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Full-Text Articles in Life Sciences
Environmental Regulation Of Tidal Wetland Microbial Communities And Associated Biogeochemistry, Ember Morrissey
Environmental Regulation Of Tidal Wetland Microbial Communities And Associated Biogeochemistry, Ember Morrissey
Theses and Dissertations
Microbial communities play an essential role in carrying out the biogeochemical cycles that sustain life on Earth, yet we know very little about their ecology. One question of particular interest is how environmental conditions shape microbial community structure (i.e., the types of organisms found in the community and their relative abundance), and whether such changes in structure are related to biogeochemical function. It is the aim of this dissertation to address this question via the examination of carbon (C) and nitrogen (N) cycling in wetland ecosystems, which due to their diverse hydrology have a profound influence on biogeochemical cycles. With …
The Incidence Of Antibiotic Resistance In Mesophilic Aeromonas Isolated From The Buffalo River And From A Non-Urban Site Upstream, Amy L. Chapman
The Incidence Of Antibiotic Resistance In Mesophilic Aeromonas Isolated From The Buffalo River And From A Non-Urban Site Upstream, Amy L. Chapman
Biology Theses
Antibiotics are commonly used in agriculture and industry and their discharge is commonly seen in rivers, like the Buffalo River. This antibiotic discharge may cause a selective environment which favors the growth of antibiotic resistant Aeromonas. To study the effect of urban pollution on the antibiotic resistance in Aeromonas, 229 Aeromonas isolates were collected from fish tissues as well as sediment and water samples collected from the Buffalo River and a non-urban site (Cazenovia Creek). Seven different Aeromonas taxa were identified using biochemical tests. There were 124 (54%) isolates that were classified as atypical, which was the most commonly …
Genetic And Ecological Characterization Of Indigoidine Production By Phaeobacter Sp. Strain Y4i, William Nathan Cude
Genetic And Ecological Characterization Of Indigoidine Production By Phaeobacter Sp. Strain Y4i, William Nathan Cude
Doctoral Dissertations
The Roseobacter clade is a widely distributed, abundant, and biogeochemically active lineage of marine alpha-proteobacteria. Members of the Roseobacter lineage are prolific surface colonizers in marine coastal environments, and antimicrobial secondary metabolite production has been hypothesized to provide a competitive advantage in colonization. In this work, Phaeobacter sp. strain Y4I was found to produce the water soluble, blue pigment indigoidine via a nonribosomal peptide synthase-based biosynthetic pathway encoded by a novel series of genetically linked genes, termed igiBCDFE. Comparison of wildtype, non-pigmented, and hyper-pigmented Y4I insertional mutants demonstrated a perfect correlation between indigoidine production and the inhibition of Vibrio …
Validating Approaches For Studying Microbial Diversity To Characterize Communities From Roots Of Populus Deltoides, Migun Shakya
Validating Approaches For Studying Microbial Diversity To Characterize Communities From Roots Of Populus Deltoides, Migun Shakya
Doctoral Dissertations
Microbial (archaeal, bacterial, and fungal) communities associated with plant roots are central to its health, survival, and growth. However, a robust understanding of root microbiota and the factors that govern their community structure and dynamics have remained elusive, especially in mature perennial plants from natural settings. Although the advent of Next Generation Sequencing (NGS) technologies have changed the scale of microbial ecological studies by enabling exhaustive characterization of microbial communities, the accuracy of taxonomic and quantitative inferences are affected by multiple experimental and computational steps and lack of knowledge of the true ecological diversity. To test for inaccuracies and biases, …
Thorns Of Native Lower Rio Grande Valley Plants Are Colonized By Potentially Pathogenic Bacteria, Felicia A. Charles
Thorns Of Native Lower Rio Grande Valley Plants Are Colonized By Potentially Pathogenic Bacteria, Felicia A. Charles
Theses and Dissertations - UTB/UTPA
Epiphytic pathogenic bacteria on the thorns of native LRGV plants may provide a defense mechanism for the plants. To test this, plant thorns were collected from LRGV plant species and aerobic and anaerobic bacteria were isolated in thioglycollate medium. Tests were performed to characterize the bacterial cultures. The 16S rRNA gene was sequenced to allow for species identification. Sixty-nine bacterial cultures were isolated, including gram-positive and gram-negative cell types. All utilized a variety of carbon sources for nutrients and 23% of isolates displayed hemolysis. Bacterial identification included members of the genus Bacillus, Pseudomonas, Serratia, and others. Most were opportunistic pathogens. …
Resource Legacies And Priming Regulate Microbial Communities In Antarctica's Dry Valleys, Sabrina Deni Saurey
Resource Legacies And Priming Regulate Microbial Communities In Antarctica's Dry Valleys, Sabrina Deni Saurey
Theses and Dissertations
Multiple mechanisms control bacterial community structure but two in particular, the "legacy" of past environmental conditions, and the "priming" of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. …
Hypersaline Lake Environments Exhibit Reduced Microbial Dormancy, Joshua Christopher Vert
Hypersaline Lake Environments Exhibit Reduced Microbial Dormancy, Joshua Christopher Vert
Theses and Dissertations
From acid seeps and deep-sea thermal vents to glacial ice and hypersaline lakes, extreme environments contain relatively simplified communities consisting of extremophiles that have evolved to survive and thrive under adverse abiotic conditions. In more neutral environments, microorganisms use dormancy as a common life history strategy to weather temporal fluctuations of resources or stresses until more 'optimal' conditions are present. It is unclear if dormancy is an essential survival mechanism for microorganisms in extreme environments; however, recent studies suggest that extreme environments may create stable conditions for extremophiles to the extent that dormancy is of less ecological importance. Using lake …
Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz
Revealing The Ecological Role Of Gemmatimonadetes Through Cultivation And Molecular Analysis Of Agricultural Soils, Mariam Naomi Fawaz
Masters Theses
Bacteria belonging to phylum Gemmatimonadetes are frequently detected in a variety of environments using culture-independent methods. Despite their ubiquity and prevalence, almost nothing is known about their physiology or ecology because so few strains have been isolated. The first objective of this study was to determine the distribution of Gemmatimonadetes within soil aggregates and the response of the relative abundance of Gemmatimonadetes to dry/wet cycling and soil management. The second objective was to analyze the effects of soil management, aggregate size, and atmospheric conditions on cultivability of Gemmatimonadetes. Universal and Gemmatimonadetes-specific 16S rRNA gene primers were used to …
Plant-Mediated Effects On Microbial Diversity In Mesocosms Of An Oligotrophic Bog, Karl J. Romanowicz Iv
Plant-Mediated Effects On Microbial Diversity In Mesocosms Of An Oligotrophic Bog, Karl J. Romanowicz Iv
Dissertations, Master's Theses and Master's Reports - Open
Globally, peatlands occupy a small portion of terrestrial land area but contain up to one-third of all soil organic carbon. This carbon pool is vulnerable to increased decomposition under projected climate change scenarios but little is known about how plant functional groups will influence microbial communities responsible for regulating carbon cycling processes. Here we examined initial shifts in microbial community structure within two sampling depths under plant functional group manipulations in mesocosms of an oligotrophic bog. Microbial community composition for bacteria and archaea was characterized using targeted 16S rRNA Illumina gene sequencing. We found statistically distinct spatial patterns between the …
Effects Of Dissolved Nutrient Ratios And Concentrations On Litter-Associated Microbial Activity In Streamside Channels, Timothy Burns
Effects Of Dissolved Nutrient Ratios And Concentrations On Litter-Associated Microbial Activity In Streamside Channels, Timothy Burns
Electronic Theses and Dissertations
Heterotrophic consumers, such as microorganisms and invertebrates, play a fundamental role in the flow of carbon and energy in streams. The effects of dissolved nutrient concentrations, and especially ratios, on litter—associated microorganisms and decomposition rates of detritus are poorly understood. This study addressed the responses of heterotrophic microbes to a wide range of concentrations and ratios of dissolved inorganic nitrogen (N) and phosphorus (P) in streamside channels simulating headwater streams. Two main questions were: (1) do microbial parameters and litter decomposition rates peak at a dissolved N:P ratio that approaches the nutrient ratio of microbial biomass, and (2) does microbial …
Assessing The Effects Of Titanium Dioxide Nanoparticles On Microbial Communities In Stream Sediment Using Artificial Streams And High Throughput Screening, Alexandra Ozaki
Master's Theses
Nano-titanium dioxide (nano-TiO2) is an engineered nanomaterial used in a wide array of commercial products. The production and use of large amounts of nano-TiO2 is resulting in the unintended release to the environment. Nano-TiO2 is known to be cytotoxic due primarily to its ability to generate reactive oxygen species, and negative impacts on a variety of organisms have been demonstrated, but the effects of nano-TiO2 on complex microbial communities under ecologically relevant conditions have rarely been tested. We conducted a controlled manipulative experiment using recirculating model streams dosed with a one-time amendment of 1mg L-1 nano-TiO2 (specifically P25). Within one …
Identifying Pathogenic Salmonella Serotypes Isolated From South Central Va Waterways Via Sequential Pcr Analysis, Timothy M. Smith, Jr.
Identifying Pathogenic Salmonella Serotypes Isolated From South Central Va Waterways Via Sequential Pcr Analysis, Timothy M. Smith, Jr.
Theses & Honors Papers
Researchers often debate whether all serovars of Salmonella enterica are pathogenic to humans. Broiler houses containing chickens are a major source of Salmonella and serve as potential reservoirs. Therefore, farmers must take substantial measures in order to avoid contamination with their products. The primary objective of the study was to determine whether the four most clinically relevant Salmonella spp. serovars from poultry houses could be isolated from the environmental waterways in Prince Edward and Cumberland Counties of Virginia. The study adapted a serotyping method designed for typing Salmonella to gain a perspective of possible serovars that may be found in …
Estimation Of Aerosolized Antibiotic Resistant Bacteria Concentrations From Wastewater Treatment Facilities Using Spatially-Based Dispersion Modeling, Renee Nichole Dickman
Estimation Of Aerosolized Antibiotic Resistant Bacteria Concentrations From Wastewater Treatment Facilities Using Spatially-Based Dispersion Modeling, Renee Nichole Dickman
Theses and Dissertations
Pathogenic bacteria can develop resistance to antibiotics to which they were previously sensitive, resulting in increased morbidity and mortality worldwide [1]. The increase in drug resistance in bacteria is an emerging public health concern. The activated sludge tanks of wastewater treatment plants are known sources of antibiotic resistant bacteria. These resistant bacteria can become aerosolized and disperse downwind. Using previously sampled aerosol concentrations and meteorological data, a Gaussian dispersion model was developed to estimate the concentration downwind from a selected wastewater treatment facility. The emission rate was calculated to be 7,941 CFU/m²/sec ± 2,149 CFU/m²/sec. This value was used in …