Academic literature on the topic 'Microbial populations'

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Journal articles on the topic "Microbial populations"

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Gokhale, Chaitanya S., Stefano Giaimo, and Philippe Remigi. "Memory shapes microbial populations." PLOS Computational Biology 17, no. 10 (October 1, 2021): e1009431. http://dx.doi.org/10.1371/journal.pcbi.1009431.

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Correct decision making is fundamental for all living organisms to thrive under environmental changes. The patterns of environmental variation and the quality of available information define the most favourable strategy among multiple options, from randomly adopting a phenotypic state to sensing and reacting to environmental cues. Cellular memory—the ability to track and condition the time to switch to a different phenotypic state—can help withstand environmental fluctuations. How does memory manifest itself in unicellular organisms? We describe the population-wide consequences of phenotypic memory in microbes through a combination of deterministic modelling and stochastic simulations. Moving beyond binary switching models, our work highlights the need to consider a broader range of switching behaviours when describing microbial adaptive strategies. We show that memory in individual cells generates patterns at the population level coherent with overshoots and non-exponential lag times distributions experimentally observed in phenotypically heterogeneous populations. We emphasise the implications of our work in understanding antibiotic tolerance and, in general, bacterial survival under fluctuating environments.
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Vázquez, Francisco J., María J. Acea, and Tarsy Carballas. "Soil microbial populations after wildfire." FEMS Microbiology Ecology 13, no. 2 (December 1993): 93–103. http://dx.doi.org/10.1111/j.1574-6941.1993.tb00055.x.

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Haack, Sheridan K., and Barbara A. Bekins. "Microbial populations in contaminant plumes." Hydrogeology Journal 8, no. 1 (March 13, 2000): 63–76. http://dx.doi.org/10.1007/s100400050008.

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Koskella, Britt, and Michiel Vos. "Adaptation in Natural Microbial Populations." Annual Review of Ecology, Evolution, and Systematics 46, no. 1 (December 4, 2015): 503–22. http://dx.doi.org/10.1146/annurev-ecolsys-112414-054458.

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VAZQUEZ, F. "Soil microbial populations after wildfire." FEMS Microbiology Ecology 13, no. 2 (December 1993): 93–103. http://dx.doi.org/10.1016/0168-6496(93)90027-5.

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Oleskin, Alexander V. "Social behaviour of microbial populations." Journal of Basic Microbiology 34, no. 6 (1994): 425–39. http://dx.doi.org/10.1002/jobm.3620340608.

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Bennett, Albert F., and Bradley S. Hughes. "Microbial experimental evolution." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 297, no. 1 (July 2009): R17—R25. http://dx.doi.org/10.1152/ajpregu.90562.2008.

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Microbes have been widely used in experimental evolutionary studies because they possess a variety of valuable traits that facilitate large-scale experimentation. Many replicated populations can be cultured in the laboratory simultaneously along with appropriate controls. Short generation times and large population sizes make microbes ideal experimental subjects, ensuring that many spontaneous mutations occur every generation and that adaptive variants can spread rapidly through a population. Another highly useful experimental feature is the ability to preserve and store ancestral and evolutionarily derived clones. These can be revived in parallel to allow the direct measurement of the competitive fitness of a descendant compared with its ancestor. The extent of adaptation can thereby be measured quantitatively and compared statistically by direct competition among derived groups and with the ancestor. Thus, fitness and adaptation need not be matters of qualitative speculation, but are quantitatively measurable variables in these systems. Replication allows the quantification of heterogeneity in responses to imposed selection and thereby statistical distinction between changes that are systematic responses to the selective regimen and those that are specific to individual populations.
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Duan, Xing-Zhi, Guo-Sen Guo, Ling-Fei Zhou, Le Li, Ze-Min Liu, Cheng Chen, Bin-Hua Wang, and Lan Wu. "Enterobacteriaceae as a Key Indicator of Huanglongbing Infection in Diaphorina citri." International Journal of Molecular Sciences 25, no. 10 (May 9, 2024): 5136. http://dx.doi.org/10.3390/ijms25105136.

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Extensive microbial interactions occur within insect hosts. However, the interactions between the Huanglongbing (HLB) pathogen and endosymbiotic bacteria within the Asian citrus psyllid (ACP, Diaphorina citri Kuwayama) in wild populations remain elusive. Thus, this study aimed to detect the infection rates of HLB in the ACP across five localities in China, with a widespread prevalence in Ruijin (RJ, 58%), Huidong (HD, 28%), and Lingui (LG, 15%) populations. Next, microbial communities of RJ and LG populations collected from citrus were analyzed via 16S rRNA amplicon sequencing. The results revealed a markedly higher microbial diversity in the RJ population compared to the LG population. Moreover, the PCoA analysis identified significant differences in microbial communities between the two populations. Considering that the inter-population differences of Bray–Curtis dissimilarity in the RJ population exceeded those between populations, separate analyses were performed. Our findings indicated an increased abundance of Enterobacteriaceae in individuals infected with HLB in both populations. Random forest analysis also identified Enterobacteriaceae as a crucial indicator of HLB infection. Furthermore, the phylogenetic analysis suggested a potential regulatory role of ASV4017 in Enterobacteriaceae for ACP, suggesting its possible attractant activity. This research contributes to expanding the understanding of microbial communities associated with HLB infection, holding significant implications for HLB prevention and treatment.
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Shooner, Frédéric, and Rajeshwar D. Tyagi. "Microbial ecology of simultaneous thermophilic microbial leaching and digestion of sewage sludge." Canadian Journal of Microbiology 41, no. 12 (December 1, 1995): 1071–80. http://dx.doi.org/10.1139/m95-150.

