引起文蛤暴发性死亡病原菌的分离和鉴定

Pathogens Isolation and Identification of Eruptive Epidemic Disease in Meretrix meretrix

摘要:

本文从江苏吕泗文蛤养殖区发病文蛤和养殖水体中分离到5株优势菌(病蛤中分离到3株优势菌, 养殖水体中分离到2株优势菌), 人工感染实验结果显示, 菌株WG1702能引起供试文蛤发病, 死亡率为100%, 且发病症状与原发病症状相同, 提示该菌是引起文蛤大面积死亡的主要致病菌, 对其形态、生理生化特征、分类地位及致病性进行了初步研究, 菌株WG1702为革兰氏阴性菌, 直杆状, 生理生化指标为：赖氨酸脱羧酶、鸟氨酸脱羧酶、硝酸盐还原、甘露糖、氧化酶、甲基红阳性, 精氨酸脱羧酶、精氨酸双水解酶、水杨素、V.P阴性。为确定该致病菌的分类学地位, 进行了16S rRNA分子鉴定, PCR扩增获得了大小约1.5 kb的16S rRNA部分基因片段, 对其序列进行了测定, 并进行同源性分析和系统进化树构建。结果表明, 该菌株与哈氏弧菌(DQ146937)同源性最高, 为97.4%, 结合形态、生理生化鉴定结果, 最后鉴定菌株WG1702为哈氏弧菌(Vibrio.harveyi)。

Abstract:

Five kinds of bacteria were isolated from disease Meretrix meretrix and culture water (two isolated from the M. meretrix, three from the culture water) in Lvsi harbor, Jiangsu province. The results of infection showed that strain WG1702 can cause disease with the mortality rate 100 percent and the same symptoms as original. It was cued that strain WG1702 was the pathogenic bacteria and caused the death in large scare, a preliminary research was done on the bacteria including morphological, physiological, biochemical characteristics, phylogenetic position and pathogenic. Strain WG1702 was a straight-rod gram negative bacterium, the physiological and biochemical indicators were lysine decarboxylase, ornithine decarboxylase, reduction of NO3- to NO2-, mannitose, oxidase and methylred reaction positive, arginine decarboxylase, arginine dihydrolase, salicin and voges-proskauer negative. In order to identify the bacteria phylogenetic position and a 16S rRNA molecular identification was done, PCR amplification got a size of about 1.5 kb gene fragment, The whole 16S rRNA sequences were determined, analyzed the homology of sequences and built the phylogenetic tree. Sequences analysis revealed that strain WG1702 exhibited the highest level of 97.4% similarity to Vibrio harveyi(DQ146937), combining morphological, physiological and biochemical identification results, the isolated strain WG1702 was identified as Vibrio harveyi.