Microbiology Commons^™

Combating Β-Lactamase Resistance: From Inhibitor Design To Substrate Evolution, Lian M.C. Jacobs

USF Tampa Graduate Theses and Dissertations

β-lactamase production by bacteria is a major mechanism of antibiotic resistance. These enzymes hydrolyze β-lactam antibiotics, preventing them from binding to and inhibiting PBPs. Although new β-lactam scaffolds and inhibitors are continually introduced into the clinic, resistance often emerges within a few years. Therefore, the development of cross-class inhibitors with novel scaffolds is critical to mitigate this resistance. In parallel, a deeper understanding of the structural and mechanistic basis of β-lactamase resistance is essential. Together, these approaches provide an effective strategy for combating antibiotic resistance.

The first project addressed the need of effective cross-class β-lactamase inhibitors capable of targeting SBL …

Genome-Wide Phenotypic Characterization Of Mycobacteriophage Mercurio, Tyler Downs

Departmental Honors & Graduate Capstone Projects

Bacteriophages, or phages, are being piloted as a supplemental or alternative therapeutic to antibiotics against drug-resistant Mycobacterium pathogens, such as M. tuberculosis, which pose a global public health crisis.  Characterizing bacteriophage genomes can provide insights into efficacy in phage therapy before implementation or elucidate new targets to manipulate bacterial growth.  Overexpression of individual phage genes is useful to study a gene product’s function independent of others.  Here, the results of phage Mercurio plasmid library overexpression in plate-based assays are described.  Mercurio infects nonpathogenic Mycobacterium smegmatis and is genetically related to bacteriophages infecting pathogenic Mycobacterium species.  Eleven gene products of …

Understanding Tlr3 Immune Response Activation In Cryptosporidium Parvum And Cryspovirus Pathogenesis, Surayya Hudayberganova

Biochemistry and Molecular Biology

Cryptosporidiosis is a serious gastrointestinal illness caused by a protozoan parasite known as Cryptosporidium. It is particularly dangerous for malnourished children and those with compromised immune systems. My research focuses on the Toll-like receptor 3 (TLR3) response to the Cryptosporidium parvum infection, specifically in the presence of the parasite’s viral mutualist named cryspovirus (CSpV1). Results using research methodologies like ELISA and RT-qPCR have indicated that TLR3 expression increases during the infection process of Cryptosporidium parvum (C. parvum). Furthermore, one intriguing observation concluded during this study suggests that administering the TLR3-specific inhibitor CU-CPT4a to infected cells drastically decreased this activation. This …

Understanding The Role Of Toxs As A Bile Sensing Component Of The Toxrs Virulence Regulatory System In Vibrio Spp., Minje Kim

Dartmouth College Ph.D Dissertations

Pathogenic Vibrio bacteria, such as V. cholerae and V. parahaemolyticus, colonize in the human small intestine to cause severe gastrointestinal disease. During the infection, these bacteria encounter bile salts, antimicrobial cholesterol metabolites secreted into the intestine. Pathogenic Vibrio species have evolved to utilize bile salts as signals to regulate virulence. The signaling depends in part on ToxRS, a conserved co-component transmembrane transcription regulator. ToxRS consists of the transcription factor ToxR and its membrane-tethered binding partner ToxS. ToxS is required for ToxR stability and full transcriptional activity. Although bile salts are known to influence ToxRS-dependent virulence gene expression, the molecular …

Proline To Serine Mutation In Flexible Loop Region Of Malate Dehydrogenase, Anna Molstad, Hannah Robertson

Undergraduate Research Symposium (2026- )

Malate Dehydrogenase (MDH) is an essential enzyme that converts malate to oxaloacetate using the reduction of NAD+ to NADH. In humans, MDH plays a role in energy metabolism by catalyzing a key step of the citric acid cycle, important for energy production. Other indirect roles for MDH include gluconeogenesis and reoxidizing NADH from fatty-acid β-oxidation. An important feature of MDH is a flexible loop region that can alter substrate binding and enzyme activity, but its role is not well understood. Our study investigated how Pro123 to Ser (P123S) mutation in the flexible loop region affects MDH function. We hypothesized that …

Sustainable Mitigation Of Microplastic Pollutants Using Native Plant Species, Antonio Martinez

Posters - 2026

Microplastics (MPs) are defined as small plastic particles that come from the degradation of plastics [Ziani et al. 2023], that hold a regular or irregular shape, ranging from 1μm to 5 mm [Campanale et al. 2025]. This diminutive size makes them virtually impossible to remove once released into the environment[Lee et al. 2023]. Furthermore, biological, chemical, and physical processes break MP's further down in the environment, causing them to exist in nano-level sizes (1nm-1μm) [Lee et al. 2023], further exacerbating their threat to critical habitats. However, recent studies have shown MP contamination expands beyond the natural environment as recent studies …

