肠膜明串珠菌及其近缘种dnaA和rpoB基因的系统发育分析

Phylogenetic analysis of closely related Leuconostoc mesenteroides species based on dnaA and rpoB gene homologues

比较16S r RNA基因、dna A、rpoB部分基因序列对Leuconostoc mesenteroides（Leu.mesenteroides）及其近缘种的分辨力,为肠膜明串珠菌提供快速准确的鉴定方法。以分离自自然发酵乳制品中的8株Leu.mesenteroides为研究对象,以其看家基因dnaA、rpoB部分基因序列作为分子标记,结合Gene Bank数据库中的近缘种及亚种的相应序列构建系统发育树,并与16S r RNA基因的系统发育树进行比较。研究发现,基于Leu.mesenteroides及其近缘种的dna A和rpo B部分基因序列构建的系统发育树的拓扑结构与16S r RNA基因基本一致,但分辨率高于16S r RNA基因;种间的dna A和rpo B部分基因序列相似性分别为81.7~84.8%和85.5、87.4%,而种间16S r RNA基因相似性为98.1%~99.5%。相较于16S r RNA基因,dna A和rpo B基因更容易鉴定肠膜明串珠菌及其近缘种,其中rpo B可明晰区分试验菌株与肠膜明串珠菌亚种间的系统发育关系,因此rpo B基因可作为16S r RNA基因的辅助工具用于Leu.mesenteroides及其近缘种的快速鉴定。

The study aimed to compare the efficiency of 16S rRNA, dnaA, rpoB gene on the phylogenetic relationship of Leu. mesenteroides and its related species, to provide a rapid identification method of the Leu. mesenteroides strains.Two housekeeping genes, dnaA and rpoB gene, of eight Leu. mesenteroides strains originally isolated from traditional dairy products were used as phylogenetic markers to construct the phyloge- netic trees with the published corresponding gene sequences of reference strains in Genbank. The phylogenetic trees of 16S rRNA gene of tested strains and reference strains were also constructed. The topologies of the two housekeeping genes trees were consistent with that of 16S rRNA gene. However, homology of the close related Leu. mesenteroides species based on dnaA, rpoB and 16S rRNA gene sequences was differ- ent, ranging from 81.7% to 84.8%, 85.5% to 87.4%, and 98.1% to 99.5%, respectively. Compared with 16S rRNA gene, the dnaA and rpoB gene, were more appropriate for phylogenetic identification of Leu. mesenteroides and its related species. Meanwhile, considering the rpoB gene is competent to distinguish the test strains at the subspecies level, it can be used as an auxiliary tool for rapid classification and identification of Leu. mesenteroides and its related species.