Microbiology Commons^™

Characterizing The Role Of Pa5189 Of Pseudomonas Aeruginosa In Deletion And Overexpression Mutants, Seh Na Mellick

Theses/Capstones/Creative Projects

In the context of rising multidrug resistance in biofilm-forming pathogens like Pseudomonas aeruginosa, this study investigates the role of the understudied transcription factor PA5189 in antibiotic resistance and biofilm formation. PA5189 deletion and overexpression mutants were created in a parent P. aeruginosa strain using pEX18Tc-based recombinant suicide vectors, with genotypic verification of putative triparental conjugants achieved through restriction digestion and PCR. The study revealed that PA5189 overexpression significantly increases resistance to commonly used broad spectrum antibiotics such as ciprofloxacin and imipenem. Additionally, differential expression of PA5189 was found to notably affect biofilm formation, with variations contingent on the nutrient …

Growth Of Methanogens On Kaolinite, A Clay That Has Been Identified On Mars, Hailey Littrell

Biological Sciences Undergraduate Honors Theses

Methanogens have been studied as a model for life on Mars for 28 years now in the Kral lab. The discovery of methane in the Martian atmosphere by ground-based and orbital observations as well as Curiosity Rover (Formisano, V. et al., Krasnopolsky, V.A. et al., Mumma, M.J. et al.) has added relevance to these types of studies. Methanogens were chosen due to their ability to live in harsh environments, very similar to the Martian terrain. In addition to methane in the atmosphere, phyllosilicate clays have also been identified. One of those clays is kaolinite. Kaolinite has been found to not …

Novel Microbial Guilds Implicated In N2o Reduction, Guang He

Doctoral Dissertations

N₂O is a long-recognized greenhouse gas (GHG) with potential in global warming and ozone depletion. Terrestrial ecosystems are a major source of N₂O due to imbalanced N₂O production and consumption. Soil pH is a chief modulating factor controlling net N₂O emissions, and N₂O consumption has been considered negligible under acidic conditions (pH <6). In this dissertation, we obtained solids-free cultures reducing N₂O at pH 4.5. Furthermore, a co-culture (designated culture EV) comprising two interacting bacterial population was acquired via consecutive transfer in mineral salt medium. Integrated phenotypic, metagenomic and metabolomic analysis dictated that the Serratia population excreted certain …

What Is Microbial Dormancy?, Mark D. Mcdonald, Carlos Owusu-Ansah, Jared B. Ellenbogen, Zachary D. Malone, Michael P. Ricketts, Steve E. Frolking, Jessica Gilman Ernakovich, Michael Ibba, Sarah C. Bagby, J. L. Weissman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Life can be stressful. One way to deal with stress is to simply wait it out. Microbes do this by entering a state of reduced activity and increased resistance commonly called ‘dormancy’. But what is dormancy? Different scientific disciplines emphasize distinct traits and phenotypic ranges in defining dormancy for their microbial species and system-specific questions of interest. Here, we propose a unified definition of microbial dormancy, using a broad framework to place earlier discipline-specific definitions in a new context. We then discuss how this new definition and framework may improve our ability to investigate dormancy using multi-omics tools. Finally, we …

Causes And Consequences Of Lasr Mutant Selection In Pseudomonas Aeruginosa Populations, Dallas L. Mould

Dartmouth College Ph.D Dissertations

Change is the only constant in life, and these changes, though random in nature, can have consequences. Quorum sensing is heterogeneous in phenotype and prone to negative selection. In P. aeruginosa, the regulator LasR is frequently non-functional in phylogenetically diverse isolates. Through repeated experimental evolution and mathematical modeling, we show that differences in growth enable lasR mutant evolutionary success and this requires a system enabling metabolic choices, known as carbon catabolite repression (or catabolite repression). The differences in catabolite repression between wild type and lasR mutants enable altered metabolite preferences, and the resulting differences in metabolic states enable intraspecies …

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 …

Antimicrobial Resistance In Eskape Pathogens And Its Effect On Modern Medicine And Treatment, Cameran Runge

Honors Theses

Abstract

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella

pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter

spp.) are seeing a growing resistance to multiple classes of antibiotics. Misuse and overuse of antibiotics have played directly into the resistance observed, and the problem is growing exponentially. Antibiotic resistance is partially due to several intrinsic factors limiting the drug's uptake. These include efflux pumps, increased biofilm production, and reduced cell wall permeability in the resistant bacteria. ESKAPE pathogens also acquire resistance through horizontal gene transfer and plasmids. As antibiotics have become less effective, the bacteria can continue to thrive, leading to a detrimental …