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The microbial population encountered during a simultaneous thermophilic microbial leaching and digestion process at 50 °C, based on microbial sulfur oxidation, was investigated. The cell count of the sulfuric acid producer Thiobacillus thermosulfatus increased, followed by a decrease. In the absence of sulfur (control: conventional thermophilic digestion), Thiobacillus thermosulfatus population decreased under the detection limit. Acidophilic and neutrophilic heterotrophic populations increased during the leaching process, and the final acidophilic population count was higher than the neutrophilic population. During the thermophilic digestion (control), the final neutrophilic population count was higher than the acidophilic. Six heterotrophic bacterial strains were isolated and partially characterized. Bacillus was the most predominant genus. The type of bacterial populations in thermophilic microbial leaching and digestion, as well as the thermophilic digestion process (control), were the same, while only the relative concentrations changed. In both processes, the bacterial indicators decreased under the detection limit after 12 h. Mesophilic heterotrophic population was more affected by the thermophilic microbial leaching process than by thermophilic digestion. Sludge mineralization was probably more influenced by the final cell concentration rather than the presence of an individual species or mixed population.Key words: Thiobacillus thermosulfatus, thermophilic metal leaching, thermophilic sludge digestion, indicator microorganisms.
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KOSEKI, SHIGENOBU, and KAZUHIKO ITOH. "Prediction of Microbial Growth in Fresh-Cut Vegetables Treated with Acidic Electrolyzed Water during Storage under Various Temperature Conditions." Journal of Food Protection 64, no. 12 (December 1, 2001): 1935–42. http://dx.doi.org/10.4315/0362-028x-64.12.1935.

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Effects of storage temperature (1, 5, and 10°C) on growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) on acidic electrolyzed water (AcEW)-treated fresh-cut lettuce and cabbage were determined. A modified Gompertz function was used to describe the kinetics of microbial growth. Growth data were analyzed using regression analysis to generate “best-fit” modified Gompertz equations, which were subsequently used to calculate lag time, exponential growth rate, and generation time. The data indicated that the growth kinetics of each bacterium were dependent on storage temperature, except at 1°C storage. At 1°C storage, no increases were observed in bacterial populations. Treatment of vegetables with AcEW produced a decrease in initial microbial populations. However, subsequent growth rates were higher than on nontreated vegetables. The recovery time required by the reduced microbial population to reach the initial (treated with tap water [TW]) population was also determined in this study, with the recovery time of the microbial population at 10°C being <3 days. The benefits of reducing the initial microbial populations on fresh-cut vegetables were greatly affected by storage temperature. Results from this study could be used to predict microbial quality of fresh-cut lettuce and cabbage throughout their distribution.
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Dissertations / Theses on the topic "Microbial populations"

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Gilliam, Lucy. "Impact of anti-microbial GM plants on soil microbial populations." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485401.

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The environmental risk assessment of GM plants is a fast moving area of science. Much research has focused on developing methods to evaluate potential effects on a range of organisms. Microorganisms play an essential role in many soil processes, with the rhizosphere as the prominent site of microbial activity. There is a general need for protocols to assess the effect of anthropogenic influences, the use of different crops and crop rotation an.d as well as GM plants, on the microbial community within the soil. The rhizosp~eres of three crop plants Brassica napus (Oilseed rape), Triticum aestivum (Wheat) and Solanum tuberosum (Potato) were compared using both genetic and functional diversity methods. The rhizospheres of four cultivars of potato were compared; GM potato (variety Kardal) modified with an anti-fungal transgene, GM potato (variety Kardal) with no transgene inserted (empty vector), parental .- line of potato (variety Kardal) and a different cultivar (variety Russet-Burbank). Genetic diversity of bacterial populations isolated from the rhizosphere were compared using PCR amplified DNA of 168 rRNA with denaturing gradient gel electrophoresis (DGGE) to obtain community fingerprints. Activity of the microbial populations was assessed using Biolog G.N MicroPlate™ community substrate utilisation and enzyme activity using a microplate method based on substrates linked to the fluorescent compounds methylumbelliferone (MUB) and 7-amino-4-methyl coumarin (AMC). By comparing the ~M plants to non-GM plants and other crops, observed differences are placed in context. This work shows that the GM line examined.appears to have little effect on soil microbial populations. Detected effects of1he GM potato line were minor compared with other sources of variation observed between plants cultivar or crop species, management practices and sampling time. To date, there has been little evidence that cultivation of GM plants leads to significant changes in microbial popUlations.
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Driessen, Jennifer Petronella 1973. "Microbial populations as indicators of river 'health'." Monash University, Dept. of Chemistry, 2000. http://arrow.monash.edu.au/hdl/1959.1/8780.

