Microbiology Commons^™

The Triangular Interaction Between Dietary Polyphenols, Gut Microbiota, And Metabolic Syndrome, Emily Bayliss

Senior Honors Theses

Type 2 diabetes mellitus (T2DM) is a growing global health concern characterized by peripheral insulin resistance as well as impaired insulin secretion from pancreatic β-cells. Emerging evidence suggests that the gut microbiome, specifically gut dysbiosis, an imbalance in the gut microbiome, is a critical modulator of the pathophysiology of T2DM. Dietary polyphenols, a diverse group of bioactive compounds that are abundant in plant-based foods, have recently gained attention for their potential to attenuate metabolic disorders through their antioxidant and anti-inflammatory properties as well as through modulating the composition and activity of gut microbes, thereby attenuating dysbiosis. However, the diabetic state …

Twim #261: Overwhelming Microbial Greatness, Jenny Stoval, Briana Lanzarotta, Luke Boseman, Nicole L. Podnecky, Angela Wilson

School of Medical Diagnostics & Translational Sciences Publications

Podcast annotation TWiM #261: Overwhelming Microbial Greatness from the weekly podcast series "This Week in Microbiology" (TWiM), a podcast where experts in microbiology discuss academic papers in their field in an informal way.

Advancing The Virus Diagnostic Toolkit: Development Of Accurate And Reliable Artificial Virus-Mimicking Positive Controls And Crispr-Based Detection, Habeeb Yinka Atanda

Graduate Theses and Dissertations

Accurate and reliable detection of plant viruses is critical for protecting berries and other economically important crops. Yet diagnostic programs face persistent challenges with positive control availability, biosafety concerns, and specificity limitations. This thesis advances the diagnostic toolkit for berry viruses through three complementary innovations that address fundamental gaps in current detection methodologies. First, this research developed and validated virus-mimicking artificial positive controls (ViMAPCs) for diverse viruses affecting berry crops for endpoint PCR applications. ViMAPCs incorporate size differentiation, which enables immediate visual gel band discrimination between control and natural infection signals. Amplification efficiency analysis demonstrated close correspondence with true-positive controls …

Requirement Of Prepiilin Peptidase Activity For Variovorax Paradoxus Eps Flp/Fap Pilus Assembly, Jenny L. Lanthripp

Electronic Theses, Projects, and Dissertations

Variovorax paradoxus is a Gram-negative aerobic bacterium present in both soil and the human oral microbiome. This species contributes to biotransformation of xenobiotics and promotes plant growth. Interestingly, although the genome of strain EPS lacks the flagellum operon annotated in strain S110, the microbe remains motile, and flagella can be observed microscopically. To investigate this unexpected phenotype, motility mutants were enriched from a Tn5 mutant library using a liquid culture settling strategy. A total of 122 isolates were screened for motility defects, and 57 exhibited significantly reduced motility compared to the wild type. Rescue cloning revealed that over 60% of …

Fungal Biodiversity, Microbial Communities, And Ecosystem Function In Non-Perennial Streams, Charles T. Bond

Dissertations

A global majority of steams are non-perennial, drying at some point in time and space. Despite the vital roles that fungi and other microbes play in stream ecosystems, most research on stream microbiomes comes from perennial (continuously flowing) streams. The present series of studies addresses this research gap by examining microbial community composition and function in non-perennial streams, with an emphasis on fungi. Chapter I reviews existing scientific literature on the ecological processes that shape microbiome structure and function in non-perennial streams and outlines the varieties of fungi that may live there. Chapter II uses rDNA metabarcoding to survey fungal …

Structure And Function Studies On Trna Splicing Endonuclease, Justin G. Underwood

Dissertations and Theses (Open Access)

A subset of eukaryotic pre-tRNAs have introns that must be spliced out to become mature molecules capable of functioning in translation. This essential processing step is performed by tRNA splicing endonuclease (TSEN), a highly conserved heterotetramer with two catalytic and two structural subunits. In addition to this conserved function, archaeal TSEN also processes pre-rRNA and yeast TSEN cleaves some mRNAs that encode mitochondrial proteins to initiate mRNA degradation. Interestingly, single amino acid mutations in TSEN cause the human Mendelian disease pontocerebellar hypoplasia (PCH) by an unknown mechanism. Recently, several groups have determined the structure of human TSEN, revealing similarities and …

