Microbiology Commons^™

Antimicrobial Activity Of Violacein Extracted ​ From Janthinobacterium Lividum​, Catherine M. Brownhill-Slatore

Scripps Senior Theses

Abstract

Antibiotic-resistant bacteria have been a threat since the discovery of antibiotics. The increased rise of antibiotic-resistant bacteria has created an immediate need for new antibiotics. Violacein, a purple bisindole pigment produced by Janthinobacterium lividum, has been shown to be a promising new antibiotic. Its efficacy has not been completely demonstrated, and this project aims to further investigate the effectiveness of violacein as an antibiotic. To do this, a minimum inhibitory concentration (MIC) test was conducted. Violacein was grown, extracted, purified, and tested across concentrations ranging from 1.0 to 500.00 µg/mL to cover values well above and below previously cited …

Investigating Microbe-Mediated Temperature Tolerance In Lemna Minor, Matthew Thomas Farbaniec

Honors Theses and Capstones

Temperature limits plant growth and survival more than many other environmental variables, and increases in the frequency of extreme hot or cold weather events pose significant challenges for plant growth and crop yields. Previous studies have shown that bacteria, fungi, and other microorganisms associated with plants ( i.e., the plant microbiome) can influence host response to temperature stress. These same microbes have their own temperature tolerances. We investigated whether microbial temperature tolerance correlates with plant resilience using an aquatic plant model, Lemna minor, and isolates derived from its microbiome. Microbial isolates were assessed at −10°C, 4°C, and 32°C for …

Modulating Oran Nitrate-Reducing Bacteria To Enhance Nitric Oxide Bioavailability As A Therapeutic Target For Atherosclerosis, Donovan C. Davidson

CMC Senior Theses

Atherosclerosis remains the primary driver of global cardiovascular disease, yet clinical interventions are largely restricted to high-cost, invasive procedures only after it has reached a critical stage. Recent research has identified a connection between the oral microbiome and vascular health via the enterosalivary nitrate-nitrite-nitic oxide (NO) pathway. Oral nitrate-reducing bacteria (ONRB) drive the synthesization of NO by reducing dietary nitrate into nitrite, which is then converted into bioavailable NO. NO is a potent vasodilator that maintains endothelial health by suppressing inflammation through inhibiting the expression of adhesion molecules VCAM-1 and ICAM-1. However, this pathway is easily compromised by dysbiotic oral …

Characterization Of The Human Thnatomicrobiome By Decomposition Stage Through Bioinformatic And Meta Data Analysis, Ashton C. Laughlin

Biology Theses

Estimating the postmortem interval (PMI) is one of the most crucial factors in forensic death investigations. Recent advances in forensic microbiology have led to increased interest in using the study of the human postmortem microbiome, or “thanatomicrobiome,” to improve PMI estimates. In addition to current PMI estimation techniques, microbial community succession could serve as a valuable tool in estimating PMI. Further research is needed to develop a comprehensive understanding of the human postmortem microbiome. The purpose of this study is to contribute to the expansion of this tool by reviewing the current literature and analyzing previously published data using the …

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 …

Characterizing Gut Microbial Communities And Symbiont-Mediated Detoxification In Herbivorous Insects, Rachel C. Vargas

Biology Dissertations

Insect gut bacteria are vital contributors to host physiology, yet the broader prevalence and fitness implications of symbiont-mediated detoxification remain poorly understood. This thesis investigates these dynamics across three research chapters. Chapter 1 uses 16S rRNA sequencing to characterize how grasshopper gut microbial communities vary across species, dietary breadths, and gastrointestinal segments. Chapter 2 evaluates the detoxification capacity of over 150 bacterial isolates from diverse herbivores against the plant allelochemicals phenethyl isothiocyanate, rutin, and chlorogenic acid to determine if host dietary specialization predicts microbial metabolic ability. Finally, Chapter 3 employs fitness bioassays to test whether inoculating generalist herbivores with detoxifying …