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Logeswaran, Sayanthan. "Mapping quantitative trait loci in microbial populations." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4881.

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Linkage between markers and genes that affect a phenotype of interest may be determined by examining differences in marker allele frequency in the extreme progeny of a cross between two inbred lines. This strategy is usually employed when pooling is used to reduce genotyping costs. When the cross progeny are asexual the extreme progeny may be selected by multiple generations of asexual reproduction and selection. In this thesis I will analyse this method of measuring phenotype in asexual cross progeny. The aim is to examine the behaviour of marker allele frequency due to selection over many generations, and also to identify statistically significant changes in frequency in the selected population. I will show that stochasticity in marker frequency in the selected population arises due the finite initial population size. For Mendelian traits, the initial population size should be at least in the low to mid hundreds to avoid spurious changes in marker frequency in the selected population. For quantitative traits the length of time selection is applied for, as well as the initial population size, will affect the stochasticity in marker frequency. The longer selection is applied for, the more chance of spurious changes in marker frequency. Also for quantitative traits, I will show that the presence of epistasis can hinder changes in marker frequency at selected loci, and consequently make identification of selected loci more difficult. I also show that it is possible to detect epistasis from the marker frequency by identifying reversals in the direction of marker frequency change. Finally, I develop a maximum likelihood based statistical model that aims to identify significant changes in marker frequency in the selected population. I will show that the power of this statistical model is high for detecting large changes in marker frequency, but very low for detecting small changes in frequency.
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VanInsberghe, David(David Stephen). "The eco-evolutionary dynamics of microbial populations." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122422.

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Thesis: Ph. D. in Microbiology Graduate Program, Massachusetts Institute of Technology, Department of Biology, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references.
Microbes have adapted to life in complex microbial communities in a large variety of ways, and they are continually evolving to better compete in their changing environments. But identifying the conditions that a particular microbe thrives under, and how they have become adapted to those condition can be exceedingly difficult. For instance, Clostridium difficile became widely known for being the world's leading cause of hospital associated diarrhea, but people can also have C. difficile in their gut without developing diarrhea. Although these asymptomatic carriers are now thought to be the largest source of infection, we know very little about how these people become colonized. In the first chapter of my thesis I use publicly available microbiome survey data and a mouse model of colonization to show that C. difficile colonizes people immediately after diarrheal illnesses, suggesting C. difficile is a disturbance adapted opportunist.
However, the differences between very recently diverged microbial populations that are adapted for growth in different conditions can be very difficult to detect. To address this limitation, I developed a method of identifying regions that have undergone recent selective sweeps in these populations as a means of distinguishing them, and specifically quantifying their abundance in complex environments. But part of what makes microbial evolution so difficult to interpret is the vast diversity of genes that are only shared by a fraction of all the members in a population. To better understand how these flexible regions are structured, I systematically extracted all contiguous flexible regions in nine marine Vibrio populations and compared their organization and evolutionary histories.
I found that horizontal gene transfer and social interactions have led to the evolution of modular gene clusters that mediate forms of social cooperation, metabolic tradeoffs, and make up a substantial portion of these flexible genomic regions. The observations made in these studies help us understand how microbes are organized into socially and ecologically cohesive groups, and how they have evolved to interact with complex and changing environments.
by David VanInsberghe.
Ph. D. in Microbiology Graduate Program
Ph.D.inMicrobiologyGraduateProgram Massachusetts Institute of Technology, Department of Biology
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Huber, Julie A. "Phylogenetic and physiological diversity of subseafloor microbial communities at deep-sea seamounts /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/10991.

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McCartan, Cecilia. "The assessment of toxicity in environmental microbial populations." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343059.

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Healey, David W. (David Wendell). "Phenotypic heterogeneity and evolutionary games in microbial populations." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98544.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 92-96).
One of the most interesting discoveries of the last decade is the surprising degree of phenotypic variability between individual cells in clonal microbial populations, even in identical environments. While some variation is an inevitable consequence of low numbers of regulatory molecules in cells, the magnitude of the variability is nevertheless an evolvable trait whose quantitative parameters can be "tuned" by the biochemical characteristics and architecture of the underlying gene network. This raises the question of what adaptive advantage might be conferred to cells that implement high variation in their decision-making. Currently, the predominant answer in the field is that stochastic gene expression allows cells to "hedge their bets" against unpredictable and potentially catastrophic environmental shifts. We proposed and experimentally demonstrated an alternative solution: that heterogeneity implements the evolutionarily stable mixed strategy (or mixed ESS), from the field of evolutionary game theory. In a mixed ESS, phenotypic heterogeneity is a result of competitive interactions between cells in the population rather than a response to uncertain environments, so unlike with bet-hedging, in a mixed ESS the evolutionary fitness of different phenotypes is frequency dependent. Each phenotype can invade the other when rare, and the resulting equilibrium-the stable mix of the two-is not necessarily the one that maximizes the population's fitness. We demonstrated these and other predictions of the mixed ESS using engineered "pure strategist" strains of the yeast GAL network. We demonstrated also that the wild type mixed strategist can invade both pure strategists and is uninvasible by either. Taken together, our results provide experimental evidence that evolutionary hawk-dove games between identical cells can explain the phenotypic heterogeneity found in clonal microbial populations.
by David W. Healey.
Ph. D.
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Martin, F. Elizabeth. "Analyses of microbial populations associated with carious pulpitis." Connect to full text, 2002. http://hdl.handle.net/2123/4414.

