[目的]探究生活在相同环境下，同年龄段健康藏族人群和汉族人群肠道细菌组成的多样性特征及其可能的成因。[方法]入选同专业的20-24岁男性健康藏族学生和汉族学生各20名，同一时间段收集新鲜粪便，提取新鲜粪便细菌总DNA，通过高通量测序和生物信息学分析，结合对饮食习惯的问卷调查，研究健康藏族学生与汉族学生肠道细菌多样性与饮食习惯之间的关系。[结果]从40份样本中，测序共得到2880个OTU，alpha和beta多样性分析表明，生活在相同环境下，不同民族男性学生的肠道细菌组成有明显差异。Prevotella 9、Bacteroides和Lachnoclostridium等18个属为两民族学生共有，同时，Prevotella 9、Faecalibacterium和Succinivibrio等10个属细菌为对两民族学生肠道细菌组成差异具有显著性影响的标志性菌属。进一步聚类分析表明，所有学生样本分为ET F型、ET P型、ET F和ET B混合型3种不同肠型，随访调查结果显示不同类型分别对应以脂肪为主和以淀粉为主的不同饮食习惯。[结论]生活在相同环境下，健康藏族和汉族学生的肠道细菌组成特征及其差异可能与遗传因素及饮食习惯密切相关。
[Objective] To understand the diversity characteristics and possible causes of gut bacterial composition of healthy Tibetan and Han population in the same age group living in the same environment. [Methods] Healthy male students including 20 Tibetan and 20 Han aged 20-24 in the same major of the same campus volunteered for this study. Total DNA was extracted from fresh feces collected at the same day from male healthy Tibetan and Han students in the same grade. The V3-V4 region of 16S rRNA were amplified by PCR then sequenced on Illumina MiSeq platform. The sequencing results were analyzed with bioinformatic softwares combined with Dietary status questionnaire to study the relationship between gut bacterial diversity and dietary habits of healthy Tibetan and Han students. [Results] A total of 2880 OTUs were obtained from 40 samples. Alpha and beta diversity analysis showed that male students from different ethnic groups had significantly different gut bacterial compositions under the same environment. Prevotella 9, Bacteroides, Lachnoclostridium and other 15 genera are shared by both Tibetan and Han students. Meanwhile, the composition and abundance of 10 genera, such as Prevotella 9, Faecalibacterium, Succinivibrio etc., are the biomarkers that have significant influence on the difference of intestinal bacteria composition between the two ethnic students. Further cluster analysis showed that all the student samples were divided into three enterotypes:ET F, ET P, mixed ET F and ET B. The follow-up survey results showed that different enterotypes corresponded to different dietary habits based on fat and starch. [Conclusion] Living in the same environment, the composition and differences of gut bacteria of healthy Tibetan and Han students may be closely related to genetic factors and dietary habits.