Microbiology Commons^™

Modulation Of Coxsackievirus Protease Activity By Polyamines, Courtney Noelle Dial

Master's Theses

Coxsackievirus type B (CVB3) is one of the six serotypes of the Coxsackievirus family of non-enveloped, linear, and positive-sense single-stranded RNA viruses. It is a pathogenic enterovirus that belongs to the same genus as the notable pathogen poliovirus. CVB3 can cause a range of illnesses from a fever to gastrointestinal distress but is most noteworthy for the ability to cause viral myocarditis, a swelling of the heart muscle. Coxsackievirus, like all RNA viruses, tends to develop mutations rapidly due to its error prone polymerase and lack of proofreading activity. These mutations can be advantageous for the virus, allowing it to …

Longitudinal Urinary Microbiome Studies: A Need To Transition To Voided Urine, Baylie Hochstedler

Master's Theses

It is now established that the bladder is not sterile; it contains communities of microbes (microbiota). While the healthy bladder microbiota have been defined using expanded quantitative urine culture (EQUC) and urines obtained by transurethral catheterization (TUC), longitudinal and population studies have not previously been possible. These studies cannot be done using TUC urines, as it would be impractical to catheterize participants daily. Instead, we must transition to using voided urines.In order to make this switch, we have addressed three main issues raised by using voided urine. First, we showed that EQUC out performs standard urine culture on voided urines …

Engineering Yeast To Evaluate Human Proteins Involved In Selective Rna Packaging During Hiv Particle Production, Ryan M. Bitter

Master's Theses

Despite recent advances in antiretroviral therapy, nearly 37 million people continue to live with human immunodeficiency virus (HIV). Basic and applied research on the assembly of HIV could be enhanced by using a genetically tractable organism, such as yeast, rather than mammalian cells. While previous studies showed that expression of the HIV Gag polyprotein in Saccharomyces cerevisiae spheroplasts resulted in the production of virus-like particles (VLPs), many questions regarding the utility of yeast in HIV assembly remain uninvestigated. Here, we report use of S. cerevisiae for both the production of VLPs with selectively packaged RNA and to evaluate the human …

Detecting A Probiotic Product Within The Gut Of Broiler Chickens, Anneka Pisula

Master's Theses

As of January 2017, the U.S. poultry industry banned the use of antibiotics and now relies on alternatives such as probiotics to help protect animal health. Although probiotic use is not a new concept in the poultry industry, identifying the best combination of bacterial strains to generate an effective probiotic formula requires further investigation. This study aimed to detect a probiotic product of four bacterial strains (Pedioccoccus acidilactici, Pediococcus pentosaceus, Lactobacillus plantarum, and Bacillus subtilis) in a feeding trial with broiler chickens. Birds given the probiotic were predicted to show an improved growth performance with …

Detection, Activity Measurement And Phylogeny Of Ureolytic Bacteria Isolated From Elasmobranch Tissue, Yimu Yang

Master's Theses

Free-ranging marine elasmobranch tissue-associated micro-organisms were cultured from free-ranging Atlantic stingray (Dasyatis sabina) and Atlantic sharpnose sharks (Rhizoprionodon terraenovae). 16S rRNA gene phylogeny indicated bacteria community structure in both elasmobranchs were under phylum Proteobacteria, Firmicutes and Actinobacteria. By conducting split-plot ANOVA, we found the microbial richness is significantly different (P=0.0814) between two superorders of elasmobranch, which may largely due to their preferred habitats and feeding habits. Urease presentence and activity was detected in phylogenetically diverse bacterial strains. Species with high urea-hydrolyzing ability, such as Micrococcus luteus (shark blood isolate: 46.84 mU/mg protein; stingray blood isolate: 24.36 …

The Role And Contribution Of Saprotrophic Fungi During Standing Litter Decomposition Of Two Perennial Grass Species, Schizachyrium Scoparium And Schizachyrium Tenerum, Matthew Lodato

Master's Theses

In terrestrial ecosystems, most of the plant biomass produced enters the detrital pool, where microbial decomposers colonize, enzymatically degrade, and assimilate plant litter carbon and nutrients in amounts sufficient to bring about the decomposition of plant litter. Here, I estimated the biomass and production of fungi and microbial respiration associated with decaying Schizachyrium scoparium and Schizachyrium tenerum leaf litter, and constructed a partial organic matter budget estimating C flow into and through fungal decomposers. Significant losses in S. scoparium (57%) and S. tenerum (68%) leaf mass was observed during litter decomposition along with concomitant increases in fungal biomass, which reached …

