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RESEARCH PRODUCT

A Polyphasic Approach to Study the Intraspecif ic Diversity Amongst Vibrio vulnificus Isolates

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Summary A polyphasic taxonomic approach using phenotypic and molecular genetic techniques, was carried out on the species Vibrio vulnificus in order to study its intraspecific diversity. Seven techniques, including phenotypic (API 20E, BIOLOG, total protein profiles, serotyping, ELISA), and genotypic methods (ribotyping and AFLP), were employed on 80 V. vulnificus strains of biotypes 1 and 2, including 9 reference cultures. The isolates came from different geographic origins (USA, Spain, Belgium, Sweden, Norway, Japan, Thailand) and types of samples (clinical, health/diseased fish, seafood, water). Diversity indexes calculated for strains of both biotypes revealed a higher phenotypic and genetic diversity of biotype 1 strains in contrast with the homogeneity shown by biotype 2 strains. A species profile was established for the species V. vulnificus by BIOLOG and SDS-PAGE. Serotyping allowed a clear separation within species level, and grouped typical and atypical biotype 2 strains in one serovar. Genetic fingerprinting techniques, especially AFLP, were able to differentiate within strains belonging to the same serovar, allowing the tracking of specific clones in epidemiologic or ecological studies. The techniques employed do not support the maintenance of the two biotypes established for the species.