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

The taxonomic identity of mio groups of bacteria from the intestinal microbial flora of fish in sea water previously called ''Gut vibrios'' were investigated. A number of strains were tested with respect to morphology, motility, nutrient requirements, salinity and temperature optima and ranges, susceptibility to antibacterials, pathogenicity, guanine-plus-cytosine contents of their deoxyribonucleic acid, DNA-DNA similarities and 16S ribosomal RNA (16S rRNA) sequences. It was confirmed that both groups of bacteria belong to the genus Vibrio. The first group appears to represent a Vibrio species not previously described. We propose the name Vibrio iliopiscarius sp. nov. for this new species. Strains of the other bacterial group were identified as strains of V. salmonicida. These ''intestinal strains'' of V. salmonicida differ from the previously described pathogenic strains with respect to biochemical and serological characteristics. The importance of the cold-water vibriosis bacterium, V. salmonicida, as part of the indigenous flora of fish is discussed.