基于多位点序列分型对新疆人及动物食品源性粪肠球菌种群进化关系解析

Clonal Relationships among Enterococcus faecalis from Humans and Animal-Origin Foods in Xinjiang Characterized by Multilocus Sequence Typing

从母乳、奶酪、马奶、驼奶以及冷水鱼肠道中共分离得到59株粪肠球菌。通过多位点序列分型技术分析不同来源分离株的种群结构和进化关系。结果表明,59株分离株被划分为12个序列型,3个克隆复合体和3个独特型,没有序列型被划分为高风险克隆复合体。持家基因分裂分解分析结果显示,基因重组在粪肠球菌进化过程中发挥了重要的作用。通过最小生成树分析发现,粪肠球菌遗传关系与分离地区的相关性较弱。尽管eBURST和系统发育分析表明母乳源和冷水鱼源的粪肠球菌具有一定的宿主特异性,但在奶酪、驼奶和马奶中仍然可以检测到与其密切相关的粪肠球菌克隆。结果表明,来自不同宿主的粪肠球菌将适应新的生态位,并通过生产实践和食物链传播。为减少人畜共患病的潜在风险,有必要进行持续监测。

In this study,the population structure and evolutionary relationships of 59 Enterococcus faecalis strains isolated from breast milk,cheese,camel milk,mare milk and cold water fish from Xinjiang were analyzed by multilocus sequence typing(MLST).All the isolates were allocated into 12 sequence types,including three clonal complexes and three singletons.None of the sequence types were found to belong to high risk clonal complexes.Housekeeping gene split decomposition analysis indicated that gene recombination could be a major driving force in the evolution of E.faecalis.The results of minimum spanning tree indicated these E.faecalis strains were relatively weakly related to their geographical origin.Although eBURST and phylogenetic analysis demonstrated that the isolates from breast milk and cold water fish exhibited host specificity,E.faecalis clones closely related to them were still detected in breast milk,cheese,mare milk and camel milk.Taken together,E.faecalis from different hosts can adapt to new niches and spread via production practice and the food chain.Continuous monitoring is necessary to reduce the potential risk of zoonotic diseases.