一株斑点叉尾致病菌的分离鉴定  

Isolation and identification of a pathogenic bacteria strain in channel catish(Ictalurus punctatus)

作　　者：任燕[1] 巩华[1] 陶家发[1] 梁慧丽[1] 刘礼辉[1] 石存斌[1] 吴淑勤[1] 

机构地区：[1]中国水产科学研究院珠江水产研究所,广州510380

出　　处：《淡水渔业》2011年第2期73-77,共5页Freshwater Fisheries

基　　金：农业公益性行业科研专项(200803013);现代农业产业技术体系建设专项资金(nycytx-49-14)

摘　　要：从斑点叉尾(Ictalurus punctatus)肝脏分离到的一株细菌GD091027,对该菌进行人工感染试验、生理生化特性测定和16S rRNA序列测定并构建系统发育树,同时进行了抗菌药物敏感性试验。结果显示:当人工感染剂量大于1.0×107 CFU/尾时,能引起斑点叉尾100%发病死亡,对斑点叉尾的LD50为6.2×104 CFU/g。分离株GD091027为革兰氏阴性短杆菌,氧化酶阴性,在25℃、35℃均有运动性,能耐3%的NaCl,不发酵葡萄糖、麦芽糖、蔗糖、D-甘露醇及L-阿拉伯糖,不利用西蒙氏柠檬酸盐,不利用丙二酸,赖氨酸脱羧酶和鸟氨酸脱羧酶阳性,产生硫化氢和吲哚,甲基红(MR)试验阴性。在16S rRNA系统发育树中,该菌与迟缓爱德华氏菌(Edwardsiella tarda)聚为一分支。分离株GD091027对氨苄西林、庆大霉素、妥布霉素等16种抗菌药物敏感,利福平、青霉素等3种抗菌药物不敏感。除不产生溶血、不发酵葡萄糖和麦芽糖、甲基红(MR)试验阴性外,病原菌形态及生理生化特征符合迟缓爱德华氏菌,结合16S rRNA序列分析结果将其鉴定为迟缓爱德华氏菌。A Gram-negative,rod shaped bacterium（designated as strain GD091027） was isolated from the liver of diseased channel catish（Ictalurus punctatus）.Artificial infection proved that GD091027 was the pathogen of the disease.When artificial infection dose reached 1.0×107 CFU/fish,the challenged channel catish presented 100% mortality and the LD50 to channel catish was 6.2×104 CFU/g.The isolated GD091027 was preliminarily identified as Edwardsiella tarda with the characteristics of gram-negative bacilli,motility at 25 ℃ or 35 ℃,growth in 3% salt water,Oxidase-negative;non-fermentation of glucose,maltose,sucrose,D-Mannitol,L-arabinose;non-utilization of Simmons citrate and malonic acid,lysine decarboxylase-positive,ornithine decarboxylase-positive,produce of H2S and Indole,methy1-red-negative.A phylogenetic tree was constructed by comparing the 16S rRNA gene sequence of the isolated GD091027 with other relative bacteria species in the RDP and GenBank databases.In the phylogenetic tree,the isolate and some E.tarda strains converged and constituted a branch,which confirm the identication of the isolated GD091027 as E.tarda.The drug sensitivity results showed the isolate GD091027 was highly sensitive to 16 kinds of antibiotics,such as ampieilin,gentamicin,tobramycin;while resistant to rifampicin,sulfamethoxazole trimethoprim,and penicillin.According to the morphological,physiological,biochemical characteristics and 16S rRNA gene analysis,the isolate（GD091027） was identified as E.tarda.

关 键 词：斑点叉尾(Ictalurus punctatus) 迟缓爱德华氏菌(Edwardsiella tarda) 16S RRNA 鉴定 

分 类 号：S961.2[农业科学—水产养殖]