The Coral Microbiome Under Climate Change: Shifting Symbiotic Interactions, Katherine E. Parker, Kate M. Quigley

Biological Sciences Faculty Publications

Host–microbe symbioses are central to organismal health, yet these complex partnerships are often strongly shaped by the environment. Climate change is increasingly altering environmental conditions, disrupting the balance of host–microbe interactions and pushing them along a continuum from mutualism (both partners benefit) toward parasitism (one partner gains at the other’s expense). Reef-building corals provide a clear example of this vulnerability, as the coral holobiont, an ecological unit comprising diverse photosynthetic algal symbionts (Symbiodiniaceae) and other microbial partners, depends largely on these mutualistic interactions for nutrition, immunity, and stress tolerance. Increasingly, evidence suggests that under heat stress, the algal symbionts retain …

The Effect Of The Affordable Care Act Medicaid Expansion On The Risk Of Hospital Closure And Adolescent Hpv Immunization In Rural Counties, Juliette Des Rosiers

Scripps Senior Theses

From 2005 to 2025, over 200 rural hospitals shut their doors, often citing increased operational costs, staffing shortages, low patient volume, regulatory barriers, financial challenges exacerbated by the COVID-19 pandemic, and uncompensated care as common contributors to the closures. Rural patients are often referred by their primary care physician to a hospital for regular immunizations, since smaller clinics have less capacity to provide immunizations due to a shortage of pediatricians and limited vaccine stock. A crucial vaccine that is not required by schools and underutilized in rural areas is that against human papillomavirus (HPV), a virus that infects cutaneous and …

Lead Biosorption By Oceanobacillus Profundus Kbz 3-2: Strategies For Bioremediation Systems In Kabwe, Danielle S. Desmarteau

Scripps Senior Theses

Lead contamination remains a significant global public health concern, particularly in Kabwe, Zambia, the site of a former lead mining operation. Bioremediation, which utilizes biological materials and processes to remove environmental contaminants, represents a promising approach for addressing lead pollution. However, the development of effective bioremediation systems requires a detailed understanding of the mechanisms underlying metal removal and the feasibility of implementation in low-resource settings. Oceanobacillus profundus KBZ 3-2, a bacterium isolated from Kabwe mine waste, has demonstrated the ability to remove lead from aqueous environments. This study proposes to investigate the mechanism of lead biosorption by this organism, …

The Ecological Consequences Of Horizontal Transmission Of Symbionts, Bibek Singh Parajuli

Biology Dissertations

Most multicellular organisms depend on their microbial symbionts for various functions, such as digestion, nutrient supplementation, pesticide degradation, and defense. While many insects acquire their symbionts vertically from their parents, thousands of species of true bugs (Hemiptera) across different families acquire their microbial symbiont, Caballeronia, from the environment each generation. Acquiring symbionts from the environment (horizontal transmission) has various ecological consequences for the host. In this study, I used the bug-Caballeronia model 1) to understand whether the free-living symbionts benefit from association with multicellular hosts, 2) to evaluate whether host specialization on symbiont strains varies across taxonomic levels, …

Remediation Impacts Metal Concentrations And Metal Tolerant Bacteria In Soils Of The Missouri Tri-State Mining District, Ophelia R. Pettington

Graduate Theses/Dissertations

After over 100 years of Zn and Pb mining in the Tri-State mining district (TSMD), former mines continue to be sources of metals. Metal contaminated soils can be remediated using plant-microbe interactions. Plants manipulate their microbiome and recruit microbes to increase metal tolerance. Remediating bacteria are site-specific and identifying native microbes can accelerate remediation efforts. Studies relating microbes and metal concentrations in remediated areas in the TSMD are scarce. I collected root and bulk zone soils associated with Andropogon virginicus from remediated and non-remediated sites in Webb City, MO. I used 16S rRNA gene amplicon sequencing to evaluate the bacterial …

Exploring The Application Of Wastewater Monitoring To Determine The Prevalence And Diversity Of Influenza On The Campus Of West Virginia University, Lakyn Renee Sanders

