4株气单胞菌临床分离株基于gyrB和rpoB基因序列的分子鉴定

目的对4株气单胞菌临床分离株进行菌种的分子鉴定,为气单胞菌的种型鉴定提供病原学依据。方法对4株系统生化鉴定为气单胞菌的菌株,提取核酸作为模板,分别使用gyrB、rpoB基因进行扩增及产物测序,将所得序列在GenBank中进行同源性搜索,与GenBank中已经公布的同源性较高的气单胞菌序列比较构建系统发育树并进行分析。结果 4株气单胞菌gyrB基因序列经同源性搜索,与多株嗜水气单胞菌和豚鼠气单胞菌同源性为99%,rpoB基因序列则与多株豚鼠气胞菌同源性为99%~100%,对gyrB基因和rpoB基因序列分别进行系统发育树分析显示,4株气单胞菌菌株在gyrB基因系统发育树中与多株嗜水气单胞菌和豚鼠气单胞菌聚为一簇,而在rpoB基因系统发育树中与多株豚鼠气单胞菌聚在同一分枝内。结论 4株气单胞菌经rpoB基因测序分析明确鉴定为豚鼠气单胞菌,gyrB基因测序分析不能有效鉴定其种型。

Molecular identification of 4 clinical Aeromonas isolates by gyrB and rpoB gene sequencing

Objective To identify the gene species of 4 clinical Aeromonas isolates and to provide the etiologic basis for the identification of Aeromonas species. Methods The isolates were identified as Aeromonas by conventional biochemical methods. The DNA of Aeromonas isolates was extracted as the template of PCR. The gyrB and rpoB gene were amplified and sequenced. Two sequence homology searches were conducted on GenBank and selected closely homology strains. Two molecular phylogenetic trees were constructed for analyze. Results The sequence homology of gyrB gene was 99% among Aeromonas isolates、 Aeromonas hydrophila and Aeromonas caviae strains,99%~100%(rpoB) among Aeromonas isolates and Aeromonas caviae strains. The phylogenetic tree of gyrB gene showed that 4 Aeromonas isolates、Aeromonas caviae strains and Aeromonas hydrophila strains were clustered in the same group. While 4 Aeromonas isolates fell into the same branch with Aeromonas caviae strains in the phylogenetic tree of rpoB gene.Conclusions Four Aeromonas isolates were identified as Aeromonas caviae by rpoB gene sequence. Aeromonas species could not be identified by gyrB gene sequence.