Molecular Biology 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 …

The Identification Of Small Molecule Inhibitors To Candida Albicans Phosphatidylserine Synthase, Yue Zhou

Doctoral Dissertations

Candida albicans phosphatidylserine (PS) synthase, encoded by the CHO1 gene, has been identified as a potential drug target for new antifungals against systemic candidiasis due to its importance in virulence, absence in the host and conservation among fungal pathogens. This dissertation is focused on the identification of inhibitors for this membrane enzyme. Cho1 has two substrates: cytidyldiphosphate-diacylglycerol (CDP-DAG) and serine. Previous studies identified a conserved CDP-alcohol phosphotransferase (CAPT) binding motif present within Cho1, and here we revealed that mutations in all but one conserved amino acid within the CAPT motif resulted in decreased Cho1. For serine, we have predicted a …

Immunomodulatory Effects Of Resolvin D2 In A Model Of Infection, Prem Yugandhar Kadiyam Sundarasivarao

Graduate School of Biomedical Sciences Theses and Dissertations

Dysregulated hyperinflammatory host immune response to underlying bacterial infections is a characteristic of sepsis. In sepsis, bacteria often trigger abnormal hyperinflammatory responses which can cause multiple organ failure and if sustained can lead to an immunosuppressive phase where the host is susceptible to secondary infections caused by opportunistic bacteria like Pseudomonas aeruginosa (P. aeruginosa). In our studies, we used a 2-hit model of cecal ligation and puncture (CLP) followed by P. aeruginosa secondary lung infection to investigate cellular and molecular mechanisms in the beneficial action of resolvin D2 (RvD2). Resolvins of the D-series are a group of fatty acids known …

The Effects Of Specialized Pro-Resolving Mediator Lipoxin A4 On Pseudomonas Aeruginosa Biofilms And Interactions With Monocytes, Julianne M. Thornton

Graduate School of Biomedical Sciences Theses and Dissertations

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen known as a major cause of hospital-acquired secondary infections, commonly causing chronic respiratory infections in immunocompromised individuals, especially those with cystic fibrosis, and often found in wound infections. P. aeruginosa uses the quorum sensing pathway to readily form protective biofilms, which reduce the efficacy of antibiotics and access by host immune cells to eradicate the pathogen. Specialized pro-resolving mediators (SPMs) are lipids endogenously produced by the host immune response to infection to aid in infection resolution. One SPM, Lipoxin A4 (LxA4), has been shown to be a robust quorum sensing inhibitor.

The …

Investigating The Antibacterial And Immunomodulatory Properties Of Lactobacillus Acidophilus Postbiotics, Rachael M. Wilson

Graduate School of Biomedical Sciences Theses and Dissertations

Probiotics are nonpathogenic microorganisms that have been extensively studied for their ability to prevent various infectious, gastrointestinal, and autoimmune diseases. The mechanisms underlying these probiotic effects have not been elucidated. However, we and other researchers have evidence suggesting that probiotic bacteria secrete metabolites that are antimicrobial and anti-inflammatory. As such, we developed a methodology to collect the secreted metabolites from a probiotic bacterium, Lactobacillus acidophilus, and tested this cell free filtrate (CFF) both in vitro and in vivo. Using this CFF, we have demonstrated that L. acidophilus secretes a molecule(s) that has specific bactericidal activity against the opportunistic pathogen, Pseudomonas …

The Type Iv Pilus Secretin Bfpb: Structural Analysis And Binding Interactions, Janay I. Little

Theses and Dissertations

Enteropathogenic Escherichia coli (EPEC) causes severe diarrhea in young children. The type IV pilus (T4P) of EPEC, known as the bundle-forming pilus (BFP), plays an important role in EPEC pathogenesis. T4Ps are a family of surface appendages that are important for adhesion, colonization, biofilm formation, virulence, twitching motility and many other functions. One essential component of the BFP system is the secretin, BfpB. Secretins are a large family of integral outer membrane proteins found in T4Ps as well as type II and type III secretion systems, and filamentous phages. Details of the secretin structure have been limited to the overall …

The Antimicrobial Resistance Plasmid Mobilome Of Salmonella Enterica And Related Enteric Species And Factors That Influence The Transfer Efficiency., Suad Algarni

