罗非鱼维罗纳气单胞菌的分离鉴定

Isolation and Identification of Aeromonas veronii in Tilapia

为了解云南某渔场罗非鱼大量死亡的原因,通过病原分离纯化,表型鉴定及16SrRNA测序分析,从发病和濒死鱼中分离纯化了4株革兰阴性杆菌(Av1、Av2、Av3、Av4),其培养特性、菌体形态、生化特征与维罗纳气单胞菌相同;用PCR方法扩增4株纯化菌的16SrRNA基因,得到大小相同的片断,选取条带明亮的Av3进行16SrRNA测序分析,与GenBank中的维罗纳气单胞菌B565株核苷酸同源性为100%。用核苷酸同源性99%以上的序列构建系统进化树,Av3与运动性气单胞菌聚类。综合动物回归试验结果,确定维罗纳气单胞菌(Aeromonas veronii)是导致该渔场罗非鱼大量死亡的主要病原之一。

To confirm the cause of massive death happened in a tilapia farm in Yunnan province, samples were col- lected from diseased tilapia, and the bacterial isolation, purification, phenotypic identification and 16S rRNA se- quencing analysis were conducted. Study results showed that 4 strains of Gram negative bacilli （Avl, Av2, Av3, Av4） were isolated, which similar to Aeromonas veronii in cultural traits, mycelial morphology and biochemical characters. In addition, 16 S rRNA genes of the 4 purified strains were amplified by PCR method and amplified fragments were sequenced, the nucleotide homology analysis results found that Av3 and Aeromonas veronii strain 13565 share identical 16 S rRNA genes. Phylogenetic tree were constructed by selected strains, and sequences share 99 % or more nucleotide homology from GenBank, and Av3 was clustered with Aeromonas. Combination with re- sults of experimental infection of tilapia with four isolated bacilli, the cause of outbreak was identified as Aero- monas veronii infection.