Microbiology Commons^™

Multi-Strain Assessment Of Quorum Sensing In Chlamydomonas Reinhardtii, Jacqueline Krueger

Ocean Engineering and Marine Sciences Student Publications

Quorum sensing (QS) allows microbial populations to coordinate phenotypic switching, selecting for specific behaviors that are only beneficial when expressed at high cell densities (HCD, >106 cells/mL) rather than low cell densities (LCD, < 106 cells/mL)

Investigating The Intra-Host Relationships Of The Microbiota At Multiple Sites, Ariel Jose Hernandez-Leyva

Arts & Sciences Graduate Student Theses and Dissertations

The human body hosts an abundance of microbial communities that, through complex and multi-faceted interactions, interface with host physiology and help govern health and disease. Many of these interactions are beneficial and help maintain host homeostasis or contribute to the metabolic capacity of the host. Some are detrimental, potentially inducing or further exacerbating disease. All are complicated by the vast diversity of microbes that comprise the microbiota at any given site. Identifying microbes or microbial functions that influence health and disease for study and potential use as biomarkers is tantalizing, though difficult. The vast diversity of potential community compositions, redundancy …

Elasmobranchii Oral Microbiome Diversity Within Southeast Florida: Implications Of Shark Zoonotic And Antibiotic Resistant Pathogens Associated With Human Interactions, Amanda Finnefrock

All HCAS Student Capstones, Theses, and Dissertations

Sharks are incredibly common in the Atlantic and Gulf waters surrounding Florida. Despite the prevalent nature of these animals, little research exists on the composition of their microbial communities (or “microbiomes”). Here we aim to determine the microbial makeup of the oral environment of sharks so that we can determine if there are any bacteria of clinical significance to humans, such as being antibiotic-resistant or having elevated capability for pathogenicity. A total of 41 samples were collected from the mouths and teeth of bull, Caribbean reef, great hammerhead, lemon, nurse, and sandbar sharks caught in Southeast Florida using sterile swabs …

Geographical And Anatomical Microbiome Variation In Invasive Green Iguanas (Iguana Iguana), Amanda A. Diaz

All HCAS Student Capstones, Theses, and Dissertations

The common green iguana (Iguana iguana) was introduced to South Florida in 1965 and has since been an especially pernicious threat both environmentally and economically. This highly invasive species is also expanding in range and populations at an astonishing rate. Understanding how this reptile is able to adapt and thrive in novel environments is of imperative need in order to begin managing their disruptive populations. Notwithstanding their negative impacts and significance, the microbiome of wild populations has not yet been characterized. Here, using 16S ribosomal RNA gene sequencing, this study is the first to characterize the microbiome composition …

Evaluating The Impact Of K135t Mutation On Malate Dehydrogenase Kinetic Activity, Emily Frost, Kaitlyn Mello

Undergraduate Research Symposium (2026- )

Malate Dehydrogenase (MDH) is a key protein in the citric acid cycle; its dysregulation can have catastrophic impacts, such as neurological and metabolic disorders, and various cancers. MDH catalyzes the reversible oxidation-reduction reaction between malate and oxaloacetate, also reducing NAD+ to NADH in the process. The citric acid cycle is one of the central metabolic pathways, connecting to other essential pathways, such as amino acid and fatty acid biosynthesis, highlighting the importance of understanding how MDH works. A key site in MDH is the flexible loop region (amino acids 119-137), responsible for substrate binding, catalysis, and orientation. The flexibility of …

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 …

Dietary Manipulations Of The Undernourished Infant Microbiome, Cyrus Zhou

Arts & Sciences Graduate Student Theses and Dissertations

Today, undernutrition affects approximately 150 million children worldwide. During the first two years of life, the healthy gut microbial community undergoes a series of predictable developmental transitions. These transitions are delayed in undernourished children resulting in microbiota “immaturity.” In a foundational study, immature gut microbial communities from undernourished children and normally developing communities from chronologically age-matched healthy children living in the same area were transplanted into groups of germ-free mice consuming the same diet – one representative of what consumed by the study population. Compared mice with a mature gut microbiome, mice with an immature gut microbiome had impaired weight …