Characterizing The Roles Of Staphylococcus Aureus Secreted Factors In Virulence And Modulation Of Innate Immune Cell Activity, Cameron Harvey

Master's Theses

Staphylococcus aureus is a prominent human pathogen that is responsible for a massive burden on healthcare. This thesis takes two approaches to characterize how S. aureus secreted factors subvert the innate immune response. First, characterization of the integral membrane protease 1984 showed that it regulates secretion of a putative lytic transglycosylase, IsaA, which is implicated in virulence. My results suggest IsaA and 1984 are capable of modulating immune responses that result in enhanced heart colonization in vivo. In addition, recent studies have uncovered TLR-independent pathways that induce inflammatory responses after S. aureus insult. Therefore, I hypothesized the bacterium secretes factors …

Immunobiology Of Adenovirus-Vector Vaccines For Mrsa, Emily Orvis

Master's Theses

Staphylococcus aureus is a gram-positive, extracellular bacterium that has emerged as an

important human pathogen. This bacterium is a leading cause of skin and soft tissue infections

(SSTIs) in humans, often leading to invasive and life-threatening infections. Treatment of S.

aureus infections is becoming more complicated due to the rise of methicillin-resistant S. aureus

(MRSA) strains, which are becoming increasingly resistant to a number of antibiotics. In the

United States, invasive MRSA infections result in more deaths annually than any other infectious

agent.

Despite a dire need, there is currently no vaccine against S. aureus infections. The failure

of past …

Surveying Host Innate Immune Responses To Interferon Antagonist-Deficient Murine Coronaviruses, Aaron Brian Volk

Master's Theses

Two coronaviruses (CoVs)—severe acute respiratory syndrome (SARS) virus and Middle East respiratory syndrome (MERS) virus—have emerged in the 21st century from animal reservoirs into the human population, each causing an epidemic associated with significant disease and mortality. CoV epidemics are currently only controllable by rigorous public health measures; no targeted therapeutics or vaccines exist to treat or prevent any human CoV infection. One method of generating attenuated CoV strains to be studied as vaccine candidates involves specifically disrupting CoV-encoded interferon (IFN) antagonists, thereby rendering the virus vulnerable to host innate antiviral immunity. Deubiquitinating (DUB) activity encoded within CoV nonstructural protein …

Characterizing Immune Response To Hiv-1 Infection In Bicd2-Knockout Cells, Omar Abdel-Rahim

Master's Theses

An important part of the HIV-1 infection cycle is the attachment of the intracellular viral core to the host microtubule network, facilitated by attachment of the viral capsid to cargo adaptor proteins. One such cargo adaptor is Bicaudal D Homolog Protein 2 (BICD2). BICD2 can attach to both the HIV-1 capsid and the dynein/dynactin complex and facilitate the trafficking of the viral core towards the host nucleus. Removal of BICD2 can disrupt this viral translocation, resulting in an elevated immune response that impairs productive HIV-1 infection. In my research, we investigated what viral particles are detected in the absence of …

Understanding The Dynamics Of Protein Lipoylation In Staphylococcus Aureus, Sarah C. Flury

Master's Theses

Staphylococcus aureus is a commensal bacterium that also acts as an opportunistic pathogen. The pathogenicity of S. aureus has often been attributed to the wide range of virulence factors that the bacterium produces. While virulence factors do contribute a great deal, there is a growing field of research that aims to investigate the role of metabolism in bacterial virulence.

