Microbiology Commons^™

Unravelling The Role Of Two-Component Systems In Mycobacterium Abscessus, Andrea C. Molero Perez

Honors Undergraduate Theses

Mycobacterium abscessus (Mab) is an emerging pathogen within the nontuberculous bacteria (NTM) which poses a threat due to its complex multi-drug resistance and opportunistic nature. It is predicted that only 45.6% of patients will have successful treatment, with immunocompromised and cystic fibrosis patients being the most threatened. Moreover, investigating new treatment approaches is key to responding to this public health issue. Two-component systems (TCS) are regulatory pathways that play a pivotal role in bacterial survival and virulence. These systems are composed of a sensor histidine kinase (HK) and cognate response regulator (RR) protein that senses environmental cues and triggers specific …

Elucidating The Proteolytic Determinants Of Flavivirus Infection, Lochlain C. Corliss

All ETDs from UAB

Flaviviruses, recently renamed to orthoflaviviruses, are small, enveloped viruses with positive-sense, single-stranded RNA (ssRNA) genomes of about 11 kilobases. Upon cell entry and uncoating, the viral RNA (vRNA) is directly translated at the endoplasmic reticulum (ER) as a single polyprotein that is then processed by the viral and cellular proteases into 10 functional subunits, consisting of three structural proteins and seven nonstructural (NS) proteins. Among the NS proteins are NS2B and NS3, which form the viral protease complex. NS3 consists of a serine protease domain while NS2B is anchored to the ER and contains a cytoplasmic loop that serves as …

Backyard Chimeric Microbiomes: K-12 Participatory Science, Abigail Saucier

Honors Theses and Capstones

The US education system has seen a recent push for more secondary school curriculum to include STEM (Science, Technology, Engineering, and Mathematics) materials and activities. Middle and high school is a pivotal time when academic and personal experiences affect the development of student attitudes towards STEM (Christensen et al., 2015; Moreno et al., 2016). Teachers often utilize hands-on activities to promote student engagement with science curriculum (Brooks & Poles, 2021; Christensen et al., 2015). Hands-on activities improve student learning, but impacts vary by type of activity. When students work towards a known outcome they can feel disconnected from the work …

Microbial And Plant Biodiversity In Appalachian Agroecosystems And Their Implications For Soil Health, Kinsey Reed Close

Graduate Theses, Dissertations, and Problem Reports (ETD)

The sustainability of agricultural landscapes depends on understanding the complex interactions between plants, soil, and microbes. In Appalachia, a region shaped by complex terrain and long histories of human and ecological interaction, small family farms produce hay, livestock, and row crops. These agroecosystems, though often treated as “artificial” by many ecologists, have the potential to support both food production and biodiversity conservation if managed with an understanding of ecological complexity. This dissertation examines how plant and microbial diversity interact with soil and management to influence nutrient cycling, soil health, and long-term resilience in Appalachian agricultural systems. A literature review revealed …

The Effects Of Salinity On The Cutaneous Microbiome And Pathogen Infection On The Pacific Tree Frog (Pseudacris Regilla) In Monterey Bay, California, Usa, Hannah Eunhae Kim

EWU Masters Thesis Collection

Global climate change and infectious diseases are considered a leading cause of amphibian population declines worldwide. Changes in precipitation and salinity have altered watershed systems and microbial communities, reducing habitat availability and physiological performances for amphibian survival. The salt refuge hypothesis, however, is a proposed explanation that higher saline environments may reduce susceptibility to pathogens such as Batrachochytrium dendrobatidis (Bd). The Moro Cojo Slough State Marine Reserve (MCSSMR) (California, USA) is known as an abundant breeding ground for endangered/threatened amphibian species. To test and expand the salt refuge hypothesis, I evaluated Bd prevalence and intensity and the cutaneous microbiome of …

Parallel Inquiries: Investigation Of Social Resource Use In Early Career Stem Teachers And Impacts Of Metal Pollution On Fingernail Clam Microbiome, Emily Hamada

EWU Masters Thesis Collection

No abstract provided.

Effects Of Liraglutide On The Gut Bacterial Community, Jami Anne Bull

Graduate Theses/Dissertations

Overweight and obesity are major health concerns associated with metabolic disorders and gut dysbiosis. Treatment options such as GLP-1 receptor agonists, like liraglutide, promote weight loss and improve insulin sensitivity; however, their impact on the gut bacterial community remains unclear. This study investigated the effects of liraglutide on the gut bacterial community of diet-induced obese (DIO) mice using Illumina DNA sequencing of the bacterial 16S rRNA gene. My study used twelve-week-old male C57BL/6J DIO mice. They were placed on a high-fat diet and treated with liraglutide (0.2 mg/kg) via daily subcutaneous injection for 14 Days. High-fat and low-fat diets control …

The Influence Of Flower-Microbe Interactions On Bumble Bee Behavior And Gut Microbiome Composition, Success Chiamaka Ekemezie