Apoe As A Potential Link In Glioblastoma Therapeutic Resistance, Xiwen She, Ifelayo Adefuye

SACAD: Scholarly Activities

Glioblastoma (GBM) is a highly aggressive brain tumor characterized by recurrence and resistance to therapy, which are driven by interactions between glioblastoma stem cells (GSCs), tumor-associated macrophages (TAMs), and the tumor microenvironment. In this study, single-cell RNA sequencing data were analyzed using QIAGEN CLC Genomics Workbench to identify genes associated with tumor–immune interactions. Following clustering, differential expression, and a multi-step prioritization strategy, we identified APOE as a top candidate gene connecting tumor and immune processes, contributing to therapeutic resistance in glioblastoma.

Maintaining And Axenizing Live Cyanobacterial Cultures For Bacterial Genome Sequencing, Yufei Wang, Louisa Acquah

SACAD: Scholarly Activities

Harmful cyanobacterial blooms are an

increasing concern in western Kansas, yet the

bloom-forming species in this region remain

poorly characterized. In this study, we

established and maintained axenic

cyanobacterial cultures to support future

genomic and ecological investigations. By

ensuring low contamination levels and stable

growth conditions, this work provides a

foundation for downstream analyses of bloom-

forming cyanobacteria. It contributes to a better

understanding of freshwater ecosystem health

in western Kansas.

Evaluating Elisa-Based Domoic Acid Detection Methods In Fetal And Maternal Samples Of California Sea Lions (Zalophus Californianus), Deanie Woodruff, Emily Lickiss, Samuel Gardiner, Mia Gastile, Elizabeth Sandoval, Florybeth La Valle

Seaver College Research And Scholarly Achievement Symposium

Harmful algal blooms produced by the diatom Pseudo-nitzschia regularly expose marine mammals along the California coast to domoic acid (DA), a neurotoxin that bioaccumulates in marine food webs. In California sea lions (Zalophus californianus), domoic acid exposure is associated with seizures, hippocampal injury, and maternal-fetal transfer of the toxin that can result in abortion. Bloom events have led to large numbers of stranded sea lions along the California coast. Although some clinical and neurological effects of domoic acid toxicosis have been documented, especially with regard to the hippocampus, there is limited understanding of how domoic acid concentrations fluctuate over the …

Submarine Groundwater Discharge As A Potential Driver Of Bacterial Microbiome Shifts In Nearshore Coral Reef Ecosystems At Black Point, Maunalua Bay, Oahu, Francesca Rasi, Niyam Reddy, Emily Mendoza, Jayla Burson, Florybeth La Valle

Seaver College Research And Scholarly Achievement Symposium

Coral reefs thrive in primarily oligotrophic environments, depending on factors such as temperature and salinity for their stability. While moderate levels of nutrients sustain coral growth, excessive nutrient inputs promote algal blooms which can outcompete corals for space. Over the past century, Maunalua Bay (O'ahu, HI) has experienced dramatic development and increase in population, which has affected the water quality in the nearshore coral reefs of the bay. The main source of dissolved land-based inorganic nutrients in Black Point is submarine groundwater discharge (SGD), which is a chronic freshwater vector that is enriched with nitrates, phosphates, silicates, and more. Because …

Harnessing The Gut-Diet Axis To Enhance Chemotherapy And Immunotherapy, Jill Carline

Bryant REDay (Research and Engagement Day)

The human microbiome, a complex ecosystem of trillions of microorganisms including bacteria, fungi, and viruses, represents a critical "gut-diet axis" that significantly influences cancer progression and therapeutic efficacy. While a state of homeostasis supports systemic immunity, dysbiosis is linked to chronic inflammation and can actively promote resistance to standard cytotoxic chemotherapies and modern immune checkpoint inhibitors. Specifically, research indicates that Bacteroides fragilis (ETBF) promotes resistance to 5-Fluorouracil and Oxaliplatin in colorectal cancer by activating Notch1 receptors to inhibit apoptosis and push cancer cells into a resilient, stem-cell-like state. Conversely, the introduction of fiber-rich and fermented foods can cultivate beneficial bacteria …

Site-Directed Mutagenesis Of The He1Α Subunit Of Human Branched Chain Α-Ketoacid Dehydrogenase Complex, Riley B. Corcoran, Isabel Wilson, Bálint Csuka-Nagy, Stephen Baron

ASPIRE 2026

No abstract provided.

