Microbial Physiology Commons^™

Antimicrobial Responses Of Staphylococcus Aureus In Simulated Spaceflight Conditions, Mikayla Dutkiewicz, Yegor Bushnev

Discovery Day - Daytona Beach

Microbial persistence in confined environments, such as spacecraft, can pose challenges to astronaut health and habitat maintenance. This project investigates Staphylococcus aureus, a Gram-positive bacterium commonly associated with human microbiota and opportunistic infections, in spaceflight-relevant environmental conditions. Further, this project will assess the influence of the antimicrobial/antioxidant compound quercetin to assess its effects on bacterial growth and virulence under standard Earth gravity and simulated International Space Station (ISS) conditions. This approach will assess whether spaceflight-relevant stressors, including microgravity and radiation, alter treatment efficacy by influencing microbial physiology and antimicrobial susceptibility. Data collection and analysis are ongoing, and results are expected …

Functional Analysis Of Ligand Binding Domain 2 Of Outer Surface Protein C Of Borreliella Burgdorferi, Gavin Z. Chambers

Theses and Dissertations

Lyme disease, caused by the spirochete Borreliella burgdorferi, is the most common vector-borne infection in North America. A critical determinant of early mammalian infection is outer surface protein C (OspC), a highly variable lipoprotein that is indispensable for spirochete survival but whose precise function remains unresolved. OspC has been proposed to mediate diverse roles, including complement evasion, adhesion, tissue dissemination, and antiphagocytic activity, supporting the view that it is a multifunctional virulence factor. Structural studies have identified two putative ligand-binding domains (LBD1 and LBD2), with LBD2 forming a solvent-exposed crown at the membrane-distal end of the OspC dimer.

To …

A New Model For Polar Growth In Mycobacteria: The Role Of Wag31 And Mmpl3 In Cell Wall Synthesis, Neda Habibi Arejan

Biology Dissertations - Archive

The disease Tuberculosis (TB) is caused by the pathogen Mycobacterium tuberculosis and was the cause of over one million deaths worldwide in 2023 (World Health Organization, 2023). TB treatment is difficult due to antibiotic tolerance and emerging resistance in Mtb strains. Mycobacterial cells have different regulatory mechanisms that allow them to adjust to myriad environmental stressors: these responses often lead to antibiotic tolerance. Therefore, studying responses to stress will lead to insights about antibiotic tolerance and treatment failure. Here, we specifically study two essential mycobacterial proteins, Wag31 and MmpL3, involved in cell wall metabolism. We show that Wag31 has distinct …

Inhibition Of Biofilm Formation By The Synergistic Action Of Egcg-S And Antibiotics, Shrameeta Shinde, Lee Lee, Tinchun Chu

Department of Biology Faculty Scholarship and Creative Works

Biofilm, a stress-induced physiological state, is an established means of antimicrobial tolerance. A perpetual increase in multidrug resistant (MDR) infections associated with high mortality and morbidity have been observed in healthcare settings. Multiple studies have indicated that the use of natural products can prevent bacterial growth. Recent studies in the field have identified that epigallocatechin gallate (EGCG), a green tea polyphenol, could disrupt bacterial biofilms. A modified lipid-soluble EGCG, epigallocatechin-3-gallate-stearate (EGCG-S), has enhanced the beneficial properties of green tea. This study focuses on utilizing EGCG-S as a novel synergistic agent with antibiotics to prevent or control biofilm. Different formulations of …

Illumination Of The Golgi Apparatus Of Pathogenic And Nonpathogenic Naegleria Species, Tyler M. Poe

Theses and Dissertations

In this study, Naegleria fowleri, a pathogenic amoeba and the causative agent of Primary Amebic Meningoencephalitis (PAM), was utilized to determine the presence or absence of classically conserved Golgi molecules featured in the expression of a Golgi apparatus. Previous studies concluded no Golgi expression via light microscopy and transmission electron microscopy, but a recent report on Naegleria gruberi indicated the presence of dispersed Golgi tubules. Non-pathogenic species of the Naegleria genus such as Naegleria gruberi 30540 and Naegleria lovaniensis 30569 were utilized in Western immunoblot analysis compared to reduced whole-cell lysate proteins of two strains of N. fowleri and …

Dissecting The Mechanism Of Action Of A Novel Antifungal Peptide, Cody Bullock

Graduate Theses and Dissertations

There is an urgent need for novel treatments for Candida infections. The utility of antimicrobial peptides for antifungal therapy has garnered interest in recent years. One promising family of peptides is the Histatins, a family of naturally-occurring peptides secreted into the oral cavity that display antimicrobial activity. Histatin 5 is a twenty-four amino acid peptide with strong antifungal activity. Studies from our laboratory have identified a small histatin-derived peptide, KM29, that yields fungicidal activity 10-fold greater than Histatin 5 against multiple Candida species. Our laboratory has focused on understanding the mechanism of action of KM29 to further develop it as …

Identification Of A Tola Protein Binding Site For Bacterial Toxins, Monica Ferrante

Honors Projects

Group A colicins are proteinaceous bacteriocins encoded by plasmids that exploit the cellular envelope protein TolA to translocate the cell wall barrier and cellular envelope of the bacterium Escherichia coli. These colicins offer protocols for studying certain protein-protein interactions involved in such membrane transport functions. Previous experimentations suggest the carboxyl-terminal domain of TolA protein contains specific amino acid binding regions required for the translocation of group A colicins into E. coli. The amino acid sequence of this domain varies between E. coli and other gram-negative bacterial species. It has been suggested that this diversity could be utilized to …

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 …

Environmental Changes Turn On The Sinorhizobium Melitloti Exor-Exos/Chvi (Rsi) Host Invasion Switch, Shari N. Walcott

Dissertations, Theses, and Capstone Projects

The free-living Gram-negative soil bacterium, Sinorhizobium meliloti, must switch into its host-invading form in order to infect the root hairs of the host plant, alfalfa (Medicago sativa), and establish a nitrogen-fixing symbiosis. The activation of the switch is believed to occur inside the infection chamber that is formed by curling of the root hairs. It is not fully understood what signals in the environment of the root hairs trigger and infection chamber S. meliloti to switch into a host-invading form since these signals were not extensively examined until now. This switch can be observed directly, due to …

Characterization Of Ftsa-Ftsn Interaction During Escherichia Coli Cell Division, [email protected] K. Busiek

Dissertations and 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 …

Development And Characterization Of Eukaryotic Biomimetic Liposomes, Bradley Jay Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study developed and characterized phospholipid vesicles, or liposomes, that mimic cell surfaces. Microemulsified liposomes contained biotinylated phosphatidylethanolamine, allowing them to be immobilized to avidin-coated glass. Laminin (LN), glycosphingolipids (GMl and GM3), and Escherichia coli's mechanosensitive channel of large conductance (EcoMscL) were embedded into liposome membranes. It was determined whether these embedded molecules exhibited their physiological roles of adhesion, cell recognition, and mechanosensation, respectively. Confocal laser scanning microscopy (CLSM) was employed to examine the interaction of fluorescently probed proteins, toxins, and bacteria with the immobilized microemulsified liposomes. Capture of individual and simultaneous multiple species of bacteria by GMl, GM3, …