Environmental Change In The Northeast Pacific: Climate Impacts On Phenology, Life History, And Population Dynamics In Marine And Aquatic Populations, Genoa Sullaway

Fisheries

Climate change is rapidly transforming Northeast Pacific ecosystems and fundamentally altering environmental conditions that drive species' survival, growth, and life histories. This dissertation examines relationships between environmental change and population-level processes across Northeast Pacific marine and freshwater ecosystems. This dissertation focuses on understanding the influence of environmental change on foundational zooplankton communities in the Bering Sea and Pacific salmon populations, specifically Yukon River Chum salmon and Bristol Bay Sockeye salmon. This research addresses knowledge gaps in zooplankton systems modeling, zooplankton phenology, and salmon population dynamics. First, this dissertation evaluated the performance of a systems model that utilizes climate and physical …

Investigating The Impacts Of Azole Antifungals On Growth Of Cryptococcus Neoformans, Gnanambika Sindhe

All Theses

Cryptococcus neoformans, an opportunistic fungal pathogen is responsible for cryptococcosis, leading to approximately 181,000 deaths annually, predominantly in regions such as Sub-Saharan Africa. Fluconazole, a widely used fungistatic azole, is often administered due to its relative affordability and lower toxicity. However, resistance to fluconazole in C. neoformans can arise through aneuploidy, complicating treatment efforts. This study aims to deepen our understanding of resistance mechanisms to azole drugs by comparing fluconazole with other azoles, including both clinical and agricultural azole antifungals. Disk diffusion assays were performed to evaluate the ability of C. neoformans to develop resistance to these compounds, focusing …

Functional Analysis Of Ftsa-Mediated Recruitment Of Ftsk In Escherichia Coli, Abbigale Perkins

Dissertations and Theses (Open Access)

Bacterial cytokinesis requires precise coordination between cytoplasmic and periplasmic components of the divisome to ensure that membrane constriction and chromosome segregation occur in synchrony. The actin-like protein FtsA plays a central role in this process by tethering FtsZ to the membrane and recruiting downstream division proteins. Despite its essential function, the mechanisms by which FtsA coordinates divisome activation and the recruitment of late-acting proteins remain incompletely defined. To address this, the role of FtsA in activating septal synthesis and recruiting the DNA translocase FtsK was examined using mutational analysis in Escherichia coli.

The FtsA^{M96E R153D} variant, which has …

Twim #222: Biosensors In Bacteria, Madison Hayes, Alexis Austin, Dillon Nguyen, Angela Wilson, Rebecca Seipelt-Thiemann

School of Medical Diagnostics & Translational Sciences Publications

Podcast annotation TWiM #222: Biosensors in Bacteria from the weekly podcast series "This Week in Microbiology" (TWiM), a podcast where experts in microbiology discuss academic papers in their field in an informal way.

Twim #243: Beef And Bacillus, Sakiem Winston, Madison Wolford, Rebecca Seipelt-Thiemann, Angela Wilson

School of Medical Diagnostics & Translational Sciences Publications

Podcast annotation TWiM #243: Beef and Bacillus from the weekly podcast series "This Week in Microbiology" (TWiM), a podcast where experts in microbiology discuss academic papers in their field in an informal way.

Twim #286: Integrons And Invasion, Andrea Ayala-Lopez, Brittney Heist,, Thomas Salazar, Rebecca Seipelt-Thiemann, Mel Melendrez-Vallard, Angela Wilson

School of Medical Diagnostics & Translational Sciences Publications

Podcast annotation TWiM #286: Integrons and Invasion from the weekly podcast series "This Week in Microbiology" (TWiM), a podcast where experts in microbiology discuss academic papers in their field in an informal way.

Tracing The Journey Of Dissolved Organic Matter: From Leaf Litter Photodegradation To Microbial Processing In Tropical Streams, Samantha Nicole Sullivan

Chemistry & Biochemistry Theses & Dissertations

Dissolved organic matter (DOM) is a major reservoir of organic carbon in aquatic ecosystems and plays a central role in global carbon cycling through its transformation and remineralization to carbon dioxide (CO₂). As DOM moves from terrestrial environments into streams and rivers, its chemical composition is altered by a combination of microbial and photochemical oxidation processes that regulate both its reactivity and its persistence during transport. However, the molecular mechanisms governing these oxidative transitions, particularly in tropical ecosystems characterized by strong hydrologic seasonality and substantial inputs of plant-derived material, remain insufficiently resolved. This dissertation integrates ultrahigh-resolution mass spectrometry, optical characterization, …