Graduate Theses and Dissertations

The dynamic distribution of antimicrobial resistance genes in Salmonella enterica is considered a public health risk. S. enterica is one of the most important etiological agents of foodborne illness and has a critical impact on global human health. In S. enterica and related species, mobile genetic elements (MGEs) serve as primary vehicles for the dissemination of antibiotic resistance genes in the bacterial evolution. This dissemination can be impacted by different selective pressures that leads to diverse antibiotic response phenotypes. This project focusses on the dynamics of antimicrobial resistance genes, particularly exploring the transfer efficiency of multidrug resistance plasmids in S. …

Comparative Genomics And Virulence Studies Of Streptomyces Soil Rot And Scab Pathogen Species, Natasha Soares

LSU Doctoral Dissertations

Comparative genomic analyses were performed to gain insights into the organization and content of the genome of Streptomyces ipomoeae, the soil rot pathogen that infects sweetpotatoes. Unlike Streptomyces scab pathogens, the thaxtomin phytotoxin gene cluster (txt) in S. ipomoeae does not appear to reside within a genomic island and has diverged from its scab pathogen counterparts. Increased usage of the rare TTA codon, particularly for the txt cluster, suggests greater translational control by the bldA tRNA in S. ipomoeae. Orthologous gene searches and secondary metabolite profiling yielded ortholog groups and metabolite gene clusters that were exclusive …

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 …

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 …

Bacterial Chondronecrosis With Osteomyelitis In Broilers: Genomics, Phylogenomics, And Methods To Detect Specific Pathogens During Outbreaks., Abdulkarim Abdulaziz A. Shwani

Graduate Theses and Dissertations

Lameness is a major issue in animal welfare and the broiler industry. Bacterial chondronecrosis with osteomyelitis (BCO) is one of the main causes of lameness. Many staphylococcal species, including Staphylococcus agnetis isolate 908, have been isolated from the bones and blood of lame broilers at the University of Arkansas. Staphylococcus agnetis is a coagulase-variable, Gram-positive bacterial species that has been previously associated with subclinical or mild clinical cases of mastitis in dairy cattle. The annotated complete genome of hypervirulent strain 908 was published at NCBI. In this study, it has been compared to nine genomes we assembled for hypervirulent isolates …

Mechanisms By Which Xenorhabdus Nematophila Interacts With Hosts Using Integrated -Omics Approaches, Nicholas C. Mucci

Doctoral Dissertations

Nearly all organisms exist in proximity to microbes. These microbes perform most of the essential metabolic processes necessary for homeostasis, forming the nearly hidden support system of Earth. Microbial symbiosis, which is defined as the long-term physical association between host and microbes, relies on communication between the microbial community and their host organism. These interactions among higher order organisms (such as animals, plants, and fungi) and their bacteria links metabolic processes between interkingdom consortia. Many questions on microbial behavior within a host remain poorly understood, such as the colonization efficiency among different microbial species, or how environmental context changes their …

Screening For Binding Partners And Protein-Protein Interactions Of A Fungal Transcription Factor- Xdr1, Nishadi Punsara Gallala Gamage

Masters Theses

Clarireedia spp. (formerly Sclerotinia homoeocarpaF.T. Bennett) is the causal agent dollar spot, the most economically important turfgrass disease impacting golf courses in North America. The most effective strategy for dollar spot control is repeated application of multiple classes of fungicides. However, reliance on chemical application has led to resistance to four classes of fungicides as well as multidrug resistance (MDR). Fungi are known to detoxify xenobiotics, like fungicides, through transcriptional regulation of three detoxification phases: modification, conjugation and secretion. Little is known, however, of the protein-protein interactions that facilitate these pathways. Following next-generation RNA sequencing of Clarireedia spp., a …

A Multidisciplinary Characterization Of The Enzymology And Biology Of Reversible Glucan Phosphorylation In Toxoplasma Gondii , Robert Murphy

