Identification and Characterization of a Salmonella Hyper-biofilm isolate from mouse gallstones
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Date
2015-05
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The Ohio State University
Abstract
Typhoid fever, a human-specific disease, infects approximately 21 million people each year, resulting in greater than 200,000 deaths. The primary causative agent of typhoid fever is Salmonella enterica serovar Typhi (S. Typhi). It is estimated that 3-5% of people infected with typhoid fever become chronic carriers, who are likely responsible for much of the spread of this disease. Studies have shown a correlation between the typhoid fever carrier state and the presence of gallstones, and this correlation is a result of Salmonella biofilm formation on gallstone surfaces. In the course of a previous long term study of gallstone-bearing mice (a model for S. Typhi human infection), a S. Typhimurium isolate was recovered from a biofilm on a mouse gallstone. This isolate exhibited 3-fold increased biofilm formation over the wild type strain, a phenotype that persisted after 10 passages, suggesting that it was due to a genetic mutation and not a transient change in gene expression. Common biofilm components were tested to identify the key differences causing altered phenotype. Our experiments indicate that the mutant has significant alterations in surface appendages/matrix components that play a role in biofilm development and maintenance. In order to identify the exact mutations responsible for the new phenotype, we sequenced the complete genomes of both wild type Salmonella and our mutant. These sequences identified fourteen genes of interest that may be the cause of the hyperbiofilm phenotype. Mutations in select prioritized genes (envZ, rcsB, flagella-related) have been created and tested for enhanced biofilm capacity. These and other studies will determine if this hyperbiofilm state is due to a directed/selected genetic alteration caused by prolonged incubation in the gallbladder. These data will identify novel targets to interfere with gallstone biofilms, resolve the carrier state and eliminate the spread of typhoid fever.
Description
Denman Undergraduate Research Forum, 2nd Place Biological Sciences 2014
Center for Microbial Interface Biology Research Symposium, Best Undergraduate Poster Presentation 2014
Center for Microbial Interface Biology Research Symposium, Best Undergraduate Poster Presentation 2014
Keywords
Salmonella, Biofilm, Chronic Carriers