Graduate Theses/Dissertations

This thesis examines how microbial interactions in floral nectar and environmental variation influence bumble bee (Bombus spp.) foraging behavior and gut microbiome composition. Pollen germination experiments and behavioral assays in the lab tested whether Metschnikowia reukaufii (yeast) and Acinetobacter nectaris (bacteria) induce pollen germination and bursting in nectar and affect bee behavior subsequently. Both microbes reduced intact pollen, but bees did not alter flower preference. Furthermore, the study also assessed how floral and bee community composition shaped gut microbiome composition across six Missouri prairies. Using amplicon-sequenced fungal ITS and bacterial 16S rRNA genes, I found that fungal microbiome composition varied …

Inoculating Soybean Plants At Different Growth Stages: Selecting Bradyrhizobium, Sinorhizobium, Or Both, Matthew R. Knoll

Graduate Theses/Dissertations

Soybean plants rely on nitrogen for growth, however atmospheric nitrogen (N2) is not a usable form and needs to be converted into different forms that are available to the plant. Nitrogen fixing bacteria such as rhizobia form symbiotic relationships with Soybeans in exchange for shelter and excess plant sugars. As a result, the plant can get the nitrogen it needs. There are four main genera of rhizobia that can form root nodules on Soybean including Bradyrhizobium, Sinorhizobium, Mesorhizobium, and Rhizobium. At this point, the effect that age of the host plant has on the selection of …

Deciphering Genetic Contributions To Antibiotic Persistence: Insights From Multi-Gene Knockout Studies, Elise K. Schweer

Electronic Theses and Dissertations

Antibiotic resistance is a critical global health challenge, complicating efforts to treat bacterial infections effectively. Antibiotic persistence plays a significant role in driving resistance. Persisters are a subpopulation of non-dividing bacterial cells that often evade lethal antibiotic treatment. Once antibiotics are removed, these cells "resurrect," resuming growth and may lead to relapsing infections. Notably, the progeny of persister cells exhibit a heightened tendency to acquire mutations or incorporate antibiotic resistance genes, further compounding the challenge of antibiotic resistance. In our recent study, we knocked out seven hypothetical genes and observed a significant reduction in persister levels. Compared to the wild …

Biotransformation Of Camelina Meal Via Pretreatment And Fermentation For Functional And Nutritional Upgrading, Ram Kumar Bhattarai

Electronic Theses and Dissertations

Camelina sativa, an oilseed crop of the Brassicaceae family, has seen increased cultivation in North America in response to the rising demand for biofuels over the past two decades. With this growth, camelina meal, a byproduct of oil extraction, has emerged as a promising yet underutilized resource, particularly for applications in animal nutrition. This study aimed to evaluate the potential of camelina meal as a substrate for submerged fungal fermentation and to examine how this bioconversion affects its physicochemical and nutritional properties. The influence of mild pretreatments (unwashed, washed only, and washed/dried and ground) on fermentation outcomes was also assessed. …

Investigating Antimicrobial Efficacy Of Turmeric And Rosemary Oil Against Staphylococcus Aureus, Aishwarya Tripathi

Selected Full-Text Master Theses 2021-

This study investigates the antimicrobial efficacy of turmeric (Curcuma longa) and rosemary essential oil (Rosmarinus officinalis) against Streptococcus aureus, with a comparative analysis to phenoxyethanol, a widely used synthetic preservative. The growing consumer demand for natural cosmetic formulations have intensified the search for plant-derived alternatives to synthetic preservatives. Turmeric and rosemary oil were selected based on their documented antimicrobial, antioxidant, and anti-inflammatory properties. The objective of this research was to evaluate whether these natural agents can serve as effective preservatives in topical gel formulations, either individually or in combination, and how their efficacy compares to phenoxyethanol.

Eight gel-based formulations were …

Microbial Mavericks: Turning Hazards Into Snacks, Alison G. Blanton

Biology Dissertations - Archive

Symbiotic associations with microbes are widespread across life and provide hosts with essential and beneficial functions. A growing concern in pest management is symbiont-mediated detoxification (SMD), a form of metabolic resistance to insecticides. The best-known example of SMD involves the bean bug Riptortus pedestris, where an environmentally acquired but obligate Caballeronia symbiont confers resistance to the organophosphorus insecticide fenitrothion. Motivated by this model, I began my work in another known bug-Caballeronia symbiosis: Leptoglossus phyllopus, native to the United States. I then expanded the study to include two additional U.S.-native hosts, Leptoglossus zonatus and Anasa tristis. Representative …

Microbiological Examination Of Yellow Mealworm (Tenebrio Molitor) Larvae Under Various Processing And Storage Conditions As Potential For Human Consumption, Rachel Midkiff

Graduate Theses, Dissertations, and Problem Reports (ETD)

Yellow mealworm (Tenebrio molitor) larvae have gained attention as a sustainable and nutritionally balanced food source, yet their high natural bacterial load raises food safety concerns. This study investigates the impact of pre-processing, processing, and storage conditions on microbial load and diversity in mealworms, comparing thermal (hot) and non-thermal (cold) treatments. These treatments include freeze-drying, wet heat treatments, dry heat treatments, and the combination of wet and dry heat treatments against untreated controls. Microbial loads were quantified by plate counts after day 0, day 10, and day 28 of vacuum-sealed refrigerated (4°C) storage. Water activity (Aw), pH, and moisture content …