Effect Of Novel Antimicrobial Compounds On Fungal And Bacterial Pathogens, Megan Wilderman

Honors Program: Senior Projects (Public)

Antimicrobial resistance is a growing concern in medicine¹ leading to a need for the development of novel compounds. Two compounds were tested in this study, 2-hydroxyethylhydrazine (HEH) and para-nitrophenyl-isocyanide (NPIC). HEH targets phosphatidylcholine (PC) production², and NPIC targets mitochondrial function³. Choline (Cho) is a compound that bypasses the inhibition of HEH through the Kennedy pathway.² Two-fold serial dilutions were conducted in 96-well plates to test the sensitivity of different bacteria to HEH and fungi to HEH and NPIC in different media types. A choline condition was also included in the HEH dilutions to test …

Tlr3 Mediated Type I Interferon Response In Mammalian Cell Defense Against Cryptosporidium Parvum Infection., Anjelica Matias

Biochemistry and Molecular Biology

Cryptosporidium parvum is a major cause of a diarrheal disease which affects many children in the USA as well as the rest of the world, yet the contribution of its double stranded RNA (dsRNA) viral symbiont, Cryspovirus (CSpV1) to host innate immunity remains unclear. This study investigated whether CSpV1 activates Toll Like Receptor 3 (TLR3) signaling pathways and downstream Interferon type I (IFN I) responses in mammalian intestinal epithelial cells. Confluent Human Ileocecal Colorectal Adenocarcinoma cells (HCT8) were exposed to CSpV1, and the expression levels of Tumor Necrosis Factor Receptor-Associated Factor 3 (TRAF3), Nuclear Factor-𝜅-light chain enhancer of activated B-cells …

The Geminivirus Al2 Protein Interacts With Host Proteins Involved In The Plant Antiviral Response, Pheobean Atieno Odongo

Graduate Research Theses & Dissertations

Geminiviruses are economically important plant DNA viruses infecting a broad range of plant species and causing devastating crop diseases, resulting in up to 100% crop loss. As a result of these heavy losses on food and cash crops, these viruses represent a new threat to global food security and sustainability. In this research, I use Tomato golden mosaic virus (TGMV) to study host-virus relationships with an overall goal of developing sustainable and eco-friendly crop resistance. TGMV belongs to the Geminivirus subgroup, Begomovirus, that is characterized by a split genome consisting of two single-stranded circular DNAs. The TGMV genome encodes proteins …

Characterizing The Human Metapneumovirus Matrix Protein And Its Role In Infection, Chase J. Heim

Theses and Dissertations--Molecular and Cellular Biochemistry

Human metapneumovirus (HMPV) causes severe respiratory tract infections in all cohorts, but especially in vulnerable groups such as children, older adults, and the immunocompromised. The matrix (M) protein of HMPV, like the M proteins of other members of the Mononegavirales order, is involved in virus assembly and budding. However, other functions of the HMPV M protein have yet to be elucidated. To investigate these various functions of the M protein, we used a peptide-conjugated phosphorodiamidate morpholino oligomer (PPMO) antisense agent designed to block translation of the M gene to reduce M expression during infection. Treatment with varying concentrations of an …

Role Of The Osaa Transcription Factor Gene In Development, Secondary Metabolism And Virulence In The Mycotoxigenic Fungus Aspergillus Flavus, Farzana Ehetasum Hossain

Graduate Research Theses & Dissertations

Aspergillus flavus colonizes oil-seed crops, contaminating them with aflatoxins; highly carcinogenic mycotoxins that cause severe health and economic losses. Genetic studies may reveal new targets for effective control strategies. Here, we characterized a putative WOPR transcription factor gene, osaA, in A. flavus. Our results revealed that osaA regulates conidiation and sclerotial formation. Importantly, deletion of osaA reduces aflatoxin B1 production, while, unexpectedly, transcriptome analysis indicated upregulation of aflatoxin biosynthetic genes, suggesting post-transcriptional or cofactor-mediated regulation. Cyclopiazonic acid production also decreased in the absence of osaA. In addition, the osaA mutant exhibited upregulation of genes in the imizoquin and aspirochlorine clusters. …

From Theory To Ecosystems: Exploring Biodiversity And Ecosystem-Function In Pitcher Plant (Darlingtonia Californica) Microbial Communities, Gavin Sutter

