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Quorum Sensing in the Hawaiian Coral Pathogen Vibrio coralliilyticus strain OCN008.

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Title:Quorum Sensing in the Hawaiian Coral Pathogen Vibrio coralliilyticus strain OCN008.
Authors:Burger, Andrew H.
Contributors:Microbiology (department)
Keywords:Vibrio coralliilyticus
quorum sensing
coral disease
Date Issued:Aug 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Coral disease represents a serious threat to reefs worldwide. Reef ecosystems have been
reshaped by coral disease in the Caribbean, Florida Keys, and the Great Barrier Reef. Reefs
represent millions of dollars in economic value as well as contribute heavily to marine primary
production, thus efforts to minimize such damage have become crucial. Coral disease in Hawaiʻi
has presented less of a problem when compared to the Caribbean, but emerging diseases over the
past decade have brought the potential for similar destruction. One disease of concern in
Kāneʻohe Bay, Oahu, is Acute Montipora White Syndrome (aMWS), a rapidly progressing
tissue-loss disease affecting the reef-building coral Montipora capitata. Early efforts studying
this disease identified Vibrio coralliilyticus strain OCN008 as an etiological agent of aMWS.
Interestingly, OCN008 produces and utilizes the antibiotic andrimid as a novel virulence factor.
This discovery represented one of only a handful (<5) of known virulence factors in the field of
coral disease, and potentially provides a point at which to begin investigations into preventative
and/or curative strategies. This work describes the quorum sensing (cell-density dependent
bacterial communication/behavior) mechanics of strain OCN008. The main objectives were the
identification and characterization of putative quorum sensing circuits and the role they play in
the infection of M. capitata. Despite possessing homologs of four known Vibrio quorum sensing
pathways, OCN008 requires only one, the LuxPQ/S pathway (AI-2), to activate the high cell
density response. Quorum sensing also contributes to the virulence of OCN008 at both low and
high cell densities. Since the novel virulence factor andrimid was shown here to be under
regulation of AI-2 mediated quorum sensing, a scenario is presented in which OCN008 can
initiate andrimid production in response to a quorum of AI-2 producing bacteria, regardless of
taxonomy. Interestingly, the two most severe outbreaks of aMWS were recorded following
periods of heavy rain, events known to cause increased bacterial abundance and perturbations in
coastal microbial communities. Shifts in coral microbiota have been linked to increased
incidents of coral disease. This work offers one potential mechanism behind this phenomenon.
In addition, this work offers the first direct evidence that quorum sensing is involved in coral
disease.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017.
URI:http://hdl.handle.net/10125/62546
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Microbiology


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