predominated, especially diatoms of various genera. The diatom consortium isolated from a 100% of the river's water sampled in spring (April), was formed mainly by a population of Nitzchia frustulum and in less extent of Navicula sp. It showed a significantly higher specific growth rate when cultivated in water from the river, compared to cultures in synthetic modified diatom medium (MDM) and at 32°C, compared to cultures incubated at 25°C. The consortium was able to remove 95.45% and 95.78% of ammonia nitrogen, 60% and 62.5% of nitrates at 32°C and 25°C, respectively, after 2 days. It also removed 95% of phosphates at 32°C and 67% at 25°C after 4 days from the polluted river. Diatoms also showed significant accumulation of lipids after 10 days of cultivation when stained with Sudan III. In

  1. Mixed heterolobosean and novel gregarine lineage genes from culture ATCC 50646: Long-branch artefacts, not lateral gene transfer, distort α-tubulin phylogeny.

    PubMed

    Cavalier-Smith, Thomas

    2015-04-01

    Contradictory and confusing results can arise if sequenced 'monoprotist' samples really contain DNA of very different species. Eukaryote-wide phylogenetic analyses using five genes from the amoeboflagellate culture ATCC 50646 previously implied it was an undescribed percolozoan related to percolatean flagellates (Stephanopogon, Percolomonas). Contrastingly, three phylogenetic analyses of 18S rRNA alone, did not place it within Percolozoa, but as an isolated deep-branching excavate. I resolve that contradiction by sequence phylogenies for all five genes individually, using up to 652 taxa. Its 18S rRNA sequence (GQ377652) is near-identical to one from stained-glass windows, somewhat more distant from one from cooling-tower water, all three related to terrestrial actinocephalid gregarines Hoplorhynchus and Pyxinia. All four protein-gene sequences (Hsp90; α-tubulin; β-tubulin; actin) are from an amoeboflagellate heterolobosean percolozoan, not especially deeply branching. Contrary to previous conclusions from trees combining protein and rRNA sequences or rDNA trees including Eozoa only, this culture does not represent a major novel deep-branching eukaryote lineage distinct from Heterolobosea, and thus lacks special significance for deep eukaryote phylogeny, though the rDNA sequence is important for gregarine phylogeny. α-Tubulin trees for over 250 eukaryotes refute earlier suggestions of lateral gene transfer within eukaryotes, being largely congruent with morphology and other gene trees. PMID:25769111

  2. Generation of T memory cells in one-way mixed lymphocyte culture. IV. Primary and secondary responses to soluble and insoluble membrane preparations and to ultraviolet-light-inactivated stimulator cells.

    PubMed

    Häyry, P; Anderson, L C

    1976-01-01

    Neither normal CBA (H-2k) nor purified spleen T cells respond in vitro to soluble or insoluble membrane preparations or to ultraviolet-light-inactivated stimulator cells of the allogeneic DBA/2 (H-2d) strain. However, CBA spleen cells deprived of phagocytic cells show a slight proliferative response under these conditions. After being primed against mitomycin-blocked DBA/2 cells in one-way mixed lymphocyte culture, the secondary blast-derived T 'memory' cells display a good secondary blast (proliferative) response to both membrane antigens and to ultraviolet-light-inactivated stimulator cells. In addition to this, the secondary T lymphocytes--in contrast to nonprimed T cells--respond by cytotoxicity when ultraviolet-light-inactivated cells are used as the second stimulant.

  3. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    PubMed

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%.

  4. Mixed Dementia

    MedlinePlus

    ... bodies , What Is Alzheimer's? NIA-Funded Memory & Aging Project Reveals Mixed Dementia Common Data from the first ... disease. For example, in the Memory and Aging Project study involving long-term cognitive assessments followed by ...

  5. Mixed oxide nanoparticles and method of making

    DOEpatents

    Lauf, Robert J.; Phelps, Tommy J.; Zhang, Chuanlun; Roh, Yul

    2002-09-03

    Methods and apparatus for producing mixed oxide nanoparticulates are disclosed. Selected thermophilic bacteria cultured with suitable reducible metals in the presence of an electron donor may be cultured under conditions that reduce at least one metal to form a doped crystal or mixed oxide composition. The bacteria will form nanoparticles outside the cell, allowing easy recovery. Selection of metals depends on the redox potentials of the reducing agents added to the culture. Typically hydrogen or glucose are used as electron donors.

  6. Multiplex real-time PCR and culture methods for detection of Shiga toxin-producing Escherichia coli and Salmonella Thompson in strawberries, a lettuce mix and basil.

    PubMed

    Delbeke, S; Ceuppens, S; Holvoet, K; Samuels, E; Sampers, I; Uyttendaele, M

    2015-01-16

    An appropriate approach of high throughput multi-screening was verified for Shiga toxin-producing Escherichia coli (STEC) and Salmonella spp. in strawberries, lettuce and basil. Sample replicates were inoculated with STEC O157 or O26 and Salmonella Thompson (ca. 10-70, 100-700 and 1000-7000 cfu/25 g) and analysed after 1 and 5 days of storage (strawberries and lettuce at 7 °C and basil at 10 °C). After 18-24 h of enrichment at 37 °C in buffered peptone water, detection was performed using the GeneDisc multiplex PCR (stx1, stx2, eae and iroB genes) and selective culture media for isolation of STEC (with immunomagnetic separation (IMS)) and Salmonella spp. in parallel. After 1 day, the pathogenic strains were recovered from all samples for all inoculum levels, whereas reduced detection rates of STEC O157 and S. Thompson were observed after 5 days of storage in case of strawberries, in particular for the lowest inoculums level, suggesting superior survival potential for STEC O26. Overall, this study indicates the ability of PCR based screening methods for reproducible multi-detection of low numbers (10-70 cfu/25 g) of STEC and Salmonella in this type of foods. However, for the basil samples, PCR needed twofold dilution of the DNA extract to overcome inhibition. It was noted that on several occasions growth of competitive microbiota obstructed finding presumptive colonies on the selective agar media, whereas the use of an additional agar medium such as CHROMagar STEC (without IMS) improved recovery rate of STEC. PMID:25462916

  7. Hydrogenotrophic culture enrichment reveals rumen Lachnospiraceae and Ruminococcaceae acetogens and hydrogen-responsive Bacteroidetes from pasture-fed cattle.

