Microbiology Commons^™

Functional Characterization Of The Hdt5 Gene In Aspergillus Flavus Morphogenesis, Mycotoxin Production, And Fungal Phytopathogenicity, Brenda Omburo

Graduate Research Theses & Dissertations

The present study aimed at elucidating the role of hdt5 in fungal morphology, mycotoxin production and in plant virulence in Aspergillus flavus. Currently, methodologies to prevent the negative impact of A. flavus are insufficient. It is known that expression of the hdt5 gene is dependent on hbx1, a master regulatory gene that affects expression of hundreds of genes in the A. flavus genome, controlling both development and secondary metabolism. However, while the aflatoxin gene cluster has been elucidated, the genetic regulatory mechanisms controlled by hdt5 are not fully understood. For this study, therefore, a complete strain set composed of a …

An Exploration Of Social Isolation’S Effects On The Gastrointestinal And Metabolic Health Of A Social Mammal, Daniel Adam Nuccio

Graduate Research Theses & Dissertations

Human health can be impacted considerably by subjective feelings of loneliness, resulting in mental illness and the dysregulation of normal cardiovascular, immune and endocrine functioning. This occurs because social isolation serves as a form of chronic stress for social mammals, spurring physiological responses akin to those associated with more standard forms of stress. On account of their highly social nature, prairie voles (Microtus ochrogaster) subsequently have become one of the model organisms of choice for investigating the effects of social isolation on the development of disease in social mammals.

This dissertation seeks to expand the scientific community’s understanding of the …

Impact Of Submarine Groundwater Discharge On Microbial Communities In A Highly Anthropized Coastal Lagoon (Mar Menor, Se Spain), Daniel Romano-Gude, Júlia Dordal-Soriano, Júlia Rodriguez-Puig, Andrea G. Bravo, Irene Alorda-Montiel, Aaron Alorda-Kleinglass, Marc Diego-Feliu, Cristina Romera-Castillo, Rebeca Mallenco-Fornies, Javier Gilabert, Jordi Garcia-Orellana, Valentí Rodellas, Clara Ruiz-González

OES Faculty Publications

Submarine groundwater discharge (SGD) supplies large quantities of nutrients and other terrestrial elements to coastal ecosystems, impacting marine biota and ecosystem functioning. Despite the relevance of prokaryotes for marine biogeochemistry, little is known about their responses to groundwater inputs. Here we explored the impact of SGD on the spatiotemporal patterns of prokaryotic communities from the Mar Menor (Murcia, Spain), a highly anthropized hypersaline coastal lagoon that receives large amounts of nutrient-polluted SGD. Using 16S rRNA amplicon sequencing, activity assays, and flow cytometry, we investigated the dynamics of prokaryotic communities across the lagoon and its connected environments (freshwater streams, groundwater, soils, …

Evaluation And Identification Of Novel Viruses In Wild Fishes Using Varied Molecular Biology Techniques, Clayton Douglas Raines

Graduate Theses, Dissertations, and Problem Reports (ETD)

Viruses are among the most abundant biological entities on Earth, yet their diversity and ecological roles in aquatic vertebrates, particularly fishes, remain poorly characterized. This dissertation advances fish virology through integrative approaches that combine historical context, molecular diagnostics, and genomic discovery. A novel hepadnavirus (ApHBV) was identified in asymptomatic Alosa pseudoharengus, emphasizing the prevalence of subclinical infections in migratory forage species. In Catostomus commersonii, transcriptomic profiling revealed sexually dimorphic immune responses to hepatitis B and C-like viruses, highlighting complex host-pathogen dynamics. In Micropterus nigricans, next-generation sequencing uncovered a novel nackednavirus and multiple adomaviruses within hyperpigmented lesions, expanding …

Watershed-Level Survey Of Antimicrobial Resistance From Onsite Wastewater Systems, Trey Franklin Clark

Graduate Theses, Dissertations, and Problem Reports (ETD)

The emergence of antimicrobial resistance (AMR) has quickly become one of the largest global health and development threats. Research related to environmental modes of transmission of AMR has accelerated in recent years, and the US Environmental Protection Agency is particularly interested in this emerging contaminant. Knowledge of how onsite (decentralized) wastewater treatment systems contribute to this issue is lacking, so this research serves to analyze and quantify the environmental dissemination of AMR and fecal contamination from these sources at a watershed level while using statistical analysis to assess relationships between physiochemical, spatial, and sampling parameters. This research surveyed four watersheds …

Age-Related Variations In Hba1c Improvemecnts: Insights From A Telehealth-Supported Community-Based Intervention, Laura Porterfield, Xiaoying Yu, Amber B Amspoker, Craig A Johnston, Aanand D Naik, Salim S Virani, Christie M Ballantyne, Ashok Balasubramanyam, Elizabeth M Vaughan

Faculty, Staff and Students Publications

Background and objectives: We previously demonstrated that a telehealth-supported community health worker (CHW) intervention significantly improved clinical outcomes in diabetes care. However, the extent to which these benefits vary across different age groups remains unclear. This study evaluated the effectiveness of a CHW-led multidimensional diabetes intervention in reducing HbA1c across age groups.

