STUDIES ON BACTERIAL SEPTICAEMIC INFECTION AND CHARACTERIZATION OF PATHOGENIC BACTERIA ISOLATED FROM STONE FLOUNDER (KAREIUS BICOLORATUS L.)

We conducted examinations to two cases occurring farmed Stone flounder(Kareius bicoloratus L.)in 2001 and 2002 respectively, all diseased fishes exhibited traits of septicaemia infection. Preliminary pathogen identification studies based on bacteriological examination of damaged tissues, isolation and identification of pathogenic bacteria and experimental infection, showed that two examined cases were infected by the same Aeromonas salmonicida, in addition, Acinetobacter which was thought successive infection was examined from two in examined ten fishes. Identification of extensive phenotypic informations for60 pure cultures of A. salmonicida and 6 pure cultures of Acinetobacter were conducted, the 16S rRNA gene were sequenced to repre-sentative strains, molecular phylogenetic dendrogram was constructed. The results showed that the examined A. salmonicida was identified a new subspecies, the examined Acinetobacter was identified a newmorphotypeof Acinetobacter junii ; the phenotyicin-formations of this bacteria have been re-checked and identified by China Center for Type Culture Collection (CCTCC), and the mol % G +C ratio of the DNA for representative strains were detected, and nemed Aeromonas salmonicida as Aeromonas salmoni-cida subsp. flounderacida subsp. nov. ; and named A. junii as A. junii morphovar Ⅰ.