    PubMed

    Gagen, Emma J; Padmanabha, Jagadish; Denman, Stuart E; McSweeney, Christopher S

    2015-07-01

    Molecular information suggests that there is a broad diversity of acetogens in the rumen, distinct from any currently isolated acetogens. We combined molecular analysis with enrichment culture techniques to investigate this diversity further. Methane-inhibited, hydrogenotrophic enrichment cultures produced acetate as the dominant end product. Acetyl-CoA synthase gene analysis revealed putative acetogens in the cultures affiliated with the Lachnospiraceae and Ruminococcaceae as has been found in other rumen studies. No formyltetrahydrofolate synthetase genes affiliating with acetogens or with 'homoacetogen similarity' scores >90% were identified. To further investigate the hydrogenotrophic populations in these cultures and link functional gene information with 16S rRNA gene identity, cultures were subcultured quickly, twice, through medium without exogenous hydrogen, followed by incubation without exogenous hydrogen. Comparison of cultures lacking hydrogen and their parent cultures revealed novel Lachnospiraceae and Ruminococcaceae that diminished in the absence of hydrogen, supporting the hypothesis that they were likely the predominant acetogens in the enrichments. Interestingly, a range of Bacteroidetes rrs sequences that demonstrated <86% identity to any named isolate also diminished in cultures lacking hydrogen. Acetogens or sulphate reducers from the Bacteroidetes have not been reported previously; therefore this observation requires further investigation.

  8. Hydrogenotrophic culture enrichment reveals rumen Lachnospiraceae and Ruminococcaceae acetogens and hydrogen-responsive Bacteroidetes from pasture-fed cattle.

    PubMed

    Gagen, Emma J; Padmanabha, Jagadish; Denman, Stuart E; McSweeney, Christopher S

    2015-07-01

    Molecular information suggests that there is a broad diversity of acetogens in the rumen, distinct from any currently isolated acetogens. We combined molecular analysis with enrichment culture techniques to investigate this diversity further. Methane-inhibited, hydrogenotrophic enrichment cultures produced acetate as the dominant end product. Acetyl-CoA synthase gene analysis revealed putative acetogens in the cultures affiliated with the Lachnospiraceae and Ruminococcaceae as has been found in other rumen studies. No formyltetrahydrofolate synthetase genes affiliating with acetogens or with 'homoacetogen similarity' scores >90% were identified. To further investigate the hydrogenotrophic populations in these cultures and link functional gene information with 16S rRNA gene identity, cultures were subcultured quickly, twice, through medium without exogenous hydrogen, followed by incubation without exogenous hydrogen. Comparison of cultures lacking hydrogen and their parent cultures revealed novel Lachnospiraceae and Ruminococcaceae that diminished in the absence of hydrogen, supporting the hypothesis that they were likely the predominant acetogens in the enrichments. Interestingly, a range of Bacteroidetes rrs sequences that demonstrated <86% identity to any named isolate also diminished in cultures lacking hydrogen. Acetogens or sulphate reducers from the Bacteroidetes have not been reported previously; therefore this observation requires further investigation. PMID:26109360

  9. Biomass conversion to mixed alcohols

    SciTech Connect

    Holtzapple, M.T.; Loescher, M.; Ross, M.

    1996-10-01

    This paper discusses the MixAlco Process which converts a wide variety of biomass materials (e.g. municipal solid waste, sewage sludge, agricultural residues) to mixed alcohols. First, the biomass is treated with lime to enhance its digestibility. Then, a mixed culture of acid-forming microorganisms converts the lime-treated biomass to volatile fatty acids (VFA) such as acetic, propionic, and butyric acids. To maintain fermentor pH, a neutralizing agent (e.g. calcium carbonate or lime) is added, so the fermentation actually produces VFA salts such as calcium acetate, propionate, and butyrate. The VFA salts are recovered and thermally converted to ketones (e.g. acetone, methylethyl ketone, diethyl ketone) which are subsequently hydrogenated to mixed alcohols (e.g. isopropanol, isobutanol, isopentanol). Processing costs are estimated at $0.72/gallon of mixed alcohols making it potentially attractive for transportation fuels.

  10. [Mixed cryoglobulinemia].

