草鱼肠炎嗜水气单胞菌分离株的主要特性及系统发育学分析

Biological characterization and phylogenetic analysis of Aeromonas hydrophila from grass carp Ctenopharyngodon idellus

目的对分离于草鱼(Ctenopharyngodonidellus)肠炎的病原嗜水气单胞菌(Aeromonashydrophila),进行了主要理化特性方面较系统的表观分类学指征检验及系统发育学分析,为对该菌的有效鉴定提供依据。方法对死于肠炎病的鱼中分离到的5株病原嗜水气单胞菌(HC960715-1至HC960715-5),按常规方法进行形态特征、培养特性、主要生化及药物敏感性的检测。同时,择代表菌株(HC960715-1)进行16SrRNA基因的分子鉴定,测定16SrRNA基因序列、分析相关细菌相应序列的同源性,构建系统发生树。结果5株供试菌的主要生物学性状表现一致,代表菌株(HC960715-1)的16SrRNA基因序列长度为1429bp(GenBank登录号:AY966887),与GenBank数据库中的气单胞菌基因序列的相似性在98%和100%。结论根据表观分类学指征及系统发育分析结果,表明供试5株菌均为嗜水气单胞菌。对37种供试抗菌类药物的敏感性在株间无明显差异。

The identification of the phenotypie information of 5 strains of Aeromonas hydrophila isolated from Ctenopharyngodon idellus were conducted , including the morphological and cultural characteristics, physiological and biochemical properties as welt as the antimicrobial susceptibility testing. In addition, the molecular characterization of the representative strain HC960715-1 was undertaken to study the molecular identification and sequence determination of the 16S rRNA gene, as well as the homology analysis of the corresponding sequences among the related bacteria, from which it made the phylogenetic analysis possible. The results showed that the main biological characteristics of these 5 strains of A. hydrophila were identical. The 16S rRNA gene sequence of the representative strain HC960715-1 （ Database Accession Number in NCB1; AY966887） was 1429 bp in length and its similarity with Aeromonas species in GenBank database was 98%- 100%. All strains were highly sensitive to 25 antimierobial agents including cephadine eephradine, and moderately sensitive to 5 antimicrobial agents including eefazolin ere, but resistant to 7 antimicrobial agents including penicillin ete. However, no significant difference in drug susceptibility exists among different strains.