SPECIES-SPECIFIC DETECTION OF VIBRIO-ANGUILLARUM IN MARINE AQUACULTURE ENVIRONMENTS BY SELECTIVE CULTURE AND DNA HYBRIDIZATION

Methods for specific detection of Vibrio anguillarum in complex microb ial communities within diverse marine aquaculture environments were ev aluated, A system for the detection of culturable cells based on the c ombined use of a selective medium and a nonradioactlvely labeled oligo deoxynucleotide complementary to 16S rRNA was developed. Four hundred fourteen bacterial cultures were evaluated in order to assess the spec ificity of the method. When both the selective medium and the specific probe gave positive results, the cultures were always identified as V . anguillarum. The selectivity for colony hybridization was 1 V, angui llarum cell in 10,000 total bacterial cells in environmental samples, The utility of the method was also compared with detection by dot blot hybridization of either raw DNA purified from environmental samples o r PCR-amplified DNA of 16S rRNA genes, using universal eubacterial pri mers. The post-PCR hybridization was more sensitive (8 x 10(2) cells) than direct hybridization of the whole purified DNA (10(6) cells). How ever, the selective medium-probe combined method was as sensitive as p ost-PCR hybridization, albeit more specific.