    PubMed

    Roque, R; Ramiro, S; Vinagre, F; Cordeiro, A; Godinho, F; Santos, Maria José; Gonçalves, P; Canas da Silva, J

    2011-01-01

    The authors describe two clinical cases of cryoglobulinemia. A 70 years old woman, having skin ulcers on lower limbs, arthralgias, paresthesias and constitutional symptoms, for about 10 months. Exams revealed mild anemia, elevation of the biological parameters of inflammation and aminotransferases, positive cryoglobulin and rheumatoid factor in serum, and a severe reduction in C4 complement fraction. Hepatitis C virus (HCV) serology was negative. Idiopathic mixed cryoglobulinemia was diagnosed and corticosteroid therapy started. Given the lack of response, cyclophosphamide and plasmapheresis were added. Two weeks later the patient died in septic shock. The second case refers to a 41 years old female, with untreated hepatitis C who developed over a 6 month period petechiae and livedoid lesions on the lower limbs, peripheral neuropathy, and constitutional symptoms and was admitted with intestinal necrosis. Exams were consistent with the diagnosis of mixed cryoglobulinemia associated, with HCV. She started therapy with ribavirin and pegylated interferon-alpha, with improvement. PMID:22113605

  11. American Mixed Race. The Culture of Microdiversity.

    ERIC Educational Resources Information Center

    Zack, Naomi, Ed.

    This book presents a collection of papers on microdiversity that underscore the reality and scholarship of racial difference within single individuals and groups. The book includes 22 papers in 5 parts. Part 1, "Autobiography," includes: (1) "Five Arrows" (Susan Clements); (2) "Color Fades Over Time" (Brunetta R. Wolfman); (3) "Racelessness"…

  12. Transformative Paradigm: Mixed Methods and Social Justice

    ERIC Educational Resources Information Center

    Mertens, Donna M.

    2007-01-01

    The intersection of mixed methods and social justice has implications for the role of the researcher and choices of specific paradigmatic perspectives. The transformative paradigm with its associated philosophical assumptions provides a framework for addressing inequality and injustice in society using culturally competent, mixed methods…

  13. A mix of S and ΔS variants of STAT3 enable survival of activated B-cell-like diffuse large B-cell lymphoma cells in culture

    PubMed Central

    Zheng, M; Turton, K B; Zhu, F; Li, Y; Grindle, K M; Annis, D S; Lu, L; Drennan, A C; Tweardy, D J; Bharadwaj, U; Mosher, D F; Rui, L

    2016-01-01

    Activated B-cell-like diffuse large B-cell lymphoma (ABC DLBCL) is characterized by increased expression and activator of signal transducer and activator of transcription 3 (STAT3). ABC DLBCL cells require STAT3 for growth in culture. In ABC DLBCL cells, eosinophils and perhaps all cells, four variant STAT3 mRNAs (Sα, ΔSα, Sβ and ΔSβ) are present as a result of two alternative splicing events, one that results in the inclusion of a 55-residue C-terminal transactivation domain (α) or a truncated C-terminal domain with 7 unique residues (β) and a second that includes (S) or excludes (ΔS) the codon for Ser-701 in the linker between the SH2 and C-terminal domains. A substantial literature indicates that both α and β variants are required for optimal STAT3 function, but nothing is known about functions of ΔS variants. We used a knockdown/re-expression strategy to explore whether survival of ABC DLBCL cells requires that the four variants be in an appropriate ratio. No single variant rescued survival as well as STAT3Sα-C, Sα with activating mutations (A661C and N663C) in the SH2 domain. Better rescue was achieved when all four variants were re-expressed or Sα and ΔSα or Sβ and ΔSβ were re-expressed in pairs. Rescue correlated with expression of STAT3-sensitive genes NFKBIA and NFKBIZ. We consider a variety of explanations why a mix of S and ΔS variants of STAT3 should enable survival of ABC DLBCL cells. PMID:26727576

  14. Housing Mix, School Mix: Barriers to Success

    ERIC Educational Resources Information Center

    Camina, M. M.; Iannone, P.

    2014-01-01

    Recent UK policy has emphasised both the development of socially mixed communities and the creation of balanced school intakes. In this paper, we use a case study of an area of mixed tenure in eastern England to explore policy in practice and the extent to which mechanisms of segregation impact on both the creation of socially mixed neighbourhoods…

  15. Mixing and Transport.

    PubMed

    Chang, Chein-Chi; Chapman, Tom; Siverts-Wong, Elena; Wei, Li; Mei, Ying

    2016-10-01

    This section covers research published during the calendar year 2015 on mixing and transport processes. The review covers mixing of anaerobic digesters, mixing of heat transfer, and environmental fate and transport. PMID:27620101

  16. ACETOGENIC AND SULPHATE-REDUCING BACTERIA INHABITING THE RHIZOPLANE AND DEEP CORTEX CELLS OF THE SEAGRASS HALODULE WRIGHTII

    EPA Science Inventory

    Recent declines in sea grass distribution underscore the importance of understanding microbial community structure-function relationships in sea grass rhizosphere that might affect the viability of these plants. Phospholipid fatty acid analyses showed that sulfate-reducing bacter...

  17. Molecular survey of sulphate-reducing bacteria in the deep-sea sediments of the west Pacific Warm Pool

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Xiao, Xiang; Zhang, Haiyan; Wang, Fengping

    2008-08-01

    The sulfate-reducing bacteria (SRB) community in the deep-sea sediments of the west Pacific Warm Pool (WP) was surveyed by molecular phylogenetic analyses using primers targeting the 16S rRNA gene fragments of SRB. Specific 16S rRNA gene libraries from five sediment layers (1-cm, 3-cm, 6-cm, 10-cm and 12-cm layer) of the 12-cm core of WP-0 were constructed. The clones in the five libraries were differentiated by restriction fragment length polymorphism (RFLP) and representative clones were selected to sequence. It was found that the clones fell into four groups, which were closest related to Desulfotomaculum, Desulfacinum, Desulfomonile and Desulfanuticus. Desulfacinum-like clones were only detected in the upper layers of the sediment core, whereas Desulfomonile-like clones were only present in the deeper layers. Fluorescence in situ hybridization (FISH) was further carried out to visualize and count the SRB and bacteria in the five sediment layers. It was found that SRB constituted only a small proportion of the bacteria community (0.34% 1.95%), it had the highest content in the 3-cm layer (1.95%) and had a depth-related decreasing tendency along the 12-cm core.

