不同来源粪肠球菌的比较基因组学分析

Complete genome analysis of food-derived Enterococcus faecalis

目的分析不同来源粪肠球菌全基因组特征及其分子进化规律。方法对收集的不同来源粪肠球菌进行全基因组序列测序,利用比较基因组学分析粪肠球菌的基因特征、耐药基因和毒力基因携带情况,并以此进行泛基因组和核心基因组分析,构建系统发育树,进行系统进化分析。结果6株不同来源粪肠球菌染色体全基因组序列全长为2450754~2731452 bp,共含有2669~3085个基因,基因组的平均GC含量为38.0%。粪肠球菌具有开放型泛基因组,而核心基因组为稳定型。不同来源菌株基因组中均含有3~14种耐药基因和8~17种毒力基因。基于核心基因系统进化树分析显示,不同来源的粪肠球菌分子进化均匀分布,相互重叠,无明显聚类趋势。结论粪肠球菌具有开放型泛基因组,其核心基因为稳定型,不同来源分离菌株进化均匀分布,这些结果为后续揭示粪肠球菌分子遗传进化规律等研究奠定了基础。

Objective To analyze the molecular characteristics of whole genome and the molecular evolution of diverse-source Enterococcus faecalis.Methods Diverse-source E.faecalis strains were collected,and whole-genome sequencing was performed using solexa sequencing technology.The comparative genomics approach was used to analyze genetic characteristics,drug-resistance genes and virulence genes in E.faecalis genomes.Furthermore,pan-genome and core genome analysis was performed and the phylogenetic tree was constructed.Results The whole-genome of six different-source E.faecalis ranged from 2,450,754 to 2,731,452 bp in length,of which contained 2,669 to 3,085 genes.These genomes had an average GC content of 38.0%.It was found that E.faecalis had an open pan-genome,while the core genome was stable.The genomes of strain from different sources contained 3~14 drug resistance genes and 8~17 virulence genes,respectively.The phylogenetic tree analysis based on core genes showed that the molecular evolution of E.faecalis from different sources was evenly distributed,overlapping,and no obvious trend were observed.Conclusion E.faecalis has an open pan-genome,and its core genes are stable and evolutionarily evenly distributed.These results will provide the foundation for understanding molecular genetic evolution of E.faecalis.