Pathogenic Microbiology Commons^™

Regulation Of Hyaluronate Lyase (Hyla) Expression By Regr A Transcriptional Repressor In Streptococcus Pyogenes, Alexis A. Kordis

Biological Sciences Theses & Dissertations

Streptococcus pyogenes, group A streptococci (GAS), causes diseases ranging from asymptomatic to life threatening. Some strains of S. pyogenes produce extracellular hyaluronate lyase (HylA), a potential virulence factor. HylA is an enzyme that degrades hyaluronic acid, which is found in the extracellular matrix of human tissues. The breakdown of the host tissue contributes to the spread of infection. The hylA gene is not constitutively expressed in vitro, which implies regulation.

A proposed regulator of hyaluronate lyase expression is RegR, a LacI/GalR like protein. A vector containing disrupted regR was electro-transformed into S. pyogenes M-type 22 strain 10403. Growth characteristics …

Antimicrobial Activity Screening Of Recombinant And Synthetic Varasin A Defensin From The Hard Tick Dermacentor Variabilis Against Various Bacteria, Julia A. Sharp

Biological Sciences Theses & Dissertations

Hematophagous arthropods, such as ticks and mosquitoes, rely on their innate immune system for defense against pathogens ingested in a blood meal as well as those acquired through injury. In response to pathogen recognition, the production of antimicrobial peptides, such as defensin, is typically upregulated. Varisin, a defensin, is thought to be a key component in the immunocompetence of the hard tick D. variabilis against Borrelia burgdorferi, the causative agent of Lyme disease. To study the antimicrobial effects of varisin, recombinant varisin was expressed by both insect cells and E coli. Purification of the protein followed by enterokinase treatment yielded …

Characterization Of Spy1600 A Putative Hyaluronidase Gene In Group A Streptococci, Karin M. Berling

Biological Sciences Theses & Dissertations

Group A Streptococci (GAS), also known as Streptococcus pyogenes, can cause a variety of human diseases ranging from asymptomatic to life threatening. Exactly how a single type of organism is able to inflict such a multitude of diseases remains to be fully understood. One possibility includes the large number of secreted virulence factors expressed by the organism. The recent sequencing of three streptococcal genomes has indicated the existence of several previously unknown genes, some of which may encode possible virulence factors. Among these is Spy1600, which based on its sequence similarities has been proposed to encode a hyaluronidase, a …

Interactions Between Aquatic Chromogenic Bacteria And Pathogenic Vibrio Spp., John Louis Harris

Biological Sciences Theses & Dissertations

Interactions between populations inhabiting an ecosys­tem are responsible, in large part, for determining which species coexist in that ecosystem. In this study, interac­tions between selected Vibrio species, V. alginolyticus and V. anguillarum, and marine heterotrophic, chromogenic bac­teria in aquatic microcosms were investigated. The ultimate goal of this project was to evaluate the feasibility of ex­ ploiting competitive interactions as a means to biologically control growth of the pathogenic marine bacteria, V. alginolyticus and V. anguillarum. In the majority of ex­periments (14/16), if chromogenic species were allowed to develop stable populations before a Vibrio spp. was intro­duced into a …

The Development Of Techniques For The Enumeration Of Selected Pathogenic Bacteria In Lynnhaven Estuarine Sediments, Mark T. Frank

Biological Sciences Theses & Dissertations

Methodologies for the improved recovery of selected pathogenic bacteria from estuarine sediments were investigated. Laboratory and field studies were conducted to document the sensitivity of the techniques for isolating Salmonella species, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Vibrio parahaemolyticus-like organisms were enriched in a seawater yeast extract broth and isolated from Thiosulfate Citrate Bile Salts Sucrose plated media. Enrichment procedures with and without elevated temperatures and subsequent transfers to selective and differential plated media have been examined for the isolation of Salmonella species and P. aeruginosa. These pathogens were initially assayed for utilizing primary enrichments of asparagine …