  18. Enumeration of sulphate-reducing bacteria for assessing potential for hydrogen sulphide production in urban drainage systems.

    PubMed

    Karunakaran, Esther; Vernon, Dejan; Biggs, Catherine A; Saul, Adrian; Crawford, David; Jensen, Henriette

    2016-01-01

    Urban drainage structures have increasing demands which can lead to increasing hydrogen sulphide related problems forming in places where they have not previously been prevalent. This puts pressure on the methods currently used to monitor and diagnose these problems and more sophisticated methods may be needed for identifying the origin of the problems. Molecular microbiological techniques, such as quantitative polymerase chain reaction, offer a potential alternative for identifying and quantifying bacteria likely to be causing the production of hydrogen sulphide, information that, when combined with an appropriate sampling programme, can then be used to identify the potentially most effective remediation technique. The application of these methods in urban drainage systems is, however, not always simple, but good results can be achieved. In this study bacteria producing hydrogen sulphide were quantified in three small combined sewer overflow storage tanks. Bacterial counts were compared between wastewater, biofilms and sediments. Similar numbers were found in the wastewater and biofilms, with the numbers in the sediments being lower. If remediation methods for hydrogen sulphide are deemed necessary in the tanks, methods that target both the wastewater and the biofilms should therefore be considered. PMID:27332857

  19. Using a Mixed Methods Sequential Design to Identify Factors Associated with African American Mothers' Intention to Vaccinate Their Daughters Aged 9 to 12 for HPV with a Purpose of Informing a Culturally-Relevant, Theory-Based Intervention

    ERIC Educational Resources Information Center

    Cunningham, Jennifer L.

    2013-01-01

    The purpose of this sequential, explanatory mixed methods research study was to understand what factors influenced African American maternal intentions to get their daughters aged 9 years to 12 years vaccinated in Alabama. In the first, quantitative phase of the study, the research questions focused on identifying the predictive power of eleven…

  20. Mixed Heritage in Young Adult Literature. Scarecrow Studies in Young Adult Literature #32

    ERIC Educational Resources Information Center

    Reynolds, Nancy Thalia

    2009-01-01

    Mixed-heritage people are one of the fastest-growing groups in the United States, yet culturally they have been largely invisible, especially in young adult literature. "Mixed Heritage in Young Adult Literature" is a critical exploration of how mixed-heritage characters (those of mixed race, ethnicity, religion, and/or adoption) and real-life…

  1. Cultural Variations in Learning and Learning Styles

    ERIC Educational Resources Information Center

    Omidvar, Pegah; Tan, Bee Hoon

    2012-01-01

    The need for cross-cultural understanding of the relationship between culture and learning style is becoming increasingly important because of the changing cultural mix of classrooms and society at large. The research done regarding the two variables is mostly quantitative. This review summarizes results of the existing research on cultural…

  2. Urine culture

    MedlinePlus

    Culture and sensitivity - urine ... when urinating. You also may have a urine culture after you have been treated for an infection. ... when bacteria or yeast are found in the culture. This likely means that you have a urinary ...

  3. Endocervical culture

    MedlinePlus

    Vaginal culture; Female genital tract culture; Culture - cervix ... During a vaginal examination, the health care provider uses a ... fungus grow. Further tests may be done to identify the specific ...

  4. Stool Culture

    MedlinePlus

    ... Bacterial Culture, stool; Feces Culture Formal name: Enteric Pathogens Culture, stool Related tests: Ova and Parasite Exam , ... Shiga toxin-producing Escherichia coli , Widal Test , Gastrointestinal Pathogens Panel All content on Lab Tests Online has ...

  5. Fecal culture

    MedlinePlus

    Stool culture; Culture - stool ... stool tests are done in addition to the culture, such as: Gram stain of stool Fecal smear ... Giannella RA. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Feldman M, Friedman LS, Brandt LJ, ...

  6. A comparison of carbon/energy and complex nitrogen sources for bacterial sulphate-reduction: potential applications to bioprecipitation of toxic metals as sulphides.

    PubMed

    White, C; Gadd, G M

    1996-08-01

    Detailed nutrient requirements were determined to maximise efficacy of a sulphate-reducing bacterial mixed culture for biotechnological removal of sulphate, acidity and toxic metals from waste waters. In batch culture, lactate produced the greatest biomass, while ethanol was more effective in stimulating sulphide production and acetate was less effective. The presence of additional bicarbonate and H2 only marginally stimulated sulphide production. The sulphide output per unit of biomass was greatest using ethanol as substrate. In continuous culture, ethanol and lactate were used directly as efficient substrates for sulphate reduction while acetate yielded only slow growth. Glucose was utilised following fermentation to organic acids and therefore had a deleterious effect on pH. Ethanol was selected as the most efficient substrate due to cost and efficient yield of sulphide. On ethanol, the presence of additional carbon sources had no effect on growth or sulphate reduction in batch culture but the presence of complex nitrogen sources (yeast extract or cornsteep) stimulated both. Cornsteep showed the strongest effect and was also preferred on cost grounds. In continuous culture, cornsteep significantly improved the yield of sulphate reduced per unit of ethanol consumed. These results suggest that the most efficient nutrient regime for bioremediation using sulphate-reducing bacteria required both ethanol as carbon source and cornsteep as a complex nitrogen source.

