CHARACTERIZATION AND IDENTIFICATION OF 2 VIBRIO SPECIES INDIGENOUS TOTHE INTESTINE OF FISH IN COLD SEA-WATER - DESCRIPTION OF VIBRIO-ILIOPISCARIUS SP-NOV

The taxonomic identity of mio groups of bacteria from the intestinal m icrobial flora of fish in sea water previously called ''Gut vibrios'' were investigated. A number of strains were tested with respect to mor phology, motility, nutrient requirements, salinity and temperature opt ima and ranges, susceptibility to antibacterials, pathogenicity, guani ne-plus-cytosine contents of their deoxyribonucleic acid, DNA-DNA simi larities and 16S ribosomal RNA (16S rRNA) sequences. It was confirmed that both groups of bacteria belong to the genus Vibrio. The first gro up appears to represent a Vibrio species not previously described. We propose the name Vibrio iliopiscarius sp. nov. for this new species. S trains of the other bacterial group were identified as strains of V. s almonicida. These ''intestinal strains'' of V. salmonicida differ from the previously described pathogenic strains with respect to biochemic al and serological characteristics. The importance of the cold-water v ibriosis bacterium, V. salmonicida, as part of the indigenous flora of fish is discussed.