南方鲇溃疡综合症病原菌的分离与鉴定

Isolation and Identification of Pathogenic Bacteria Causing Ulcer Disease of Silurus meriordinalis Chen

从南方鲇(Silurus meriordinalis Chen)病鱼体表溃疡部及内脏分离出细菌12株,经人工感染证实其中6株治病,生化鉴定6株为同一种菌即为引起该鱼溃疡综合症的病原菌,命名为DKN-1。该菌为革兰氏染色阴性,兼性厌氧发酵型短杆菌,极生单鞭毛,对除葡萄糖、麦芽糖、甘露糖、海藻糖、甘露醇、水杨苷、七叶苷以外多种糖不利用,氧化酶、过氧化氢酶、DNA酶、脂酶、蛋白酶、精氨酸双水解酶阳性,MR、VP阳性。在以该菌16S rDNA序列和GenBank及RDP数据库内同源性较高的细菌16S rDNA序列构建的系统发育树中,DKN-1与豚鼠气单胞菌(Aeromonas caviae)同源性达到99.6%,综合该菌在形态、生理生化的结果,鉴定其为豚鼠气单胞菌。该病病原对美满霉素、大观霉素、妥布霉素高度敏感。

12 strains of bacteria were isolated from ulcered and internal organs of Silurus meriordinalis Chen. It was proved that one of the bacteria was the pathogenic bacteria of ulcer disease by artificial infection experiment, and this bacteria was designated as DKN-1. The isolated strain was rod in shape, Gram negative, oxidase, catalase, DNAase, lipoidase, protease, arginine dihydrolase M-R and V-P positive, non-fermentative, polar flagellum. Excepting for glucose, malt- ose, mannose, mycose, manicol, manicol and manicol, many carbohydrates couldn＇ t be utilized with the production of acid. A phylogenetic tree was constructed by DNAstar based on 16S rDNA sequences of strain DKN-1 and other relative species in the RDP and GenBank databases. The phylogenetic tree showed that DKN-1 shared homologies of 99. 6% with A. caviae. Traditional biochemical and phylogenetic analysis identification revealed that DKN-1 was A. cavlae. The pathogenic bacteria was hypersensitive to minocycline, spectinomycin and tenemycin.