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Thesis (Ph. D.)--Institute of Dental Research, Faculty of Dentistry, University of Sydney, 2002.
Title from title screen (viewed Apr. 23, 2009) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Dentistry. Includes bibliography. Also available in print form.
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Martinez, Robert J. "Multiscale analyses of microbial populations in extreme environments." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24754.

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Thesis (Ph.D.)--Biology, Georgia Institute of Technology, 2008.
Committee Chair: Patricia Sobecky; Committee Member: Ellery Ingall; Committee Member: Jim Spain; Committee Member: Martial Taillefert; Committee Member: Thomas DiChristina.
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Martin, Fjelda Elizabeth. "Analyses Of Microbial Populations Associated With Carious Pulpitis." Thesis, The University of Sydney, 2002. http://hdl.handle.net/2123/4860.

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Books on the topic "Microbial populations"

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Braddock, Joan F. Microbiology of subtidal sediments: Monitoring microbial populations. Fairbanks, AK (P.O. Box 757000, Fairbanks 99775-7000): Institute of Arctic Biology, University of Alaska Fairbanks, 1994.

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Kozhevin, P. A. Microbial Populations in Nature (Mikrobnye populi͡a︡t͡s︡ii v prirode). Moskva: Izd-vo Moskovskogo universiteta (Moscow University Press), 1989.

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S, Wolfe M., Caten C. E, and British Society for Plant Pathology., eds. Populations of plant pathogens: Their dynamics and genetics. Oxford [Oxfordshire]: Blackwell Scientific Publications, 1987.

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Malakieh, Nadia. Characterization of microbial populations native to an acid mine drainage environment. Sudbury, Ont: Laurentian University, Department of Biology, 2002.

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Clarke, K. J. Free viruses in the freshwater environment: A scoping study. Marlow, Bucks: Foundation for Water Research, 1998.

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Skujins, J. Waste oil biodegradation and changes in microbial populations in a semiarid soil. S.l: s.n, 1985.

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A, Schroeder Roy, Martin Peter 1953-, United States Marine Corps, and Geological Survey (U.S.), eds. Microbial populations in a jet-fuel-contaminated shallow aquifer at Tustin, California. Sacramento, Calif: U.S. Dept. of the Interior, Geological Survey, 1985.

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A, Schroeder Roy, Martin Peter 1953-, United States Marine Corps, and Geological Survey (U.S.), eds. Microbial populations in a jet-fuel-contaminated shallow aquifer at Tustin, California. Sacramento, Calif: U.S. Dept. of the Interior, Geological Survey, 1985.

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Preseau, Tina Louise. Isolation and characterization of microbial populations indigenous to acid mine drainage environments. Sudbury, Ont: Laurentian University, School of Graduate Studies, 2005.

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T, Grenfell B., and Dobson Andrew P, eds. Ecology of infectious diseases in natural populations. Cambridge: Cambridge University Press, 1995.

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Book chapters on the topic "Microbial populations"

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Baake, Ellen, and Anton Wakolbinger. "Microbial populations under selection." In Probabilistic Structures in Evolution, 43–68. Zuerich, Switzerland: European Mathematical Society Publishing House, 2021. http://dx.doi.org/10.4171/ecr/17-1/3.

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Yergeau, Etienne. "Climate Change and Microbial Populations." In Antarctic Terrestrial Microbiology, 249–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-45213-0_13.

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Carr, Noel G. "Microbial Cultures and Natural Populations." In Molecular Ecology of Aquatic Microbes, 391–402. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79923-5_21.

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Frederick, Lloyd R. "Microbial Populations by Direct Microscopy." In Agronomy Monographs, 1452–59. Madison, WI, USA: American Society of Agronomy, Soil Science Society of America, 2016. http://dx.doi.org/10.2134/agronmonogr9.2.c47.

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van Verseveld, Henk W., Wilfred F. M. Röling, Diman van Rossum, Anniet M. Laverman, Stef van Dijck, Martin Braster, and Fred C. Boogerd. "Phenetic and Genetic Analyses of Bacterial Populations in Fermented Food and Environmental Samples." In Microbial Communities, 19–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60694-6_3.

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Szumacher-Strabel, Malgorzata, and Adam Cieślak. "Essentials Oils and Rumen Microbial Populations." In Dietary Phytochemicals and Microbes, 285–309. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-3926-0_10.