A Novel Endolysin Of Phage Persinger Infecting Pseudomonas Aeruginosa: Activity Against Biofilms And Structural Prediction, Layla Abbud

James Madison Undergraduate Research Journal (JMURJ)

Endolysins are proteins that degrade bacterial cell walls. They are encoded on the genome of bacteriophages (viruses that infect and kill bacteria). At the end of the lytic cycle of a bacteriophage, endolysins cut the peptidoglycan layer of the bacterial cell wall, allowing the release of viral progeny. Pseudomonas aeruginosa is a well-known multidrug-resistant human pathogen that causes serious problems, especially in patients diagnosed with cystic fibrosis (CF). One property of P. aeruginosa is the production of biofilms, which is a defense against antibiotics. Previous research has shown that endolysins from bacteriophages can degrade biofilms. The endolysin protein from Persinger, …

Biosensors For Biomedicine, Drake O'Leary

Miners Solving for Tomorrow Research Conference

This project investigated the use of engineered bacterial reporter systems to detect cellular stress responses associated with antibiotic activity. While constructs were successfully introduced and tested against known antibiotics, the reporter consistently produced a blue signal across conditions, limiting the ability to distinguish specific stress responses. This suggests issues such as leaky expression, insufficient regulatory control, or lack of specificity in the reporter design. Although results were inconclusive, this work highlights key challenges in developing reliable biosensors and provides a foundation for future optimization. Improving signal specificity and reducing background expression will be critical for enabling accurate characterization of antibiotic …

Quantifying The Antifungal Properties Of Bacteria Using Cotton Strips, Lily Lofton

Honors Theses

Many bacteria have been known to have antifungal properties. Research has begun to determine how these bacteria can be used to protect cotton and other cellulose-rich textiles. In the present study, standardized cotton strips were inoculated with two different bacterial consortia that have exhibited anti-fungal properties. These strips were then inoculated with the melanized cellulolytic fungi, Chaetomium globosum and Rhinocladiella similis. Similarly, some cotton strips were also inoculated with a non-melanized fungus, Rhodotorula toruloides, which is also thought to be cellulolytic. The tensile strength of cotton strips was measured along with the ergosterol concentrations (fungal biomass) for each cotton strip …

Ecovoltaic Solar Energy Development Creates Novel Microclimate, Temperature, And Soil Moisture Patterns Under Solar Panels In A Warm Desert, Juan Pinos, Seth M. Munson, Claire C. Karban, Matthew D. Petrie

Life Sciences Faculty Research

Background As solar energy development expands in desert regions, new installation practices and solar technologies seek to balance ecosystem conservation and energy generation (ecovoltaics). The Gemini Solar Project, a large ecovoltaic facility located in the northeastern Mojave Desert, employed low impact installation methods to reduce disturbance of the desert ecosystem within arrays of bifacial panels mounted on solar tracking systems. We evaluated microclimate and environmental conditions across five locations: four within-facility microsites (underneath solar panels, east and west panel driplines, and interspaces between panel rows) and one in the undisturbed desert outside the facility. Results Under panel microsites experienced lower …

Signaling Response Of Epinephrine Treated Cards Toxin-Infected Thp-1 Macrophages, Trinity Martinez

Posters - 2026

Aspiration pneumonia is a common mild case of pneumonia, a disease where the lungs are inflamed and filled with fluid, compromising respiration and gas exchange. One common cause of mild pneumonia is bacterial infection via a pathogen known as Mycoplasma pneumoniae. M. pneumoniae causes a variety of respiratory illness- ranging from pharyngitis, tracheobronchitis, mild pneumonia- and in rare cases encephalitis. M. pneumoniae produces the CARDS toxin, which participates in ADP-ribosylation and vacuolization (Kannan et al., 2006)1. The CARDS toxin causes aspiration pneumonia by paralyzing the cilia that lines the respiratory tract. Epinephrine, or Adrenaline- is a hormone that is medically …

