Microbiology Commons^™

E. Coli Persister Cell Survival And Rhizobia Attachment To Soybean Roots, Tanim Islam

Electronic Theses and Dissertations

The theme of this thesis revolves around how bacteria respond and thrive during stress. Chapters 1-3 are about how bacteria deal with life-threatening antibiotics. Chapter 4 covers new research on how bacteria can move from a stressful individual lifestyle (free-living bacteria) to initiating a symbiotic relationship with a plant (a less stressful lifestyle). In Chapter 1, I briefly summarize the current state of knowledge in the field of antibiotic resistance and persistence. In Chapter 2, I add to this knowledge by providing new insights into several antibiotics' potency and exploring the antibiotic Eagle effect. In Chapter 3, I use pyruvate …

Regulation Of Skeletal Muscle Plasticity By The Gut Microbiome, Taylor R. Valentino

Theses and Dissertations--Physiology

Recent evidence suggests that the gut microbiome could play a role in skeletal muscle plasticity, providing novel treatments for muscle wasting diseases and/or performance enhancements. I first sought to determine if the gut microbiome is necessary for skeletal muscle adaptation to exercise. Forty-two, four-month old, female C57Bl/6J underwent nine weeks of weighted wheel running or remained in cage with a locked wheel, without or without the administration of antibiotics (treated). In response to wheel running, I found that antibiotic depletion of the microbiome led to a blunted hypertrophic response in the soleus muscle as measured by normalized muscle wet weight …

Dissecting The Role Of Actin-Myosin Motor And Calcium – Based Organelle Secretion In Motility Of Sarcocystis Neurona, Parul Suri

Theses and Dissertations--Veterinary Science

Sarcocystis neurona is a protozoan parasite that causes a rare neurological disorder in horses called Equine Protozoal Myeloencephalitis (EPM). Apicomplexa use actin-myosin based motor and organelle secretion to interact with the host cell and invade it. Despite the importance of motility and invasion-needed factors, the mechanisms by which S. neurona employs host cell association strategies to interact remains largely undefined. To address this knowledge gap, we hypothesize that just like other Apicomplexa, S. neurona utilizes actin polymerization for substrate-dependent gliding. Moreover, we also hypothesize that micronemes of S. neurona secrete proteins that are calcium-dependent. Based on previous studies in T. …

Exploration Of Lignin-Based Superabsorbent Polymers (Hydrogels) For Soil Water Management And As A Carrier For Delivering Rhizobium Spp., Toby Adjuik

Theses and Dissertations--Biosystems and Agricultural Engineering

Superabsorbent polymers (hydrogels) as soil amendments may improve soil hydraulic properties and act as carrier materials beneficial to soil microorganisms. Researchers have mostly explored synthetic hydrogels which may not be environmentally sustainable. This dissertation focused on the development and application of lignin-based hydrogels as sustainable soil amendments. This dissertation also explores the development of pedotransfer transfer functions (PTFs) for predicting saturated hydraulic conductivity using statistical and machine learning methods with a publicly available large data set. A lignin-based hydrogel was synthesized, and its impact on soil water retention was determined in silt loam and loamy fine sand soils. Hydrogel treatment …

Examining Behavioral Defenses Of The Fungus-Growing Ant Trachymyrmex Septentrionalis Against Trichoderma-Derived Metabolites, Darren Lee

Holster Scholar Projects

Fungus-growing ants defend their fungal mutualist against pathogens through a number of chemical and behavioral mechanisms. Work by Dr. Jonathan Klassen’s lab has found that Trachymyrmex septentrionalis ants maintain their fungal symbionts’ health through physical removal (“weeding”) upon infection with pathogenic fungi in the genus Trichoderma. Ants also exhibited weeding behavior when the fungus was inoculated with peptaibols, a class of secondary metabolites produced by Trichoderma, suggesting that these molecules act as chemical cues that induce ant weeding. However, the mechanisms by which weeding behaviors are communicated between the ants and their fungal symbiont are unknown. Behavioral experiments demonstrated that …

Pre-Exposure Of Escherichia Coli And Staphylococcus Aureus To Sub-Bactericidal Concentrations Of Benzalkonium Chloride And Its Effect On Low-Level Antimicrobial Resistance, Logan Fette

All Graduate Theses, Dissertations, and Other Capstone Projects

Antimicrobial resistance that develops in bacteria is a highly studied aspect of microbiology due to the concerns that it poses for public health. Antibiotics remain our primary care option when dealing with bacterial infections. The concept of tolerance of bacteria to disinfectants is similar and it also poses a significant health risk. Since use of disinfectants for sanitation is a primary manner in which we are able to prevent potential infections from occurring in the first place, it can be a helpful means to preventing development of antimicrobial resistance. However, what has not been explored to the same extent is …