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Juška, Alfonsas. "Growth and decline of microbial populations." In Analysis of biological processes, 59–79. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-7373-7_7.

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Schattenhofer, Martha, and Annelie Wendeberg. "Capturing Microbial Populations for Environmental Genomics." In Handbook of Molecular Microbial Ecology I, 735–40. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118010518.ch76.

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Dehority, B. A., and C. G. Orpin. "Development of, and natural fluctuations in, rumen microbial populations." In The Rumen Microbial Ecosystem, 196–245. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1453-7_5.

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Pace, Norman R., David A. Stahl, David J. Lane, and Gary J. Olsen. "The Analysis of Natural Microbial Populations by Ribosomal RNA Sequences." In Advances in Microbial Ecology, 1–55. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4757-0611-6_1.

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Conference papers on the topic "Microbial populations"

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Fernstad, Sara Johansson, Jimmy Johansson, Suzi Adams, Jane Shaw, and David Taylor. "Visual exploration of microbial populations." In 2011 IEEE Symposium on Biological Data Visualization (BioVis). IEEE, 2011. http://dx.doi.org/10.1109/biovis.2011.6094057.

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Armalytė, Julija, and Eglė Lastauskienė. "Anthropogenic Activities and Microbial Populations: War, Peace or Adaptation?" In International Conference EcoBalt. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/proceedings2023092075.

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Best, Aaron A., Tena Baar, Jade Laughlin, Sydney Les, Lexi Schoonover, Adam Slater, Meghana Sunder, et al. "GLOBAL SURVEY OF MICROBIAL POPULATIONS IN UNTREATED DRINKING WATER SOURCES." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-324228.

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Langen Corlay-Chee, Edmundo Robledo S., Edna Álvarez S., Joel Pérez N., and David Cristóbal A. "Soil Microbial Populations in the Conversion of Conventional to Conservation Tillage." In 2001 Sacramento, CA July 29-August 1,2001. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2001. http://dx.doi.org/10.13031/2013.3837.

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Ren, Xinying, Christian Cuba Samaniego, Richard M. Murray, and Elisa Franco. "Bistable State Switch Enables Ultrasensitive Feedback Control in Heterogeneous Microbial Populations." In 2021 American Control Conference (ACC). IEEE, 2021. http://dx.doi.org/10.23919/acc50511.2021.9482836.

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Huang, Xiaolan, Jian Zhang, Ting Zhang, and Baoqing Hu. "Analysis of microbial populations in River-lake ecotone of Poyang Lake." In 2016 5th International Conference on Energy and Environmental Protection (ICEEP 2016). Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/iceep-16.2016.89.

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Verma, Rama. "HIGH-THROUGHPUT SEQUENCING ANALYSIS OF MICROBIAL POPULATIONS IN ARCTIC ROCK SAMPLE." In 18th International Multidisciplinary Scientific GeoConference SGEM2018. STEF92 Technology, 2018. http://dx.doi.org/10.5593/sgem2018v/6.4/s07.003.

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Grigorova-Pesheva, Bilyana, and Boyka Malcheva. "COMPOSTING OF BIODEGRADABLE PLASTIC WASTE - CHANGES IN THE MICROBIAL COMMUNITY." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023v/4.2/s18.03.

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The present study aimed to track the changes in microbial communities during home composting of biodegradable plastic products (PLA). 6 waste mixtures and controls were prepared, with C:N about 30, placed in containers. The amount of PLA compared to the compostable mixture is 1%. Different depositing methods were used - active composting and placing part of the material in biodegradable bags. Temperature, humidity, pH, C:N ratio were measured. The amounts of bacteria, actinomycetes, micromycetes were recorded during the individual phases of composting, including the initial mixing of the materials. The microbiological analyzes were performed using the counting plate method. The reading is done in colony forming units. Total microbial number (TMN) was calculated. The ratio of the microbial populations in the studied samples with PLA was compared with the dynamics of development of the microbial populations in the control samples. Samples with added PLA have a higher TMN. For samples placed in a biodegradable bag, the thermophilic phase occurs faster and the amounts of microorganisms are higher. In all tested variants, the controls gave lower values of TMN. Some of the biodegradable materials (cutlery) are still discernible at the end stage of the composting process. Standard dynamics were observed in changing the percentage participation of individual microbial groups during the different phases of composting, regardless of added PLA. PLAs stimulate the composting process.
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Garcia, Alfonso, Trevor Place, Michael Holm, Jennifer Sargent, and Andrew Oliver. "Pipeline Sludge Sampling for Assessing Internal Corrosion Threat." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33113.

