VIBRIO ICHTHYOENTERI SP-NOV, A PATHOGEN OF JAPANESE FLOUNDER (PARALICHTHYS-OLIVACEUS) LARVAE

Seven similar strains which were pathogens of Japanese flounder (Paral ichthys olivaceus) larvae with opaque intestines had characteristics o f the genus Vibrio, These strains were divided into two genomic specie s (species 1 containing six strains, and species 2 containing one stra in) on the basis of the results of DNA-DNA hybridization experiments i n which the membrane filter method was used, and these two species cou ld be differentiated from each other by the following characteristics: acid production from D-galactose and utilization of D-glucuronate and P-hydroxybutyrate, Strain F-2, the type strain of species 1, exhibite d levels of DNA relatedness with 29 previously described Vibrio specie s of 5 to 18%, The flounder isolates belonging to species 1 were also differentiated from the previously described Vibrio species phenotypic ally by the following characteristics: they were nitrate reduction pos itive; each cell had a single polar flagellum; they did not produce ar ginine dihydrolase, chitinase, gelatinase, and lipase; they did not ut ilize D-cellobiose and citrate; and they did not grow at 35 degrees C, The G+C contents of the DNAs of four species 1 strains were 43 to 44 mol%, The name Vibrio ichthyoenteri sp. nov. is proposed for genomic s pecies 1. The type strain of V. ichthyoeenteri is strain F-2 (= IFO 15 847), Species 2 was also considered a new genomic species, but a speci es name is not proposed in this paper because only one strain is avail able and the phenotypic variability of the species is not known.