Research design and methods: We conducted a retrospective analysis of 10 studies (n = 301) that focused on low-income Hispanic adults with or at risk for type 2 diabetes. The intervention included CHW-participant coaching via mobile Health (mHealth), monthly CHW-led group education, and bidirectional mHealth feedback among …

Microbial Hydrocarbon Degradation And Carbon Cycling In Marine And Freshwater Sediments: A Comparative Metagenomic Analysis, Yogita M. Warkhade

Dissertations, Master's Theses and Master's Reports

Microbes are essential in keeping our environment balanced, especially by fixing carbon dioxide and breaking down hydrocarbons in aquatic sediments. This thesis explores how microbial communities perform these tasks in different sediment environments, including marine areas (Caspian Sea and Mediterranean Sea) and freshwater ecosystems (Great Lakes). The first part of this thesis reviews current knowledge about how microbes degrade hydrocarbons. It highlights the importance of different pathways microbes use depending on oxygen availability. The second part provides a detailed study of the microbial communities found in marine sediments from the Caspian Sea and Mediterranean Sea, showing that microbes in these …

Molecular Characterization Of Fungus-Arthropod Associations, Angie M. Martin

Graduate Theses, Dissertations, and Problem Reports (ETD)

Arthropods, or phylum Arthropoda, are the largest group of animals, accounting for over three quarters of all animal records on NCBI Taxonomy. And yet, only 40% of all deposited sequences on NCBI Nucleotide come from arthropods. Clearly, arthropods are an understudied group of animals: they are small, often drab, and lead lives very alien to our own. Arthropods have chitinous exoskeletons, segmented bodies, and jointed appendages, and include crabs, barnacles, insects, spiders, and millipedes. Since the era of DNA based studies took off in the 1980s, DNA and other small molecules have been integral to our understanding of the Earth …

Soils From Different Solidago Altissima Clones Mediate Intraspecific Interactions In Schizachyrium Scoparium, Sarah Alharbi

Masters Theses

While previous studies have examined plant intraspecific competition and soil microbial effects separately, fewer studies have investigated how these factors interact, particularly in the context of genotype-specific soil conditioning effects. Plant-soil feedbacks can significantly alter interspecific competitive outcomes, yet few studies have examined how local variation in soil conditioning influences plant responses to density-dependent competition. I investigated how soil inocula derived from four Solidago altissima clones that were previously shown to differ in their soil conditioning effects (Foster et al., 2022) affected the growth and root traits of Schizachyrium scoparium across a gradient of intraspecific competition (1, 2, or 4 …

Influence Of Thermophilic Biofilms On Proliferation Of Opportunistic Pathogens In Domestic Water Systems, Olajumoke Akinbami

Masters Theses

Domestic hot-water systems quietly grow biofilms under elevated temperatures that can serve as shelter to Opportunistic Premise Plumbing Pathogens. Although focus has been placed on microbes in domestic systems, there has been no clear conclusion on the mechanism of survival and persistence of opportunistic pathogens despite various disinfection strategies. In this study, we determined the distinction between showerhead and drip-flow biofilms at the whole-community level and analyzed the coexistence of thermotolerant organisms with opportunistic genera, such as Legionella. We sampled eight showerheads and simulated four biofilm samples in the laboratory using the drip-flow biofilm reactor.

We observed a strong …

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

EWU Masters Thesis Collection

No abstract provided.

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

EWU Masters Thesis Collection

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

Identification Of Gut Bacterial Symbionts From Atlantic Salmon That Are Involved In Metabolizing Feed Ingredients Derived From Soybean Meal, Emily Fowler

Electronic Theses and Dissertations

In the aquaculture industry, plant-based protein sources have emerged as an economically and environmentally sustainable replacement for traditional animal protein sources. Yet, due to reduced digestibility, the presence of anti-nutritional factors, as well as an increased risk of inflammation of the digestive system, the inclusion of plant-based protein ingredients must be limited, especially in the diets of carnivorous fishes. To gain further insight on how to adapt the fish digestive tract to more effectively utilize or tolerate plant-based protein ingredients, slurry from cultured Atlantic Salmon (Salmo salar) was used as a proxy in an in vitro model system to identify …

Quantification Of Auxin-Cytokinin Response During Lateral Root And Nodule Development In Medicago, Aniket Singh

