INVESTIGATING THE ECOLOGICAL, PATHOGENIC, AND DORMANT LIFESTYLES OF THE ESTUARINE BACTERIUM, VIBRIO VULNIFICUS
1 online resource (171 pages) : PDF
University of North Carolina at Charlotte
Vibrio vulnificus is ubiquitous in estuarine and coastal waters worldwide and associates naturally with a variety of aquatic organisms. Notably, it is a highly invasive human pathogen capable of causing septicemia and multi-organ failure in persons consuming raw or undercooked shellfish, and can also cause flesh-eating disease upon entry into open wounds, both of which can lead to death in susceptible individuals. Of great importance is the persistent number of V. vulnificus cases documented in the US, and the significantly increasing rate of wound infections worldwide. Interestingly some strains of this species are more often implicated in human disease (clinical [C-] genotypes) and have identifiable genetic distinctions from strains that are typically less virulent and more often isolated from oysters and estuarine waters (environmental [E-] genotypes). The goal of this dissertation collection was to address the following three primary aspects of the biology of V. vulnificus: the ecology, pathogenicity, and dormancy dynamics of this organism. While V. vulnificus thrives in warmer waters, it can also endure cold seasons by overwintering in a dormant state referred to as the viable but non-culturable (VBNC) state which facilitates persistence of the organism in the environment. Here, we elucidate the molecular mechanisms responsible for awakening from the VBNC state, and identify quorum sensing (a wide-spread bacterial communication system) to be the phenomenon that underpins this dormancy state. To better understand the ecology of this organism, we have investigated the molecular and physical factors that facilitate chitin attachment, a substrate known to serve as a reservoir for the persistence of Vibrio species in the environment. These studies revealed significant differences in the behavioral properties of C- and E-genotypes, offering insight into their documented environmental distribution. Lastly, to improve our understanding of the differential pathogenic capabilities of C- and E- genotypes, we set out to identify the molecular mechanisms that underlie these differences by use of next-generation sequencing techniques, including genome and transcriptome sequencing. This allowed for the identification of several putative virulence factors that could potentially aid this bacterium in disease progression. Furthermore, this allowed us to characterize the different gene expression profiles of C-genotypes as they transition from environmental to host-like conditions. Collectively, these studies advance our understanding of V. vulnificus as a natural inhabitant of the estuary, and as a human pathogen.
Parrow, MatthewTroutman, JerrySokolova, InnaRingwood, AmyGibas, Cynthia
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2015.
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