岩原鲤致病性维氏气单胞菌的分离与鉴定

Identification of a pathogenic Aeromonas veronii isolated from rock carp,Procypris rabaudi

目的 2016年6月从重庆永川某养殖场濒临死亡的岩原鲤内脏分离到一株维氏气单胞菌,分析其生物学特征,为预防和治疗该病提供理论依据和参考。方法从患病鱼体获得一株致病菌YY01,经形态学观察、生理生化特性测定、16S rRNA和gyrB基因序列分析其分类地位;通过人工感染试验和毒力基因检测确定其致病性,并同时开展药物敏感试验筛选其敏感药物。结果病原菌16SrRNA与gyrB序列构建的进化树显示该菌与维氏气单胞菌同聚为一支,相似性在99%以上;结合其形态学特征和生理生化特性,确认为维氏气单胞菌(Aeromonas veronii)。人工感染试验结果显示菌株YY01对岩原鲤的半致死量为5.06×104 CFU/g。通过病原菌毒力基因检测发现,能从菌株YY01基因组中扩增到气溶素(Aer)、溶血素(Hly)、外膜蛋白(OmpA)和黏附素(Aha)4种毒力基因。药敏试验表明菌株YY01对多粘霉素B、阿米卡星、先锋霉素V等22种药物敏感;对青霉素、羧苄西林等11种药物耐药。结论所检出的维氏气单胞菌为岩原鲤的致病菌,该菌对岩原鲤有较强的致病性。

In June 2016,a disease among the cultured rock carp（Procypris rabaudi）in Yongchuan of Chongqing Municipality occurred.The aim of this study was to investigate biological characteristics and provide reference for Aeromonas veronii identification diagnosis and treatment.Pathogenic bacteria strain YY01 from the dying fishes were examined and isolated.Strain YY01＇s taxonomic status was identified by observing the morphology,studying the physiological and biochemical characters and sequencing the 16 SrRNA and housekeeping gene gyrB.Its pathogenicity was checked by artificial infection experiment and virulence genes.Furthermore,effective medicine was detected by drug sensitivity.The 16 SrRNA and gyrBgene sequence of the strain YY01 was more than 99% homology with that of Aeromonas veronii,suggesting that the pathogen was Aeromonas veronii,which was also identified by the results of biochemical analysis.The LD50 of strain YY01 to rcok carp was5.06×104 CFU/g.Four virulence genes were detected from YY01,including aerolysin（aer）,hemolysin（Hly）,Outer Membrane Protein Gene A（OmpA）and adhesion（Aha）genes.Antibiotic sensitivity assays showed that among 40 antibiotics tested,22 were sensitive and 11 were resistant.In conclusion,the strain YY01 is identified as Aeromonasveroniiand it is proved to have strong pathogenicity.