一株引起香鱼出血症的嗜水气单胞菌的鉴定

Isolation,Identification and Phylogenetic Analysis of a Bacterium Aeromonas hydrophila Causing Ayu(Plecoglossus altivelis)Hemorrhage Disease

从发生出血症的香鱼体腔液分离到一高致病性的菌株（ayu-ah0201）,经人工侵染试验证实该菌能引起香鱼出血症。对该菌的形态、生理生化及16S rDNA序列分析结果表明,其为革兰氏阴性,短杆状,极生鞭毛。对蔗糖、阿拉伯糖、七叶苷、氧化酶、精氨酸双水解酶、赖氨酸脱羧酶呈阳性,鸟氨酸脱羧酶呈阴性。可利用葡萄糖产酸产气。在以该菌16S rDNA序列和GenBank数据库内同源性较高的细菌16S rDNA序列构建的系统发育树,表明分离菌ayu-ah0201与嗜水气单胞菌聚在一簇,与嗜水气单胞菌核苷酸序列同源性最高,为99.6%~99.7%,与其他相关气单胞菌属成员的核苷酸序列同源性小于98.9%。结合形态和生理生化特点将其鉴定为嗜水气单胞菌。

A pathogenic bacterium （ayu-ah0201） was isolated from the coelomic fluid of ayu（Plecoglossus altivelis）with hemorrhage disease. Artificial infection proved that hemorrhage disease of the ayu was induced by this bacterium. The strain was examined for morphological, physiological, and biochemical characteristics, and 16S rDNA sequencing proved to be a kind of gram negative, with polar multi-flagella, ornithine decarboxylase-negative, glucose-positive, sucrose-positive, rhamnose-positive, esculin-positive, lysine decarboxylase-positive and Arginine dihydrolase-positive. The bacterium can utilize glucose for production of acid and gas. A phylogenetic tree was constructed by comparing with the 16S rDNA sequence of the isolated strain with other relative bacterium species in GenBank. The ayu-ah0201 and Aeromonas hydrophila clustered into one clade. The homoeology between the two strains was 99.6%-99.7%. According to morphological, physiological, biochemical characteristics and phylogenetic analysis, the isolated strain （ayu-ah0201） was identified as Aeromohas hydrophila.