Theses and Dissertations--Molecular and Cellular Biochemistry

Toxoplasma gondii is an opportunistic, protozoan parasite of all warm-blooded animals, infecting roughly one-third of humans worldwide. Humans acquire infections by consuming T. gondii tissue cysts in undercooked meat or from oocysts shed in cat feces. Encysted parasites convert into rapidly growing tachyzoites that disseminate throughout the body, defining the acute phase of infection. Under host immune pressure, tachyzoites convert into bradyzoites that populate tissue cysts found in CNS or muscle tissue and persist for the lifetime of the host, defining the chronic phase of infection. Tissue cysts are responsible for transmission via carnivory, but also possess the ability to …

Oxydifficidin-Producing Bacillus Presents Novel Antimicrobial Activity Against Neisseria Gonorrhoeae Involving The Deda Protein, Jingbo Kan

Dissertations, Theses, and Capstone Projects

Bacterial human pathogens cause severe infectious diseases which are the second most common cause of death next to cancer and cardiovascular diseases in the world, especially in developing countries. Gonorrhea particularly, is the second most common sexually transmitted infection (STI) which is caused by the microorganism Neisseria gonorrhoeae (GC). Centers for Disease Control and Prevention (CDC) estimates that more than 1.6 million new gonorrhea cases emerged in USA in 2018 (“Detailed STD Facts - Gonorrhea” n.d.). Also, the WHO (World Health Organization) shows that gonorrhea is the most antibiotic resistant STI (“PAHO/WHO | Gonorrhea” n.d.), highlighting the shortage of efficient …

The Role Of The Msaabcr Operon In Cell Wall Integrity And Programmed Cell Death During Biofilm Development, Bibek G C

Dissertations

Staphylococcus aureus is an important human pathogen in both community and health care settings. Biggest challenges with S. aureus as a pathogen is its ability to acquire antibiotic resistance and produce robust biofilms. In this work, we investigated the nature of the cell wall defect in the msaABCR operon mutant in the Mu50 (VISA) and USA300 LAC methicillin-resistant Staphylococcus aureus (MRSA) strains. Results showed that msaABCR-mutant cells had decreased cell wall thickness and cell wall crosslinking in both strains. These defects are most likely due to increased murein hydrolase activity and/or nonspecific processing of murein hydrolases mediated by increased …

Pathogenicity Of Staphylococcus Agnetis Associated With Lame Broilers With Osteomyelitis, Sura Faris Salih Zaki

Graduate Theses and Dissertations

We developed High Resolution Melt Analysis (HERMA) as a rapid and reliable molecular diagnostic assay for the detection and identification of the main bacterial species recovered from the blood and lesions of bacterial chondronecrosis with osteomyelitis (BCO) from the lame broilers at the University of Arkansas poultry research farm. Also, the present study confirms that raising young birds on suspended wire flooring has been proved to successfully induce lameness attributable to BCO with birds being more susceptible to bacteraemia than those that were raised on litter flooring. The newly described pathogen, Staphylococcus agnetis, has been reported to be overrepresented in …

Analysis Of Biofilm Remediation Capacity For Octenyl Succinic Anhydride (Osa), A Bioactive Food Starch Modifier Compound, Matthew R. Borglin

Master's Theses

Matthew R. Borglin

This thesis demonstrates efficacy of Octenyl Succinic Anhydride (OSA), as a biofilm sanitizer. Biofilms allow bacteria to adhere to solid surfaces with the use of excreted polymeric compounds. For example, surfaces found in food production or processing facilities such as the interior of a raw milk holding tank, are some of the most susceptible to biofilm contamination. When present, biofilms can cause a variety of negative effects, which include; reduction of product shelf life, corrosion, and outbreaks of foodborne illnesses. The close association of biofilms with the majority of foodborne illness cases led the US Environmental Protection …

A Putative Cystathionine Beta-Synthase Homolog Of Mycolicibacterium Smegmatis Is Involved In De Novo Cysteine Biosynthesis, Saroj Kumar Mahato

Graduate Theses and Dissertations

Mycobacteria include serious pathogens of humans and animals. Mycolicibacterium smegmatis is a non-pathogenic model that is widely used to study core mycobacterial metabolism. This thesis explores mycobacterial pathways of cysteine biosynthesis by generating and study of genetic mutants of M. smegmatis. Published in vitro biochemical studies had revealed three independent routes to cysteine synthesis in mycobacteria involving separate homologs of cysteine synthase, namely CysK1, CysK2, and CysM. However, in vivo data were lacking. The M. smegmatis genome encodes only a CysM homolog and lacks orthologs for CysK1 or CysK2. The gene that codes for CysM is a part of an …

