Microbiology Commons^™

Assessing The Role Of The Microbiome, Parasite Infections, And Movement In Avian Health, Olivia N. Choi

Electronic Theses and Dissertations

Avian health encompasses the physical, physiological, and behavioral well-being of birds. Assessing avian health is not only important for the conservation and management of wild birds and the recreational economy, but also for the management of infectious diseases that threaten public health and agriculture. Birds, comprising approximately 10,000 species and an estimated 50 billion individuals worldwide, are known to be involved in the spread of pathogens, some of which are zoonotic (from animals to humans), such as avian influenza and West Nile viruses. Individual measures of avian health may include physical measurements (e.g., body mass, wing length), pathogen infection status, …

Pseudomonas Aeruginosa Enhances Fluconazole Activity Against Candida During Polymicrobial Infection, Siham Hattab

Electronic Theses and Dissertations

Polymicrobial infections pose a significant challenge in the field of medicine due to our incomplete understanding of how pathogens interact during infection and how these interactions impact the effectiveness of drug treatments. Among the opportunistic pathogens, Candida albicans and Pseudomonas aeruginosa stand out, as they are often found in similar infection sites, such as burn wounds, the lungs of patients with cystic fibrosis and those on mechanical ventilation. Candida albicans is an opportunistic fungus responsible for invasive candidiasis, a condition associated with a high mortality rate of 40% in hospitals. Pseudomonas aeruginosa, on the other hand, is the primary pathogen …

Interactions Between Streptococcus Agalactiae And Candida Albicans Affect Persistence And Virulence, Kathryn Patenaude

Electronic Theses and Dissertations

Streptococcus agalactiae (Group B Streptococcus or GBS), a Gram-positive bacterium, and Candida albicans, a polymorphic fungus, are commensal microbes in most of the population they colonize but are also capable of causing severe and sometimes fatal infections in certain patient groups. Both organisms share similarities including the colonization the same tissue environments and causing infections in specific patient groups including those who are newborn, pregnant, suffering from chronic conditions like diabetes and HIV, as well as elderly patients. Previous research discovered that GBS and C. albicans can synergize to enhance the colonization of GBS in the bladders of mice, but …

Breaking Virulent: The Coincidental Evolution Of Virulence Factors In Bacteria., Rhiannon Emmanuelle Cecil

Electronic Theses and Dissertations

Understanding how innocuous organisms can evolve to be pathogenic to humans is of increasing global concern. Further, understanding how existing pathogens may evolved to be more virulent is also vital to our ability to provide healthcare to people afflicted with diseases that promote chronic bacterial infections, such as cystic fibrosis. With the rise of antibiotic resistance in both bacteria and fungi it is paramount that new therapeutics are identified. Understanding what mutations occur that result in increased virulence in microbes can potentially provide new targets for antimicrobial drugs to combat antibiotic resistance. The Coincidental Evolution Hypothesis is a fundamental hypothesis …

Analyzing Pseudomonas Aeruginosa With Bacteriophage Tags Using Photoacoustic Flow Cytometry, Jennifer C. Schinke

Electronic Theses and Dissertations

The number of daily bacterial infections is climbing and the CDC explains that this is due to the antibiotic-resistant threat in the United States. Finding a faster way of bacterial identification is necessary as it currently takes 1-4 days for a medical lab to culture and identify bacteria. Photoacoustic flow cytometry (PAFC) can be used as an alternative method resulting in swift identification within an hour (Edgar, 2019). Pseudomonas aeruginosa, cell line PA01, will be coated in up to a few hundred red dyed phages making it detectible by the photoacoustic flow cytometry system. Bacteriophages (phages) are viruses that …

Use Of Transposon Screening For Salicylic Acid-Assisted Desiccation Killing In Salmonella, Shannon D. Elliott

Electronic Theses and Dissertations

Salmonella enterica serovar Typhimurium is one of the most prevalent food-borne pathogens, affecting millions around the world every year, making it a threat to global health. Salmonella possesses the ability to survive the normally lethal condition of desiccation, however, discovery of the genes and mechanisms behind this phenomenon are still ongoing. Using a transposon mutagenesis approach to construct a broad transposon library, this study aimed to uncover genes that may be contributing to changes in Salmonella’s survivability under desiccation, particularly when exposed to the antimicrobial molecule salicylic acid. Building on previous findings showing salicylic acid can alter cell viability …

The Future Is Now In Twisted Coil Polymer Actuators (Tcpa), Ryan Ronquillo

Electronic Theses and Dissertations

This thesis aimed to fabricate and test twisted coiled polymer actuators (TCPA) to understand the mechanical and thermal aspects of this artificial muscle fiber. The purpose of this thesis was to find a linear relationship using the LVDT sensor, fabricating TCPA fibers, and interpreting the data. The project tested whether nylon/polymer could be used as a better artificial muscle fiber.