My project focuses on the necessity of a metabolic cofactor, lipoic acid. To ensure sufficient amounts of lipoic acid are available for enzyme activity, S. aureus has evolved two pathways to obtain the important nutrient. The lipoic acid salvage pathway is …

An Assessment Of Potential False Positive E.Coli Pyroprints In The Cplop Database, Skyler A. Gordon

Master's Theses

The genetic information found in each species of organism is unique, and can be used as a tool to differentiate at the molecular level. This has caused rapid genotyping methods to become the cornerstone of a new area of research dependent on reading the genome as a form of identification. One of these specific identification methods, known as pyroprinting, relies on the small variation of DNA sequences within the same species to develop a unique, reproducible fingerprint. By simultaneously pyrosequencing multiple polymorphic loci within the ribosomal operons known as the intergenic transcribed spacers, a reproducible output is obtained, known as …

Defining The Roles Of The Lipoic Acid Ligases In Promoting Staphylococcus Aureus Metabolic Homeostasis And Virulence, Irina Laczkovich

Master's Theses

Staphylococcus aureus is a major human pathogen known to cause disease in a wide range of tissues. In order to thrive in such diverse environments, S. aureus uses multiple adaptive traits such as trace metal/nutrient acquisition, shifts in metabolic activity, and expression of detoxification systems, all of which allow the bacterium to proliferate and survive in nutritionally deficient and inhospitable environments.

One essential metabolite used by S. aureus is lipoic acid, a cofactor of enzyme complexes used in aerobic metabolism, fatty acid biosynthesis, glycine detoxification, and maintenance of redox homeostasis. Prior studies in the lab used a genetic approach to …

Phenotyping Temperature-Sensitive Coronaviruses, Amani Eddins

Master's Theses

Coronaviruses (CoVs) can cause a range of symptoms; from a mild common cold to life threatening acute respiratory distress syndrome (ARDS) upon infection. These emerging viruses have the ability to be highly pathogenic and detrimental to the human population. Two prime examples of CoV emergence, SARS-CoV (Severe Acute Respiratory Syndrome) and MERS-CoV, (Middle Eastern Respiratory Syndrome), which exhibits the pandemic potential of emerging CoVs that gain human tropism. Given the increasing potential of an emerging CoV outbreak there is a state of urgency to develop vaccines that will help protect the human population against current and future circulating strains. The …

Utilizing Genetic Techniques To Identify Amino Acids Within The Putative Glycosyltransferase Sypq That Are Essential For Its Role In Biofilm Formation By Vibrio Fischeri, Mary Kathryn Flaherty

Master's Theses

The polysaccharide component of the V. fischeri biofilm is produced by proteins encoded by the symbiosis polysaccharide (syp) locus. The syp locus encodes 18 genes, six of which are putative glycosyltransferases (GTs). One of these GTs, sypQ, encodes a putative family 2 glycosyltransferase (GT-2). The mechanism by which SypQ facilitates biofilm formation is not yet understood. To uncover which specific residues are essential for the function of SypQ, I utilized Bioinformatics, site-directed mutagenesis, and random mutagenesis. The Bioinformatics identified putative GT-2 motifs in the SypQ primary sequence. The mutagenesis (both site-directed and random), identified five residues (D95, D151, S153, D236, …

Optimizing Clean Catch Urine Collection And Its Applications In Urinary Microbiome Studies, Danielle Johansen

Master's Theses

Clean catch was developed before the advancement of more sensitive assays for culturing urinary bacteria. I reassessed clean catch, endeavoring to optimize this method. Periurethral swabs and voided urines were routinely collected, while analyzing different aspects of the method. I determined that midstream urine contained the least amount of vulvo-vaginal contamination and that the time of collection did not impact the results. I also determined that the use of antiseptic wipes prior to void increased the level of vulvo-vaginal contamination. A small cohort of females collected daily urines over a 17-day period and kept a strict alcohol diary. Females who …

Characterization Of Inhibitory Molecules Produced By Lactobacillus Crispatus, Giuseppe Anthony Pistone

Master's Theses

Lactobacillus species are widely accepted as beneficial bacteria of the human microbiota1-8. Lactobacilli spp. are well documented to inhibit pathogens by production and secretion of hydrogen peroxide (H2O2), organic acids, and/or proteinaceous bacteriocins into their environment. Most research attributes bactericidal activity of cell free supernatant (CFS) to H2O2 and/or lactic acid. Here, I demonstrate that CFS from a clinical isolate of Lactobacillus crispatus contains a molecule(s) that inhibits uropathogenic Escherichia coli (UPEC) colony formation independently of H2O2 and organic acids. Physiologic concentrations of H2O2 and organic acids produced by L. crispatus do not inhibit UPEC colony formation. Incubation of UPEC …