A Novel Mode Of Action Of C-Reactive Protein In Protecting Against Streptococcus Pneumoniae Infection And Synergy With Antibiotics, Donald Ngwa

Electronic Theses and Dissertations

C-reactive protein (CRP) is a part of the innate immune system, is synthesized in the liver, its blood level increases in inflammatory states, and it binds to Streptococcus pneumoniae. The conformation of CRP is altered under conditions mimicking an inflammatory milieu and this non-native CRP also binds to immobilized/aggregated/pathogenic proteins. Experiments in mice have revealed that one of the functions of CRP is to protect against pneumococcal infection. For protection, CRP must be injected into mice within two hours of administering pneumococci, thus, CRP is protective against early-stage infection but not against late-stage infection. It is unknown how CRP protects …

The Role Of Manganese In Streptococcus Sanguinis, Tanya M. Puccio

Theses and Dissertations

Streptococcus sanguinis is primarily associated with oral health as a commensal bacterium. As an opportunistic pathogen, S. sanguinis is capable of colonizing heart valve vegetations, leading to the disease infective endocarditis. Previous studies from our lab have identified the high-affinity manganese transporter SsaACB as important for endocarditis virulence. The impact that manganese depletion has on S. sanguinis had never been evaluated and a secondary manganese transporter has not been identified. Thus, we employed the use of a fermentor to control large-scale growth over time and depleted manganese in an ΔssaACB mutant using a metal chelator, EDTA. The changes in …

Molecular Facet Of Host-Pathogen Interactions In Fusarium Head Blight In Wheat ( Triticum Aestivum L.), Bimal Paudel

Electronic Theses and Dissertations

Fusarium head blight (FHB) is a severe disease of wheat (Triticum aestivum L.). It not only reduces the quantity of the harvested grains but also decreases the grain quality due to mycotoxins contamination, especially Deoxynivalenol (DON). Qfhb1 (or simply called Fhb1) is the most important quantitative trait locus (QTL) for FHB resistance. Our lab has previously identified wheat gene WFhb1-1 (aka. Wfhb1_c1) as a candidate for FHB resistance gene. Here we report that WFhb1-1 has been cloned. The gene (GenBank # KU304333.1) consists of a single exon, encoding a putative membrane protein of 127 amino acids. WFhb1-1 protein produced in …

Incidence And Prevalence Of Francisella Noatunensis Subsp. Orientalis (Fno) Pathogenic Infections In Feral Hawaiian Tilapia, Daquille Peppers

Biology Theses

Aquaculture has become a major food source for many countries and continues to grow each year. However, many of the fishes that are farmed are susceptible to pathogenic infections such as Francisellosis, a bacterial infection that contributes to disease and high mortality rate in many populations of farmed and wild fish around the world. In 1994, feral and farmed populations of tilapia (e.g. Oreochromis mossambicus) on Oahu, Hawaii were found to be infected with a novel Francisellosis strain, Francisella noatunensis subsp. orientalis (Fno). To prevent the spread of this pathogen, the Hawaii Department of Aquaculture (HDOA) initiated …

A High Throughput Assay For The Detection Of Stimulator Of Interferon Genes (Sting) Agonists, Michael J. Ingling

Graduate School of Biomedical Sciences Theses and Dissertations

The innate immune system includes a menagerie of different cell types, each with a different role in the process of monitoring the body for invaders and presenting gathered debris (antigen) to the adaptive immune system. Somatic cells have intracellular receptors for the same purpose. Cancer cells, however, have avoided these methods of detection despite, in many cases, the tumor’s immunogenic traits. Immuno-oncology is a field dedicated to the immunological traits of tumors, more recently finding ways of instigating an immune response against tumors. In this regard, STING, a receptor of cyclic dinucleotides (CDN), has come to the forefront of immuno-oncology. …