Strategic Enhancement Of Biofuel Production Using Bacillus Subtilis As A Model Organism: A Dual Approach Of Gene Essentiality Mapping And Optimization, Angela A. Zebede

Electronic Theses and Dissertations

With rising global demand for renewable energy, enhancing microbial platforms for biofuel production is vital. This study engineered Bacillus subtilis to improve resilience to solvent stress by targeting membrane lipid biosynthesis pathways essential for integrity. Growth curve analysis (OD₆₀₀) showed that phosphatidylserine (PS) and phosphatidylethanolamine (PE) knockout strains grew significantly slower than wild type (168), indicating the importance of these lipids under stress. Laurdan fluorescence spectroscopy was used to assess membrane properties. Generalized polarization (GP) analysis revealed a concentration-dependent reduction in membrane order upon 1%–2% 1-butanol exposure. GP values declined progressively from control to 2% treatment, reflecting increased membrane fluidity …

Antifungal Effects Of Fatty Acids On The Growth Of Ophidiomyces Ophiodiicola In A Simulated Snake Skin Environment, Krupa S. Patel, Lizbeth Delarosa, Jacey Cardenas, Thalia Rodriguez, John Niedzwiecki

Science University Research Symposium (SURS)

Emerging infectious diseases have increasingly threatened wildlife populations worldwide, with devastating impacts observed in frogs, bats, and more recently, snakes. Snake fungal disease (SFD), caused by the pathogenic fungus Ophidiomyces ophiodiicola (Oo), currently poses a serious threat to snake populations across multiple regions. Infected snakes exhibit disrupted skin shedding, rough or scaly patches, crusty sores, and ulcers that compromise their health and survival. Although the mechanisms underlying transmission and susceptibility to SFD remain unclear, the snake cutaneous microbiome is known to act as a defensive barrier, mediating interactions between the host and invading pathogens. The lipid layer is a key …

Fungal Foes And Fatty Defenses: How Simulated Snake Skin Lipids Influence Ophidiomyces Ophiodiicola Growth, Thalia Rodriguez, Jacey Cardenas, Lizbeth Delarosa, Krupa Patel, John Niedzwiecki

Science University Research Symposium (SURS)

Emerging fungal diseases are a continuous threat to wildlife health as well as biodiversity. Fungal diseases, such as white nose syndrome in bats, can devastate populations by disrupting their ecosystems. Many other species around the world are affected by fungal diseases, such as amphibians, birds, and snakes. In more recent years, snake fungal disease (SFD) emerged due to the fungal pathogen Ophidiomyces ophiodiicola (O.o). Like Pseudogymnoascus destructans, the fungal pathogen responsible for white nose syndrome, O.o targets the skin which contains many fatty acids. Some studies have shown that fatty acids present in bat skin are able to inhibit fungal …

Investigating The Mechanisms Of Microbial Interactions Using A Model Cystic Fibrosis Polymicrobial Community, Bassam El Hafi

Dartmouth College Ph.D Dissertations

Cystic fibrosis (CF) airway microbial communities are complex ecosystems where interspecies interactions influence pathogen survival and disease progression. We leverage a CF-relevant in vitro four-species model composed of Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus sanguinis, and Prevotella melaninogenica, alongside a microbiome dataset with over 4,000 respiratory samples from publicly available sequencing data of CF patient samples, to explore the dynamics of microbial interactions in CF. On a broader scale, we performed microbial network analysis to examine how the latest modulator therapy, elexacaftor/tezacaftor/ivacaftor (ETI), might influence CF microbial communities. Our analysis revealed a reduction in node connections and …

First Report Of A Bat Guano Fire From A Cave In Southeast Asia, Sopark Jantarit, Martin Ellis, Pruet Kalasuwan, Neeranuch Phusunti, Pimonsri Mittraparp-Arthorn, Jiranan Pattano, Arnon Chukamnerd, Turdtun Tong-In, Natthawut Khrueaaunruean

International Journal of Speleology

Fires occurring in cave guano are a rare and unusual phenomenon and the occurrence of such events in Southeast Asia is particularly novel. In this study, we document the first recorded instance of a bat guano fire in a tropical cave at Tham Chao Ram in Sukhothai province, northern Thailand. A bacteriological analysis was made of the guano at the fire site and from a control site within the cave. We give a comprehensive review of global reports on bat guano fires in caves, conduct an initial investigation of the physical factors at the fire site and discuss the potential …