Effect Of Temperature On The Microbiome Of A Laboratory-Reared Colony Of Haemaphysalis Longicornis Ticks, Brianna L. Mitchell

Honors Theses

Haemaphysalis longicornis ticks are invasive to the United States with potential to transmit several tick-borne pathogens that are native to the United States. Based on existing locations of H. longicornis in its native regions in Asia, as well as its invasive populations that are established in the United States, several geographic range prediction models have been produced to help understand future range expansion and distribution of this invasive tick in North America. Unfortunately, these models do not all agree and there is uncertainty associated with the potential geographic range expansion of H. longicornis ticks in North America. Climate can affect …

Enrichment Media Selection And Co-Culture Potential Among Exoelectrogen Bacteria Vary With Ecological Factors, Nur Syafira Khoirunnisa, Syaiful Anwar, Untung Sudadi, Dwi Andreas Santosa

Makara Journal of Science

Staphylococcus saprophyticus ICBB 9554 and Citrobacter freundii ICBB 9763 are exoelectrogen bacteria applied as microbial fuel cells (MFC). We selected enrichment media for both these exoelectrogen bacteria, characterized their synergistic traits, and evaluated the growth conditions under different ecological factors. In this study, different enrichment media, such as those containing sugar, molasses, and palm sugar (2, 4, and 6% w/v) were tested for S. saprophyticus ICBB 9554. Meanwhile, technical sodium acetate (NaAc), commercial vinegar 25%, and cider vinegar (5, 10, and 15 mM acetate concentration) were tested for C. freundii ICBB 9763. Both the exoelectrogen bacteria were tested for the …

Conformational Rearrangements In The Sensory Rcsf/Omp Complex Mediate Signal Transduction Across The Bacterial Cell Envelope, Sarah Rosemarie Lach Phd

Dissertations & Theses (Open Access)

Timely detection and repair of envelope damage are paramount for bacterial survival. The Regulator of Capsule Synthesis (Rcs) stress response is a complex signaling cascade that monitors gram-negative cell envelope integrity and can transduce the stress signals across the multilayered envelope to regulate gene expression in the cytoplasm. The outer membrane (OM) lipoprotein RcsF is the sensory component, but how RcsF functions remains elusive. RcsF interacts with the β-barrel assembly machinery (Bam) complex, which assembles RcsF in complex with OM proteins (OMPs), resulting in RcsF’s partial cell surface exposure. RcsF can also interact with the periplasmic domain of the negative …

Treponema Denticola Synthesizes C-Di-Amp And Encodes The Cdaa-Type Diadenylate Cyclase Cdaa, Claire R. O'Brien

Theses and Dissertations

Periodontitis is a form of oral disease characterized by dysbiosis of the oral microbiome, leading to inflammation, bone resorption, and in severe cases, entire tooth loss, affecting 42% of adults in the US. One of the bacteria most associated with periodontal disease progression is Treponema denticola (Td), an oral spirochete which inhabits the mouth in small quantities during health but which can dominate the biofilms that form during periodontal disease. The ability of Td to survive in a disease environment and contribute to the progression of disease requires the use of robust signaling networks. Analysis of Td cultures …

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 …

Identification Of The Type Eleven Secretion System (T11ss) And Characterization Of T11ss-Dependent Effector Proteins, Alex S. Grossman

Doctoral Dissertations

Host-associated microbes live in dangerous environments as a result of host immune killing, nutrient provisioning, and physiological conditions. Bacteria have evolved a host of surface and secreted proteins to help interact with this host environment and overcome nutrient limitation. The studies included within this dissertation describe the identification of a novel bacterial secretion system which has evolved to transport these symbiosis mediating proteins. This system, termed the type eleven secretion system (T11SS), is present throughout the Gram negative phylum Proteobacteria, including many human pathogens such as Neisseria meningitidis, Acinetobacter baumanii, Haemophilus haemolyticus, and Proteus vulgaris. Furthermore, …

Understanding The Molecular Mechanism Of Ilv1 Stress Sensitivity In Yeast By Examination Of Differential Patterns Of Gene Expression Between Wild-Type And Ilv1 Knockout Strains Of Saccharomyces Cerevisiae, Emily Schuster