Take A Hit? Take A Hit: Quantifying Cell Death In E-Cigarette Exposed Bronchial Epithelial Cells Following Cards Toxin Treatment, Truman Havrda, Hannah Jiron, Sierra Trevino

Posters - 2026

The rapid rise of e-cigarette use among young adults has created a significant public health challenge, as the popularity of "vaping" has grown faster than our understanding of its long term cellular consequences. Current research indicates that e-cigarette vapor (ECV) induce high levels of oxidative stress and impair the lungs' ability to clear bacterial pathogens. Furthermore, ECV exposure upregulates specific receptors on the surface of airway cells, essentially making it easier for bacteria to adhere to and infect the lungs. While we know that both e-liquids and vapor trigger inflammatory responses and cytotoxicity, there is limited data on how these …

Sustainable Mitigation Of Microplastic Pollutants Using Native Plant Species, Antonio De Jesus Martinez De La Rosa, Emily Lancaster

Research Papers

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 …

Assessing The Influence Of Temperature And Water Level On Gill Disease In Goldfish, Moses Elijah Cadawas, Emmalie Turner, Darlene Panvini

SPARK Symposium Presentations

Gill disease in fish is a strong biological indicator of water quality and environmental stress. These diseases are commonly caused by bacterial or parasitic infections that target gill tissues and can lead to severe physiological impairment and ultimately mortality. Several environmental factors, including water level and temperature, play a critical role in determining fish susceptibility to these infections. Changes in these conditions can act as stressors that weaken immune defenses and promote pathogen proliferation. This study aimed to evaluate the relative impact of environmental stressors on the development of gill-associated disease in Carassius auratus (goldfish) under controlled conditions. Following exposure …

Life Line Spring 2026, Jonathan Atwood

Life Line - The Biology Department Newsletter

In This Issue:

Greetings and Farewell: Part Deux; Signs for Trees; Passing of Dr. Mary Gahbauer: a Beloved Friend and Colleague; Dr. Lisa Marr Retires; The Department Welcomes Dr. Ann Feke; Dr. Kevin Svitana Retires; Ms. Donna Rhodeback Retires; Tucker Adds Swan Specimen to Otterbein's Collection; An UnbeLEAFable Year for the Otterbein Chapter of Botanical Society of America; Field Geology Course Visits Death Valley and Beyond; Agar Art: An Unexpected Canvas; Dr. Kevin Svitana Wins the Anderson Award for Outstanding Contribution to Groundwater Research; Introducing Opi: A New Face for Zoo and Conservation Ambassador Work; Michael Hoggarth, Professor Emeritus, Wins …

Imidacloprid Effects On The Survival And Cutaneous Microbiome Of Northern Leopard Frogs, Evelyn Margaret Osterloo

Honors Thesis

Amphibians are experiencing population declines due to habitat loss, climate change, and diseases, particularly chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis. Protection from this fungal infection stems from the cutaneous microbiome. Pesticides have been shown to affect amphibians in a variety of ways, including reducing survival, locomotor performance, and accumulation in body tissues. Pesticides may also lead to changes in the cutaneous microbiome affecting amphibians who rely on these organisms as an anti-Bd defense mechanism. To investigate the effect of imidacloprid, a neonicotinoid insecticide, Northern Leopard frogs (Lithobates pipiens) were subjected to sublethal concentrations (control = …

Effects Of “Zero Sugar” Energy Drinks On Microbial Proliferation In Relation To The Gastrointestinal Microbiome, Madison Hines

Honors Theses

Energy drinks have rapidly increased in popularity and availability in recent years. With the rise of high-caffeine beverages, complications due to caffeine consumption have become more common in younger populations. The aim of this study was to use controlled laboratory methods to determine the effect of energy drinks on a variety of organisms commonly found in the gastrointestinal (GI) tract. The diverse and dynamic nature of microbes in the gut makes conditions of the GI tract difficult to replicate in a laboratory setting. As an alternative, isolates of bacteria commonly found as normal flora in the GI tract were plated …

