Vibrio vulnificus is an opportunistic human and animal pathogen with the highest death rate of any foodborne disease agent. The capsular polysaccharide (CPS) is essential for virulence. Over 100 CPS types (carbotypes) have been identified among natural isolates, yet little is known about the genetic mechanisms that drive such diversity. Chitin, the second most abundant polysaccharide in nature, induces competence in Vibrio species. We found that transformation frequency varies by strain and (GlcNAc)2 was the shortest chitin-derived polymer capable of inducing competence. We confirmed that V. vulnificus can undergo chitin-dependent carbotype conversion following the uptake and recombination of complete cps loci from exogenous genomic DNA. The acquisition of a partial locus was also demonstrated when internal regions of homology between the endogenous and exogenous loci existed. Thus, the same mechanism governing the transfer of complete cps loci also contributes to their evolution by generating novel combinations of CPS biosynthesis genes.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31364 |
| Date | 15 December 2011 |
| Creators | Neiman, Jana |
| Contributors | Rowe-Magnus, Dean |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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