Cal Poly Humboldt theses and projects

The relationship between biodiversity and ecosystem-function (BEF) has been a central focus of ecological research for the last three decades, yet the role of space in shaping BEF relationships remains relatively unknown. Research has shown that community diversity and composition can strongly influence productivity, nutrient cycling, and decomposition, but much of this work treats communities as spatially isolated, leaving open how dispersal and other spatial processes shape BEF at broader scales. To begin addressing this gap, I used microbial communities inhabiting Darlingtonia californica pitcher plant leaves to evaluate how spatial organization and successional change shape biodiversity and ecosystem-functioning. I quantified …

The Importance Of The Proline Residue In The Ldiapa Motif Of Cholera Toxin, Akash Bharathan

Honors Undergraduate Theses

Cholera is currently on its seventh global pandemic, disproportionately affecting developing countries. Vibrio cholerae, the bacterial etiologic agent, is able to cause infection by adhering to intestinal epithelial cells and secreting cholera toxin (CT), an AB-type exotoxin that dysregulates signaling pathways. Previous research by the Teter lab has shown that Hsp90, a host cytosolic chaperone, is required for CT to enter the cytosol where it produces toxic effects. Hsp90 binds to CT at two specific motifs, RPPDEI and LDIAPA. The prolines in the RPPDEI motif are essential for binding, but the proline in the LDIAPA has yet to be …

Interaction Of The Gram-Positive Human Pathogen Staphylococcus Aureus With Host Lipids, Sharanya Paul

Theses and Dissertations

Staphylococcus aureus is a prominent pathogen that is known to incorporate straight-chain unsaturated fatty acids (SCUFAs) into its lipids in addition to the normally biosynthesized branched-chain fatty acids (BCFAs) and straight-chain fatty acids (SCFAs). Furthermore, it has recently been shown that the incorporation of oleic acid into S. aureus lipids significantly enhanced the growth of the organism at low temperatures due to the greater fluidity imparted to the membrane. Together with others in the Wilkinson and Dahl laboratory, I have shown that low-temperature growth is enhanced by various SCUFAs, including the human antimicrobial fatty acids sapienic acid, linoleic acid, and …

Targeted And Screening Based Approaches To Analyze Drm Transcriptional Repressor Complex Activity In Caenorhabditis Elegans, Emily Washeleski

Dissertations, Master's Theses and Master's Reports

The molecular machinery that control the eukaryotic cell cycle, specifically the processes that mediate the switch between cellular division or quiescence, are essential for cellular and organismal viability. However, how the same machinery integrates with developmental or differentiation programs is less well understood. In Caenorhabditis elegans, the 8-subunit DRM complex (for Dp, Rb and MuvB), whose subunits belong to the Synthetic Mulitivulva (SynMuv) B class genes, is a central regulator of the cell cycle but also prevents inappropriate cell fate specification. The conserved mammalian DREAM complex (for Dp, Rb, E2F, And MuvB) is best known as a transcriptional repressor …

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 …

Detection Method For Escherichia Coli Using Real-Time Polymerase Chain Reaction Targeting The Yhav Gene, Muktiningsih Nurjayadi, Anisa Fitriyanti, Royna Rahma Musie, Gusti Angieta Putri, Puan Aqila Azizah, Helzi Angelina, Grace Grace, Ananda Indah Putri Sihombing, Agus Setiawan, Jefferson Lynford Declan, Gladys Indira Putri, Dandy Akbar Juliansyah, Siti Fatimah, Ayu Berkahingrum, Irma Ratna Kartika, Fera Kurniadewi, Vira Saamia, Shyi-Tien Chen, Bassam Aboemolak, Hesham Ali El Enshasy

Makara Journal of Science

Escherichia coli is a foodborne pathogenic bacterium that can cause diarrhea, while yhaV is a virulence-associated gene linked to the toxin–antitoxin system in E. coli. This study was aimed at evaluating the confirmation, specificity, and sensitivity of a yhaV gene primer using real-time polymerase chain reaction. The yhaV-targeting PCR successfully amplified a DNA fragment with an amplicon length of 207 bp (base pairs) under an annealing temperature optimized to a range of 54 °C to 62 °C via gradient PCR. The PCR using the primer pair produced a consistent Ct (cycle threshold) of 14.14 ± 0.05 and showed …

Effect Of Histidine Tag On The Enzymatic Activity Of Pseudolysin And Its Interaction With The Streptomyces Metalloprotease Inhibitor (Smpi) Protein, Adewale Adeboye Adewole

