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Organismal Biological Physiology Commons™
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Articles 1 - 12 of 12
Full-Text Articles in Organismal Biological Physiology
Novel Microbial Guilds Implicated In N2o Reduction, Guang He
Novel Microbial Guilds Implicated In N2o Reduction, Guang He
Doctoral Dissertations
N2O is a long-recognized greenhouse gas (GHG) with potential in global warming and ozone depletion. Terrestrial ecosystems are a major source of N2O due to imbalanced N2O production and consumption. Soil pH is a chief modulating factor controlling net N2O emissions, and N2O consumption has been considered negligible under acidic conditions (pH <6). In this dissertation, we obtained solids-free cultures reducing N2O at pH 4.5. Furthermore, a co-culture (designated culture EV) comprising two interacting bacterial population was acquired via consecutive transfer in mineral salt medium. Integrated phenotypic, metagenomic and metabolomic analysis dictated that the Serratia population excreted certain …6).>
The Stringent Response In Pseudomonas Aeruginosa Influences The Phenotypes Controlled By The Gac/Rsm System, Michael Shawn Hooker
The Stringent Response In Pseudomonas Aeruginosa Influences The Phenotypes Controlled By The Gac/Rsm System, Michael Shawn Hooker
Electronic Theses and Dissertations
Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen that causes acute and chronic infections. Infection is typically initiated via motile and virulent strains. After exposure to stressors, acute infections make both genotypic and phenotypic switches to a chronic, sessile strain. This is due to intricate regulatory networks directing gene expression in response to stressors. One network, GacA/GacS, has been established to control virulence factors. The stringent response of bacteria is mediated by alarmones produced primarily by RelA which responds to starvation.
To study the effect of the stringent response on the virulence switch. A series of experiments were run in both …
Role And Regulation Of Staphylococcal Cell Death, Abdulelah Ahmed Alqarzaee S
Role And Regulation Of Staphylococcal Cell Death, Abdulelah Ahmed Alqarzaee S
Theses & Dissertations
The transition from growth to stationary phase is a natural response of bacteria to starvation and stress. When stress is alleviated and more favorable growth conditions return, bacteria resume proliferation without a significant loss in fitness. Although specific adaptations that enhance persistence and survival of bacteria in stationary phase have been identified, mechanisms that help maintain the competitive fitness potential of non-dividing bacterial populations have remained obscure. This dissertation demonstrates that staphylococci entering stationary phase following growth in excess glucose undergo regulated cell death to maintain the competitive fitness potential of the population. Upon a decrease in extracellular pH, the …
Identifying Determinants Of Target Specificity In Two Related Bacterial Peptide Toxins, Andrew D. Holmes
Identifying Determinants Of Target Specificity In Two Related Bacterial Peptide Toxins, Andrew D. Holmes
Honors Thesis
Toxin-antitoxin (TA) systems were originally identified as two-component systems ensuring the stable inheritance of plasmids in bacterial populations. Recently, they have been identified on bacterial chromosomes where their functions remain mostly undefined. The par locus of E. faecalis plasmid pAD1 (parpAD1) was the first TA system defined in a Gram-positive bacterium and a homolog encoded on the E. faecalis chromosome (parEF0409) was later described. Related loci numbering in the hundreds have been identified throughout Gram-positive bacteria based on homology to the toxin of the system, Fst, and similarities in genetic organization and regulation. Despite …
Regulation Of The Tubulin Homolog Ftsz In Escherichia Coli, Monika S. Buczek
Regulation Of The Tubulin Homolog Ftsz In Escherichia Coli, Monika S. Buczek
Dissertations, Theses, and Capstone Projects
Escherichia coli is a well-known pathogen, and importantly, a widely used model organism in all fields of biological sciences for cloning, protein purification, and as a model for Gram-negative bacterial species. And yet, researchers do not fully understand how this bacterium replicates and divides. Every year additional division proteins are discovered, which adds complexity to how we understand E. coli undergoes cell division. Due to their specific roles in cytokinesis, some of these proteins may be potential targets for development of antibacterials or bacteriostatics, which are much needed for fighting the current global antibacterial deficit. My thesis work focuses on …
Toxicity Of Engineered Nanomaterials To Plant Growth Promoting Rhizobacteria, Ricky W. Lewis
Toxicity Of Engineered Nanomaterials To Plant Growth Promoting Rhizobacteria, Ricky W. Lewis
Theses and Dissertations--Plant and Soil Sciences
Engineered nanomaterials (ENMs) have become ubiquitous in consumer products and industrial applications, and consequently the environment. Much of the environmentally released ENMs are expected to enter terrestrial ecosystems via land application of nano-enriched biosolids to agricultural fields. Among the organisms most likely to encounter nano-enriched biosolids are the key soil bacteria known as plant growth promoting rhizobacteria (PGPR). I reviewed what is known concerning the toxicological effects of ENMs to PGPR and observed the need for high-throughput methods to evaluate lethal and sublethal toxic responses of aerobic microbes. I addressed this issue by developing high-throughput microplate assays which allowed me …