Nascent Dna Proteomics Analysis Uncovers Dna Replication Dynamics In The Human Pathogen Trypanosoma Brucei, Maria Rocha Granados

Doctoral Dissertations

DNA is the substrate of many cellular processes including DNA replication, transcription and chromatin remodeling. These processes are coordinated to maintain genome integrity and ensure accurate duplication of genetic and epigenetic information. Genome-wide studies have provided evidence of the relationship between transcription and DNA replication timing. A global analysis of DNA replication initiation in T. brucei showed that TbORC1 (subunit of the origin recognition complex, ORC) binding sites are located at the boundaries of transcription units. Although recent studies in T. brucei indicate functional links among DNA replication and transcription, the underlying mechanisms remain unknown. In this study, we adapted …

Functional Similarity Of Prd-Containing Virulence Regulators In Bacillus Anthracis, Malik Raynor

Dissertations & Theses (Open Access)

Bacillus anthracis produces three regulators, AtxA, AcpA, and AcpB, that control virulence gene expression and are members of an emerging class of regulators termed “PCVRs” (Phosphoenolpyruvate-dependent phosphotransferase regulation Domain-Containing Virulence Regulators). AtxA controls expression of the toxin genes; lef, cya, and pag, and is the master virulence regulator and archetype PCVR. AcpA and AcpB are less well studied. AcpA and AcpB independently positively control transcription of the capsule biosynthetic operon capBCADE, and culture conditions that enhance AtxA activity result in capBCADE transcription in strains lacking acpA and acpB. RNA-Seq was used to assess the regulons of the …

The Characterization Of The Transcription Factor Msab And Its Role In Staphylococcal Virulence, Justin Batte

Dissertations

Staphylococcus aureus is a common human pathogen that is responsible for a wide range of infections, ranging from relative minor skin infections to life-threatening disease such as bacteremia, septicemia, and endocarditis. S. aureus possesses many different virulent factors that aid in its ability to cause this wide array of infections. One major virulence factor includes the production of capsular polysaccharide (CP). The production of CP plays a major role in the virulence response during infection specifically by providing S. aureus an antiphagocytic mechanism that allows the pathogen to evade phagocytosis during an infection. S. aureus has developed complex genetic regulatory …

The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu

Doctoral Dissertations

Helicobacter pylori is a bacterium that has colonized the human gastric mucosa of over 50% of the world population. Persistent infection can cause gastritis, peptic ulcers, and cancers. The ability of H. pylori to colonize the acidic environment of the human stomach is dependent on the activity of the nickel containing enzymes, urease and NiFe-hydrogenase. The nickel metallochaperone, HypA, was previously shown to be required for the full activity of both enzymes. In addition to a Ni-binding site, HypA also contains a structural Zn site, which has been characterized to alter its averaged structure depending on pH and the presence …

Relationships Between Factors Influencing Biofilm Formation And Pathogen Retention In Complex Rhizosphere Microbial Communities, Aaron Coristine

Theses and Dissertations (Comprehensive)

Riparian wetlands are unique habitats facilitating all forms of life. The riverbanks of these environments provide ideal conditions for bacteria, plants, and higher organisms. Of particular interest to this research was the variation in microbial community structure at high, intermediate and poor water quality impacted areas. Assessing the capabilities of plants to retain microbial pathogens was identified. Root systems and corresponding soil are ideal locations for bacterial deposition, resulting in attachment at these areas. Biofilm production in these regions is important for long-term establishment, leading to persistence and potential naturalization. Opportunistic pathogens originating from mammalian fecal matter are introduced into …

Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone

Graduate Theses and Dissertations

Foodborne illnesses are a leading cause of infectious diseases in the world. Among enteric organisms Salmonella is a key pathogen. It’s high prevalence in poultry and other food-animal sources make it imperative to study. Salmonella has the ability to modify its genetic content with help of mobile genetic elements such as plasmids. Incompatibiltiy group 1 (IncI1) plasmids are commonly reported in Salmonella. This study evaluates role on IncI1 plasmids in antimicrobial resistance and virulence in Salmonella. Genetic determinants of resistance and virulence are noted among our IncI1-containing Salmonella isolates. These genetic elements are also transferable and reported to carry respective …