日本鳗鲡腐皮病病原菌的分离及鉴定

从患腐皮病的日本鳗鲡(Anguilla japonica)体表溃烂处分离到1株病原菌(322A),对其进行了人工感染实验和生理生化分析,测定了该菌株的16S rRNA基因序列和促旋酶(gyrase)B亚单位gyrB基因序列,并分别构建系统发育树。结果显示:感染实验证实菌株322A具有致病性;生理生化分析鉴定该菌株属于气单胞菌属(Aero-monassp.);16S rRNA基因分析显示,该菌株与气单胞菌属细菌的同源性均在99%~100%,构建的系统树显示,菌株322A与嗜水气单胞菌(A.hydrophila(FJ462702))亲缘关系最近;gyrB基因分析表明,该菌株与A.hydrophila种内序列的相似性为96%~98%,种间序列的相似性为94%~95%,构建的系统树结果显示,该菌株与A.hydrophila(FJ608553、FJ608552、AF208259)聚为一个分支。综合上述实验结果,菌株322A可鉴定为嗜水气单胞菌(A.hydrophila)。

Isolation and identification of the pathogen associated with skin canker of Japanese eel (Anguilla japonica)

Bacterial strain 322A was isolated from the sick Japanese eel(Anguilla japonica) with skin canker,its pathogenity was tested by muscle injection test.The strain was identified by physiological and biochemical method.16S rRNA and gyrase subunit beta(gyrB) genes sequences were determined,and phylogenetic trees were seperately based on the two genes.Strain 322A was proved to be a pathogen by infection test,and belonged to genus Aeromonas by physiological and biochemical identification method.Analysis of 16S rRNA genes showed that strain 322A exhibited 99%～100% similarity to Aeromonas sp..Phylogenetic tree indicated that strain 322A showed the highest level of similarity to A.hydrophila(FJ462702).Analysis of gyrB genes showed that strain 322A exhibited 96%～98% similarity to A.hydrophila,and 94%～95% similarity to the other species in genus Aeromonas.Phylogenetic tree showed that strain 322A clustered together with A.hydrophila(FJ608553,FJ608552,AF208259).Based on the results obtained,strain 322A was identified as A.hydrophila.