  7. Safeguards Culture

    SciTech Connect

    Frazar, Sarah L.; Mladineo, Stephen V.

    2012-07-01

    The concepts of nuclear safety and security culture are well established; however, a common understanding of safeguards culture is not internationally recognized. Supported by the National Nuclear Security Administration, the authors prepared this report, an analysis of the concept of safeguards culture, and gauged its value to the safeguards community. The authors explored distinctions between safeguards culture, safeguards compliance, and safeguards performance, and evaluated synergies and differences between safeguards culture and safety/security culture. The report concludes with suggested next steps.

  8. Mixing in explosions

    SciTech Connect

    Kuhl, A.L.

    1993-12-01

    Explosions always contain embedded turbulent mixing regions, for example: boundary layers, shear layers, wall jets, and unstable interfaces. Described here is one particular example of the latter, namely, the turbulent mixing occurring in the fireball of an HE-driven blast wave. The evolution of the turbulent mixing was studied via two-dimensional numerical simulations of the convective mixing processes on an adaptive mesh. Vorticity was generated on the fireball interface by baroclinic effects. The interface was unstable, and rapidly evolved into a turbulent mixing layer. Four phases of mixing were observed: (1) a strong blast wave phase; (2) and implosion phase; (3) a reshocking phase; and (4) an asymptotic mixing phase. The flowfield was azimuthally averaged to evaluate the mean and r.m.s. fluctuation profiles across the mixing layer. The vorticity decayed due to a cascade process. This caused the corresponding enstrophy parameter to increase linearly with time -- in agreement with homogeneous turbulence calculations of G.K. Batchelor.

  9. Mixing in astrophysics

    SciTech Connect

    Fryer, Christopher Lee

    2011-01-07

    Turbulent mixing plays a vital role in many fields in astronomy. Here I review a few of these sites, discuss the importance of this turbulent mixing and the techniques used by astrophysicists to solve these problems.

  10. Draft Genome Sequence of Marinobacter sp. Strain P4B1, an Electrogenic Perchlorate-Reducing Strain Isolated from a Long-Term Mixed Enrichment Culture of Marine Bacteria.

    PubMed

    Stepanov, Victor G; Xiao, Yeyuan; Lopez, April J; Roberts, Deborah J; Fox, George E

    2016-01-01

    The perchlorate-reducing strain Marinobacter sp. strain P4B1 was isolated from a long-term perchlorate-degrading enrichment culture seeded with marine sediment. The draft genome of Marinobacter sp. P4B1 is comprised of the bacterial chromosome (3.60 Mbp, G+C 58.51%, 3,269 predicted genes) and its associated plasmid pMARS01 (0.14 Mbp, G+C 52.95%, 165 predicted genes). PMID:26798109

  11. Small Cultures.

    ERIC Educational Resources Information Center

    Holliday, Adrian

    1999-01-01

    Presents a notion of small culture as an alternative to what has become the default notion of large culture in applied linguistics, social science, and popular usage. A small-culture view of English-language curriculum settings reveals mismatches between professional-academic and organizational cultures at the mezzo level of the institution. (VWL)

  12. Foundations of chaotic mixing.

    PubMed

    Wiggins, Stephen; Ottino, Julio M

    2004-05-15

    The simplest mixing problem corresponds to the mixing of a fluid with itself; this case provides a foundation on which the subject rests. The objective here is to study mixing independently of the mechanisms used to create the motion and review elements of theory focusing mostly on mathematical foundations and minimal models. The flows under consideration will be of two types: two-dimensional (2D) 'blinking flows', or three-dimensional (3D) duct flows. Given that mixing in continuous 3D duct flows depends critically on cross-sectional mixing, and that many microfluidic applications involve continuous flows, we focus on the essential aspects of mixing in 2D flows, as they provide a foundation from which to base our understanding of more complex cases. The baker's transformation is taken as the centrepiece for describing the dynamical systems framework. In particular, a hierarchy of characterizations of mixing exist, Bernoulli --> mixing --> ergodic, ordered according to the quality of mixing (the strongest first). Most importantly for the design process, we show how the so-called linked twist maps function as a minimal picture of mixing, provide a mathematical structure for understanding the type of 2D flows that arise in many micromixers already built, and give conditions guaranteeing the best quality mixing. Extensions of these concepts lead to first-principle-based designs without resorting to lengthy computations.

  13. Mixing and compaction temperatures for Superpave mixes

    NASA Astrophysics Data System (ADS)

    Yildirim, Yetkin

    According to Superpave mixture design, gyratory specimens are mixed and compacted at equiviscous binder temperatures corresponding to viscosities of 0.17 and 0.28 Pa.s. respectively. These were the values previously used in the Marshal mix design method to determine optimal mixing and compaction temperatures. In order to estimate the appropriate mixing and compaction temperatures for Superpave mixture design, a temperature-viscosity relationship for the binder needs to be developed (ASTM D 2493, Calculation of Mixing and Compaction Temperatures). The current approach is simple and provides reasonable temperatures for unmodified binders. However, some modified binders have exhibited unreasonably high temperatures for mixing and compaction using this technique. These high temperatures can result in construction problems, damage of asphalt, and production of fumes. Heating asphalt binder to very high temperatures during construction oxidizes the binder and separates the polymer from asphalt binder. It is known that polymer modified asphalt binders have many benefits to the roads, such as; increasing rutting resistance, enhancing low temperature cracking resistance, improving traction, better adhesion and cohesion, elevating tensile strength which are directly related to the service life of the pavement. Therefore, oxidation and separation of the polymer from the asphalt binder results in reduction of the service life. ASTM D 2493 was established for unmodified asphalt binders which are Newtonian fluids at high temperatures. For these materials, viscosity does not depend on shear rate. However, most of the modified asphalt binders exhibit a phenomenon known as pseudoplasticity, where viscosity does depend on shear rate. Thus, at the high shear rates occurring during mixing and compaction, it is not necessary to go to very high temperatures. This research was undertaken to determine the shear rate during compaction such that the effect of this parameter could be

