罗伊氏乳杆菌肠道分离株的遗传多样性研究

Genetic diversity of Lactobacillus reuteri isolated from intestines

摘要:

动物体内定殖着丰富且多样的细菌，其对宿主的健康发挥着举足轻重的作用。罗伊氏乳杆菌（Lactobacillus reuteri）是存在于动物肠道中的益生菌，是研究肠道菌群与宿主进化关系的模式菌种。[目的]以下载自NCBI的分离自猪、家禽类、人类、啮齿类动物的116株L. reuteri和分离自内蒙古锡林郭勒牛、羊和马肠道中的16株L. reuteri为研究对象，解析L. reuteri不同分离株的遗传多样性和宿主特异性，为L. reuteri的开发利用提供理论依据。[方法]利用MLST技术，以ddl、pkt、leuS、gyrB、dltA、rpoA、recA共7个看家基因为研究靶点，对L.reuteri分离株遗传多样性进行研究，推演分离株与宿主生境的进化关系。[结果]132株L.reuteri共划分为63个序列型，6个克隆复合体。等位基因序列重组分析发现，在L. reuteri的进化中发生了个别的重组事件，eBURST、MSTree分析表明不同分离源的L. reuteri分离株经历了不同的进化过程，系统发育分析表明132株L. reuteri来自5个Clusters且与分离源表现出较强的相关性。[结论]本研究利用MLST技术完成了132株L. reuteri肠道分离株的遗传多样性分析，利用MSTree、系统发育等群体结构分析，发现不同分离源菌株有着高度的宿主特异性，表明L. reuteri为适应不同生存环境经历了不同的进化过程。

关键词:罗伊氏乳杆菌;多位点序列分型技术;肠道;宿主特异性

Abstract:

Thousands of bacteria are colonized in the intestinal tract of animals. Lactobacillus reuteri is a probiotic in animal gut and model strain for studying the evolutionary relationship between gut microbiota and host. [Objective] To study genetic diversity and host specificity of different isolates of L. reuteri, we analyzed 132 strains of L. reuteri including 116 strains isolated from human, poultry, rodents and pigs downloaded from NCBI database and 16 strains isolated from cow, sheep and horse in Inner Mongolia. [Methods] Seven housekeeping genes including ddl, pkt, leuS, gyrB, dltA, rpoA, and recA were used as targets in MLST (multilocus sequence typing) technology to study the genetic diversity of 132 L. reuteri and evolutionary relationship between strains and host habitats. [Results] All 132 strains of L. reuteri were assigned into 63 STs and 6 clonal complexes. Recombination analysis revealed that individual recombination events occurred during the evolution of L. reuteri. The eBURST and MSTree analysis showed that L. reuteri from different sources experienced distinct evolutionary processes. The 132 L. reuteri isolates were classified into 5 clusters by phylogenetic analysis, according to their correlation with the sources. [Conclusion] L. reuteri from different sources had high host specificity, indicating that L. reuteri may experience different evolutionary processes to adapt the distinct living environments.

Key words:Lactobacillus reuteri;multilocus sequence typing technique;intestinal tract;host specificity