鲤鱼嗜水气单胞菌的分离与鉴定

Isolation and Identification of Aeromonas hydrophila from Carp

[目的]分离、鉴定鲤鱼嗜水气单胞菌。[方法]从具有典型细菌性败血症症状的病鱼或濒死鱼中分离到2株优势菌,经分离培养、人工感染试验、毒力因子和16S rRNA基因序列的测定,研究分离菌的形态、生理生化特征及致病性。[结果]分离到的2株优势菌的菌落形态特征基本一致,经鉴定,确认为嗜水气单胞菌。无菌滤液试验表明,鲤鱼细菌性败血症不是由病毒引起的。腹腔注射分离菌菌悬液的鱼在7 d内全部死亡,人工感染试验的症状与自然发病相似,且再次感染后又可分离到该菌株。分离提纯的致病菌株产生了β-溶血环,经蛋白酶试验为阳性。16S rRNA基因序列同源性分析发现同源性为98%。[结论]嗜水气单胞菌是鲤鱼细菌性败血症的致病菌。

[Objective] The aim was to isolate and identify Aeromonas hydrophila from carp.[Method] 2 dominant bacteria strains were isolated from the diseased fish or dying fish with typical symptom of bacterial septicemia and their morphology,physiological and biochemical characteristics and the pathogenicity were studied through isolation and culture,artificial infection experiment and the detection of the virulence factor and the sequence of the 16S rRNA gene.[Result] The morphological characteristics of the 2 isolated dominant bacteria colonies were basically identical and they were A.hydrophila through identification.The results from culture filtrate showed that carp bacterial septicemia was not caused by virus.The fish injected intraperitoneally with bacterial suspension of the isolated bacteria were all died in 7 d.The symptom by artificial infection experiment was similar to that by natural infection and the strain was also obtained by isolation after secondary infection.The isolated and purified pathogenic strains produced β-hemolytic loop which was positive through the protease experiment.The analysis of the sequence homology of 16S rRNA gene found that the homology was 98%.[Conclusion] A.hydrophila was the pathogenic bacteria of carp bacterial septicemia.