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Internal corrosion sometimes occurs under deposits of solid particles on the bottom of transmission pipelines. The solids trap water with soluble products and other nutrients which can support the development of microbial communities and may lead to Microbiologically Influenced Corrosion (MIC). Corrosion processes associated with the metabolic activities of specific bacteria have been discussed elsewhere, but the simple presence of large microbial populations may increase the risk of internal corrosion owing to the ability of biofilms to extract and concentrate water at the pipe floor. As a method to monitor the internal corrosion threat in transmission pipelines and recommend mitigating activities for corrosion management, reliable microbial content and corrosion activity correlations are desired. Sludge samples have been obtained from cleaning pigs at the pipe trap and analyzed using Biological Activity Reaction Test (BART™) (or serial dilution test), Dean-Stark analysis, XRD and EDX. These tests provide information about certain bacterial populations, water / solid / hydrocarbon content, and crystalline/elemental composition of these solids, respectively. Despite best efforts, bacterial population/activity of pipeline sludge samples exhibit high variability and are difficult to correlate to actual internal corrosion in a pipeline. Considering that bacterial populations in pipeline sludge may be a meaningful representation of the internal corrosion threat to a transmission pipeline, a more rigorous approach on the sludge sampling procedure is necessary to improve the accuracy and reliability of the bacterial assays. It is also important to control such variables as storage temperature of the samples, exposure to air, and storage duration prior to enumeration — as these may affect the viability of the sample and enumeration results. This report presents historical pipeline sludge analysis data and suggests a method to evaluate data containing high variability. Practical recommendations to reduce data variability through handling and storage of sludge samples are also discussed.
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West, Julia M., Ian G. McKinley, and Simcha Stroes-Gascoyne. "Implications of Microbial Redox Catalysis in Analogue Systems for Repository Safety Cases." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16336.

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A detailed assessment of studies of oxidising redox fronts around fractures at depth in otherwise “reducing” environments suggests that the usual explanation, in terms of past disturbances that have resulted in deep penetration of oxidising water, are incompatible with hydrogeological and/or geochemical observations. An alternative hypothesis, microbial catalysis of kinetically slow or hindered reactions involving oxyanions such as sulphate or carbonate, appears potentially more credible. Although still not always taken into account by the geochemical community, the role of microbial metabolism in low temperature geochemistry is supported by the rapidly expanding database on subsurface microbial populations. These populations are demonstrated to be viable and, therefore, could potentially be active at levels close to or below current detection limits in deep geological systems. Indeed, inspection of information available from several analogue studies or repository site characterisation programmes suggests that such activity may explain some of the geochemical anomalies encountered. This paper examines the current (indirect) evidence for microbial redox catalysis in relevant subsurface rock matrix environments and considers the implications that this would have for the development of site understanding — and in particular the identification of factors that may distinguish between different locations during site selection. Further, it examines the wider implications of more extensive roles of microbes in repository systems on the overall post-closure safety case and the need for further focused analogue studies to develop answers to these open questions.
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Reports on the topic "Microbial populations"

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Kienzler, Mariann, D. H. Alban, and D. A. Perala. Soil Invertebrate and Microbial Populations Under Three Tree Species on the Same Soil Type. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station, 1986. http://dx.doi.org/10.2737/nc-rn-337.

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Knotek-Smith, Heather, and Catherine Thomas. Microbial dynamics of a fluidized bed bioreactor treating perchlorate in groundwater. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45403.

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Optimization of operation and performance of the groundwater treatment system regarding perchlorate removal at Longhorn Army Ammunition Plant (LHAAP) is dependent on specific conditions within the reactor and the larger groundwater treatment process. This study evaluated the microbial community compositions within the plant during periods of adequate perchlorate degradation, sub-adequate perchlorate degradation, and non-operating conditions. Factors affecting the performance of the LHAAP ground water treatment system (GWTS) perchlorate de-grading fluidized bed reactor (FBR) are identified and discussed. Isolation of the FBR from naturally occurring microbial populations in the groundwater was the most significant factor reducing system effectiveness. The microbial population within the FBR is highly susceptible to system upsets, which leads to declining diversity within the reactor. As designed, the system operates for extended periods without the desired perchlorate removal without intervention such as a seed inoculant. A range of modifications and the operation of the system are identified to increase the effectiveness of perchlorate removal at LHAAP.
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Iske, Cayla, Cheryl L. Morris, and Kelly Kappen. Evaluation of Microbial Populations in Raw Meat Diets Fed to Captive Exotic Animals in Zoological Institutions. Ames (Iowa): Iowa State University, January 2016. http://dx.doi.org/10.31274/ans_air-180814-257.

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Jensen, Erik. Portable microfluidic platform for real-time, high sensitivity identification and analysis of microbes and microbial populations. Office of Scientific and Technical Information (OSTI), November 2016. http://dx.doi.org/10.2172/1335521.

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Happel, A., T. Legler, and S. Kane. Investigation and Testing of Methods to Measure Changes in Microbial Populations Due to the Use of Oxygenates in Fuels Released to the Subsurface. Office of Scientific and Technical Information (OSTI), February 2002. http://dx.doi.org/10.2172/15013325.

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Thomashow, Linda, Leonid Chernin, Ilan Chet, David M. Weller, and Dmitri Mavrodi. Genetically Engineered Microbial Agents for Biocontrol of Plant Fungal Diseases. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696521.bard.