Function And Expression Of Ribonucleotide Reductase-Encoding Genes In Flavobacterium Johnsoniae, Hunter Scott Doheny

All Graduate Theses, Dissertations, and Other Capstone Projects

Ribonucleotide reductases (RNRs) are essential enzymes that are involved in DNA synthesis. While this makes them ideal targets for antiproliferative drugs, most known RNR targeting agents are nonspecific. This poses a problem when considering antimicrobials, but several groups of bacteria have RNRs that utilize unique mechanisms that could be exploited if fully understood. One such bacteria, Flavobacterium johnsoniae, has the gene for a class Id RNR with a novel activation mechanism. Class Id RNRs belong to the aerobic class I RNRs and seem to have a unique metallocofactor and activation mechanism involving superoxide and manganese. The goal of this research …

Development Of Genetic Manipulation Techniques For The Fish Pathogen Flavobacterium Psychrophilum, Seada Sloboda

All Graduate Theses, Dissertations, and Other Capstone Projects

Flavobacterium psychrophilum is a known fish pathogen, causing bacterial cold-water disease (BCWD) and rainbow trout fry syndrome (RTFS), predominantly in salmonids. The disease causes tissue damage and tail rot in young and adult fish. The issue is prevalent in fisheries in the Pacific Northwest and the treatments often entail the use of antibiotics. Genetic manipulations in F. psychrophilum are scarce, due to most of the strains’ ability to destroy foreign DNA via restriction enzymes. The virulence mechanisms of F. psychrophilum are not well understood. Lack of genetic manipulation tools in F. psychrophilum has also hampered the development of live attenuated …

Beneficial Plant-Microbe Interactions To Improve Nutrient Uptake And Biotic Stress Response In Crops, Jaya Krishna Yakha

Electronic Theses and Dissertations

Mutualism is a very common phenomenon among living organisms on earth. Legumes because of their high protein content, serve as a great nutrient resource for animals. This group of plants can form a mutualistic symbiosis with beneficial microbes. For example, Alfalfa (Medicago) and soybean (Glycine max) can get colonized with arbuscular mycorrhizal fungi (AMF) and rhizobia bacteria simultaneously forming a complex tripartite interaction for nutrient benefits. Most of the previous research evaluated individual symbionts, either rhizobia bacteria or AMF, but not both. There are only a few reports which discuss the nutrient exchange mechanisms in a tripartite interaction. Thus, there …

Microbial Communities And Nitrogen Dynamics In Prairie And Cropland Soils, Bikram Kumar Das

Electronic Theses and Dissertations

Soil microbial communities are affected by many factors, such as soil nitrogen (N) and the quantity of grass-root exudates, changing seasons, fertilization method, plant diversity, and their origin. This holds for both natural and fertilized soils. This research was intended to expand the current understanding of soil microbial interactions associated with ecological functions. The objectives of the research were (I) to characterize prokaryotic soil communities, estimate functional potential, and quantify nitrogen cycle-associated prokaryotic gene expressions across three phases of the growing season, (II) to explore the diazotrophic community composition in a natural system using nifH sequencing as well as 16S …

Exploring Bioprocessing Technologies For Diverse Industrial Application Of Canola, Ahmad Fawzi N Alhomodi

Electronic Theses and Dissertations

Globally, canola is the second largest oilseed crop after soybean, which is processed for the commercial production of high value oil. The industrial processing steps for canola oil extraction include preprocessing (cleaning, pressing, flaking, and cooking), mechanical pressing, and/or organic solvents. This process results in large quantities of protein-rich (~ 40% dry basis) meal as a co-product. The meal is used partially in animal diet (<30% inclusion) due to high levels of antinutritional factors (ANFs) such as high fibers, phytic acid, and glucosinolates, and low metabolizable energy. Thus, this research was designed to examine various bioprocessing technologies (i.e., traditional sprouting, solid state fermentation, submerged state fermentation, co-culture fermentation, mild pretreatments, and their combinations) for possible advancement in canola use. Canola seed sprouting for 6-day period led to an increase in protein content and a reduction in ANFs and oil content of sprouts compared to ungerminated seed. Subsequent submerged state fermentation of 6- day old sprouts using three different strains (Aureobasidium pullulans, Trichoderma reesei and Neurospora crassa) further increased protein content and lowered ANFs. Solid-state fermentation of 144 h old sprouts using A. pullulans, N. crassa and T. reesei enhanced the protein content and reduced ANFs of sprouts. Sprouting canola seed for three days helped in hull removal, leading to high protein meal accompanied by low fiber and phytic acid level. Three-day seed sprouting had no effect on oil yield, but free fatty acid content was higher compared to seed oil. Co-culture fermentation of HECM under solid state process showed maximum reduction in fiber content with co-culture of A. pullulans and N. crassa while a combination of A. pullulans and T. reesei promoted the highest GLS and phytic acid reductions compared to other combinations, which indicated the advantage of coculture inoculation over monoculture in terms of ANFs reduction. Mild pretreatment of HECM using deionized water resulted in washed HECM (WHECM) with lower soluble sugars and GLS compared to untreated HECM, whereas protein and amino acid were concentrated due to the removal of soluble components. WHECM compared to HECM showed higher protein digestibility when fed to rainbow trout. Subsequent mono- and coculture fermentation of HECM and WHECM under submerged process resulted in higher protein and amino acid content and lower ANFs levels compared to uninoculated controls. The results of cellulase, endoglucanase and β-glucosidase activity indicated the crucial role of used substrates, fungi, fermentation modes (solid state/submerged stated) and inoculation methods (mono-/co-culture) on enzyme activities.