Electronic Theses and Dissertations

Pseudolysin (PLN) protein is a major virulent factor in Pseudomonas aeruginosa infection. PLN belongs to the family of zinc-dependent metalloproteases. It is naturally inhibited by a smaller protein called streptomyces metalloprotease inhibitor (SMPI), secreted by Streptomyces nigrescens. Previous and current studies demonstrate that the interaction between PLN and SMPI offers unique mechanistic insights for drug development against infections caused by P. aeruginosa. This study investigated the effect of N-terminal Histidine (His) tag on the enzymatic activity of PLN and its interaction with SMPI. His-tagged PLN and SMPI proteins were expressed in bacteria and purified by affinity chromatography …

Role Of Cellular Proteins In The Regulation Of Herpes Simplex Virus Type 1 Gene Expression And Dna Replication, Joseph R. Heath

Electronic Theses and Dissertations

Herpes simplex virus type 1 (HSV-1) is a ubiquitous human pathogen that infects the majority of the human population. To facilitate infection, this virus relies on a combination of host and viral factors. Previous studies have revealed a number of host proteins that associate with the HSV-1 genome throughout infection but their putative role(s) in this process remain undefined. This study aims to examine two such proteins to determine their contributions to HSV-1 gene expression and DNA replication. The first of these factors is Ints3, a subunit of the Integrator complex. This protein complex functions in transcription regulation, and Ints3 …

In Silico Prediction Of Cytotoxic T-Cell Epitopes From Helicobacter Pylori Virulence Factors Using An Immunoinformatics Approach, Demy Valerie Chacon, Kiana Alika Co, Daphne Noreen Enriquez, Aubrey Love Labarda, Reanne Eden Manongsong, Edward Kevin B. Bragais

Biology Faculty Publications

Background: Helicobacter pylori infects approximately half of the global population, leading to gastric and duodenal ulcers. Despite the availability of antibiotics, challenges such as patient reluctance, high treatment costs, and antibiotic resistance limit their effectiveness, making vaccination a promising alternative. This study used immunoinformatics to identify candidate epitopes for a multiepitope vaccine construct against H. pylori.

Material and methods: The protein variability server was utilized for conservation analysis. The epitopes were screened for antigenicity, allergenicity, toxicity, cross-reactivity, and population coverage. Selected epitopes were docked with their corresponding human leukocyte antigen (HLA) alleles, and thermodynamic quantities were determined. Five virulence …

Investigating A Link Between Dna Repair And Dna Replication In Escherichia Coli Using A Bacterial Two-Hybrid System, Lo Cooper

University Honors Theses

Cells rely on nucleotide excision repair (NER) to remove bulky DNA lesions, such as those caused by UV light. In Escherichia coli, NER involves the UvrABC complex, and includes two main pathways, global genomic repair and transcription-coupled repair (TCR). While TCR, which preferentially removes lesions that block RNA polymerase on the transcribed strand of active genes, is well studied, less is known about whether a similar coupling between repair proteins and replisomes blocked by damaged DNA exists. Such a process has been suggested by a high throughput interactome study, using the replisome subunit HolC as bait and the damage …

Characterization Of Sars-Cov-2 Replication And Transcription Complexes Via Structural And Evolutionary Approaches, Amelie Ghirardo, Ben Shabatian, Avishai Aghelian, Kyle Tau, Eleonora Gianti

Undergraduate Research

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused around 700M cases and over 7M COVID-19-related deaths recorded worldwide (World Health Organization, March 2025). Aiming to effectively combat this and other disease-causing Coronaviruses (CoV), unprecedented research efforts led to the development of new vaccines and antiviral therapies. Due to emergence of variants of concern (VOCs) with increased transmissibility, immune evasion from vaccination, and potential to resist the available treatments, SARS-CoV-2 continues to represent a major threat to global health. Hence, there is a pressing need to discover new antivirals with broad-spectrum efficacy against multiple SARS-CoV-2 variants and related CoVs. This project …

Navigating The Challenges Of Coccidioides Surveillance: Insights From The Environment Of El Paso County, Texas, Tanzir Hossain

Open Access Theses & Dissertations

Coccidioidomycosis, or Valley fever, is a fungal infection resulting from the inhalation of spores from the Coccidioides species (C. immitis and C. posadasii), native to arid areas of the Western Hemisphere. Coccidioidomycosis presents considerable health hazards and can be fatal. It affects between 206,000 and 360,000 individuals annually, leading to 700 to 1,100 fatalities in the United States alone. In response to these issues, extensive research has concentrated on therapeutic goals for this infectious disease. Nonetheless, more limited research has focused on the environmental detection of its causative fungi, which is crucial for forecasting treatment needs and formulating preventive strategies. …

