NUMERICAL TAXONOMY OF VIBRIONACEAE ISOLATED FROM OYSTERS AND SEAWATER ALONG AN ANNUAL CYCLE

A numerical taxonomic study on Gram negative heterotrophic facultative anaerobic bacteria isolated from marine samples (oysters and seawater of Western Mediterranean Sea) was performed. Three hundred sixty eight strains, including reference strains of most species of the Vibrionaceae, were characterized (96 tests per strain). Cluster analysis of similarity matrices obtained with S-SM and S-J coefficients was performed and S-J-based tree and 0.75 S level selected for definition of phena. Larger phena corresponded to nonluminescent Vibrio splendidus biotype 1 and V. harveyi. The species V. tubiashii (an oyster larvae pathogen), V. pelagius, V. mediterranei, V. orientalis and Photobacterium angustum were also represented. Minor phena corresponded to V. damsella, V. fisheri, V. alginolyticus and several unidentifiable phena that might represent new species of Vibrionaceae. The absence of human pathogens such as V. parahaemolyticus and V. vulnificus was noticeable. Some identification problems concerning xanthine and arginine dihydrolase (ADH) tests were highlighted by the analysis.