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 …

Enhancing Urban Garden Capacity By Linking Biodiversity And Ecosystem Function, Mary T. Nguyen, Carleen Rauh, Shelby Gresch, Charlotte Correiro, Heidi Elmendorf, Adriane Fugh-Berman, Gina Wimp, Alexandra L. Decandia

Virginia Journal of Science

Urban agriculture broadly describes food and plant cultivation in metropolitan areas. While biodiversity is thought to support ecosystem health and resilience, the relationship between above-ground and below-ground diversity has been understudied in urban green spaces. This study examines plant, animal, bacterial, and fungal diversity across three distinct urban habitats: a turf lawn, a forb garden, and a farming space. Using bacterial 16S rRNA and fungal ITS2 sequencing, soil nutrient analyses, and surveys of vegetation and wildlife, we connect diverse philosophies in urban agriculture to their role in advancing community diversity and ecosystem function. We found that different urban gardens support …

Antibiotics And You: A Comprehensive Guide, Brady Haas

Senior Theses

Antibiotic resistance is a rapidly emerging issue within public health. As resistance grows, the effectiveness of traditional antibiotic therapies diminishes while risk of treatment grows. Alongside novel therapies, public knowledge is a strong combatant of the resistance-related risks of antibiotic usage. Through a comprehensive review of current literature, this work serves as an accessible guide to the mechanisms of antibiotics, bacterial resistance, and the challenges related to current antibiotic usage. Additionally, the ability of current policy and emerging novel treatments, such as nanoparticles and bacteriophage therapy, to fight antibiotic resistance is evaluated. This analysis highlights the importance of improving public …

Evolution Of Antibiotic Responses During Chronic P. Aeruginosa Infections In The Human Lung, David Frank Ritz

Dartmouth College Ph.D Dissertations

Typical antibiotic susceptibility testing (AST) of microbial samples is performed in homogeneous cultures in batch environments, which does not account for the highly heterogeneous and dynamic nature of antibiotic responses. The most common mutation found in P. aeruginosa lineages evolved during chronic cystic fibrosis infections in the human lung, a loss of function of repressor MexZ, increases basal levels of multidrug efflux MexXY, but does not increase resistance by traditional minimal inhibitory concentration (MIC) assays. Here, we use single cell microfluidics to show that P. aeruginosa’s response to aminoglycosides is highly heterogeneous, with only a subpopulation of cells surviving exposure. …

The Effects Of Mycoplasma Pneumoniae Cards Toxin On M2 Macrophage Polarization And Formation, Ria Modi

Posters - 2026

Macrophages are key cells of the innate immune system, playing essential roles in host defense, tissue homeostasis, and inflammation. Depending on stimuli, macrophages can polarize into distinct functional phenotypes, characterized as classically activated (M1) or alternatively activated (M2) macrophages. M2 macrophages are associated specifically with anti-inflammatory responses, tissue repair, and immune regulation. They contribute to wound healing and can regulate host responses during infection. Community-acquired respiratory distress syndrome (CARDS) toxin, a key virulence factor of Mycoplasma pneumoniae, plays a role in altering host immune responses, but its impact on M2 macrophage function and polarization remains unclear.

Role Of Listeria Adhesion Protein In Monocyte-Associated And Extracellular Translocation Of Listeria Monocytogenes Across The In Vitro Placental Barrier Co-Culture Model, Ayesha Atique

Biological Sciences Theses & Dissertations

Listeria monocytogenes is a facultative intracellular foodborne pathogen capable of crossing the placental barrier, leading to miscarriage, stillbirth, and neonatal sepsis, and has a fetal/neonatal fatality rate of ~20–30%. Although the importance of canonical virulence factors such as Internalin A (InlA) and Internalin B (InlB) in L. monocytogenes crossing of the placental barrier has been demonstrated, clinical strains lacking functional canonical internalins have been reported to cause severe neonatal disease, suggesting additional mechanisms of placental translocation.

To investigate these virulence mechanisms, we adapted a physiologically relevant co-culture human placental barrier Transwell model composed of BeWo trophoblasts and primary human placental …