  14. Cultural psychology.

    PubMed

    Heine, Steven J; Ruby, Matthew B

    2010-03-01

    Humans are a cultural species, constantly navigating a complex web of culturally bound practices, norms, and worldviews. This article provides a brief overview of the relatively young field of cultural psychology, which investigates the many ways psychology and culture interweave with one another. Highlighting the cultural nature of the human species, it draws upon research on cultural evolution, enculturation, and developmental processes. This review further summarizes a number of cultural differences in how people perceive the self, and the behavioral consequences that follow from these differences, in the domains of internal and external attribution styles, motivations for self-enhancement, approach/avoidance, primary and secondary control, as well as motivations for distinctiveness and conformity. Additionally, the review discusses research on the intersection of culture and emotion, as well as cultural differences in cognition, perception, and reasoning. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website.

  15. Adenylyl cyclase activation underlies intracellular cyclic AMP accumulation, cyclic AMP transport, and extracellular adenosine accumulation evoked by beta-adrenergic receptor stimulation in mixed cultures of neurons and astrocytes derived from rat cerebral cortex.

    PubMed

    Rosenberg, P A; Li, Y

    1995-09-18

    We have previously shown that stimulation of cortical cultures containing both neurons and astrocytes with the beta-adrenergic agonist isoproterenol (ISO) results in transport of cAMP from astrocytes followed by extracellular hydrolysis to adenosine [Rosenberg et al. J. Neurosci. 14 (1994) 2953-2965]. In this study we found that the endogenous catecholamines epinephrine (EPI) and norepinephrine (NE), but not dopamine, serotonin, or histamine, all at 10 microM, significantly stimulated intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation in cortical cultures. Detailed dose-response experiments were performed for NE and EPI, as well as ISO. For each catecholamine, the potencies in evoking intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation were similar. These data provide additional evidence that a single common mechanism, namely beta-adrenergic mediated activation of adenylyl cyclase, underlies intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation. It appears that regulation of extracellular adenosine levels via cAMP transport and extracellular hydrolysis to adenosine may be a final common pathway of neuromodulation in cerebral cortex for catecholamines, and, indeed, any substance whose receptors are coupled to adenylyl cyclase.

  16. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Competitive exclusion culture. 529.469 Section 529... Competitive exclusion culture. (a) Specifications. Each packet of lyophilized culture contains either 2,000 or... contents of one 2,000-dose packet of lyophilized culture. Mix thoroughly. (2) For 5,000-dose packet,...

  17. 21 CFR 529.469 - Competitive exclusion culture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Competitive exclusion culture. 529.469 Section 529... Competitive exclusion culture. (a) Specifications. Each packet of lyophilized culture contains either 2,000 or... contents of one 2,000-dose packet of lyophilized culture. Mix thoroughly. (2) For 5,000-dose packet,...

  18. Culture, law and psychiatry in Hawaii.

    PubMed

    Schultz-Ross, R A; Jenkins, L

    1998-12-01

    Hawaii is a set of islands with a broad mix of cultures. The law is American, but it was predominantly derived from English Common Law. Thus, the law is derived from a very distant culture. Theoretically, this 'transplanted' law could cause difficulties for people from Pacific cultures. Indeed, it appears to create difficulties for individuals with mental illness. A substantial number of these people are arrested for disobedience of a law that is not sensible for their culture. This problem is an example of the need for cultural knowledge when a psychiatrist conducts an examination for the legal system. An individual may appear legally guilty or medically insane when acting within cultural norms.

  19. Mixed matrix membrane development.

    PubMed

    Kulprathipanja, Santi

    2003-03-01

    Two types of mixed matrix membranes were developed by UOP in the late 1980s. The first type includes adsorbent polymers, such as silicalite-cellulose acetate (CA), NaX-CA, and AgX-CA mixed matrix membranes. The silicalite-CA has a CO(2)/H(2) selectivity of 5.15 +/- 2.2. In contrast, the CA membrane has a CO(2)/H(2) selectivity of 0.77 +/- 0.06. The second type of mixed matrix membrane is PEG-silicone rubber. The PEG-silicone rubber mixed matrix membrane has high selectivity for polar gases, such as SO(2), NH(3), and H(2)S.

  20. Mixed oxide solid solutions

    DOEpatents

    Magno, Scott; Wang, Ruiping; Derouane, Eric

    2003-01-01

    The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

  1. Enhanced truncated-t-PA (CT-b) expression in high-cell-density fed-batch cultures of Pichia pastoris through optimization of a mixed feeding strategy by response surface methodology.