Interactions Between Microplastics, Biofilms, And Antimicrobials In Freshwater Streams, Ryan Thomas Krantz

Dissertations

Microplastics (MPs) are ubiquitous contaminants in freshwater ecosystems that could be hotspots for the interaction of antimicrobial compounds and surface-attached microbial biofilm communities. MPs and antimicrobials are both common in wastewater and urban freshwaters and MPs can adsorb contaminants like antimicrobials to their surface. Within aquatic habitats, MPs also support colonization by microbial biofilms. Therefore, we hypothesized that the adsorption of antimicrobials to MP surfaces would affect microbial communities colonizing MPs, altering their diversity, composition, and antimicrobial resistance. We investigated the effects of these interactions across two studies. The first study, discussed in Chapter 2, used a microcosm approach to …

Antibody-Induced Multicellular Behaviors Of Salmonella Typhimurium, Samantha K. Lindberg

Electronic Theses & Dissertations (2024 - present)

Salmonella enterica is a globally distributed bacterial pathogen that is commonly acquired through consumption of contaminated food and water. The enterica subspecies includes over 1500 unique subvariants, or serovars, that are classified by antigen presentation. Due to its global environmental prevalence, broad host range, and increasing pathogenicity, serovar Typhimurium is of particular concern for human and animal health, as well as food safety. Once in the gastrointestinal tract, Salmonella Typhimurium (STm) exploits host immune mechanisms, implements an arsenal of virulence factors, and outcompetes the microbiota to invade the intestinal epithelium. While STm infections are generally self-limiting and relatively mild, emerging …

The Role Of Fruiting Bodies In Protecting A Community Of Myxococcus Xanthus Spores From The Environment, Dave Lall

Wayne State University Dissertations

Environmental microorganisms have evolved a variety of strategies to survive fluctuations in environmental conditions, including the production of biofilms and differentiation into spores. Myxococcus xanthus are ubiquitous soil bacteria that produce starvation-induced multicellular fruiting bodies filled with environmentally resistant spores (a specialized biofilm). Isolated spores have been shown to be more resistant than vegetative cells to heat, ultraviolet radiation, and desiccation. The evolutionary advantage of producing spores inside of fruiting bodies is not clear. Here, we examine a hypothesis that the fruiting body provides additional protection from environmental insults. We developed a high-throughput method to compare the recovery (outgrowth) of …

Optimizing Crispri Gene Silencing Of Putative Drug Targets In Mycobacterium Abscessus, Max Ivanov

Honors Undergraduate Theses

Among nontuberculous mycobacteria (NTM), Mycobacterium abscessus (Mab) poses a particular threat to patients with cystic fibrosis and chronic obstructive pulmonary disease due to the lung damage and higher mortality rate it causes. Current treatments involve prolonged multi-antibiotic regimens that are often ineffective, highlighting the need for new drug targets.

The CRISPR Interference (CRISPRi) system uses a deactivated Cas9 protein (dCas9) to enable inducible gene silencing, offering a potential approach to identifying new targets. Genes that lead to a loss of Mab viability when silenced are considered essential, an important attribute of potential drug targets. While CRISPRi has shown …

Development Of A Proposed Selective Medium For The Isolation And Differentiation Of P. Sordellii, Dimyana Bottros

Honors Undergraduate Theses

Clostridium, a genus of anaerobic, spore-forming bacteria, includes clinically and ecologically significant species like Clostridium difficile and Paeniclostridium sordellii. C. difficile causes antibiotic-associated colitis, while P. sordellii is linked to fatal infections and spontaneous abortions. Recent studies found both species in marine sediments, suggesting their role in environmental and wildlife health disturbances, including the 2013 mass mortality of over 300 manatees in the Indian River Lagoon. However, isolating and differentiating P. sordellii is challenging due to the lack of selective media optimized for its growth. This thesis proposes a novel selective medium tailored to P. sordellii’s physiological …

Investigation Of Hydrogen Gas Production And Motility In Δselab And Δfdhf Mutants Of Clostridioides Difficile, Ria D. Gupta

Honors Undergraduate Theses

Clostridioides difficile is a Gram-positive, spore-forming, anaerobic bacterium and the leading cause of antibiotic-associated diarrhea worldwide. During infection, antibiotic-induced disruption of the gut microbiota allows C. difficile to colonize and proliferate. Motility, enabled by flagella, is an important factor in colonization and may be influenced by metabolic activity. Recent experiments have observed gas production during C. difficile motility assays, but the biochemical basis of this phenomenon remains unknown. Because gas formation in other bacteria such as E. coli involves the formate hydrogenlyase complex and the enzyme formate dehydrogenase (FDH), we hypothesize that C. difficile gas production under motility conditions is …