This research accomplished three goals: (1) designing and fabricating a system capable of creating supercoiled muscle fibers consistently, (2) calibrating the Linear Variable Differential Transformer (LVDT) and Core, and (3) analyzing/interpreting the data of the Twisted Coiled Polymer Actuators (TCPA) …

Investigating The Impact Of Prophages On Bacterial Fitness Of Streptococcus Agalactiae, Caitlin Wiafe-Kwakye

Electronic Theses and Dissertations

Streptococcus agalactiae (Group B Streptococcus or GBS) is a common bacterium found in pregnant women that can cause severe infections in neonates. Although detecting maternal colonization and administering antibiotics during labor can prevent early-onset GBS disease in neonates, antibiotics negatively affect newborns' microbiota, leading to complications like gastrointestinal disorders and immune system dysregulation. Therefore, alternative therapeutic measures are necessary to improve maternal and neonatal outcomes. Understanding GBS disease pathology and developing effective preventive measures and treatments is essential. GBS evolves from a commensal bacterium to an invasive disease-causing pathogen using various mechanisms, such as adapting to the host immune response, …

The Stringent Response In Pseudomonas Aeruginosa Influences The Phenotypes Controlled By The Gac/Rsm System, Michael Shawn Hooker

Electronic Theses and Dissertations

Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen that causes acute and chronic infections. Infection is typically initiated via motile and virulent strains. After exposure to stressors, acute infections make both genotypic and phenotypic switches to a chronic, sessile strain. This is due to intricate regulatory networks directing gene expression in response to stressors. One network, GacA/GacS, has been established to control virulence factors. The stringent response of bacteria is mediated by alarmones produced primarily by RelA which responds to starvation.

To study the effect of the stringent response on the virulence switch. A series of experiments were run in both …

Identification Of A Role Beyond Iron Acquisition For Yersiniabactin During Yersinia Pestis Infection., Sarah Price

Electronic Theses and Dissertations

Yersinia pestis is a Gram-negative re-emerging bacterial pathogen that is responsible for bubonic, septicemic, and pneumonic plague. Y. pestis and other bacteria require transition metals, such as iron, zinc, and manganese, to maintain intermediary metabolism, transcriptional regulation, and virulence. To inhibit infection, eukaryotic organisms have developed distinct mechanisms, called nutritional immunity, to sequester these important nutrients from invading bacteria. For pathogens to colonize the vertebrate host, they have evolved dedicated acquisition systems for transition metals. During infection, Y. pestis overcomes iron limitation by secreting the siderophore yersiniabactin. Additionally, Y. pestis requires zinc for infection and utilizes high affinity transporters to …

The Alphaviral Capsid Protein Inhibits Irak1-Dependent Tlr Signaling To Promote Pathogenesis., V. "Trey" Landers

Electronic Theses and Dissertations

Alphaviruses are positive-sense RNA viruses spread by mosquitos. They can cause a severe multi-joint febrile arthritis or encephalitis resulting in death or life-long cognitive impairments. To date there are no approved antiviral therapeutics or vaccine strategies for the treatment of alphaviruses creating a critical need to better understand the host pathogen interactions of alphaviruses that enable pathogenesis. It is known that alphaviruses evade innate immune responses by shutting down host transcription and translation, but these methods are dependent on viral gene expression and leave a critical time frame during early infection before viral gene expression has begun that the virus …

Stem And Pre-Health Students’ Diminishing Online Conversation Volume Regarding Majors And Careers Within The Field: Why Higher Education Should Care, Susan Roh

Electronic Theses and Dissertations

The purpose of this study was to determine the STEM and pre-health online mention volume change regarding STEM and pre-health majors, careers, and universities, with the data collection period encompassing August of 2018 through June of 2021. We evaluated if the mention sentiment shifted between academic year periods. The data gathered for this study was procured in collaboration with Campus Sonar and the social-listening tool of Brandwatch, which allowed for specifications of the data collected. Kruskal-Wallis tests were used to determine the means of the majors, careers, and universities mentions and mean sentiment volumes. Changes in not only online conversation …

Effectiveness Of Atmospheric Cold Plasma In Inactivating Microorganisms, Nadee Shanika Kaluwahandi