Implications Of Type Iv Pilus Retraction For Dna Uptake By Acinetobacter Baumannii, Yafan Yu

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Horizontal gene transfer (HGT) via natural competence allows bacteria to incorporate extracellular DNA (eDNA) into their genomes, facilitating genetic diversity and adaptation. In Acinetobacter species, natural competence depends on DNA binding and uptake mediated by type IV pili (T4P). T4P are dynamic extracellular filaments composed primarily of the major pilin subunit PilA, along with a few minor subunits. T4P drive a range of cellular functions including twitching motility, biofilm formation, and DNA uptake, with some functions dependent on pilus retraction and others not. However, how Acinetobacter T4P bind DNA and how T4P/eDNA interactions impact biofilm formation remain unclear. Here, I …

Metabolite Analysis To Understand Factors Limiting Microbial Fermentation At High Substrate Concentrations, Bishal D. Sharma

Dartmouth College Ph.D Dissertations

Clostridium thermocellum, a thermophilic anaerobic bacterium, holds promise as a biocatalyst for conversion of lignocellulosic biomass into biofuels. This microbe has been subjected to various metabolic engineering strategies, including the deletion of genes encoding secondary fermentation products such as H₂, formate, acetate, and lactate, as well as the expression of heterologous genes to redirect carbon flux toward ethanol production. Despite these efforts, achieving economically viable ethanol titers remains a challenge. We hypothesized that studying how intracellular metabolite concentrations change as fermentation stops could reveal metabolic bottlenecks or regulatory mechanisms limiting ethanol production at high titers. However, metabolomics studies at …

Exploring Oxylipins In Host–Microbe Interactions And Their Impact On Infection And Immunity, Robert J. Neff, Christopher D. Radka

Markey Cancer Center Faculty Publications

Plasma lipids are essential components of biological systems, transported through interactions with proteins to maintain cellular functions. These lipids exist in various forms, such as fatty acids, glycerolipids, glycerophospholipids, sphingolipids, sterols, and prenol lipids, derived from dietary intake, adipose tissue, and biosynthesis. While the association between certain fatty acids and cardiovascular diseases has been widely recognized, polyunsaturated fatty acids (PUFAs) exhibit cardioprotective effects, reducing risks of arrhythmias and heart-related mortality. This is due to their role in the production of eicosanoids, which modulate inflammation. Chronic inflammation, particularly in obesity, is significantly influenced by fatty acids, with saturated fatty acids promoting …

Characterization Of Legionella Pneumophila Effector Protein Ceg10, Emmanuella Ofoka

Masters Theses & Specialist Projects

Legionella pneumophila, the causative agent of Legionnaires' disease, utilizes a Type IV secretion system (T4SS) to transport effector proteins into host cells. This bacterium is said to have over 300 effector proteins. Among these, the Ceg10 effector protein had remained uncharacterized, despite evidence suggesting the importance of bacterial effector proteins in the host-pathogen interaction. This study aimed to perform a structural and functional characterization of Ceg10 through transcriptomic, bioinformatics, and molecular analyses. Transcriptomic profiling of HEK 293T cells expressing Ceg10 revealed significant differential gene expression, with approximately 20 upregulated genes, including leucine-rich repeat, as well as other downregulated genes. …

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 …

Molecular Interactions Between The Shellfish Pathogen Vibrio Coralliilyticus Re22 And The Probiont Phaeobacter Inhibens S4sm, Jessica Coppersmith

Open Access Dissertations

Oyster larvae aquaculture is an important industry, both economically and environmentally, helping to create sustainable food systems by supplying seed oysters to farms, and also to restoration projects aimed at building coastal resilience and improving water quality by rejuvenating wild populations. However, oyster larvae are highly susceptible to rapid mortality events, crashes, which can seriously impact the industry. One source of these crashes in hatchery systems is vibriosis, caused by pathogenic species of Vibrio bacteria that are ubiquitous in temperate coastal waters, and with rising surface water temperatures their prevalence and virulence are increasing. To prevent these larval crashes from …

Reversible Degradation Of Peptidoglycan By Lytic Transglycosylases, Aaron Devereaux

Theses and Dissertations (Comprehensive)

Antimicrobial resistance continues to be a burden on the global healthcare system with an estimated cost of billions of dollars and millions of deaths each year. Recently, there has been little to no development on new antibiotics to treat bacterial infection, and any that are developed become resisted to within a few years. Both Gram-positive and Gram-negative bacteria contain a mesh-like layer called peptidoglycan (PG) that surrounds their cells providing strength, cell shape, and protection from their environments. This layer is a polymer of N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) connected via a b-1,4-glycosidic bond, with each strand being cross-linked …