Graduate Theses, Dissertations, and Problem Reports (ETD)

Influenza viruses (IV) affect populations globally, with the World Health Organization (WHO) estimating that IV are responsible for an estimated 3-5 million infections and 290,000 – 650,000 deaths annually^1–3. More specifically, the 2019-2020 IV season is associated with an estimated 38 million illnesses and 22,000 deaths in the United States alone⁴. IV are rapidly spread between individuals through direct contact with infected individuals, contaminated surfaces, or aerosolized virus particles². Traditional IV infection monitoring relies on clinical screening of patients presenting influenza-like symptoms, commonly through the use of multi-target panel tests such as the BioFire …

The Role Of Temperature And Carbon Source In Nutrient Acquisition For Peptidoglycan Synthesis In A Gfp-Expressing Borreliella Burgdorferi, Barrett-Anne Conner Briggs

Graduate Theses, Dissertations, and Problem Reports (ETD)

Lyme disease is the most common vector-borne disease in the United States with an estimated yearly incidence rate of more than 300,000 cases. Borreliella burgdorferi, the etiological agent of Lyme disease, is transmitted by the bite of an infected Ixodes scapularis tick and can cause debilitating pathologies affecting numerous body systems. Symptoms include fever, fatigue, joint pain, and a characteristic bull’s eye rash (erythema migrans) at the site of the tick bite. The timely and appropriate use of antibiotics effectively treats early Lyme disease; however, uncomfortable side effects reduce treatment compliance. If left untreated, long-term complications can arise including facial …

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. …

Assessing The Impact Of Storing Water Samples At Ambient Temperature On Plankton Metabarcoding, Stephanie N. Lievano

Honors Undergraduate Theses

Increasing incidence of Harmful Algal Blooms (HABs) has led to fish kills, air quality hazards, and economic impacts. One economic impact is on tourism, one of the main sources of Florida’s income, where billions of dollars are lost to such events. The Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute (FWC-FWRI), with the help of collaborators, collects water samples from across the state for HAB monitoring. These samples are stored at ambient temperature for up to 24 hours which could directly affect data analyses. Here, in collaboration with FWRI-FWC, I investigated whether this storage technique affects plankton …

Population Genomics And Evolution Of Pseudomonas Aeruginosa, Samara T. Choudhury

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is a Gram-negative bacterium ubiquitous in diverse environments and an opportunistic pathogen in humans. It is a leading cause of chronic lung infections in cystic fibrosis patients and of hospital-acquired pneumonia and sepsis. With a large flexible genome and abundant mobile genetic elements, P. aeruginosa exhibits high levels of antimicrobial resistance (AMR), making it a significant public health threat. Evolutionary processes such as homologous recombination, and horizontal gene transfer generate extensive genomic diversity in this species and facilitate the spread of resistance genes. In this dissertation, I investigate the genetic and evolutionary factors shaping P. aeruginosa population structure …

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 …

Microplastic Exposure Alters Tubulin Leading To Alterations In Insulin Secretion By Pancreatic Beta Cells, Anakaren Garcia

Honors Program Theses and Research Projects

Abstract

Diabetes mellitus is a metabolic disorder characterized by elevated blood glucose levels due to impaired insulin secretion or diminished cellular response to insulin (resistance). Pancreatic β-cells depend on a well-organized cytoskeleton, particularly microtubules composed of α- and β-tubulin heterodimers, to transport insulin granules to the plasma membrane during glucose-stimulated insulin secretion (GSIS). Disruption of microtubule organization can impair granule trafficking and reduce insulin release. However, emerging environmental toxicants such as microplastics that interfere with β-cell cytoskeletal function remains largely unexplored.

Microplastics (MPs) are small plastic particles (< 5 mm) that have become widespread environmental contaminants and can enter biological systems. Previous studies have shown that MPs can induce cellular stress and protein misfolding, but their effects on microtubules in pancreatic β-cells are not well characterized. This study investigates whether exposure to fluorescent polystyrene microplastics alters microtubule organization and insulin secretion in βTC-6 cells.

