Date of Award

Summer 8-2012

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Jay Grimes

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Crystal Johnson

Committee Member 3

Kevin Dillon

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Vibrio vulnificus, Vibrio cholerae, and Vibrio parahaemolyticus are the three most commonly encountered human pathogens in the Vibrio genus. They are frequent agents of foodborne illness contracted from seafood. The work presented here focuses on three aspects of detection of these bacteria. First is a novel agar formulation designed to isolate and directly enumerate V. vulnificus from oyster tissue by using x-gal, a chromogenic analog to lactose, as a carbon source and agent of differential morphological colony growth. Second is a field study on the relative abundance of the three main pathogenic Vibrios following the opening of the Bonnet Carre spillway to prevent the Mississippi River from flooding New Orleans. This influx of fresh water into the Mississippi sound had a significant impact on the salinity and enabled V. cholerae growth to dominate over the other two pathogenic Vibrios during the time the spillway was open. The third and last chapter of work presented here is the development and validation of a novel method for enumeration of V. parahaemolyticus in the viable but nonculturable state. This dormant state prevents the bacteria from being enumerated by standard methods. The work presented here allows enumeration of the bacteria from environmental waters in total, and when coupled with other methods, allows enumeration of the VBNC portion of the population. The work presented in this thesis serves to further characterize these bacteria and presents novel methods for their detection that may be used to mitigate their risk to human health.

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