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The objectives of the project were: a) to construct the site-specific integrative expression cassettes carrying: (i) the chiA gene for a 58-kDa endochitinase, (ii) the pyrrolnitrin biosynthesis operon, and (iii) the acdS gene encoding ACC deaminase; b) to employ these constructs to engineer stable recombinant strains with an expanded repertoire of beneficial activities; c) to evaluate the rhizosphere competence and antifungal activity of the WT and modified strains against pathogenic fungi under laboratory and greenhouse conditions; and d) to monitor the persistence and impact of the introduced strains on culturable and nonculturable rhizosphere microbial populations in the greenhouse and the field. The research generally support our concepts that combining strategically selected genes conferring diverse modes of action against plant pathogens into one organism can improve the efficacy of biological control agents. We hypothesized that biocontrol agents (BCAs) engineered to expand their repertoire of beneficial activities will more effectively control soilborne plant pathogens. In this work, we demonstrated that biocontrol activity of Pseudomonas fluorescens Q8r1-96 and Q2-87, both producing the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) effective against the plant pathogenic fungus Rhizoctonia solani, can be improved significantly by introducing and expressing either the 1.6-kb gene chiA, encoding the 58-kDa endochitinase ChiA from the rhizosphere strain SerratiaplymuthicaIC1270, or the 5.8-kb prnABCDoperon encoding the broad-range antibiotic pyrrolnitrin (Prn) from another rhizosphere strain, P. fluorescens Pf-5. The PₜₐcchiAandPₜₐcprnABCDcassettes were cloned into the integrative pBK-miniTn7-ΩGm plasmid, and inserted into the genomic DNA of the recipient bacteria. Recombinant derivatives of strains Q8r1-96 and Q2-87 expressing the PₜₐcchiA or PₜₐcprnABCD cassettes produced endochitinase ChiA, or Prn, respectively, in addition to 2,4-DAPG, and the recombinants gave significantly better biocontrol of R. solani on beans under greenhouse conditions. The disease reduction index increased in comparison to the parental strains Q8r1-96 and Q2-87 to 17.5 and 39.0% from 3.2 and 12.4%, respectively, in the case of derivatives carrying the PₜₐcchiAcassette and to 63.1 and 70% vs. 2.8 and 12,4%, respectively, in the case of derivatives carrying the PₜₐcprnABCDcassette. The genetically modified strains exhibited persistence and non-target effects comparable to those of the parental strains in greenhouse soil. Three integrative cassettes carrying the acdS gene encoding ACC deaminase cloned under the control of different promoters were constructed and tested for enhancement of plant growth promotion by biocontrol strains of P. fluorescens and S. plymuthica. The integrative cassettes constructed in this work are already being used as a simple and efficient tool to improve biocontrol activity of various PGPR bacteria against fungi containing chitin in the cell walls or highly sensitive to Prn. Some parts of the work (e. g., construction of integrative cassettes) was collaborative while other parts e.g., (enzyme and antibiotic activity analyses) were fully synergistic. The US partners isolated and provided to the Israeli collaborators the original biocontrol strains P. fluorescens strains Q8r1-96 and Q2-87 and their mutants deficient in 2,4-DAPG production, which were used to evaluate the relative importance of introduction of Prn, chitinase or ACC deaminase genes for improvement of the biocontrol activity of the parental strains. The recombinant strains obtained at HUJI were supplied to the US collaborators for further analysis.
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Crowley, David E., Dror Minz, and Yitzhak Hadar. Shaping Plant Beneficial Rhizosphere Communities. United States Department of Agriculture, July 2013. http://dx.doi.org/10.32747/2013.7594387.bard.