The Elasmobranch-Microbe Relationship: Trimethylamine N-Oxide Synthesis, Urea Hydrolysis, And Microbe-Osmolyte Interactions In The Atlantic Stingray, Dasyatis Sabina, Kaitlin Kelly Doucette

Master's Theses

The elasmobranch osmoregulatory strategy is predicated on the accumulation of nitrogenous compounds, primarily urea and trimethylamine n¬-oxide (TMAO). Despite the abundance of these plasma osmolytes, it is notable that elasmobranchs appear to lack urease and TMA oxidase (Tmase), enzymes that scavenge urea-nitrogen and synthesize TMAO, respectively. However, urease and Tmase are found in many species of bacteria. Therefore, I hypothesized that intestinal bacteria are responsible for urease and Tmase activity in elasmobranchs. Absent dietary nitrogen sources, I evaluated the effects of reduced intestinal microbiota on osmoregulation in Atlantic stingray (Dasyatis sabina) in vivo. D. sabina were given …

Fecal Bacterial Communities As An Indicator Of Trophic Interactions Among Anuran Larvae, Steven Jacob Everman

Master's Theses

Anurans are mass spawners, often with multiple females spawning together, resulting in thousands of tadpoles sharing a habitat. Such large numbers of tadpoles with limited dispersal can lead to intense competition for resources. Inter and intra-specific competition for food could have negative impacts on the growth and survival of smaller tadpoles. Fecal bacterial communities have the potential to be used as indicators of changes in diet making it possible to determine if tadpoles in the wild are eating the same food or not. After feeding on two prepared diets that differed in the percentage of complex carbohydrates, the fecal bacterial …

The Effects Of Quorum Sensing And Temperature On The Soluble Proteome Of Vibrio Salmonicida, Christopher L. Massey

Master's Theses

Vibrio salmonicida causes cold-water vibriosis in salmon populations around the world and causes financial damage to fisheries designed to farm these salmon. Very little is known about the physiology of how V. salmonicida causes disease and measures to contain vibriosis are restricted to either vaccinating individual fish against disease or administering antibiotics when an outbreak is detected. These procedures are costly and increase the risk for selection of antibiotic-resistant V. salmonicida strains. A recent reoccurrence of outbreaks in Norwegian fisheries provided incentive to better understand the virulence mechanisms of V. salmonicida. In this thesis, a proteomic approach was used to …

Investigation Of A Ubiquitous Spore Surface Protein, Justyna Kordzikowska

Master's Theses

All bacterial spores are comprised of concentric shells. All spores are encased in a layer called the coat. Some spores have an additional layer outside of the coat called the exosporium. Presumably, this morphological variation is an adaptation to variation in the environments in which these species can be found. However, spores from species with and without exosporia can often be found in the same niche. We hypothesize, therefore, that spores with and without exosporia share a common surface protein. Bacillus anthracis possess a well characterized surface protein called BclA. A BclA homologue is also present on the surface of …

Lipoate Metabolism In Staphylococcus Aureus Pathogenesis, Maria Azul Zorzoli

Master's Theses

Lipoate is an essential cofactor of several proteins involved in cellular energy homeostasis and catabolism. Lipoate metabolism has been linked to pathogenesis in some microbial species, but its role in Staphylococcus aureus infections had not been explored. In this thesis, we tested the hypothesis that lipoate acquisition mechanisms promote S. aureus infectivity. We used a bacterial genetics approach to elucidate the biological function of the S. aureus genes involved in lipoate metabolism. Our findings allowed us to propose a model for lipoic acid de novo biosynthesis and salvage pathways in S. aureus. Moreover, we detail hitherto undescribed genetic arrangements of …

Land-Use And Algal Species Influence Bacterial Community Composition And Activity In Streams, Miguel Rojas

Master's Theses

Microbial biofilms can be found on virtually all submerged surfaces in aquatic habitats, including rivers and streams. Biofilms are complex, taxonomically diverse communities of microorganisms (including algae and bacteria) that colonize solid surfaces and support a wide range of metabolic activities. Biofilms are critical components of river and stream ecosystems because they are key drivers of nutrient cycling processes (including nitrogen cycling) and because they serve as an important food source for higher trophic levels. Biofilms in urban streams are subject to a number of anthropogenic stressors, but research on the ecology of urban biofilms and their response to stressors …

