大鲵源弗氏柠檬酸杆菌的分离鉴定及胞外酶活性研究  

The Isolation,Identification and Extracellular Enzyme Analysis of a Pathogen from Diseased Giant Salamander

作　　者：曹朕娇[1] 丁诗华[1] 凌空[1] 金娟[1] 吴兴镇 

机构地区：[1]西南大学动物科技学院水产系/水产科学重庆市市级重点实验室,重庆400715

出　　处：《西南大学学报（自然科学版）》2016年第5期13-18,共6页Journal of Southwest University(Natural Science Edition)

基　　金：重庆市科委应用开发项目(CSTC2013yykf80006)

摘　　要：为了确定重庆武隆大鲵养殖场患病大鲵的病原菌,并进行菌种鉴定及胞外酶活性研究,从具有典型症状的病鲵肝脏分离出一株菌株TNL12,根据形态学特征、生理生化特性及16SrDNA分析对菌株进行种类鉴定,通过人工感染试验确定病原菌株的致病性,利用平板法检测胞外酶活性.结果显示,所获菌株为革兰氏阴性短杆菌,无芽孢,其生理生化特性与弗氏柠檬酸杆菌一致.16SrDNA分析表明,TNL12与弗氏柠檬酸杆菌的同源性为99%,在系统发育树上与弗氏柠檬酸杆菌聚为一支.该病原菌可引起健康青蛙、大鲵出现感染症状,且感染症状与自然发病症状相似.胞外酶活性检测发现该菌可产卵磷脂酶、淀粉酶,但不产脂酶、蛋白酶、明胶酶、脲酶等胞外酶.这些研究结果表明,从患病大鲵中分离出的病原菌为弗氏柠檬酸杆菌,且对大鲵有较强的致病性.To isolate the pathogen of diseased giant salamander Andrias davidianus, identify the bacteria species, and determined its several extracellular enzymatic activities, a bacteria stain （TNL12） was separa ted from the liver of diseased individuals. The morphological, physiological and biochemical characteris- tics, and 16S rDNA sequence were analyzed for species identification. Its pathogenicity was tested by artifi- cial infection. The extracellular enzymatic activities were detected by plate method. The results showed that the bacteria strain was Gram-negative short bacillus without spores, and the physiological and bio- chemical characteristics were consistent with Citrobacter freundii. Its 16S rDNA sequence shared high ho- mology of 99 with Citrobacter freundii, and was in the same cluster as Citrobacter freundii on the phy- logenetic tree. Artificial infection with the bacteria to healthy frog and giant salamander induced the same diseased symptoms as occurred naturally. The pathogen produced lecithinase and amylase, but no activity of lipases, proteases, gelatinase, and urease were detected. In conclusion, the bacteria stain isolated from diseased giant salamander was Citrobacter freundii, which showed strong pathogenicity to giant salaman der.

关 键 词：大鲵 弗氏柠檬酸杆菌 分离鉴定 胞外酶活性 

分 类 号：S947.3[农业科学—水产养殖]