Chen X, Song Y Q, Xu H Y, Menghe B L G, Zhang H P, Sun Z H
Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, P. R. China.
Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, P. R. China.
J Dairy Sci. 2015 Aug;98(8):5183-93. doi: 10.3168/jds.2015-9571.
Enterococcus faecalis is part of the natural gut flora of humans and other mammals; some isolates are also used in food production. So, it is important to evaluate the genetic diversity and phylogenetic relationships among E. faecalis isolates from different sources. Multilocus sequence typing protocol was used to compare 39 E. faecalis isolates from Chinese traditional food products (including dairy products, acidic gruel) and 4 published E. faecalis isolates from other sources including human-derived isolates employing 5 housekeeping genes (groEL, clpX, recA, rpoB, and pepC). A total of 23 unique sequence types were identified, which were grouped into 5 clonal complexes and 10 singletons. The value of standardized index of association of the alleles (IA(S)=0.1465) and network structure indicated a high frequency of intraspecies recombination across these isolates. Enterococcus faecalis lineages also exhibited clearly source-clustered distributions. The isolates from dairy source were clustered together. However, the relationship between isolates from acidic gruel and one isolate from a human source was close. The MLST scheme presented in this study provides a sharable and continuously growing sequence database enabling global comparison of strains from different sources, and will further advance our understanding of the microbial ecology of this important species.
粪肠球菌是人类和其他哺乳动物自然肠道菌群的一部分；一些分离株也用于食品生产。因此，评估来自不同来源的粪肠球菌分离株之间的遗传多样性和系统发育关系很重要。采用多位点序列分型方案，利用5个管家基因（groEL、clpX、recA、rpoB和pepC）比较了39株来自中国传统食品（包括乳制品、酸粥）的粪肠球菌分离株和4株已发表的来自其他来源（包括人源分离株）的粪肠球菌分离株。共鉴定出23种独特的序列类型，它们被分为5个克隆复合体和10个单态型。等位基因标准化关联指数（IA(S)=0.1465）的值和网络结构表明这些分离株中种内重组频率较高。粪肠球菌谱系也表现出明显的来源聚类分布。来自乳制品来源的分离株聚集在一起。然而，来自酸粥的分离株与一株人源分离株之间的关系密切。本研究中提出的多位点序列分型方案提供了一个可共享且不断增长的序列数据库，能够对来自不同来源的菌株进行全球比较，并将进一步增进我们对这一重要物种微生物生态学的理解。
