Bacteriology Commons^™

Exploring Competitive Dynamics Between Pseudomonas Baetica And Salmonella In A Polymicrobial System, Braxton E.M. Stout

Electronic Theses and Dissertations

The global rise in antimicrobial resistance has catalyzed a greater focus on polymicrobial research aimed at characterizing microbial interactions and uncovering new therapeutic strategies. Though it has long been of interest, environmental soil-derived bacteria remain largely under-represented in research and thus uncharacterized in this field. This project aimed to identify soil microbes that display inhibitory mechanisms to potential nosocomial pathogens. Soil sample S1S3-2 displayed inhibitory phenotypes toward numerous bacteria and was identified as Pseudomonas baetica. In both planktonic and biofilm growth, P. baetica was able to inhibit Salmonella arizonae through a contact-dependent and temperature-dependent manner. Screening of a transposon insertion …

Oral Streptococcus And Vitamin B12 Deficiency In E-Cigarette Users: A Microbial–Nutrient–Neurotransmitter Axis Linking To Mood Disturbances, Maryam Sabah Naser, Ali Jabbar Abd Al-Hussain Alkawaz, Ali Abbas Hashim Almusawi, Ali Jalil Obaid, Hasanain Ayed Mohammed Al-Khafaji, Reihaneh Sabbaghzadeh

Karbala International Journal of Modern Science

Background: With the rising popularity of e-cigarettes, questions have emerged regarding their broader influence on oral ecology, nutrient absorption, and psychological health. Disruptions in the oral microbiome may alter vitamin B12 dynamics. This, in turn, may indirectly influence serotonin biosynthesis and mood regulation.

Methods: An observational cross-sectional study involved 150 young adults segregated into groups of 50 each as vapers, smokers, or non-users. Streptococcus sanguinis and vitamin B12 metabolism-related variable statuses methylmalonic acid and holotranscobalamin were quantified in samples, along with inflammatory markers interleukin-6, kynurenine/tryptophan ratio, and serotonin. Statistical techniques, including ANOVA and the Kruskal-Walli’s test, correlation, and serial mediation …

Coordinating The Layers: Regulation Of Peptidoglycan Synthesis And Cell Wall Assembly In Mycobacterium Smegmatis By Murj And Pgfa, Karen Emmanuella Samaga-De-Tembiwa

Biology Dissertations

The mycobacterial cell envelope consists of three covalently linked layers whose synthesis must be coordinated to maintain structural integrity during polar growth. While the biosynthetic enzymes for each layer are well characterized, the molecular mechanisms that coordinate synthesis across layers have remained poorly understood. This thesis investigates two essential transmembrane proteins, PgfA and MurJ, that regulate peptidoglycan metabolism in Mycobacterium smegmatis and provide new insight into how mycobacteria synchronize cell wall assembly.

We present evidence that PgfA functions as a bifunctional regulator that links peptidoglycan metabolism to the availability of trehalose monomycolate (TMM), a key mycolic acid precursor. Through epistasis …

Fostering Entrepreneurial Thinking And Practice Through Teaching And Learning Integration, Mohammad G. Sabbir

Learning and Educational Center Virtual Teaching and Learning Conference

This session explores an innovative, evidence-based approach to integrating entrepreneurial thinking into undergraduate neuroscience education through hands-on gene editing experiences. Using the commercially available Bio-Rad CRISPR/Cas9-based “Out of the Blue” kit for bacterial LacZ gene editing, students are guided not only through the scientific principles underlying modern gene editing technologies but also through the entrepreneurial challenge of replicating and manufacturing the kit using existing lab resources. This model empowers students to extend their learning beyond the classroom by engaging in cost-effective, scalable biotechnology practices—particularly valuable for institutions with limited funding. Classroom-based research demonstrates increased student engagement, deeper conceptual understanding, and …

Competence Protein Comea And Oxidative Stress In Bacillus Subtilis Stationary Phase Mutagenesis, Angeline Roldan, Sam Schauf

Undergraduate Research Symposium Posters

Stationary Phase Mutagenesis is a process where a bacterium can accumulate mutations in the absence of cell division. This may occur via competent DNA uptake and oxidant DNA damage and repair. ComEA is a transmembrane protein in B. subtilis that is required for the transport of exogenous DNA into the cell. (Figure 1)

Presence Of The Ade Multidrug Systems And Response To Triclosan Exposure In Acinetobacter Baumannii From Animal Origins, Sirawit Pagdepanichkit, Rungtip Chuanchuen

