柠檬明串珠菌及相近种部分持家基因的系统发育分析

Phylogenetic analysis of closely related Leuconostoc citreum species based on partial housekeeping genes

【目的】利用16S rRNA、dnaA、murC和pyrG基因分子标记研究Leuconostoc citreum(Leu.citreum)及相近种间的种系发育关系,并比较这些基因序列对Leu.citreum及相近种的区分能力。【方法】以分离自酸面团中的7株Leu.citreum为研究对象,以dnaA、murC和pyrG基因片段为标记,通过PCR扩增、测序,结合已公布的近缘种及亚种相应序列,计算遗传距离,构建系统发育树,并与16S rRNA基因进行比较。【结果】研究发现Leu.citreum及相近种间的dnaA、murC和pyrG基因构建的系统发育树拓扑结构与16S rRNA基因基本一致,区别在于相似性的不同,其分别为75.5%-97.2%、50.2%-99.7%、65.0%-99.8%和98.5%-100%。【结论】在Leu.citreum及相近种间的种系发育关系中,dnaA、murC和pyrG基因与16S rRNA基因系统进化关系都具有很好的一致性,但这三个持家基因的遗传距离显著高于16S rRNA基因。因此,采用dnaA、murC和pyrG基因可以用于Leu.citreum及相近种的分类鉴定。

[ Objective] Using the 16S rRNA, dnaA, murC and pyrG gene sequences, we identified the phylogenetic relationship among closely related Leuconostoc citreum species. [ Methods] Seven Leu. citreum strains originally isolated from sourdough were characterized by PCR methods to amplify the dnaA, murC and pyrG gene sequences, which were determined to assess the suitability as phylogenetic markers. Then, we estimated the genetic distance and constructed the phylogenetic trees including 16S rRNA and above mentioned three housekeeping genes combining with published corresponding sequences. [ Results] By comparing the phylogenetic trees, the topology of three housekeeping genes trees were consistent with that of 16S rRNA gene. The homology of closely related Leu. citreum species among dnaA, murC, pyrG and 16S rRNA gene sequences were different, ranged from75.5% to 97.2% , 50.2% to 99.7% , 65.0% to 99.8% and 98.5% 100%, respectively. [ Conclusion] The phylogenetic relationship of three housekeeping genes sequences were highly consistent with the results of 16S rRNA gene sequence, while the genetic distance of these housekeeping genes were extremely high than 16S rRNA gene. Consequently, the dnaA, murC and pyrG gene are suitable for classification and identification closely related Leu. citreum species.