Electronic Theses and Dissertations

In the food processing industry, Cold Plasma (CP) is an emerging green process with a number of potential applications. Cold plasma has mostly been used to reduce microbial counts in foodstuffs and biological materials as well as in different levels of packaging, particularly in cases where there is thermal sensitivity. Recent studies have demonstrated that CP technology is being developed for use in the food and agriculture industries. The primary focus is on the interactions between reactive species and food-borne microbes to inactivate them. The literature review discusses both proven and potential applications for cold plasma in food processing, as …

Indigenous Toxin Affects Cell Viability, While An Artificial Proteolytic Queueing Causes The Upregulation Of Specific Genes, Mohammed Salahuddin

Electronic Theses and Dissertations

Studying bacterial physiology is crucial to understand the fundamental mechanisms that govern bacterial growth, survival, and adaptation. This thesis combines two chapters investigating bacterial physiology by studying important cellular processes like bacterial toxin-antitoxin systems and proteolytic pathways. The first chapter involves studying bacterial toxin-antitoxin systems to understand the regulation and function of hypothetical toxin-antitoxin (TA) systems of bacteria and the effects of these TA systems on bacterial growth and survival. The emergence of these genetic modules in bacterial research and the unrevealing of some of their important roles in cell physiology in recent years has drawn much attention in scientific …

Detection And Diagnosis Of Bacterial Pathogens In Blood And Urine Using Laser-Induced Breakdown Spectroscopy, Emma J.M. Blanchette

Electronic Theses and Dissertations

The aim of this thesis is to expand on and improve the existing techniques used for detecting and identifying bacterial pathogens in clinical specimens with laser-induced breakdown spectroscopy (LIBS). Specifically, the existing experimental procedures, including bacterial sample preparation and data acquisition, as well as the data analysis with chemometric algorithms were investigated. Substantial reductions in LIBS background signal were achieved by implementing rigorous cleaning steps and the introduction of the use of ultrapure water. Following this, a database of LIBS spectra was acquired from specimens of E. coli, S. aureus, E. cloacae, M. smegmatis, and P. …

Next-Generation Sequencing Shows Increasing Temperatures Affect Stream Fungal Communities, Regan Hodgson

Electronic Theses and Dissertations

Under climate change predictions, surface air temperature is expected to continue to rise and will likely affect functioning of stream ecosystems and microbial communities. Aquatic hyphomycetes are key fungal decomposers of plant litter in headwater streams controlling carbon, energy, and nutrient flows to higher trophic levels. This project addressed the effects of temperature on stream fungal communities in two recently conducted experiments (microcosm and streamside channel studies) using Illumina sequencing. The objectives were to determine (1) if temperature affects community structure of stream fungi based on relative abundances of ITS2 rDNA sequences, (2) if the effects of temperature on aquatic …

Investigating The Pi3k/Akt/Atm Pathway, Telomeric Dna Damage, T Cell Death, And Crispr/Cas9-Mediated Gene Editing During Acute And Chronic Hiv Infection, Sushant Khanal

Electronic Theses and Dissertations

Human Immunodeficiency Virus (HIV) infection initiates major metabolic and cell- survival complications. Anti-retroviral therapy (ART) is the current approach to suppress active HIV replication to a level of undetected viral load, but it is not a curative approach. Newer and sophisticated gene editing technologies could indeed be a potent antiviral therapy to achieve a clinical sterilization/cure of HIV infection. Chronic HIV patients, even under a successful ART regimen, exhibit a low-grade inflammation, immune senescence, premature aging, telomeric DNA attrition, T cell apoptosis, and cellular homeostasis. In this dissertation, we investigated CD4 T cell homeostasis, degree of T cell apoptosis, an …

Death Of A Bacterium: Exploring The Inhibition Of Staphylococcus Aureus By Burkholderia Cenocepacia., Tiffany Brandt

Electronic Theses and Dissertations

Antimicrobial resistance is a phenomenon of increasing concern as antimicrobial overuse and misuse eliminate current therapeutic options, ushering society into a post-antimicrobial era. Antibiotic discovery and synthesis efforts are urgently needed to counter the increasing burden of antimicrobial resistance. Staphylococcus aureus is a causative agent of a variety of clinical manifestations including bacteremia, endocarditis, soft tissue infection, osteomyelitis, and device-related infections. S. aureus infection presents additional treatment challenges due to its capacity for biofilm formation, which is a mode of growth that confers protection from antibiotics and physical elimination, and the emergence of antibiotic resistant strains, including methicillin-resistant S. aureus …

Neural Stem Cells: Age-Dependent Outcomes During Viral Infections In The Central Nervous System, Manisha N. Chandwani

