TAXONOMICAL REEXAMINATION OF 2 PATHOGENIC VIBRIO SPECIES ISOLATED FROM MILKFISH AND SWIMMING CRAB

A taxonomical re-examination of two pathogenic bacteria belonging to t he genus Vibrio, one from an eye disease of milkfish (Chanos chanos) i n the Philippines and the other from vibriosis of larval swimming crab (Portunus trituberculatus) in Japan, was made by examining their phen otypic features and measuring DNA-DNA relatedness. As a result, the ba cterium from milkfish was identified as V. harveyi based on the high D NA homology value of above 84% between the two milkfish isolates and t he type strain of V. harveyi and coincidence in phenotypic characteris tics. Strain 85Z-1, the representative strain of the causative bacteri um (Vibrio sp. Zoea) of vibriosis in swimming crab, showed higher DNA relatedness than 75% to other 3 strains of Vibrio sp. Zoea, about 50% relatedness to strains of V. harveyi, and lower relatedness than 46% t o the other species examined. These results indicate that Vibrio sp. Z oea is a new genomic species most closely to V, harveyi. However, it i s difficult to distinguish phenotypically Vibrio sp. Zoea from V, harv eyi isolated from milkfish, thus species name for Vibrio sp. Zoea coul d not be proposed.