Links Between Electrophilic Stress And Antifungal Resistance In Pathogenic Candida Species, Amy R. Biermann

Dartmouth College Ph.D Dissertations

Collectively, Candida species are the most prevalent cause of both superficial and invasive fungal infections worldwide. Invasive Candida infections have a high mortality rate and predominantly affect individuals with underlying diseases, such as diabetes, HIV, or cancer. Unfortunately, many invasive Candida infections are recalcitrant to antifungal treatment, while intrinsically multidrug-resistant pathogens, like Candida auris, are increasing in prevalence. Although the canonical mechanisms of antifungal resistance in Candida species are well established, i.e., overexpression of efflux pumps and overexpression of or mutations in genes encoding drug targets, factors affecting the natural evolution and regulation of resistance mechanisms remain poorly understood. …

Identification Of The Role Of Swra In Copper Induced Poly-Gamma-Glutamic Acid Production In Bacillus Subtilis, Maya Addison

Scripps Senior Theses

Each year over 2.8 million Americans are infected by an antibiotic resistant strain of bacteria with over 35, 000 dying as a result (CDC). The lack of development of new antibiotics has renewed interest in the antimicrobial properties of copper. Gram positive bacterium such as Bacillus subtilis produce poly-gamma-glutamic acid (γ-PGA) to sequester excess copper ions. swrA has shown to be essential for proper activation of the pgs operon by phosphorylated DegU via an unknown mechanism. This study seeks to determine the role of swrA in copper induced gamma-PGA production and if swrA and ppsB are involved in copper resistance. …

An Investigation Of Hhv6'S Impact On The Cognitive Progression And Microglial Changes In An Alzheimer's Disease Cohort, Charles E. Seaks

Theses and Dissertations--Physiology

The role of herpesviruses and, more specifically, HHV6 in the development of Alzheimer’s disease (AD) and associated cognitive decline is still being investigated. High ubiquity and prevalence in the population have led to a high degree of skepticism about HHV6 as a potential contributor to cognitive decline and dementias. However, recent evidence related to another herpesvirus, herpes simplex virus 1, suggests that reactivation, not carriage, of the virus may be the key factor to explain the dissonance between the virus’ ubiquity and contributions to dementias. With that in mind, we set out to assess cases from the Sanders-Brown Center on …

Evaluate The Efficacy Of A Mixture Of Peroxyacetic Acid And H2o2 Against The Survival And Cross-Contamination Of The Salmonella Surrogate Enterococcus Faecium On Tomatoes During Triple-Wash, Corey Waitman Coe

Graduate Theses, Dissertations, and Problem Reports (ETD)

Triple-wash with a mixture of peroxyacetic acid and H2O2 (SaniDate-5.0) during post-harvest processing of fresh produce has been recommended by West Virginia Small Farm Center to improve microbial safety. It has been well recognized that the washing of produce is more important for preventing cross-contamination than reducing foodborne pathogens. Furthermore, it may help improve public confidence in that the produce they obtain from locally grown farmers is safe for their consumption. determine the efficacy of SaniDate-5.0 for reducing the survival and preventing cross-contamination of the Salmonella surrogate Enterococcus faecium on tomatoes during triple-wash.

