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Louisiana State University

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Articles 1 - 9 of 9

Full-Text Articles in Bacteriology

Elucidation Of A Role In Biofilm Production For The Tyrosine Catabolism Pathway In Vibrio Cholerae And Analysis Of Reversible Phase Variation In Vibrio Vulnificus, Aheli S. Mukerji Jul 2025

Elucidation Of A Role In Biofilm Production For The Tyrosine Catabolism Pathway In Vibrio Cholerae And Analysis Of Reversible Phase Variation In Vibrio Vulnificus, Aheli S. Mukerji

LSU Doctoral Dissertations

Biofilms produced by the cholera pathogen Vibrio cholerae not only enhance its ability to survive in the environment but also allow pathogenic success of the bacterium. This organism also undergoes phase variation, switching between smooth and rugose colonial phenotypes, the latter forming much more vibrio polysaccharide (VPS) resulting in more robust biofilms and subsequently having an increased level of persistence. In a previous study, many genes were found to be upregulated in the transition from the smooth to the rugose phenotype. Here, several of these upregulated genes were investigated for their potential role in biofilm production, and an additional gene, …


Harmonizing Soybean-Associated Beneficial Bacteria For Sustainable Cultivation, Jonas J. Padilla Apr 2024

Harmonizing Soybean-Associated Beneficial Bacteria For Sustainable Cultivation, Jonas J. Padilla

LSU Master's Theses

Long-term reliance on agrochemicals, such as fertilizers and pesticides, to improve crop productivity can severely impact soil physicochemical properties and health. This eventually leads us to completely depend on these chemicals to sustain the needs of our crops. To resuscitate the deteriorating state of our arable lands, we need to shift from traditional farming to more sustainable crop management. One of the alternatives that we can use instead of these chemicals is the utilization of microorganisms that can perform a variety of beneficial functions for the growth and development of crops. Recently, seed-treating materials made up of bacterial consortia were …


A Membrane Transporter Required For Quorum Sensing And Virulence Of The Rice Pathogen Burkholderia Glumae, Asif Iqbal Oct 2022

A Membrane Transporter Required For Quorum Sensing And Virulence Of The Rice Pathogen Burkholderia Glumae, Asif Iqbal

LSU Doctoral Dissertations

Burkholderia glumae is a Gram-negative bacterium causing bacterial panicle blight (BPB) in rice. BPB can cause severe damage to rice and reduce rice yield up to 75%, while no effective treatment has been developed to control the disease. B. glumae produces and secretes an essential virulence factor, toxoflavin, which is mainly responsible for the symptoms of BPB. Synthesis and transport of toxoflavin are regulated in a quorum-sensing dependent manner. Members of the DedA superfamily are putative membrane transporters and found in nearly all species. Mutation of dedA in Burkholderia species results in sensitivity to colistin, an antibiotic belonging to the …


Comparative Genomics And Virulence Studies Of Streptomyces Soil Rot And Scab Pathogen Species, Natasha Soares Aug 2022

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 …


Antimicrobial Strategies For Topical Applications, Kelsey Marie Lopez Jun 2020

Antimicrobial Strategies For Topical Applications, Kelsey Marie Lopez

LSU Doctoral Dissertations

Bacteria can thrive in diverse environments and are often harmless or beneficial. Bacteria in digestive tracts is one example of beneficial bacteria; however, bacteria can be harmful and when this type proliferates, it can cause infections within hosts. Bacterial infections are easily treated with antibiotics in most cases. However, bacteria are also capable of developing mutations which could cause them to become multi-drug resistant and eventually, “superbugs.” Therefore, the development of novel antimicrobial agents and materials capable of combating drug-resistant bacteria is necessary. Research presented in this dissertation focuses on different strategies for minimizing and preventing topical bacterial infections using …


Mechanism Of Neutrophil Homeostasis And Immunity In Pneumonia And Sepsis, Sagar Paudel Oct 2019

Mechanism Of Neutrophil Homeostasis And Immunity In Pneumonia And Sepsis, Sagar Paudel

LSU Doctoral Dissertations

Severe bacterial pneumonia and septicemia are pressing health problems. A better understanding of cellular and molecular players of neutrophil immunity and homeostasis in bacterial pneumonia and sepsis is critical for inspiring novel therapeutics. Chemokine CXCL1 is a widely secreted neutrophil attractant and Nod-like receptor (NLRC4) is commonly expressed cytoplasmic pathogen sensor in hematopoietic compartments. How these innate mediators convert pathogen signals into molecular cues of immune response in context of Gram-positive bacterial pneumonia and septicemia largely remain unknown. Utilizing Cxcl1 gene deficient mice, we demonstrate CXCL1 regulates neutrophil influx, bacterial clearance, and host survival in pneumococcal pneumonia-derived sepsis. Furthermore, Cxcl1 …


Infection Potential Of Rickettsia Felis Via Ingestion, Matthew M. Schexnayder Jul 2019

Infection Potential Of Rickettsia Felis Via Ingestion, Matthew M. Schexnayder

LSU Master's Theses

Rickettsia felis is the etiologic agent of flea-borne spotted fever (FBSF) in humans and a poorly described cause of fever in animals. It is transmitted by its primary arthropod vector and reservoir host, the cat flea Ctenocephalides felis. Known routes of Rickettsia felis transmission between Rickettsia felis-infected cat fleas and vertebrate hosts include cutaneous bites and contamination of cutaneous wounds with infective flea feces. The bulk of FBSF infections occur in young children in Africa, though infections of people at all ages all over the world have been confirmed. As mammals and young children frequently come into contact …


Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert Dec 2018

Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert

LSU Doctoral Dissertations

Biofilm formation, through the production of Vibrio polysaccharide (VPS), greatly enhances the environmental fitness and pathogenic success of Vibrio cholerae. As a result of phase variation, V. cholerae can switch from a smooth form to rugose, whose cells produce excess VPS, resulting in highly structured biofilms and greater resistance to stress. To further characterize the reversible process of phase variation, we isolated three colonial lineages. Each lineage began with a smooth parent, N16961, and contained a rugose variant derived from the parent, N16961R, as well as a smooth revertant of the rugose, N16961SD. We found clear phenotypic and transcriptomic …


Characterization Of The Interaction Between R. Conorii And Human Host Vitronectin In Rickettsial Pathogenesis, Abigail Inez Fish Apr 2018

Characterization Of The Interaction Between R. Conorii And Human Host Vitronectin In Rickettsial Pathogenesis, Abigail Inez Fish

LSU Doctoral Dissertations

Spotted Fever Group Rickettsia are inoculated into the mammalian host during hematophagous arthropod feeding. Once in the bloodstream and during dissemination, the survival of these pathogens is dependent upon their ability to evade innate host defenses until a proper cellular target is reached. The establishment of a successful infection also relies on the ability of the bacteria to attach and invade target cells, as failure to do so results in destruction of the bacterium. Rickettsia conorii expresses an outer membrane protein, Adr1, which binds the multifunctional human glycoprotein, vitronectin, to promote resistance to complement mediated killing. Homologs of Adr1 are …