In Vitro Antiviral Activity Of Cat’S Claw (Uncaria Tomentosa) Bark Extract Against Human Influenza A Virus, Juliann N. Makau, Keith K. Talaam, Mike Odiwuor, Janet M. Majanja, Sophia Musenjeri, Ratika Rahmasari, Samoel A. Khamadi, Ken Watanabe

Pharmaceutical Sciences and Research

Influenza A viruses mutate very fast and this leads to the development of resistance to antivirals, hence the need to find new therapeutics. Due to their extensive traditional use, natural products are crucial resources for the discovery of drugs. Cat’s claw (Uncaria tomentosa), is a tropical vine known for various health benefits and in this study we evaluated its anti-influenza activity. Pulverized material of the stem bark was extracted using 80% ethanol, hot water, and 1% sodium bicarbonate. The extracts were dried and dissolved in dimethylsulfoxide before testing for cytotoxicity and antiviral activity using crystal violet assay. The …

Mentoring First-Year Stem Students Through Collaborative Research In The Haynes Scholars Program, Alex Capaldi, Laura Tipton

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Mathematically Modeling Stoichiometric Drivers Of Heterotrophic N2 Fixation, Corday R. Selden, Rebecca Everett, Halvor H. Halvorson, Megan E. Berberich, Luca Schenone, Angela Peace, Renn Schipper, Edwin Cruz-Rivera, James Powell, Keisuke Inomura, Robinson W. Fulweiler, Amy M. Marcarelli, J Thad Scott

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Fostering Entrepreneurial Thinking And Practice Through Teaching And Learning Integration, Mohammad G. Sabbir

Learning and Educational Center Virtual Teaching and Learning Conference

This session explores an innovative, evidence-based approach to integrating entrepreneurial thinking into undergraduate neuroscience education through hands-on gene editing experiences. Using the commercially available Bio-Rad CRISPR/Cas9-based “Out of the Blue” kit for bacterial LacZ gene editing, students are guided not only through the scientific principles underlying modern gene editing technologies but also through the entrepreneurial challenge of replicating and manufacturing the kit using existing lab resources. This model empowers students to extend their learning beyond the classroom by engaging in cost-effective, scalable biotechnology practices—particularly valuable for institutions with limited funding. Classroom-based research demonstrates increased student engagement, deeper conceptual understanding, and …

A Multi-Faceted Study Of Antibiotic-Resistant, Opportunistic Pathogens In Wastewater And Environmental Water, Jeanette Calarco

USF Tampa Graduate Theses and Dissertations

More than 2.8 million infections due to antibiotic-resistant bacteria occur annually in the United States, and more than 35,000 people die as a result. Domestic wastewater (sewage), which contains antibiotic-resistant bacteria and antibiotic resistance genes, is collected at treatment plants for removal of contaminants, e.g. pathogenic microorganisms and nutrients. While wastewater treatment is designed to remove antibiotic-resistant bacteria and other microorganisms through treatment and disinfection, some bacteria may escape treatment. Treated wastewater effluent is generally discharged into surface waters; however, some fraction of the effluent may be used as recycled water. Compromised wastewater collection infrastructure and sewage spills can disseminate …

Solvent Extracts Of Pulvigera Papillosa (Orthotrichaceae) Show No Antimicrobial Properties In Disk Diffusion Tests, Ryan A. Solorzano, Justin Paulin, Grayson Prater, Michael Lanier

Humboldt Journal of Microbiology

Abstract As antibiotic-resistant bacteria become more prevalent, the search for novel forms of antibiotics in the natural world has become an increasingly worthwhile endeavor. Many mosses have been found to contain antimicrobial properties, including those in the family Orthotrichaceae. Pulvigera papillosa, an Orthotrichaceous moss native to California, has thus far not been investigated to determine whether it contains antimicrobial properties. Extraction techniques using polar and nonpolar solvents have proven to be effective in extracting the secondary metabolites that allow mosses to defend themselves against a hostile microbial world. This study takes a preliminary look into the antimicrobial properties of P. …

Assessing Antimicrobial Properties Of Plant-Derived Ellagic Acid Supplements, Noah S. Schuhmann, Andrew Mclaughlin, Julian Barrera

