小鼠不同肠道段内容物和粪便中微生物的宏基因组测序和比较分析

Metagenomic Sequencing of Gut Microbiota along the Intestinal Tracts and Feces in Mice

随着二代测序技术的迅速发展，从宏基因组角度了解环境微生物成为可能。目前，动物肠道微生物研究大多以粪便作为实验样品，对肠道内部微生物情况了解甚少。研究以小鼠为模型，分别对十二指肠、空回肠、盲肠、结肠4个部分内容物进行了宏基因组测序和分析。结果显示，（1）在门水平上，十二指肠比其他肠段厚壁菌门减少、变形菌门增多；（2）在属水平上，大肠的优势菌属为螺杆菌、真细菌等，小肠优势菌属为链球菌、大肠杆菌、梭菌、肠球菌等，而且粪便与大肠优势菌分布趋势类似；（3）大肠和小肠肠道微生物相似度为0．62～0．77，粪便与各肠段微生物相似度为0．7～o．9；（4）粪便和肠道内容物细菌功能差异同其生理功能有一定关联。研究表明，小肠内容物与大肠内容物和粪便中微生物有明显差异，尽营粪便微生物与大肠内容物微生物类似。这一结果暗示着粪便微生物不能完全代表动物宿主肠道微生物的真实情况。

High speed development of metagenome and next generation sequencing made investigation of gut microbiota popular. The past researches related to microbe were mostly focused on feces instead of intestinal segment. In this study, contents of different intestinal segments including duodenum,jejunumileum,cecum,and colon were collected to examine the composition and distribution of microbiota by using the 16S rRNA sequencing technique in C57 mice. Results showed that（l）On the phylum level, duodenum contained less Firmicutes but more Proteobacteria. （2） On the genus level, the dominant genus in large intestine were Helicobacter,Eubacterium and so on while in small intestine contained more Streptococcus, Escherichia/Shigella,Clostridiurn,Enterococcus. （3）The relevancy between small and large intestine were 0. 62-0. 77,between feces and intestinal segments were 0. 7-0. 9. （4）The different function between feces and intestinal segment, which associated with infectious disease and xenobioties, were derived from the differences of that between feces and microbial community between small small intestine. We concluded that there were significant differences of and large intestine,feces and intestinal contents, respectively,through the similar microbial composition between feces and large intestine. Our study extended the understanding of dynamic shift of gut microbes along intestinal tract, also indicated the profile of feces microbiota couldn t completely reflected the actual circumstances of host gut microbiota.