Electronic Theses and Dissertations

Viral infections in the central nervous system (CNS) are associated with neurodevelopmental and neurobehavioral deficits. The outcomes of viral infections can be driven by damage and death of neurons. Neural stem cells (NSCs) play key roles in neurodevelopment, repair, and physiological brain function. During a viral infection, NSC activity can disturbed by direct infection of NSCs by the virus or by anti-viral immune response. Here, we aimed to assess whether the anti-viral immune response can impact NSC activity during an immunocompetent response in the adult brain. We utilized a transgenic mouse model of Measles virus infection where only the CNS …

Novel Signal Sequences And Fusion Partners For Paratransgenesis In Asaia, Christina Grogan

Electronic Theses and Dissertations

Mosquitoes transmit many pathogens that cause human disease. One such disease, malaria, is caused by parasites in the genus Plasmodium, infecting over 200 million people and killing over 600,000 per year. Current strategies to control vector-transmitted diseases are increasingly undermined by mosquito and pathogen resistance. Research has turned to additional and novel methods of control, such as altering the microbiota of the vectors. In this method, called paratransgenesis, symbiotic bacteria are genetically modified to affect the mosquito’s phenotype by engineering them to deliver antiplasmodial molecules into the midgut to kill parasites. These molecules must be released by the …

Investigating Host Defenses Of North American Salamanders Against The Recently Emerged Chytrid Pathogen, Batrachochytrium Salamandrivorans, Kenzie Pereira

Electronic Theses and Dissertations

A recently emerged chytrid fungal pathogen, Batrachochytrium salamandrivorans (Bsal) threatens salamander biodiversity. Bsal susceptibility varies between and within salamander species, but little is known about the mechanisms underlying these differences. Susceptibility is likely influenced by numerous interacting factors, but my dissertation studied the role of host immune responses.

My first aim investigated between species differences by studying the bioactive properties of salamander skin peptides against Bsal and the related pathogen, B. dendrobatidis (Bd). Skin peptides were collected from five salamander species, used for in vitro assays, and analyzed by RP-HPLC. While skin peptides from one …

Identification And Characterization Of Genetic Elements That Regulate A C-Di-Gmp Mediated Multicellular Trait In Pseudomonas Fluorescens, Collin Kessler

Electronic Theses and Dissertations

Microbial communities contain densely packed cells where competition for space and resources are fierce. These communities are generally referred to as biofilms and provide advantages to individual cells against immunological and antimicrobial intervention, dehydration, and predation. High intracellular pools of cyclic diguanylate monophosphate (c-di-GMP) cause cells to aggregate during biofilm formation through the production of diverse extracellular polymers. Genes that encode c-di-GMP catalytic enzymes are commonly mutated during chronic infections where opportunists display enhanced resistance to phagocytosis and antibiotics. Our lab uses an emergent multicellular trait in the model organism Pseudomonas fluorescens Pf0-1 to study the emergence of c-di-GMP mutations …

Cyclic Di-Gmp Regulates Motility, Biofilm Formation, And Desiccation Tolerance In Acinetobacter Baumannii, Garrett Reynolds

Electronic Theses and Dissertations

Acinetobacter baumannii is an increasingly multidrug-resistant pathogen contributing to hospital-acquired infections necessitating the discovery of novel treatments. A bacterial second messenger, cyclic diguanosine monophosphate (cyclic di-GMP), can regulate various persistence factors that are potentially advantageous for survival in hospital environments. Cyclic di-GMP–modulating enzymes and cyclic di-GMP–binding effectors predictively are encoded in the Acinetobacter baumannii genome. I hypothesized that cyclic di-GMP controls motility, biofilm formation, and desiccation tolerance in Acinetobacter baumannii. Disrupting cyclic di-GMP–modulating enzymes or cyclic di-GMP–binding effectors should alter the regulatory effectiveness of these phenotypes. I tested the multidrug-resistant isolate Acinetobacter baumannii strain AB5075 and identified several transposon …

Defining The Importance Of The Hnrnp I Interaction To The Sindbis Virus Subgenomic Viral Rna Using An Innovative Tethering Approach., Claire Westcott

Electronic Theses and Dissertations

Old World alphaviruses cause significant outbreaks of illness and debilitating multi-joint arthritis for prolonged periods. Currently, there are no FDA approved vaccines or antiviral therapies; and thus, there is a critical need to identify and characterize the molecular biology of alphaviruses. Alphaviruses rely on the host cell machinery to complete the viral lifecycle and are dependent on interactions with host RNA binding proteins. Accordingly, several host heterogenous nuclear ribonucleoprotein proteins (hnRNPs) have been found to bind to the Sindbis virus (SINV) RNAs. Disrupting the interaction sites in the viral RNAs of these RNA:Protein interactions results in decreased viral titers in …