Electronic Theses and Dissertations

Lateral roots (LRs) and nodules are post-embryonic root organs in legumes formed through the activity of de novo meristem. LRs, which are present in all vascular plants, are developed primarily via intrinsic developmental cues, whereas root nodules, found only in a small group of plants known as legumes, are formed in response to legume–rhizobium symbiosis. LRs arise from the pericycle layer of the root, whereas nodule initiation can begin either in the pericycle (indeterminate nodules with persistent meristem, as in Medicago) or in the cortex (determinate nodules with transient meristem, as in soybean), pointing toward a conserved developmental origin, especially …

Fungal Biotransformation Of Thin Stillage And Soybean Hulls And Bacterial Production Of Lysine In Ethanol Industry Co-Products, Bhawana Khadka

Electronic Theses and Dissertations

Thin stillage (TS) and whole stillage (WS) are major by-products of the corn ethanol industry. These by-products are generated in large quantities and contain nutrients that remain after yeast fermentation. Current industrial utilization of these by-products involves a series of downstream processing steps such as centrifugation and evaporation, which are energy-intensive and often result in nutrient losses. Traditionally, these by-products are dried to produce distillers dried grains with solubles. In this study, microbial fermentation was investigated as an alternative bioprocessing tool to expand the utilization of these by-products. The first objective was to explore the upcycling of TS, both alone …

Engineering Extracellular Vesicles (Evs) To Combat Infection And Inflammation In Cystic Fibrosis, Sharanya Sarkar

Dartmouth College Ph.D Dissertations

Cystic Fibrosis (CF) is a multisystemic genetic disorder caused by mutations in the CFTR gene, resulting in chronic pulmonary infections, hyperinflammation, and progressive lung damage. Among the pathogens that colonize CF lungs, Pseudomonas aeruginosa (P. aeruginosa) is predominant, infecting over 50% of adults with CF and developing antibiotic resistance over time. Current modulator therapies fail to address persistent bacterial infections, chronic inflammation, or irreversible lung damage, underscoring the need for novel therapeutic strategies. In our previous in vitro studies, we demonstrated that extracellular vesicles (EVs) secreted by primary Human Bronchial Epithelial Cells (HBECs) inhibit P. aeruginosa growth by reducing the …

Biochemical And Molecular Analysis Of Anr-Dependent Microoxic Fitness Factors In Pseudomonas Aeruginosa, Stacie E. Balsam

Dartmouth College Ph.D Dissertations

Pseudomonas aeruginosa is a prominent opportunistic pathogen that is often found in microoxic environments like sites of infection and colony biofilms. P. aeruginosa can grow at oxygen (O2) at concentrations as little as 3 μM and also grows anaerobically by generating energy using nitrate as an alternate electron acceptor. An important way P. aeruginosa adapts to low O2 is through Anr, a transcription factor that upregulates many genes important for microoxic and anoxic fitness.

Specifically, Anr regulates mhr which encodes a hemerythrin protein (Mhr) that binds O2 with affinities relevant to microoxia and is also necessary for full fitness of …

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

All ETDs from UAB

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

Reducing Stress: The Role Of The Rcl Operon In Bacterial Stress Response To Hypothiocyanite, Julia Meredith

All ETDs from UAB

The human immune system utilizes a variety of weapons against bacterial communities within the body, which allow it to control the overall microbial population. Understanding how some bacterial species are able to better deal with and survive damage by the immune system while others are not, can help us elucidate the complex relationship between us and our microbiome. One tool that immune cells use for microbial control is the potent oxidant hypothiocyanite/hypothiocyanous acid (-OSCN/HOSCN). The response mounted by Escherichia coli and other bacterial species in order to survive damage caused by HOSCN is the focus of this dissertation. In the …

Analysis Of The Microbiome Of Amblyomma Americanum In The Statesboro Region, Ella Zierdt, Lorenza Beati, Mary Humphrey, Saviour Dralabu

Honors College Theses

The lone star tick, Amblyomma americanum, is the most common tick in Georgia. It is mainly known as an Ehrlichia spp. vector, but its microbiome can be diverse, depending on geography, developmental stage, and season. Little is known about bacterial diversity in ticks from the southeastern U.S. A Nanopore MinION sequencer was used for a preliminary analysis of the bacterial microbiome in A. americanum from the Statesboro region. DNA was extracted from 39 nymphs, 35 males, and 39 females. DNA samples were pooled by month of collection and life stage/sex, amplified with barcoded 16SrDNA primers, and sequenced. Approx. 77% …

Interactions Between Lipopolysaccharide And Capsule Retention In Klebsiella Pneumoniae And The Resultant Effects On Macrophages, Juliane Leigh Nguy