E. faecium ATCC-8459 (resistant to 100-ppm nalidixic-acid) …

Cross-Kingdom Interactions Shape Soil Biogeochemistry In Natural And Agricultural Ecosystems, Jennifer Lynne Kane

Graduate Theses, Dissertations, and Problem Reports (ETD)

Microorganisms influence life on earth in innumerable ways, including in medical, industrial, environmental, and agricultural contexts. Given the increasingly apparent consequences of climate warming, interest in how to better predict and manage Earth’s carbon sinks has never been greater. Soil, the largest terrestrial carbon sink, harbors an incredibly taxonomically and functionally diverse microbial community. These soil-dwelling microbes govern the fate of soil carbon and nutrients by cycling organic matter as they live, grow, and die. It has only been relatively recently that technological advancement has allowed for in-depth surveys of the vast diversity of soil microbes. High throughput analytical capabilities …

Tracking Cryptic Sars-Cov-2 Lineages Detected In Nyc Wastewater, Davida S. Smyth, Monica Trujillo, Devon A. Gregory, Kristen Cheung, Anna Gao, Maddie Graham, Yue Guan, Caitlyn Guldenpfennig, Irene Hoxie, Sherin Kannoly, Nanami Kubota, Terri D. Lyddon, Michelle Markman, Clayton Rushford, Kaung Myat San, Geena Sompanya, Fabrizio Spagnolo, Reinier Suarez, Emma Teixeiro, Mark Daniels, Marc C. Johnson, John J. Dennehy

Publications and Research

Tracking SARS-CoV-2 genetic diversity is strongly indicated because diversifying selection may lead to the emergence of novel variants resistant to naturally acquired or vaccine-induced immunity. To monitor New York City (NYC) for the presence of novel variants, we deep sequence most of the receptor binding domain coding sequence of the S protein of SARS-CoV-2 isolated from the New York City wastewater. Here we report detecting increasing frequencies of novel cryptic SARS-CoV-2 lineages not recognized in GISAID’s EpiCoV database. These lineages contain mutations that had been rarely observed in clinical samples, including Q493K, Q498Y, E484A, and T572N and share many mutations …

Magnaporthe Oryzae Telomeric Retrotransposon (Moter) Relics Further Highlight Telomere Dynamics In A Rapidly Evolving Fungal Pathogen, Jane Ellen Dostart

Online Theses and Dissertations

The telomeres of M. oryzae can experience unique rearrangements within a single generation. These rearrangements are frequently attributed to the presence of two retrotransposons (MoTeR 1 and MoTeR 2) that are endemic to the telomeres. These rearrangements can leave footprints within the interior of the genome that document previous telomere breakage events. The purpose of this study was to examine MoTeR relics within 10 genomes of strains of M. oryzae to document telomere instability among strain lineages, as well as to uncover MoTeR relic distribution, shared evolutionary history, and associated genome rearrangements. A series of local BLASTn and grep searches …

Ifn-Γ Increases The Expression Of Sars-Cov-2 Receptors On Vero E6 Cells, Bindu Madhavi Madabattula

Browse all Theses and Dissertations

Respiratory epithelial cells are the initial target for SARS-CoV-2 infection. IFN-γ is known to increase the expression of ACE-2, an initial receptor for SARS-CoV-2, on epithelial cells. This study focuses on examining the effect of IFN-γ for ACE-2, TMPRSS2, and neuropilin-1 on Vero E6 cells using two immunofluorescence methods, namely, direct (membrane) fluorescence method and Cytation5 method. Direct fluorescence was determined using an Accu-Scope and ImageJ analysis. Using this method, significance (p<0.023) was observed only for ACE-2 when Vero E6 cells were treated with IFN-γ. Cytation5 fluorescence was determined using a Bio-tek Cytation5 plate reader. The results showed that IFN-γ significantly increased (p<0.001) the expression of ACE-2, neuropilin-1, and TMPRSS2. These results indicate Cytation5 is a more sensitive method for determining the expression of receptors on Vero E6 cells. The elevated levels of SARS-CoV-2 receptors expression resulting from IFN-γ treatment makes the epithelial cells more susceptible targets of SARS-CoV-2 infection. IFN-γ is most likely provided by innate immune cells in the initial COVID-19 infection, consequently contributing to the severity of disease.

Expression Of Sars Cov2 Receptors Influenced Upon Cytokine Polarizations (Il-4 And Ifnγ) In Hemangioendothelioma Cells, Chandra Lekha Koopari

Browse all Theses and Dissertations

Endothelial cells are distinct multifunctional cells with essential metabolic and synthetic roles along with their ability to function as selective permeability barrier. Endothelial cells (ECs), the major component of blood vessels, essentially interact directly yet differently with inflammatory cytokines. ECs are well recognized to be polarized cells, but little is known about the potential function of inflammatory mediators. Covid 19 may have long-term health effects on par with chronic illnesses. Vascular inflammatory disease and coagulopathy linked to COVID-19 are exacerbated by endothelial cell (EC) dysfunction. SARS-CoV-2 enters the host cell through the Angiotensin Converting Enzyme 2 (ACE2) receptor and primes …