The Thai Journal of Veterinary Medicine

Thirty Acinetobacter baumannii from animal origins were obtained from 210 animal carcasses submitted for post-mortem examination, including dogs (n=112), cats (n=45), rabbits (n=17), birds (n=15), pigs (n=7) and exotic animals (n=14). All the isolates were evaluated for antimicrobial susceptibility with absence and presence of efflux inhibitors i.e. reserpine and carbonyl cyanide m-chlorophenylhydrazone (CCCP) and expression profile of important six multidrug efflux systems (i.e. AdeABC, AdeDE, AdeFGH, AdeIJK, AbeM and AmvA). Fifteen isolates expressing different Ade multidrug efflux pumps were selected for determining transcription levels and regulatory mutations. A continuous in vitro exposure experiment with benzalkonium chloride, chlorhexidine and triclosan …

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 …

Managing Stress: A Study Of Stress Response Mechanisms In Mycobacteria, Augusto C. Hunt Serracin

Biology Dissertations - Archive

Mycobacteria encompass many pathogenic species known to cause severe disease in humans. A well-known example is Mycobacterium tuberculosis (Mtb), the causative agent of the lung disease tuberculosis, which kills millions of humans worldwide yearly. Pathogenic mycobacteria like Mtb are challenging to treat because of their innate ability to adapt to environmental stress. Their unique cell physiology and conserved stress responses allow them to combat biological insults, regulate growth, and regulate genes involved in stress; all these responses increase tolerance to antibiotics. The current therapies to treat mycobacterial infections are lengthy and, at times, unsuccessful, partly due to antibiotic tolerance. A …

Contributions Of The Replication Initiator Protein Dnaa To Physiology And Virulence Of The Lyme Disease Spirochete, Andrew Krusenstjerna

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Borrelia burgdorferi, the etiological agent of Lyme disease, is the most prevalent vector-borne disease in the United States. The spirochetal population is naturally maintained by consistently cycling between Ixodid ticks and small vertebrates. To survive within these diverse niches, B. burgdorferi has evolved a unique physiology and regulatory network to sense and respond to environmental fluxes. Replication is a hallmark of the Lyme spirochete’s enzootic life cycle, specifically at the nymphal tick-to-vertebrate interface. The mechanisms and regulatory schema for the basic cellular processes in B. burgdorferi, or indeed any member of the phylum spirochaetota, are largely unknown. The central hypothesis …

Ribosome Hibernation Factor Induces Antibiotic Persisters Of Mycobacterium Tuberculosis In Neutrophil-Rich Lung Lesions, Jamie Corro

Electronic Theses & Dissertations (2024 - present)

Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, is a prescient global health threat and the leading cause of death by an infectious agent. Treatment of Mtb infection involves administering 2-4 antibiotics for a minimum of 6 months. This extended drug regimen is required to target a subpopulation of persistent bacilli. As their name implies, these bacteria can “persist” by acquiring nonhereditary and transient antibiotic tolerance. Although the precise mechanism is unknown, it’s often attributed to slowing cellular growth and metabolic processes. During zinc deprivation, bacteria can remodel their ribosomes by replacing their zinc-binding paralogues containing the CXXC motif (C+) …

Spatial Structure Formation By The Post-Transcriptional Gene Regulator Rsme In Pseudomonas Fluorescens Pf0-1, Anton Evans

Electronic Theses and Dissertations

Microorganisms are often found in microbial communities we call biofilms. Organisms living in these crowded environments have significant evolutionary pressure to retain access to the resources necessary to sustain life. My research uses the bacterium Pseudomonas fluorescens Pf0-1 to study how organisms evolve strategies to solve this crowding problem as aging colonies repeatedly generate mutant patches. These mutants expand the reach of the colony resulting in decreased local density as they push themselves up to the resource rich surface. These spatial structures result from social interactions between the mutant and the parental cells mediated through extracellular secretions, resulting in the …

Overexpressing Two Helicobacter Pylori Small Rnas From A Bacterial Pathogenicity-Related Chromosomal Region To Investigate Their Regulation Of Virulence Genes, Roxanne N. Mcpeck, Olivia F. Morgan, Andrea R. Castillo Phd