Isolation And Identification Of Bacterial Endosymbionts In The Brooding Brittle Star Amphipholis Squamata, Abbey Rose Tedford
Isolation And Identification Of Bacterial Endosymbionts In The Brooding Brittle Star Amphipholis Squamata, Abbey Rose Tedford
Honors Theses and Capstones
Symbiotic associations with subcuticular bacteria (SCB) have been identified and studied in numerous echinoderms, including the SCB of the brooding brittle star, Amphipholis squamata. These SCB, however, have not been studied using current next generation sequencing technologies. Previous studies on the SCB of A. squamata placed these bacteria in the genus Vibrio (γ-Proteobacteria), but subsequent studies suggested that the SCB are primarily composed of α-Proteobacteria. The present study examines the taxonomic composition of SCB associated with A. squamata from the Northwest Atlantic. DNA was extracted using a CTAB protocol and 16S rRNA sequences were amplified …
Exploring The Physiological Role Of Vibrio Fischeri Pepn, Sally L. Cello
Exploring The Physiological Role Of Vibrio Fischeri Pepn, Sally L. Cello
Master's Theses
The primary contributor to Vibrio fischeri aminopeptidase activity is aminopeptidase N, PepN. Colonization assays revealed the pepN mutant strain to be deficient at forming dense aggregates and populating the host’s light organ compared to wildtype within the first 12 hours of colonization; however the mutant competed normally at 24 hours. To address the role of PepN in colonization initiation and establish additional phenotypes for the pepN mutant strain, stress response and other physiological assays were employed. Marked differences were found between pepN mutant and wildtype strain in response to salinity, acidity, and antibiotic tolerance. This study has provided a foundation …
Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood
Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood
Doctoral Dissertations
Microbial chemotaxis receptors (chemoreceptors) are complex proteins that sense the external environment and signal for flagella-mediated motility, serving as the GPS of the cell. In order to sense a myriad of physicochemical signals and adapt to diverse environmental niches, sensory regions of chemoreceptors are frenetically duplicated, mutated, or lost. Conversely, the chemoreceptor signaling region is a highly conserved protein domain. Extreme conservation of this domain is necessary because it determines very specific helical secondary, tertiary, and quaternary structures of the protein while simultaneously choreographing a network of interactions with the adaptor protein CheW and the histidine kinase CheA. This dichotomous …
Characterization Of Ftsa-Ftsn Interaction During Escherichia Coli Cell Division, Kimberly.Busiek@Gmail.Com K. Busiek
Characterization Of Ftsa-Ftsn Interaction During Escherichia Coli Cell Division, Kimberly.Busiek@Gmail.Com K. Busiek
Dissertations & Theses (Open Access)
Division of a bacterial cell into two equal daughter cells requires precise assembly and constriction of the division machinery, or divisome. The Escherichia coli divisome includes nearly a dozen essential cell division proteins that assemble at midcell between segregating sister chromosomes. FtsZ, a homolog of eukaryotic tubulin, is the first essential cell division protein to localize at midcell where it polymerizes into a ring-shaped scaffold (Z ring). Establishment of the Z ring is required for recruitment of downstream cell division proteins including FtsA, a cytoplasmic protein that tethers the Z ring to the inner membrane. Following localization of FtsA and …
Effects Of Land Use In The Ohio River Basin On The Distribution Of Coliform And Antibiotic Resistant Bacteria In The Ohio River, Gene Chou
Theses, Dissertations and Capstones
Recent studies indicate that antibiotic resistant bacteria can be useful as indicators of water quality (1, 2, 5, 7, 8, 9, 10). Studies in our laboratory have shown that fecal pollution did not fully explain the distribution or the frequency of antibiotic resistant bacteria in the Ohio River (27, 28). Therefore, it is important to understand the factors that affect the distribution of antibiotic resistant bacteria in aquatic habitat. The purpose of this study was to examine the correlations between land use, water quality, and concentration of antibiotic resistant bacteria in the Ohio River. Mid-channel water samples were collected at …
Affinity Purification And Characterization Of E. Coli Molecular Chaperones, Seung-Hee Nam
Affinity Purification And Characterization Of E. Coli Molecular Chaperones, Seung-Hee Nam
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The molecular chaperones are a group of proteins that are effective in vitro and in vivo folding aids and show a well documented affinity for proteins lacking tertiary structure.
Heat-induced Escherichia coli BL21 cell lysate (10 mg protein) was applied to immobilized ɑ-casein (45 mg/g beads) or β-casein (30 mg/g beads) column. After removing a majority of nonspecifically bound proteins with 1 M NaCl, the molecular chaperones were eluted with cold water, 1 mM Mg-ATP, or 6 M urea. Western analysis identified five Escherichia coli molecular chaperones including DnaK, DnaJ, GrpE, GroEL, and GroES. Among samples, ATP eluates showed the …