广西北部湾大宗海水养殖鱼类卵形鲳鲹感染溶藻弧菌及其致病性研究

【目的】2016年广西钦州湾近海网箱养殖的卵形鲳鲹(Trachinotus ovatus)发生以体表皮肤溃烂、皮下出血、内脏器官病变为典型症状的细菌性疾病,通过对患病卵形鲳鲹中病原菌进行分离、鉴定与保存,为后续开展病原菌快速检测技术和防控技术等研究,以及控制相关病原菌在海水养殖中的暴发和流行奠定基础。【方法】利用LB平板和TCBS平板从患病卵形鲳鲹体表溃烂病灶、肾脏、肝脏组织中分离纯化疑似病原菌,并对其进行常规形态特征和生理生化反应的生物学检验,通过16SrDNA基因测序对疑似病原菌株进行分子生物学鉴定,在细胞和鱼体水平开展病原菌的致病性研究,同时进行人工感染的回接试验。【结果】分离得到4株疑似病原菌(TOQZ01,TOQZ02,TOQZ03,TOQZ04),基于其表型、分子生物学特征和进化关系,判定4株菌株均为弧菌属的溶藻弧菌(Vibrio alginolyticus),且细胞毒性试验和回归试验证实,分离得到的溶藻弧菌为此次卵形鲳鲹发病的病原菌。【结论】溶藻弧菌是引起广西沿海地区海水养殖鱼类发生细菌性鱼病的主要致病菌之一,未来将基于本研究中分离得到的溶藻弧菌开展病害快速检测技术和防控技术等现代海水生态健康养殖关键技术研究,以实现对广西海水养殖溶藻弧菌病的快速诊断、实时监控和有效预防。

Isolation, Identification and Pathogenicity of Vibrio alginolyticus from Marine Cultured Trachinotus ovatus in Beibu Gulf, Guangxi

Objective] The Trachinotus ovatus cultured in offshore cages in Qinzhou Bay of Guangxi Province showed typical symptoms of bacterial diseases in 2016, including skin ulceration, subcutaneous bleeding and visceral lesions.By isolating, identifying and preserving the pathogenic bacteria in the diseased T.ovatus, it established the foundation for the follow-up research on the rapid detection technology and prevention and control technology of pathogenic bacteria, as well as controlling the outbreak and epidemic of related pathogenic bacteria in the marine culture.Methods] Four suspected pathogen strains were isolated from the ulcer lesions, kidney and liver of diseased T.ovatus by using LB and TCBS plates.Biological tests were conducted to check the conventional morphological characteristics and physiological and biochemical reactions.Molecular biology identification of the suspected pathogenic strains was performed by 16S rDNA gene sequencing.The pathogenicity of pathogenic bacteria was carried out at the level of cells and fish, and the re-inoculation of artificial infection was carried out simultaneously.Results] Four strains of suspected pathogens (TOQZ01, TOQZ02, TOQZ03, TOQZ04) were isolated and these four strains were identified as Vibrio alginolyticus based on their phenotypes, molecular biological characteristics and evolutionary relationships.The cytotoxicity and regression tests confirmed that the isolated V.alginolyticus were the pathogen, which caused the bacterial diseases in T.ovatus.Conclusion] Vibrio alginolyticus is one of the main pathogenic bacteria that cause bacterial fish disease in marine culture fish in the coastal areas of Guangxi.In the future, Vibrio alginolyticus isolated from this study will be used to carry out rapid disease detection technology and prevention and control technology and other key technologies of modern seawater eco-health farming in order to realize the rapid diagnosis, real-time monitoring and effective prevention of Vibrio alginolyticus in marine culture of Guangxi.