2023 Symposium

The bacterial pathogen Helicobacter pylori infects the stomachs of approximately 50% of humanity, causing symptomatic disease (e.g., stomach ulcers, gastric cancer, and MALT lymphoma) in 10-15% of the infected. Colonizing the acidic, inhospitable stomach requires H. pylori to tightly regulate gene expression despite lacking many common bacterial genetic regulatory elements. The pathogen may compensate by using abundant non-protein-coding small RNAs (sRNAs) to regulate gene expression, including of infection-intensifying virulence genes. Additionally, severe disease and cancer correlate with infection by H. pylori strains that contain a nonessential chromosomal region, the cytotoxin-associated gene pathogenicity island (cagPAI). This encodes powerful virulence …

Diagnosis Of Urinary Tract Infections And Rapid Molecular Characterization Of Antibiotic Resistance, Mohammed Harris

All Dissertations

Urinary tract infections (UTIs) are one of the most common infectious clinical entities in both community and hospital settings. They have a broad range of clinical severity yet inflict large epidemiological burden of morbidity and mortality on patients and the healthcare system with billions of dollars in cost of treatment. Understanding what methods are optimal for diagnosing UTIs are critical to mitigate the marked impact and cost of these infections.

Chapter 1 and 2 in this work surveys the broad array of diagnostic modalities for UTIs and highlights their advantages and limitations in the context of the current standard of …

Genetic Determinants Involved In Acquisition Of Iron In The Opportunistic Pathogen Mycobacterium Abscessus, Manal F. Farhat

Dissertations, Theses, and Capstone Projects

The opportunistic pathogen Mycobacterium abscessus subsp. abscessus (Mab) has become an emerging public health threat due to the increasing number of Mab-associated chronic pulmonary disease cases. Infection cure rates are only 50% due to the complex resistance of Mab to most antimicrobial drugs and chemotherapy.

Deeper knowledge of Mab biology is needed to illuminate potential candidates for development of improved therapeutics against Mab infections. The ESX-3 type VII protein secretion system of Mab plays an important role in host inflammatory and pathological responses during infection.

In this study, we demonstrate a functional link between the ESX-3 secretion …

Functional Residues Of Cjpata, Robert Lamont

Theses and Dissertations (Comprehensive)

Antibiotic resistance in pathogenic bacteria continues to challenge clinicians and threaten the lives of infected individuals. For this reason, new classes of antibiotics or new targets for antibiotic therapy are needed to circumvent this global health crisis. In Gram-negative bacteria, the enzymes peptidoglycan O-acetyltransferase A and B (PatA and PatB), are responsible for adding acetyl groups to the C-6 hydroxyl group of N-acetyl muramic acid (MurNAc) in peptidoglycan (PG). These acetyl groups are responsible for inhibiting the activity of lysozyme from host organisms that hydrolyze the β1-4 glycosidic linkage between MurNAc and N-acetylglucosamine (GlcNAc). The acetyl groups …

Elucidation Of Gene Essentiality And Genetic Determinants Of Intrinsic P-Aminosalicylic Acid Resistance In Mycobacterium Kansasii, Keith J. Levendosky

Dissertations, Theses, and Capstone Projects

Mycobacterium kansasii (Mk) is an opportunistic pathogen capable of causing tuberculosis-like pulmonary disease in immunocompromised individuals and those with other risk factors including chronic obstructive pulmonary disease or malignancy. Mk is frequently isolated from man-made water sources where it forms resilient biofilms, posing a health risk to these susceptible individuals. Despite its medical relevance as an environmental pathogen, and a close phylogenetic relationship with the obligate pathogen Mycobacterium tuberculosis (Mtb), few studies to date have probed the molecular biology and genetics of Mk. Here, we sought to apply a transposon (Tn) mutagenesis tool to dissect …

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 …

Genomic Analysis And Characterization Of Surface Properties Of Naphthalene Degrading Acinetobacter Isolates, Gunn Emilie Berge

Graduate Theses and Dissertations (2019 - present)

No abstract provided.

Resolving The Repression Pathway Of Virulence Gene Hila In Salmonella, Alexandra King, Lon Chubiz Phd, Brenda Pratte, Lauren Daugherty

Undergraduate Research Symposium

Salmonella is a relatively abundant, virulent species of bacteria that is most known for spreading gastrointestinal diseases through food. These illnesses result in approximately 1.35 million infections, including over 25,000 hospitalizations each year, in the U.S. alone (CDC.gov). As antibiotic resistance becomes an increasingly urgent public health problem, the importance of developing alternative treatment methods is only becoming more crucial. One of the genes responsible for this virulence is known as hilA. HilA is the main transcriptional regulator of Salmonella Pathogenicity Island-1 gene (UniProt). SPI-1 plays an important role in the invasion of Salmonella into epithelial cells. The proteins encoded …

