ENUMERATION AND DIFFERENTIATION OF VIBRIO-PARAHAEMOLYTICUS AND VIBRIO-VULNIFICUS BY DNA-DNA COLONY HYBRIDIZATION USING THE HYDROPHOBIC GRIDMEMBRANE FILTRATION TECHNIQUE FOR ISOLATION

We have developed a means of differentiating and enumerating Vibrio pa rahaemolyticus and Vibrio vulnificus by DNA-DNA colony, hybridization directly on HGMF filters. V. parahaemolyticus can be detected by a tdh -3-radiolabeled gene probe and V. vulnificus detected by a specific cy totoxin-hemolysin-radiolabeled probe with enumeration directly from au toradiograms. This procedure is more rapid than current techniques all owing enumeration and identification of these two species in samples a s diverse as seawater, oyster (Crassostrea gigas), and shrimp (Pandali dae family) within 4 d. Our method is based on a rapid technique (18 h ) for isolation and enumeration of V. parahaemolyticus from food using a membrane filtration technique with hydrophobic grid filters (HGMF). With the HGMF method, however, it is not possible to differentiate V. parahaemolyticus from V. vulnificus since on the HGMF-sucrose-based a gar used, the two species are indistinguishable as both species are un able to ferment sucrose. Using a combination of the HGMF and selective gene probes, these two species can be differentiated.