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Abstracts
Workgroup: Public Health and Processing
Depuration of Galveston Bay Oysters (Crassostrea virginica) against Vibrio vulnificus Using Probiotic Bacteria
Principal Investigator(s):
Joe M. Fox, Texas A&M University, jfox@falcon.tamucc.edu
Funding Period: 1999-2000
The objectives of this study were to: 1) identify species/strains of probiotic bacteria to which V. vulnificus is sensitive; 2) evaluate probiotic depuration of oysters artificially infected with V. vulnificus; 3) compare this induced depuration to that of depuration of oysters having natural or inherent colonization; 4) evaluate semi-commercial depuration of oysters using criteria developed from the previous trials; and 5) make recommendations to the industry regarding appropriate depuration guidelines. Two studies were undertaken: Study 1), laboratory-scale in vitro and in vivo studies in aquaria; and Study 2), semi-commercial scale trials in 500 L tanks. Results from Study 1 indicated good sensitivity of ATCC Vibrio vulnificus to Alken-Murray Clear-FloTM 7026. Success in depuration was achieved under the following conditions: 800,000 cfu/mL density of probiotic, 48 h purging, 72 h contact with probiotic, 26 C and 22 ppt. Semi-commercial trials identified additional useful probiotic mixes, but indicated success at depuration was difficult with levels of autochthonous V. vulnificus in excess of 1,000 cfu/g. Semi-commercial depuration appears to be a function of both natural purging (holding) and use of probiotics. Some signs of enrichment were shown with depurant densities in excess of 800,000 cfu/mL. Depuration also appeared more successful at holding temperatures less than 26 C. Future research needs to be conducted in determining optimal environmental criteria for depuration using various probiotic mixes.
PROJECT PUBLICATIONS AND PRESENTATIONS:
Fox, J.M., Williams, K.R., Mott, J.B., and Samocha, T.M., 2001. Depuration of Galveston Bay Oysters Crassostrea virginica against Vibrio vulnificus using probiotic bacteria: Progress Report to National Sea Grant College Program. World Aquaculture 2001, January 21-25, Lake Buena Vista, Florida.
Williams, K.R., Fox, J.M., and Mott, J.B., 2001. Preliminary evaluation of the depuration of Galveston Bay oysters, Crassostrea virginica, against Vibrio vulnificus using probiotic bacteria: inherent variability of autochthonous levels. World Aquaculture 2001, January 21-25, Lake Buena Vista, Florida (poster).
Williams, K.R., Fox, J.M., Mott, J.B., and Samocha, T.M., 2001. Depuration of Galveston Bay Oysters Crassostrea virginica against Vibrio vulnificus using probiotic bacteria: a preliminary investigation. World Aquaculture 2002, January 27-30, Town and Country Resort, San Diego, California.
Bonnot, C.S., Fox, J.M., Mott, J.B., Samocha, T.M., and McKee, D.A., 2001. Evaluation of the depuration of Galveston Bay oysters, Crassostrea virginica, against Vibrio vulnificus under semi-commercial conditions using probiotic bacteria. World Aquaculture 2002, January 27-30, Town and Country Resort, San Diego.
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