Characterization Of A Helicobacter Pylori Small Rna By Rt-Pcr, Roxanne Mcpeck, Andrea Castillo

2022 Symposium

Helicobacter pylori, a bacterial gastric pathogen infecting approximately 50% of the human population, produces gastritis, ulcers, and gastric cancers. Colonizing the inhospitable and fluctuating environment in the stomach requires tight genetic control. However, H. pylori lacks many genetic regulatory elements present in other bacteria to control gene expression. Instead, over 200 small RNAs (sRNAs; noncoding RNAs shorter than 300 nucleotides) have been found in this bacterium, but few have been fully characterized. Of those, many are antisense to virulence genes. Characterizing these sRNAs is important in understanding the mechanisms of molecular genetics and potentially supporting medical management of this …

Insights Into Halophilic Microbial Adaptation: Analysis Of Integrons And Associated Genomic Structures And Characterization Of A Nitrilase In Hypersaline Environments, Sarah Sonbol

Theses and Dissertations

Hypersaline environments are extreme habitats that can be exploited as biotechnological resources. Here, we characterized a nitrilase (NitraS-ATII) isolated from Atlantis II Deep brine pool. It showed higher thermal stability and heavy metal tolerance compared to a closely related nitrilase.

We also studied integrons in halophiles and hypersaline environments. Integrons are genetic platforms in which an integron integrase (IntI) mediates the excision and integration of gene cassettes at specific recombination sites. In order to search for integrons in halophiles and hypersaline metagenomes, we used a PCR-based approach, in addition to different bioinformatics tools, mainly IntegronFinder.

We found that integrons and …

A Peek Inside The Machines Of Bacterial Nucleotide Excision Repair, Thanyalak Kraithong, Silas Hartley, David Jeruzalmi, Danaya Pakotiprapha

Publications and Research

Double stranded DNA (dsDNA), the repository of genetic information in bacteria, archaea and eukaryotes, exhibits a surprising instability in the intracellular environment; this fragility is exacerbated by exogenous agents, such as ultraviolet radiation. To protect themselves against the severe consequences of DNA damage, cells have evolved at least six distinct DNA repair pathways. Here, we review recent key findings of studies aimed at understanding one of these pathways: bacterial nucleotide excision repair (NER). This pathway operates in two modes: a global genome repair (GGR) pathway and a pathway that closely interfaces with transcription by RNA polymerase called transcription-coupled repair (TCR). …

Characterizing The Physiology And Genetics Of Contact Dependent Growth Inhibiton Systems In Burkholderia Species, Alice Elizabeth Oates

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Contact-dependent growth inhibition (CDI) systems mediate interbacterial competition. The genes encoding these systems are widespread among Gram-negative bacteria, including Burkholderia pathogens. CDI systems of Burkholderia species are composed of two-partner secretion pathway proteins and function to deliver the toxic C-terminus of a polymorphic surface-exposed exoprotein BcpA (Burkholderia CDI protein A) to the cytoplasm of neighboring recipient bacteria upon cell-cell contact. Specific outer and inner membrane proteins facilitate BcpA translocation both out of the donor bacterium and into the recipient cell cytoplasm. Most Burkholderia species-specific CDI translocation factors in recipient cells are unknown. BcpA intoxication functions as a mechanism by …

Circadian Rhythmicity And Melatonin Sensitivity In The Human Gut Commensal Bacterium Klebsiella Aerogenes, Kinga Graniczkowska

Theses and Dissertations--Biology

While the expression of circadian rhythms is nearly universal among multicellular eukaryotic organisms, demonstration of this phenomenon in prokaryotes has been largely restricted to photosynthetic cyanobacteria until very recently. Further, growing interest in gastrointestinal microbiomes has revealed a complex temporal relationship between the gastrointestinal clock and the bacterial microbiome within. At least one member of the gut microbiome, Klebsiella (née Enterobacter) aerogenes, responds to the indoleamine hormone melatonin, secreted by the gastrointestinal system itself. Further research revealed that K. aerogenes also expresses a circadian rhythm in motility and gene expression that is temperature compensated. Although rhythmicity is unaltered …

Characterization Of The Broad-Spectrum Inhibitory Capability Of Alcaligenes Faecalis And A. Viscolactis Against Potential Pathogenic Microorganisms, Andrew Fuqua