Honors Theses

As arguably the most widely used industrial eukaryote, Saccharomyces cerevisiae has become one of the many model organisms used to study molecular genetics. A recent unpublished study at the University of Tennessee - Chattanooga showed that yeast cells that had the ILV1 gene knocked out had reduced survivability under stress conditions. This study then focused on the role of ILV1 in the stress response of cells by measuring the expression levels of 11 candidate genes that are all involved in some critical pathway in the yeast to see how gene expression was influenced as a result of the loss of …

Functional Characterization Of Mycobacterium Smegmatis Phage Moomoo Gene Products: Identification Of Toxic Genes, Whitney Heard

Masters Theses & Specialist Projects

Mycobacteriophages are a group of phages that infect members of the genus Mycobacteria. Previous studies have conducted extensive comparisons of the mycobacteriophage genomes and amino acid sequences to establish different phage families. MooMoo is a singleton mycobacteriophage that has been characterized due to its lack of appreciable homology to other phages. Some of its unique properties include its structure and the isolation of a mutant that causes clear plaque phenotypes. The experiments described in this thesis identified three MooMoo phage (gp87, gp90, and gp91) encoded proteins that are toxic to the bacterial host, Mycobacterium smegmatis.Through the use of a …

Characterization Of Genetic Pathways Involved In Resistance To A Novel Antifungal Peptide, Kayla L. Haberman

Graduate Theses and Dissertations

Antibiotic resistance is increasing prevalence, particularly in Candida glabrata. This opportunistic pathogen is closely phylogenetically related to Saccharomyces cerevisiae; however, its characterization is limited. C. glabrata is only second to Candida albicans as a fungal pathogen in immunocompromised patients. Commonly resistant to azoles, the most common fungal therapy, it has become costly and challenging to treat. A histatin 5 derived antifungal peptide, KM29, has a high degree of efficacy in Candida species and S. cerevisiae. The objective of this work is to advance our understanding of the mechanism of action of KM29 against C. glabrata. Previous work in the lab …

Methanogen Metabolic Flexibility, Sean Carr

School of Biological Sciences: Dissertations, Theses, and Student Research

Methanogens are obligately anaerobic archaea which produce methane as a byproduct of their respiration. They are found across a wide diversity of environments and play an important role in cycling carbon in anaerobic spaces and the removal of harmful fermentation byproducts which would otherwise inhibit other organisms. Methanogens subsist on low-energy substrates which requires them to utilize a highly efficient central metabolism which greatly favors respiratory byproducts over biomass. This metabolic strategy creates high substrate:product conversion ratios which is industrially relevant for the production of biomethane, but may also allow for the production of value-added commodities. Particularly of interest are …

An Investigation On The Impact Of Intestinal Oxygen Availability On Survival And Regulation Of Virulence In Listeria Monocytogenes, Damayanti Chakravarty

Dissertations

The deadly foodborne pathogen Listeria monocytogenes is a gram positive facultative anaerobic bacterium. It is the third leading cause of death from food-borne illnesses. Once ingested, it encounters various stressors in the gastrointestinal (GI) tract, including acidic pH, bile, and alterations in oxygen availability. Various studies have been done regarding the pathogen’s survival mechanism against acid and bile. Since the lower parts of the GI tract are anaerobic, it is imperative to investigate how physiologically relevant anaerobic conditions impact L. monocytogenes’s survival. Transcriptomic analysis of L. monocytogenes under conditions mimicking the GI tract was performed. A large number of genes …

Parameter Estimation Using Nudging On The Logistic Growth Equation, Susan Rogowski

Biology and Medicine Through Mathematics Conference

No abstract provided.

Metabolism In The Colonocyte: Where Bacteria And Diet Meet, Bohye Park

Doctoral Dissertations

The host-microbiome interaction and the functions of microbial-derived metabolites, including butyrate, are important in colon health. Butyrate is the preferred energy source in colonocytes and has multiple physiological functions in the colon. A metabolic shift in colonocytes toward increased glucose utilization from butyrate oxidation is followed by several critical genetic modifications in cancerous colonocytes. Moreover, it has been suggested that the gut-microbiota composition is influenced by environmental factors, such as diets and the host's physiological status. Therefore, an understanding of the role of colonocyte metabolism toward impacting the host-microbiota commensal relationship would be an important step in understanding the functional …