Lactobacillus Crispatus Produces A Bacteridical Molecule That Kills Uropathogenic E. Coli, Katherine Diebel

Master's Theses

As many as 1 in 2 women will have at least one urinary tract infection (UTI) in their lifetime. UTIs can cause complications in pregnancy and decrease quality of life, and their treatment and prevention are expensive. Uropathogenic E. coli (UPEC) is the primary cause of UTI. The probiotic and bactericidal capacities of gut and vaginal Lactobacillus isolates have been studied, but the same attention has not been paid to urinary strains. These urinary isolates of L. crispatus appear to have a greater killing capacity against UPEC and this bactericidal activity does not depend on the cells themselves, consistent with …

Investigating The Regulatory Mechanisms By Which Arabinose And Sypa Control Biofilm Formation In Vibrio Fischeri, Sheila Paris

Master's Theses

Biofilms are surface-associated microbial communities surrounded by an extracellular matrix. Through biofilm formation, many pathogens and symbionts are able to colonize, survive, and persist in their host. A model system used to study biofilm formation is the symbiotic bacterium Vibrio fischeri, which colonizes its host, the squid Euprymna scolopes. Complex signaling between the squid and the bacteria is essential for the proper regulation of biofilm formation as well as for persistent colonization.

The signal(s) that promote host-relevant biofilm formation are as-yet unknown, but recently it was discovered that the sugar, L-arabinose, serves as a unique signal to promote biofilm formation …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

Demographics And Transfer Of Escherichia Coli Within Bos Taurus Populations, Joshua Ryan Dillard

Master's Theses

In the United States, symptoms caused by pathogenic strains of Escherichia coli are on the rise. A major source of these pathogenic strains is the E. coli in the digestive tract of cattle. The purpose of this project was to determine if E. coli are transferred between individuals of the same species and if interspecies transmission is possible. Proximity of cattle was also studied as a contributing factor to the transfer of E. coli. To accomplish this goal, E. coli isolates from cattle and cohabitating ground squirrels were compared through a new method of bacterial strain typing called pyroprinting. …

Virulence Gene Expression Of Vibrio Parahaemolyticus In The Viable But Nonculturable State, Tiffany Pui-Yun Tse

Master's Theses

Vibrio parahaemolyticus is a food-borne pathogen commonly associated with the consumption of raw or undercooked seafood resulting in primary infections of the human gastrointestinal tract. It is estimated to cause about 4500 illnesses each year in the United States. However, infection from this food-borne pathogen can be avoided if this organism is detected in the implicated food, prior to consumption. Current standard methods of detecting this organism are dependent on the culturability of the bacteria. Detection based on an organism’s culturability may be problematic as V. parahaemolyticus has been known to exist in a viable but nonculturable (VBNC) state. Bacteria …

Detection Of Hcmv Viral Il-10 (Vil-10) In Healthy Blood Donors, Vivian P. Young

Master's Theses

Human cytomegalovirus (HCMV) is widespread in the general population and can establish lifelong latency with expression of a limited subset of viral genes. The UL111A gene is expressed during both lytic and latent infection, and at least two protein isoforms are produced. During lytic infection, the full length transcript yields cmvIL-10, a potent immunosuppressive viral ortholog of human IL-10 (hIL-10). Alternative splicing of the UL111A transcript yields a truncated protein, LAcmvIL-10, which is expressed during both lytic and latent infection but with a limited range of immunosuppressive functions. The two viral cytokines, collectively termed viral IL-10 (vIL-10), are identical in …

Stressed Induced Changes In Karenia Brevis Ribosomal Rna, David Scott Jayroe

Master's Theses

Karenia brevis is a toxic marine dinoflagellate that causes harmful algal blooms (HABs), also known as red tides, in the Gulf of Mexico. These blooms are responsible for massive fish kills, shellfish bed contaminations, adverse human health effects, and vast economic loss. For these reasons, extensive research has gone into understanding the mechanisms and dynamics of bloom behavior by studying K. brevis in the field and in the lab. In order to understand higher order bloom behavior and dynamics it is imperative to understand K. brevis at the cellular level. In growing K. brevis in vitro under a variety of …