COMPARATIVE-STUDY ON FLEXIBACTER-MARITIMUS STRAINS ISOLATED FROM FARMED SEA BASS (DICENTRARCHUS-LABRAX) IN FRANCE

Following severe outbreaks of a disease with dermal necrosis, several bacterial strains were isolated from sea bass (Dicentrarchus labrax) r eared on French coasts. A phenotypic study revealed that the isolates closely resembled Flexibacter maritimus. Nine selected strains were co mpared to 8 F. maritimus reference strains from other geographical ori gins and to the type strain NCIMB 2154T. DNA base composition of the s trains tested was in the G + C range of 30.6 to 32mol%. A study on the DNA relatedness among the strains by the S1 nuclease DNA-DNA hybridiz ation method showed that the 12 strains tested formed a tight genomic species with DNA homologies above 74%. The profiles obtained from API ZYM galleries, polyacrylamide gel electrophoresis of whole-cell protei ns, and fatty acids analysis revealed that F. maritimus is a very homo geneous bacterial species. This is the first identification of this fi sh pathogen in France and its first isolation from sea bass.