Functional Characterization Of A Putative Alternative Oxidase In Sporisorium Reilianum F. Sp. Zeae., Emma A Lamb

College of Arts & Sciences Senior Honors Theses

Sporisorium reilianum is a pathogenic basidiomycete fungus with two formae speciales, each capable of infecting corn (SRZ) or sorghum (SRS), respectively. This fungus is also a dimorphic variety, meaning it can switch between its haploid, yeast-like sporidia and diploid teliospore stages over the course of its life cycle (Schirawski). When S. reilianum is found in a haploid state and conditions are favorable, it will mate with a compatible non-self mating type to begin filamentous growth and proliferation in the plant host (Zhao). S. relianum, like most fungi, utilizes the four classical components of the electron transport chain to produce …

The Characterization Of The Type I Dna Methyltransferase Hsdm1 (Hp0463) In Helicobacter Pylori, Elise Zimmerman

Undergraduate Honors Theses

Helicobacter pylori is a gram-negative spiral-shaped bacterium that colonizes the gastric epithelium and is the leading cause of gastric adenocarcinoma globally. For both H. pylori and many other bacterial species, there is an increasing body of evidence that methylation by restriction-modification systems regulates gene expression in addition to its traditional role in genome protection. The study aimed to further elucidate the mechanisms through which H. pylori achieves methylome plasticity. We demonstrated that the Type I DNA methyltransferase hsdM1 (HP0463) is regulated by the main acid sensing mechanism of H. pylori, the two-component system (TCS) ArsRS. ArsRS induces hsdM1 …

Periodic Spatial Disturbances Alter The Expression Of Quorum Sensing Virulence Factors In Pseudomonas Aeruginosa, Laura García-Diéguez

All HCAS Student Capstones, Theses, and Dissertations

Pseudomonas aeruginosa is an opportunistic pathogen associated with severe acute and chronic illnesses. Current antibiotic-based approaches fail to effectively treat P. aeruginosa infections due to the effectiveness and robustness of the quorum sensing signaling system (QS). Pathogenic bacteria, such as P. aeruginosa, employ this population density-dependent communication mechanism to confer antimicrobial resistance, propagate infection, and coordinate the expression of virulence factors, through the production and detection of autoinducing signaling molecules (AI). As such, there is a growing interest in developing novel non-antibiotic-based techniques to attenuate the pathogenicity of P. aeruginosa by disrupting the functionality of its QS system. Previous …

The Role Of Coagulase-Negative Staphylococcal Secreted Products On Staphylococcus Aureus And Staphylococcus Lugdunensis Infections, Denny Chin

Electronic Thesis and Dissertation Repository

The Staphylococcus genus is comprised of over 40 bacterial species. The most well-studied species in this genus is the notorious human pathogen Staphylococcus aureus, a bacterium that produces coagulase among many other virulence factors. Since S. aureus is a major health burden and causes a plethora of diseases in humans, it has received significant attention and much research has been done to understand its biology to treat diseases caused by this pathogen. However, the coagulase-negative staphylococci (CoNS) make up most of the staphylococcal species and have received less attention since they are thought to have a lesser impact on …

Characterization Of Streptomyces Nymphaeiformis Sp. Nov., And Its Taxonomic Relatedness To Other Polyhydroxybutyrate-Degrading Streptomycetes, Gary R. Hix, Muhammad S. Khan, Mikayla T. Miller, Elisha C. Napier, Allison L. O'Brien, Roger P. White, Stephen F. Baron Ph.D.

Biology Faculty Scholarship

A polyhydroxybutyrate (PHB)-degrading actinomycete, strain SFB5A^T, was identified as a species of Streptomyces based on its membrane fatty acid profile and the presence of LL-diaminopimelic acid in the cell wall. It formed sporulating mycelia on most agar media, but flat or wrinkled, moist colonies on trypticase soy agar. Spores were smooth, cylindrical, and borne on long, straight to flexuous chains. It produced a light brown diffusible pigment, but not melanin. Comparison of genomic digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values indicated that strain SFB5A^T was related to Streptomyces litmocidini JCM 4394^T , Streptomyces …

Your Next Celebration At Us National Parks: A Case Emphasizing Lyme Neuroborreliosis (Bannwarth Syndrome), Ganesh Arun, Farhan Ali, Sowmya Srinivas, Harsha Surath, Justin Nistico, Dayakar Reddy