Undergraduate Honors Theses

The recent rise of multidrug resistant microorganisms has grown from an isolated concern to a massive public health crisis. It has become imperative that scientists look for new ways to combat this issue. Due to the selective pressures of competition, bacteria and other microbes possess a host of defenses and weapons designed to exploit vulnerabilities in other microorganisms. Consequently, the study of these systems and microbial interactions has much to reveal in the search for novel antimicrobial treatments. Previous research from our laboratory has discovered that both Alcaligenes faecalis and Alcaligenes viscolactis, two rarely studied and generally non-virulent bacteria, …

Antibiotic Resistant Bacteria, Antibiotic Resistance Genes And Potential Drivers In The Aquatic Environments, Shuo Shen

Dissertations

As antibiotic resistance genes in aquatic environment have been increasing across the world, affecting water quality and public health, many studies documented concentrations of antibiotic resistance genes and some studies discussed their potential drivers. However, systematic and quantitative reviews that link antibiotic resistance genes (ARGs) to anthropogenic and environmental factors are limited. Nevertheless, this information will be important for developing regulation policy on controlling antibiotic use and therefore reducing potential risks to antibiotic resistance. I conducted meta-analysis of ARGs concentration at a global scale using Bayesian inference to explore climatic and socio-economic factors as drivers. I found local-scale climatic variables …

Identification Of Antibiotic Producing Soil Bacteria Against Bacillus Subtilis, Morgan Brockhouse, Dr. Lori Scott

Identifying and Characterizing Novel Antibiotic Producing Microbes From the Soil

This project is a collaboration with the Tiny Earth Project Initiative (TEPI), which is a global network of educators and students focused on student-sourcing antibiotic discovery from soil. Individual strains of soil bacteria were isolated and produced antibiotic against Bacillus subtilis. Two of these samples were sequenced using the 16S rRNA gene to reveal they are very closely related to the genus Pseudomonas.

Genetic And Biochemical Analysis Of A Conserved, Multi-Gene System Regulation Spore-Associated Proteins In Streptomyces Coelicolor, Joseph Sallmen

Electronic Theses and Dissertations

Streptomyces coelicolor is a Gram positive, filamentous soil dwelling bacterium that exhibits a complex life cycle including the transition from a vegetative mycelium to a sporulating, aerial mycelium. Early genetic studies identified two classes of genes that resulted in developmental blocks, bald and white. The bald (bld) phenotype occurs when colonies cannot produce aerial hyphae. White (whi) colonies exhibit incomplete sporulation and/or loss of production of the concurrently produced grey pigment. While some of the original mutants have been explored, the developmental functions of many of the identified genes are not well understood. Of particular interest …

Genetic Analysis Of A Novel Ftsk Homolog, Hfka, In Streptomyces Coelicolor Development-Associated Chromosome Segregation, Sumedha Sethi

Electronic Theses and Dissertations

A quintessential phenomenon occurring during prokaryotic development is accurate segregation of the replicated genomes into the daughter cells. Key energy-dependent processes like chromosome condensation and subcellular partitioning of the genomes are driven by conserved proteins like SMC, ParB, FtsK. During its complex developmental cycle, Streptomyces coelicolor segregates its genomes into chains of unicellular spores when its multigenomic syncytial aerial hyphae undergo division.

A novel ftsK-like gene, hfkA (Homolog of FtsK protein A), was examined for function and localization during development-associated chromosome segregation. Individual deletions did not affect segregation, but a ΔhfkA ΔftsK mutant exhibited 8% anucleate …

The Effect Of Intracellular Zinc Levels In Escherichia Coli On Metallo-Β-Lactamase Activity, Jill Thompson

Graduate School of Biomedical Sciences Theses and Dissertations

Antibiotic resistance is a consequence of evolution via natural selection and poses a serious threat to the world's population. Escherichia coli, and other bacterial species, have acquired genes encoding Metallo-β-Lactamases (MBLs). MBLs are zinc-dependent enzymes that degrade most β-lactam antibiotics, and have emerged as important antibacterial resistance determinants in multidrug resistant pathogens. There are several different families of MBLs, and the major clinically relevant ones are Verona Integrated-encoded Metallo-β-Lactamases (VIMs), Imipenemases (IMPs), and New Delhi Metallo-β-Lactamases (NDMs). These enzymes confer high level resistance to penicillins, cephalosporins, and carbapenems, and are not inhibited by FDA-approved β-lactamase inhibitors. Variants of NDM have …