βTC-6 cells were treated with 10 µg/mL of fluorescent polystyrene microplastics for …

Exploring The Role Of Faecalibacterium Prausnitzii Metabolites In Modulating Fatty Acid Metabolism And Protecting Hepg2 Cells During Induced Steatosis, Morgan Martin, Emerald Cole

Student Scholar Symposium

The obesity epidemic has risen to astronomical numbers with over 650 million adults being classified as obese (BMI≥30). Obesity is of critical concern as excess body fat storage is a comorbidity to various diseases including type-2 diabetes, cardiovascular disease, and cancer. Although obesity has classically been attributed to genetics and unhealthy lifestyle choices, there is a growing interest in other factors affecting obesity, including the gut microbiome. For example, mice lacking a microbiome are resistant to weight gain even when placed on a high-calorie diet. It can then be concluded that bacteria and the metabolites they produce can dramatically affect …

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 …

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 …

A Comprehensive Overview Of Chronic Wound Infections And Current Treatment Methods, Sarah Fakher, David J. Westenberg

Biological Sciences Faculty Research & Creative Works

Chronic wound infections pose significant healthcare challenges due to persistent biofilms, antibiotic resistance, and impaired healing pathways. These wounds are characterized by prolonged inflammation, microbial colonization, and disrupted tissue regeneration, leading to substantial morbidity and healthcare costs. This article reviews current knowledge on chronic wound types, their pathophysiology, and the mechanisms underlying biofilm formation to examine the latest advancements in antimicrobial-based strategies aimed at addressing these challenges. It highlights how diverse materials and technologies have been engineered to improve infection management, enhance tissue regeneration, and overcome the limitations of traditional treatments as well as advances that leverage innovations such as …

The Effects Of Plastic Mulch And Irrigation On Hemp Chemistry And Leaf Endophytes, Allison Rietman, Connor Morozumi, Robert C. Pearce, Natalie Christian

Journal of Agricultural Hemp Research

As an emerging crop, cultivation techniques for industrial hemp (Cannabis sativa L.) are still being developed and optimized. For example, irrigation and plastic mulching are some management practices that have been touted for their benefits in improving crop quality. Both techniques ensure ample water availability, which has often been attributed to improving hemp cannabinoid and terpene composition. In this study, we examined how supplemental irrigation implemented in a plastic mulch system influenced the cannabinoid and terpene profiles of one cultivar of CBD hemp, Lifter. We grew industrial hemp in field with plastic mulch and applied regular irrigation to one group …

Clinical Applications Of Probiotics: A Comprehensive Review Of Benefits And Challenges, Riyam Wissam Hassan

Maaen Journal for Medical Sciences

Probiotics are beneficial microorganisms that help balance microbes in intestines and promote growth beneficial bacteria, they vary between bacteria, yeasts, and fungi and they are helpful to human health when taken in adequate and suitable amounts. In addition to maintaining intestinal health and help with digestion and absorption, also inhibiting development and preventing spread of harmful microorganisms. It exists in different forms, in the intestines and in the foods, products fermented, and in the pharmaceutical supplements. Because human health depends largely on the interaction between humans and these microorganisms known as probiotics, it has found that these organisms have vital …

Enhancing Cataract Surgery Outcomes: Optimal Use Of Pre- And Post-Operative Eye Drops, Keith Skolnick M.D., Anu Valiaveedu

Mako: NSU Undergraduate Student Journal

Many preoperative and postoperative cataract patients struggle with comprehending the use of prescription medication as directed. Language barriers and low health literacy levels are major factors contributing to improper use of prescriptions. To increase patients comprehension, the Fort Lauderdale Eye Institute employed an educational intervention consisting of a live presentation and an instructional video. Results found that 44% of patients were hesitant to ask questions to clinical staff, 32% felt overwhelmed, and nearly 70% lacked confidence in using their prescribed eye drops. Following the intervention, 91% of patients reported increased confidence in their medications, and most indicated that the video …