Advances in Clinical Medical Research and Healthcare Delivery

Introduction:

Bannwarth syndrome is synonymous with Lyme neuroborreliosis. The neurological component consists of neuropathy, radicular pain, and lymphocytic pleocytosis. This is due to inflammation of the nerve fibers by Borrelia Burgdorferi. Borrelia Borgdorferi is a spirochete bacteria transmitted hematogenously from the Ixodes tick vector to the human host. The commonly known Lyme disease is diagnosed with symptoms of arthritis, heart block, and integumentary signs. Lyme disease can present as early disseminated or late manifestations of disease. Bannwarth syndrome takes it a step further and emphasizes the neurologic sub set of symptoms. The Centers for Disease Control and Prevention (CDC) estimates …

Size Progression Of Oxygenic Photogranules (Opgs) And Its Effect On Opg Wastewater Treatment, Ahmed S.A. Abouhend

Doctoral Dissertations

In recent years, the oxygenic photogranule (OPG) process has gained increasing interest because of its potential to treat wastewater without supplemental aeration. Oxygenic photogranules (OPGs) are dense spherical aggregates comprised of phototrophic and nonphototrophic microorganisms. In OPG wastewater treatment reactors, photogranules grow in number as well as in size. The primary goal of this dissertation was to investigate how OPGs grow in size and how the growth affects their structure and functions. We found that OPGs undergo structural changes as they grow bigger in size. As OPGs grow larger, filamentous cyanobacteria become enriched while other phototrophic microbes diminish significantly. OPGs …

Mapping Selected Polyphenols Metabolism By Gut Bacteria And Their Genes, Ermin Zhao

Doctoral Dissertations

The human gut microbiome is a huge enzyme repository for dietary polyphenols metabolism, especially considering most of the polyphenols cannot be digested in the host and their biological functions are limited. Poor bioaccessibility based on traditional pharmaceutical ADME (absorption, distribution, metabolism, and excretion) assessment is the main problem facing the widely medical application of most polyphenols. Gut bacteria have the potential to mediate a wide range of biotransformation reactions of polyphenols, which leads to the production of many bioactive metabolites. In the past decades, mounting evidence in traditional ADME study have demonstrated gut bacteria play an irreplaceable role in dietary …

The Coxsackievirus And Adenovirus Receptor Has A Short Half-Life In Epithelial Cells, Poornima Kotha Lakshmi Narayan, James M. Readler, Mahmoud S. Alghamri, Trisha L. Brockman, Ray Yan, Priyanka Sharma, Vladislav Snitsarev, Katherine J.D.A Excoffon, Abimbola O. Kolawole

Department of Biology Faculty Scholarship and Creative Works

The coxsackievirus and adenovirus receptor (CAR) is an essential cellular protein that is involved in cell adhesion, cell signaling, and viral infection. The 8-exon encoded isoform (CAREx8) resides at the apical surface of polarized epithelia, where it is accessible as a receptor for adenovirus entering the airway lumen. Given its pivotal role in viral infection, it is a target for antiviral strategies. To understand the regulation of CAREx8 and determine the feasibility of receptor down regulation, the half-life of total and apical localized CAREx8 was determined and correlated with adenovirus transduction. Total and apical CAREx8 has a relatively short half-life …

Trait Energy And Fatigue May Be Connected To Gut Bacteria Among Young Physically Active Adults: An Exploratory Study, Ali Boolani, Karyn M. Gallivan, Kristin S. Ondrak, Courtney J. Christopher, Hector F. Castro, Shawn R. Campagna, Christopher M. Taylor, Meng Luo, Scot E. Dowd, Matthew Lee Smith, Lauri O. Byerley

School of Medicine Faculty Publications

Recent scientific evidence suggests that traits energy and fatigue are two unique unipolar moods with distinct mental and physical components. This exploratory study investigated the correlation between mental energy (ME), mental fatigue (MF), physical energy (PE), physical fatigue (PF), and the gut microbiome. The four moods were assessed by survey, and the gut microbiome and metabolome were determined from 16 S rRNA analysis and untargeted metabolomics analysis, respectively. Twenty subjects who were 31 ± 5 y, physically active, and not obese (26.4 ± 4.4 kg/m2) participated. Bacteroidetes (45%), the most prominent phyla, was only negatively correlated with PF. The second …