Weaving An Interdisciplinary Microbiome Career Using Threads From Different Ecosystems, Sarah Hosler

Electronic Theses and Dissertations

Animals have trillions of microorganisms living in or on many body sites, these communities of microorganisms are called microbiomes. Microbiomes are typically host-specific, and a lot of information about the host can be determined from investigating them. Microbiome research has many real-world applications, and this thesis utilizes the One Health perspective, which acknowledges the connection of humans, animals, and environments, and emphasizes the need for collaborative, interdisciplinary research. The first interdisciplinary project is an investigation into the bacteria in wild and cultured Atlantic deep-sea scallop, Placopecten magellanicus larvae. Adults in hatcheries can be induced to spawn, but the last two …

Effect Of Mycorrhizae Inoculation On The Growth And Success Of Three Taxodium Distichum Hybrids In Saline - Impacted Coastal Soils, Elif Ilhan

Electronic Theses and Dissertations

In 2008, Galveston Island was severely impacted by Hurricane Ike, resulting in high salt deposition in the soil and groundwater. This caused a loss of many native plant species. A study was initiated to determine effective ways to promote the growth conditions of three bald cypress genotypes (Taxodium distichum var distichum and Taxodium distichum var mexicanum crosses) in salt-affected soils. The treatments applied were mycorrhizae inoculation, fertilizer application, and a combination of mycorrhizae inoculation and fertilizer application. A total of sixty (60) trees planted in plots of three rows and divided into five randomized replication blocks of four treatments …

Characterizing The Interaction Between Candida Albicans And Two Enterobacter Species, Abigail Cornett

Electronic Theses and Dissertations

Candida albicans is the most common human fungal pathogen. The relationship between C. albicans and Enterobacter bacteria have yet to be explored. The hypothesis of this study is that C. albicans and both E. aerogenes and E. cloacae have a positive relationship and work together to infect the host. In this study, the physical cell-to-cell interaction, molecular components of said interaction, and the impact of the interaction on a live organism were explored. Results indicate that Enterobacter adheres to C. albicans and inhibits growth with unidentified secreted molecules. Als1p has potential involvement in the attachment of E. cloacae to C. …

Aggregatibacter Actinomycetemcomitans Exploits And Modulates The Immune Response By Human Neutrophils For Survival In The Anaerobic Environment., Hazel Ozuna

Electronic Theses and Dissertations

Aggregatibacter actinomycetemcomitans (Aa) is a Gram-negative facultative anaerobe and an opportunistic oral pathogen, strongly associated with localized periodontitis and other inflammatory diseases. Periodontitis is a chronic inflammation of the periodontium resulting from the inflammatory response of the host towards the dysbiotic microbial community present at the gingival crevice. The host immune response creates a hostile environment for microorganisms; therefore, it is important for Aa to be able to regulate the necessary genes to survive and thrive in such an environment. Aaexpresses several virulence factors such as a cytolethal distending toxin (Cdt), lipopolysaccharide (LPS) and leukotoxin A (LtxA), …

Lysosomal Evasion Of Legionella Pneumophilia The Effector., Bethany Vaughn

Electronic Theses and Dissertations

Legionella pneumophila is a Gram-negative facultative intracellular bacterium found in freshwater environments that has co-evolved to survive and proliferate in various amoeba and protozoan species, which serve as the natural host for the bacterium. Humans are an accidental host of L. pneumophila, where infection occurs upon inhalation of aerosolized water droplets that contain the bacteria. Intracellular proliferation of L. pneumophila in alveolar macrophages is essential for manifestation of pneumonia, designated as Legionnaires’ Disease. Biogenesis of the legionella containing vacuole (LCV) occurs via interception of ER-Golgi vesicle trafficking and avoids the default endosomal/lysosomal degradation pathway. Intracellular proliferation of L. pneumophila …

Microbial Communities And Nitrogen Dynamics In Prairie And Cropland Soils, Bikram Kumar Das

Electronic Theses and Dissertations

Soil microbial communities are affected by many factors, such as soil nitrogen (N) and the quantity of grass-root exudates, changing seasons, fertilization method, plant diversity, and their origin. This holds for both natural and fertilized soils. This research was intended to expand the current understanding of soil microbial interactions associated with ecological functions. The objectives of the research were (I) to characterize prokaryotic soil communities, estimate functional potential, and quantify nitrogen cycle-associated prokaryotic gene expressions across three phases of the growing season, (II) to explore the diazotrophic community composition in a natural system using nifH sequencing as well as 16S …