一种新的异育银鲫病原———腐败希瓦氏菌

A new pathogen of gibel carp Carassius auratus gibelio-Shewanella putrefaciens

摘要:

摘要:【目的】江苏盐城一家养殖场的异育银鲫暴发疾病，通过对病原进行研究，旨在为该病的防治提供理论依据和参考。【方法】从病鱼体表病灶和内脏中分离出优势菌株，经人工感染试验证实为病原菌。采用传统的形态、生理生化表型鉴定与16S rDNA 序列分析相结合的方法确定菌株的分类地位。运用K-B琼脂法对病原菌株进行药物敏感性测定。【结果】综合菌株形态、生理生化表型以及16S rDNA 序列分析的结果，确定该分离株为腐败希瓦氏菌(Shewanella putrefaciens)。回接感染试验证实腐败希瓦氏菌即是导致此次异育银鲫发病死亡的致病原，其半数致死量(LD50)为2.1×103cfu/g。该株腐败希瓦氏菌对吡哌酸、萘啶酸、氟哌酸、氟啶酸、氟苯尼考、利福平、美满霉素、氟罗沙星、恩诺沙星、复达欣、菌必治、先锋Ⅳ、罗红霉素和左氟沙星等抗生素敏感。【结论】首次报道了异育银鲫一种新的病原，说明腐败希瓦氏菌作为一种潜在的新病原也可 能会对异育银鲫的养殖造成威胁。

Abstract:

Abstract:［Objective］We studied a novel disease occurred among cultured Carassius auratus gibelio at a farm located in Yancheng City，Jiangsu Province． ［Methods］ The dominant bacteria were isolated from diseased fish． The pure culture of the isolated strain was analyzed using conventional physiological and biochemical tests，together with 16S rDNA gene sequencing． An experimental infection of Carassius auratus gibelio with the isolated strain was performed to fulfill the Koch postulates．K-B method was used for antibiotic susceptibility testing． ［Results］ The causal agent of the disease was finally proved to be one species of bacteria that was identified as Shewanella putrefaciens． Experimental infection with S．putrefaciens resulted in the same gross signs as naturally infected fish and the same bacteria were recovered in a pure culture from freshly dead fish． The LD50 of S． putrefacien was calculated as 2.1×103cfu/g．The result of drug sensitivity test showed that S． putrefaciens was sensitive to Pipemidic acid，Nalidixic acid，Fluperacid，Enoxacin，Florfenicol，Rifampicin， Minocycline， Fleroxacin， Enrofloxacin， Ceftriaxone， Cefalexin， Ceftazidine， Roxithromycin and Levofloxacin． ［Conclusion］ This is the first report on a new pathogen of Carassius auratus gibelio，revealing that S．putrefaciens as a potential new pathogen may pose a threat to the culture of Carassius auratus gibelio．