Humboldt Journal of Microbiology

Bacteria present in the human gut microbiota are affected by compounds with antimicrobial properties. Phenolic compounds extracted from plants have been shown to exhibit significant antimicrobial capacity at certain concentrations, which makes them an area of interest to researchers. Ellagic acid is one such phenolic compound, present in nuts and berries that many people consume on a regular basis. Supplements containing concentrated ellagic acid provide an additional source for the compound. It is known that, in the body, ellagic acid is metabolized into urolithins, which contribute to health through their anticancer and anti-inflammatory qualities. In this study, we investigated the …

Comparative Analysis Of Probiotic Viability In Alcoholic And Non-Alcoholic Kombucha, Isabella N. Cerrone, Brooke Pirkle, Danielle Williamson, Gianna Vendrell, Chloe Kraft

Humboldt Journal of Microbiology

Kombucha is a fermented tea beverage valued for its probiotic and antimicrobial properties that arise from complex molecular interactions between yeast, acetic acid bacteria (AAB), lactic acid bacteria (LAB), and metabolic byproducts of fermentation. With the rising demand for non-alcoholic versions of traditionally alcoholic kombucha beverages, ethanol reduction methods have become common, though their impact on probiotic viability and antimicrobial properties remains poorly understood. This study investigates the effects of ethanol removal on kombucha’s functional properties, including probiotic survival, antimicrobial activity, and organic acid composition (pH). We compared alcoholic and non-alcoholic versions of JuneShine kombucha across five flavors. Probiotic viability …

Growth Trends In Abundance And Diversity Of Synthetic Microbial Communities Over Varying Thermal Conditions, Mariska M. Kessler, Jocelyn Wolfinger, Destiny S. Alcaraz

Humboldt Journal of Microbiology

Microorganisms create various communities that act as the foundation of ecosystems. Abiotic factors such as temperature variability and environmental fluctuations are known to produce shifts in the abundance and diversity of microbial communities, but our current understanding is limited. In this study, we aimed to address this gap by observing abundance and diversity growth patterns under different temperature conditions within individual species and communities. Samples of 4 isolates and 4 artificial communities were grown at constant and fluctuating temperatures. Results found that the isolate samples had the highest abundance under constant high temperatures, whereas the community samples had the highest …

Elucidating The Relationship Between Water Quality And Antibiotic Resistance Of Rainwater Microbes Across Western Humboldt County, Theo P. Murphy, Eve Wendley, Justice Laskowski, Tyler Paredes

Humboldt Journal of Microbiology

Limited studies have been conducted regarding the fecal contamination and microbial dispersal through rainwater, with no known studies investigating the potential connection between antibiotic resistant microbes and water quality in rainwater. This study seeks to identify the presence of a correlation between water quality and incidence of antibiotic resistance in rainwater microbes. We hypothesize that there will be a correlation between these two variables. We additionally anticipate a high incidence of fecal contamination across rural and urban collection sites alike, with fecal contamination being more prevalent in rural areas than urban locals. To determine water quality, we measured the concentration …

Comparative Analysis Of Taproot And Fibrous Root System Microbiomes Under Flooding Stress, Natalie S. Kozlowski, Leighanna Jake

Humboldt Journal of Microbiology

There has been increased interest in understanding how the microbiomes of vascular plants respond to flooding stress and, many studies have focused on monocotyledonous plants with fibrous root systems. This leaves a gap in knowledge of dicotyledonous plants with taproot systems, as previous studies have been in the context of flooding to cropland affecting major food crops which are often monocotyledonous plants with fibrous root systems. Since the structural and functional differences between these root systems may influence microbial community stability and response to flooding conditions, a study looking at both is long overdue As such, this study aims to …

Increasing Pediatric Hpv Vaccination Rates, Brooke A. Nicholas

Dissertations

Increasing Pediatric HPV Vaccination Rates

Abstract

Problem: The human papillomavirus (HPV) is a sexually transmitted infection that affects more than 80% of the population within the United States (Eisenhauer et al., 2020). HPV can develop into cervical, anogenital, and oropharyngeal cancers (Eisenhauer et al., 2020). About 4,000 individuals die from cervical cancer alone each year (O’Leary, 2022). The HPV vaccine, though recommended by the ACIP and AAP, is below national vaccination rates in comparison to other vaccines (O’Leary, 2022).

Methods: This quality improvement project is a non-randomized controlled trial that observed HPV vaccine dose completion rates for patients aged 9-14 …