UNF Graduate Theses and Dissertations

Klebsiella pneumoniae is the third most common cause of nosocomial infections in the United States. The capsular polysaccharides (CPS) are virulence factors allowing K. pneumoniae to evade host immune systems. The current model of capsule structure indicates that CPS fibrils interact with the external O-antigen of lipopolysaccharide molecules to enhance retention to the bacterial outer membrane. These interactions may influence pathogenicity in clinically relevant strains. This study characterized alterations to LPS and CPS structure, the impact of these changes on capsule retention, membrane permeability, biofilm formation, and macrophage interactions. LPS and CPS were quantified and visualized in four strains of …

Optimization Of L-Citrulline Production In Corynebacterium Glutamicum, And The Effect Of The Human Small Intestine Environment, Simran S. Ghulldu

Honors Undergraduate Theses

L-citrulline is a crucial amino acid involved in nitric oxide production, which supports cardiovascular health, physical performance, and intestinal well-being. Nitric oxide deficiency is linked to conditions like hypertension, highlighting the need for efficient L-citrulline production. This study attempts to enhance L-citrulline synthesis in Corynebacterium glutamicum, a bacterium widely used in industrial amino acid production, as well as test a The hypothesis is that overexpressing carAB, which encodes carbamoyl phosphate synthetase, will increase carbamoyl phosphate levels and boost L-citrulline production. Two C. glutamicum strains were used: a wild type and the CRBG strain, which has mutations that promote …

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

Honors Undergraduate Theses

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

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

Honors Undergraduate Theses

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

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

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

Honors Undergraduate Theses

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

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

Honors Undergraduate Theses

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

Role Of Coronavirus Envelope Protein On Infectivity, Garrett E. Zaagman

Dissertations

Coronaviruses infect a wide range of hosts and have caused recent human pandemics. While much has been learned, gaps remain in understanding viral assembly and egress, particularly the role of the envelope (E) protein in specific infectivity. To study this, recombinant MHV viruses were created with E gene deletions and HiBiT-tagged spike (S) proteins to monitor virion release. In mouse cells, MHV∆E S-HiBiT secreted less spike and fewer infectious particles, indicating reduced specific infectivity. Comparisons between human HeLa-CEACAM and mouse DBT cells showed species-specific support for virus production. TMED10, a host membrane protein, was tested as a potential E-interacting partner …

Cultures For Acid-Fast Bacilli: Are We Being Good Stewards?, Jennifer Hanrahan, Julie D. Sill, Patricia Ver Schneider, Jessica F. Copeland, Elsie Frimpongmaa Amoako-Kissi, Ogochukwu O. Ilobi, Angela J. Toepp

Department of Medicine Faculty Publications

Objective: To describe the use of cultures for acid-fast bacilli (AFB) and situations in which AFB cultures are unlikely to be of clinical benefit.

Design: Retrospective descriptive study of AFB cultures submitted to Sentara Health microbiology laboratory from December 1, 2021, to December 1, 2023. Data were collected from the electronic medical record and included patient demographics, the service line that ordered the culture, specimen source, and culture results.

Setting: Sentara Healthcare System.

Patients: All patients who had specimens submitted to the microbiology laboratory during the study period were included.

Results: A total of 13,944 AFB cultures from 8,243 …

Investigation Of Multiple Factors Influencing The Vector-Borne Transmission Of Salmonella Typhimurium Via Blattella Germanica, Landen Sean Van Hulzen

Dissertations and Theses

The German cockroach (Blattella germanica) is a common urban pest that lives ubiquitously in human structures around the world. German cockroaches are a severe public health threat as they are known carriers and vectors of human pathogens including Salmonella enterica, Escherichia coli, Shigella spp, and more. German cockroach infestations have been associated with Salmonellosis outbreaks. While mechanical transmission by the German cockroach vector is well known, new research suggests that more nuanced biological transmission has a role in maintaining and transmitting Salmonella enterica serovar Typhimurium (S. Typhimurium). Despite this recent finding, many biological variables influencing vector-borne transmission of S. Typhimurium …

Oral Microbiome And Inflammatory Bowel Disease: New Understanding And Call To Action, Michael Saadeh, Sydney Donohue, Shaina Ailawadi, Gordon Hong, David A. Johnson

Department of Medicine Faculty Publications

The oral microbiome is the second largest microbial community in the human body after the gut microbiome. It includes an array of fungi, bacteria, amoebae, flagellates, archaea, and viruses, all of which are potential pathogens. This microbiome can act as a facilitator not only for protection but also for aggravation when dysbiosis occurs. Although conventional thought is this is primarily in terms of oral health issues, such as dental caries and gingival disease. The systemic effects of the oral microbiome however, are relevant to both gastrointestinal (GI) disease and non-GI disease. These systemic risks occur for several reasons, including upregulation …