Microbial Guardians Of The Savannah: Unraveling The Gut Microbiome For African Carnivore Conservation, Laura E. Peirson

All NMU Master's Theses

Non-invasive fecal sampling is essential for wildlife gut microbiome (GMB) research, yet field conditions often limit preservation options. I compared gut bacterial communities in paired fecal samples preserved in stabilization tubes and air-dried in paper bags collected from anesthetized African lions (Panthera leo) and spotted hyenas (Crocuta crocuta) in Etosha National Park, Namibia. Additional opportunistic samples from carnivore kill sites were also analyzed. No significant differences in alpha or beta diversity were detected between preserved and dried samples, although bacterial beta diversity differed between preserved and opportunistic samples (PERMANOVA). Core bacterial communities remained consistent across sample …

The Inside Scoop: Elucidating The Three-Way Relationship Between Schistosoma Mansoni, The Gut, And Vaccines, Mariam A. Mhanna

Biomedical Sciences Theses & Dissertations

Schistosomiasis is a neglected tropical disease that affects over 250 million people worldwide. This blood fluke infection burdens communities and areas with limited to no access to clean fresh water. When a host is exposed to cercariae, the infectious agent, in a body of water, it matures in the host’s circulation into adult female and male worms. Copulated adult worms migrate to the mesentery, in the case of Schistosoma mansoni, and produce eggs that can cross the intestinal barrier and get excreted in the feces to continue the lifecycle. The effects of S. mansoni infection on the host …

Utilizing The Combinatory Power Of Chemotherapeutic Compounds In Triple Negative Breast Cancer Cells, Matthew I. Hyder

Biology Summer Fellows

Breast cancer is the leading cause of cancer-related deaths among women worldwide and the second most common cause of cancer deaths in women in the United States. Genetic variants that increase the risk of breast cancer include mutations in the breast cancer susceptibility genes 1 and 2 (BRCA1 and BRCA2). Apoptosis, or programmed cell death, is a natural process that helps the body remove aged cells. However, in cancer, deregulated apoptotic signaling—especially the activation of anti-apoptotic mechanisms—enables cancer cells to evade this process, leading to uncontrolled proliferation, tumor survival, therapeutic resistance, and cancer recurrence. Most anti-cancer drugs function as chemotherapeutic …

Bridging Prairie Restoration And Regenerative Agriculture With Compost Tea, April Hersey

2025 Symposium

Inland Pacific Northwest prairie is an endangered ecosystem that has been reduced by conversion to agriculture. There is growing interest in the role of soil microorganisms in prairie ecosystems, which may be crucial for restoration of the plant community through interspecies interactions within the soil near plant roots. One method for improving soil microorganism community composition is compost tea: enriched liquid compost extract. Compost tea is used in regenerative agriculture to improve crop yields and protect against pathogens, ostensibly through the activity of the added compost microbes. While research has supported compost tea application in regenerative agriculture, it has not …

Abstract 2587 Recombinant Expression And Purification Of A. Vinelandii Cown In E. Coli, Julie Takei, Cedric P. Owens, Katie Sanders, Neeraja Gajendran

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The goal of this project is to study the protein CowN in the diazotroph Azotobacter vinelandii (Av) in comparison to CowN in Gluconacetobacter diazotrophicus (Gd). Nitrogenase is an enzyme that catalyzes the reduction of nitrogen gas into ammonia in diazotrophic bacteria. In many diazotrophs, the protein CowN prevents nitrogenase inhibition from the environmental gas carbon monoxide (CO). Previous work studied CowN in the diazotroph G. diazotrophicus. In G. diazotrophicus, CowN binds to nitrogenase and weakens CO binding to its active site. The mechanism of CowN has only been investigated in G. diazotrophicus. Thus, we are interested in determining if CowN's …