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PGPR bacteria include taxonomically diverse bacterial species that function for improving plant mineral nutrition, stress tolerance, and disease suppression. A number of PGPR are being developed and commercialized as soil and seed inoculants, but to date, their interactions with resident bacterial populations are still poorly understood, and-almost nothing is known about the effects of soil management practices on their population size and activities. To this end, the original objectives of this research project were: 1) To examine microbial community interactions with plant-growth-promoting rhizobacteria (PGPR) and their plant hosts. 2) To explore the factors that affect PGPR population size and activity on plant root surfaces. In our original proposal, we initially prqposed the use oflow-resolution methods mainly involving the use of PCR-DGGE and PLFA profiles of community structure. However, early in the project we recognized that the methods for studying soil microbial communities were undergoing an exponential leap forward to much more high resolution methods using high-throughput sequencing. The application of these methods for studies on rhizosphere ecology thus became a central theme in these research project. Other related research by the US team focused on identifying PGPR bacterial strains and examining their effective population si~es that are required to enhance plant growth and on developing a simulation model that examines the process of root colonization. As summarized in the following report, we characterized the rhizosphere microbiome of four host plant species to determine the impact of the host (host signature effect) on resident versus active communities. Results of our studies showed a distinct plant host specific signature among wheat, maize, tomato and cucumber, based on the following three parameters: (I) each plant promoted the activity of a unique suite of soil bacterial populations; (2) significant variations were observed in the number and the degree of dominance of active populations; and (3)the level of contribution of active (rRNA-based) populations to the resident (DNA-based) community profiles. In the rhizoplane of all four plants a significant reduction of diversity was observed, relative to the bulk soil. Moreover, an increase in DNA-RNA correspondence indicated higher representation of active bacterial populations in the residing rhizoplane community. This research demonstrates that the host plant determines the bacterial community composition in its immediate vicinity, especially with respect to the active populations. Based on the studies from the US team, we suggest that the effective population size PGPR should be maintained at approximately 105 cells per gram of rhizosphere soil in the zone of elongation to obtain plant growth promotion effects, but emphasize that it is critical to also consider differences in the activity based on DNA-RNA correspondence. The results ofthis research provide fundamental new insight into the composition ofthe bacterial communities associated with plant roots, and the factors that affect their abundance and activity on root surfaces. Virtually all PGPR are multifunctional and may be expected to have diverse levels of activity with respect to production of plant growth hormones (regulation of root growth and architecture), suppression of stress ethylene (increased tolerance to drought and salinity), production of siderophores and antibiotics (disease suppression), and solubilization of phosphorus. The application of transcriptome methods pioneered in our research will ultimately lead to better understanding of how management practices such as use of compost and soil inoculants can be used to improve plant yields, stress tolerance, and disease resistance. As we look to the future, the use of metagenomic techniques combined with quantitative methods including microarrays, and quantitative peR methods that target specific genes should allow us to better classify, monitor, and manage the plant rhizosphere to improve crop yields in agricultural ecosystems. In addition, expression of several genes in rhizospheres of both cucumber and whet roots were identified, including mostly housekeeping genes. Denitrification, chemotaxis and motility genes were preferentially expressed in wheat while in cucumber roots bacterial genes involved in catalase, a large set of polysaccharide degradation and assimilatory sulfate reduction genes were preferentially expressed.
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Moghissi. L51914 Interdependent Effects of Bacteria Gas Composition and Water Chemistry on Internal Corrosion. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), April 2002. http://dx.doi.org/10.55274/r0010433.

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A recent Office of Pipeline Safety survey found that corrosion caused 17 to 20 percent of pipeline failures. Of those corrosion failures, roughly half resulted from internal corrosion. In pipelines, internal corrosion is caused by produced (carry-over) or condensed water that contains dissolved gas and/or bacteria. In many cases, chemicals with inhibiting or biocidal properties are added to mitigate corrosion. The internal corrosion in many systems occurs under slowly flowing conditions at ambient temperatures (e.g., relatively low temperature of about 15.5�C (60�F)). The overall objectives of this project were to determine the influence of microbial consortia typically found in condensed water, produced water, and hydrocarbons on the internal corrosion of steel pipeline exposed to CO2, H2S, and O2. To accomplish these objectives, a multi-year project was planned. For the first year, the specific objectives were to assemble a chemostat system capable of maintaining a mixed biofilm consortium of bacteria implicated in MIC of steels under the pressures encountered in gathering lines, identify the type of microbial populations inside pipelines and conditions under which internal MIC has been observed, and perform a limited number of corrosion tests to evaluate the effects of these bacteria on corrosion.
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2021.2141.

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In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
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Asvapathanagul, Pitiporn, Leanne Deocampo, and Nicholas Banuelos. Biological Hydrogen Gas Production from Food Waste as a Sustainable Fuel for Future Transportation. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2022.2141.

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In the global search for the right alternative energy sources for a more sustainable future, hydrogen production has stood out as a strong contender. Hydrogen gas (H2) is well-known as one of the cleanest and most sustainable energy sources, one that mainly yields only water vapor as a byproduct. Additionally, H2 generates triple the amount of energy compared to hydrocarbon fuels. H2 can be synthesized from several technologies, but currently only 1% of H2 production is generated from biomass. Biological H2 production generated from anaerobic digestion is a fraction of the 1%. This study aims to enhance biological H2 production from anaerobic digesters by increasing H2 forming microbial abundance using batch experiments. Carbon substrate availability and conversion in the anaerobic processes were achieved by chemical oxygen demand and volatile fatty acids analysis. The capability of the matrix to neutralize acids in the reactors was assessed using alkalinity assay, and ammonium toxicity was monitored by ammonium measurements. H2 content was also investigated throughout the study. The study's results demonstrate two critical outcomes, (i) food waste as substrate yielded the highest H2 gas fraction in biogas compared to other substrates fed (primary sludge, waste activated sludge and mixed sludge with or without food waste), and (ii) under normal operating condition of anaerobic digesters, increasing hydrogen forming bacterial populations, including Clostridium spp., Lactococcus spp. and Lactobacillus spp. did not prolong biological H2 recovery due to H2 being taken up by other bacteria for methane (CH4) formation. Our experiment was operated under the most optimal condition for CH4 formation as suggested by wastewater operational manuals. Therefore, CH4-forming bacteria possessed more advantages than other microbial populations, including H2-forming groups, and rapidly utilized H2 prior to methane synthesis. This study demonstrates H2 energy renewed from food waste anaerobic digestion systems delivers opportunities to maximize California’s cap-and-trade program through zero carbon fuel production and utilization.
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