    PubMed

    Kazemali, Mohammad Reza; Majidzadeh, Keivan; Sardari, Soroush; Saadati, Amir Hossein; Barkhordari, Farzaneh; Adeli, Ahmad; Mahboudi, Fereidoun; Maghsoudi, Amir

    2016-04-01

    Recently, Pichia pastoris has been the focal point of interest as an expression system for production of many recombinant proteins. The study and optimization of feeding strategy are of major importance to achieve maximum volumetric productivity in fed-batch cultivations. Among different feeding strategies used in P. pastoris fed-batch cultures, those trying to maintain a constant specific growth rate have usually resulted in superior productivities. The objective of the present study was to investigate and optimize the co-feeding of glycerol and methanol to attain maximum expression of t-PA in P. pastoris fed-batch cultures with constant specific growth rate. The experiments were designed by response surface methodology, considering the specific feeding rates of methanol and glycerol as independent variables. In each experiment, glycerol and methanol were fed according to a predetermined equation to maintain a constant specific growth rate. It was found that with glycerol feeding for higher specific growth rates, the inhibitory properties of glycerol are more pronounced, while the best expression level was achieved when the ratio of µ set glycerol to that of methanol was around 1.67. In all specific growth rates tested, almost a similar ratio of the specific glycerol feeding rate to that of methanol led to the maximum protein production and activity. The statistical model predicted the optimal operating conditions for µ set glycerol and that of methanol to be 0.05 and 0.03 h(-1), respectively. Applying the optimum strategy, maximum of 52 g/L biomass, 300 mg/L t-PA and 340,000 IU/mL enzyme activity were obtained.

  2. To Mix or Not to Mix?

    ERIC Educational Resources Information Center

    Shuttlewood, Rosemary

    2006-01-01

    In this article, the author discusses the teaching strategy of the mixed independent school where she works, in which they split the students into four or five ability sets. The sets are decided primarily either by pupil achievement in the entrance examinations prior to Y9 or by pupil performance in the prep school. The author also presents the…

  3. Culturing Protozoa.

    ERIC Educational Resources Information Center

    Stevenson, Paul

    1980-01-01

    Compares various nutrient media, growth conditions, and stock solutions used in culturing protozoa. A hay infusion in Chalkey's solution maintained at a stable temperature is recommended for producing the most dense and diverse cultures. (WB)

  4. Repellent Culture.

    ERIC Educational Resources Information Center

    Carroll, Jeffrey

    2001-01-01

    Considers defining "culture," noting how it is difficult to define because those individuals defining it cannot separate themselves from it. Relates these issues to student writing and their writing improvement. Addresses violence in relation to culture. (SG)

  5. Culture-dependent comparison of microbial diversity in deep granitic groundwater from two sites considered for a Swedish final repository of spent nuclear fuel.

    PubMed

    Hallbeck, Lotta; Pedersen, Karsten

    2012-07-01

    Site selection for a spent nuclear fuel (SNF) repository required analysis of microbial abundance and diversity at two Swedish sites, Forsmark and Laxemar-Simpevarp. Information about sulphate-reducing bacteria (SRB) was required, as sulphide could corrode copper SNF canisters. Total number of cells (TNC) and ATP were analysed, and plate counts and most probable number (MPN) analyses were conducted using eight media based on different electron donors and acceptors for specific microorganism physiological groups. Groundwater chemical composition and E(h) were analysed; sampling depths were 112-978 m below sea level. TNC was 5.5 × 10(3) to 4.7 × 10(5) cells mL(-1), correlating with ATP concentrations. Culturability in TNC percentage was 0.01-35.9, averaging 5.12. Culturable numbers varied greatly between sample positions and uncorrelated with depth. SRB were found in 29 samples and were below detection in three; the MPN of SRB correlated negatively with E(h), as did the MPN of acetogens. Data indicated that microbial sulphate reduction was ongoing in many sampled aquifers; published stable isotope data and modelling results supported this observation. The sites did not differ significantly, but the large data range suggested that analysis of more samples would enable detailed evaluation of microbial processes and their relationship with geochemical information.

  6. Mixed Ability Teaching.

    ERIC Educational Resources Information Center

    Skov, Poul

    1986-01-01

    As a basis for taking a position on the future school structure in grades 8-10 in Denmark, an extensive study was carried out on mixed ability teaching (teaching in heterogeneous classes) on these grade levels. Results showed that mixed ability teaching gave at least as good results as teaching in differentiated classes. (Author/LMO)

  7. Recurrent mixed tumor.

    PubMed

    Batsakis, J G

    1986-01-01

    Recurrence of benign neoplasms can usually be attributed to incomplete excision. Such is the case with benign mixed tumors of salivary glands. Certain histopathologic features of mixed tumors, however, appear to facilitate recurrences. These are: a predominantly myxoid composition, and transcapsular extension by the tumor. Multicentric origin is possible, but it must be regarded as a much lower order of probability.

  8. Microfluidic Mixing: A Review

    PubMed Central

    Lee, Chia-Yen; Chang, Chin-Lung; Wang, Yao-Nan; Fu, Lung-Ming

    2011-01-01

    The aim of microfluidic mixing is to achieve a thorough and rapid mixing of multiple samples in microscale devices. In such devices, sample mixing is essentially achieved by enhancing the diffusion effect between the different species flows. Broadly speaking, microfluidic mixing schemes can be categorized as either “active”, where an external energy force is applied to perturb the sample species, or “passive”, where the contact area and contact time of the species samples are increased through specially-designed microchannel configurations. Many mixers have been proposed to facilitate this task over the past 10 years. Accordingly, this paper commences by providing a high level overview of the field of microfluidic mixing devices before describing some of the more significant proposals for active and passive mixers. PMID:21686184

  9. Theory for Neutrino Mixing

    NASA Astrophysics Data System (ADS)

    He, Xiao-Gang

    2016-07-01

    Since the discovery of neutrino oscillations, for which Takaaki Kajita and Arthur B. McDonald were awarded the 2015 Nobel prize in physics, tremendous progresses have been made in measuring the mixing angles which determine the oscillation pattern. A lot of theoretical efforts have been made to understand how neutrinos mix with each other. Present data show that in the standard parameterization of the mixing matrix, θ23 is close to π/4 and the CP violating phase is close to - π/2. In this talk I report results obtained in arXiv:1505.01932 (Phys. Lett. B750(2015)620) and arXive:1404.01560 (Chin. J. Phys.53(2015)100101) and discuss some implications for theoretical model buildings for such mixing pattern. Specific examples for neutrino mixing based on A4 family symmetry are given.

  10. Theory for Neutrino Mixing

    NASA Astrophysics Data System (ADS)

    He, Xiao-Gang

    2016-07-01

    Since the discovery of neutrino oscillations, for which Takaaki Kajita and Arthur B. McDonald were awarded the 2015 Nobel prize in physics, tremendous progresses have been made in measuring the mixing angles which determine the oscillation pattern. A lot of theoretical efforts have been made to understand how neutrinos mix with each other. Present data show that in the standard parameterization of the mixing matrix, θ23 is close to π/4 and the CP violating phase is close to ‑ π/2. In this talk I report results obtained in arXiv:1505.01932 (Phys. Lett. B750(2015)620) and arXive:1404.01560 (Chin. J. Phys.53(2015)100101) and discuss some implications for theoretical model buildings for such mixing pattern. Specific examples for neutrino mixing based on A4 family symmetry are given.

  11. High-mix insulins

    PubMed Central

    Kalra, Sanjay; Farooqi, Mohammad Hamed; El-Houni, Ali E.

    2015-01-01

    Premix insulins are commonly used insulin preparations, which are available in varying ratios of different molecules. These drugs contain one short- or rapid-acting, and one intermediate- or long-acting insulin. High-mix insulins are mixtures of insulins that contain 50% or more than 50% of short-acting insulin. This review describes the clinical pharmacology of high-mix insulins, including data from randomized controlled trials. It suggests various ways, in which high-mix insulin can be used, including once daily, twice daily, thrice daily, hetero-mix, and reverse regimes. The authors provide a rational framework to help diabetes care professionals, identify indications for pragmatic high-mix use. PMID:26425485

  12. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Richard Dimenna, R; David Tamburello, D

    2008-11-13

    The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four dual-nozzle jet mixers located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The work described in this report establishes the basis for further development of the theory leading to the identified mixing indicators, the benchmark analyses demonstrating their consistency with widely accepted correlations, and the application of those indicators to SRS waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. If shorter mixing times can be shown to support Defense Waste Processing Facility (DWPF) or other feed requirements, longer pump lifetimes can be achieved with associated operational cost and

  13. ADVANCED MIXING MODELS

    SciTech Connect

    Lee, S; Dimenna, R; Tamburello, D

    2011-02-14

    The process of recovering and processing High Level Waste (HLW) the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four mixers (pumps) located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are typically set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The focus of the present work is to establish mixing criteria applicable to miscible fluids, with an ultimate goal of addressing waste processing in HLW tanks at SRS and quantifying the mixing time required to suspend sludge particles with the submersible jet pump. A single-phase computational fluid dynamics (CFD) approach was taken for the analysis of jet flow patterns with an emphasis on the velocity decay and the turbulent flow evolution for the farfield region from the pump. Literature results for a turbulent jet flow are reviewed, since the decay of the axial jet velocity and the evolution of the jet flow patterns are important phenomena affecting sludge suspension and mixing operations. The work described in this report suggests a basis for further development of the theory leading to the identified mixing indicators, with benchmark analyses demonstrating their consistency with widely accepted correlations. Although the indicators are somewhat generic in nature, they are applied to Savannah River Site (SRS) waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in

  14. Nearly discontinuous chaotic mixing

    SciTech Connect

    Sharp, David Howland; Lim, Hyun K; Yu, Yan; Glimm, James G

    2009-01-01

    A new scientific approach is presented for a broad class of chaotic problems involving a high degree of mixing over rapid time scales. Rayleigh-Taylor and Richtmyer-Meshkov unstable flows are typical of such problems. Microscopic mixing properties such as chemical reaction rates for turbulent mixtures can be obtained with feasible grid resolution. The essential dependence of (some) fluid mixing observables on transport phenomena is observed. This dependence includes numerical as well as physical transport and it includes laminar as well as turbulent transport. A new approach to the mathematical theory for the underlying equations is suggested.

  15. Unique Pathways to Resilience across Cultures

    ERIC Educational Resources Information Center

    Ungar, Michael; Brown, Marion; Liebenberg, Linda; Othman, Rasha; Kwong, Wai Man; Armstrong, Mary; Gilgun, Jane

    2007-01-01

    An international mixed methods study of resilience of 14 sites in eleven countries identified seven tensions that youth resolve in culturally specific ways. Resolution of these tensions is foundational to experiences of resilience. This paper reports on the qualitative findings from interviews with 89 youth. Results support a culturally embedded…

  16. Guidelines for mixed waste minimization

    SciTech Connect

    Owens, C.

    1992-02-01

    Currently, there is no commercial mixed waste disposal available in the United States. Storage and treatment for commercial mixed waste is limited. Host States and compacts region officials are encouraging their mixed waste generators to minimize their mixed wastes because of management limitations. This document provides a guide to mixed waste minimization.

  17. Idealized mixing impacts

    SciTech Connect

    Peterson, R.A.

    1999-12-08

    The dispersion of tetraphenylborate in continuous stirred tank reactors plays a significant role in the utility achieved from the tetraphenylborate. Investigating idealized mixing of the materials can illuminate how this dispersion occurs.