健康蒙古族人肠道中乳酸菌和双歧杆菌多样性

Diversity of lactic acid bacteria and Bifidobacterium in the intestine of healthy Mongolians

摘要:

【背景】越来越多的研究发现人类的诸多疾病与肠道菌群失衡有关。乳酸菌和双歧杆菌属于肠道中的有益菌，在不同人群肠道中的多样性不尽相同。【目的】在种水平上分析健康蒙古族人群肠道菌群中乳酸菌和双歧杆菌的多样性。【方法】以27名健康蒙古族志愿者为研究对象，其中14名来自中国内蒙古，13名来自蒙古国。首次采用乳酸菌和双歧杆菌的特异性引物扩增与PacBio SMRT三代测序技术相结合，在种水平上探讨志愿者肠道中乳酸菌和双歧杆菌的丰度和生物多样性，并进一步分析性别、BMI (Body mass index)值和地域对上述两者可能的影响，以及优势菌种之间的相关性。【结果】在种的水平上，27名志愿者肠道样品中共鉴定到68个乳酸菌和11个双歧杆菌，其中平均相对含量在1%以上的乳酸菌有8个，包括唾液链球菌(Streptococcus salivarius，36.41%)、瘤胃乳酸杆菌(Lactobacillus ruminis，17.94%)、德氏乳杆菌(Lactobacillus delbrueckii，3.11%)、罗氏乳杆菌(Lactobacillus rogosae，2.23%)、轻型链球菌(Streptococcus mitis，2.18%)、阴道乳杆菌(Lactobacillus vaginalis，2.02%)、魏斯氏乳杆菌(Weissella confusa，1.54%)和鼠李糖乳杆菌(Lactobacillus rhamnosus，1.09%)；双歧杆菌有5个，包括青春双歧杆菌(Bifidobacterium adolescentis，39.88%)、长双歧杆菌(Bifidobacterium longum，27.15%)、链状双歧杆菌(Bifidobacterium catenulatum，26.30%)、两歧双歧杆菌(B. bifidum，3.92%)和角双歧杆菌(Bifidobacterium angulatum，1.71%)，聚类分析分为链状双歧杆菌和青春双歧杆菌2个主要的类群。分析结果显示：性别、BMI值和地域均未能显著影响志愿者肠道中乳酸菌和双歧杆菌的菌群结构(p>0.05)，但男性和女性之间、中国内蒙古地区和外蒙古国的志愿者之间的个别乳酸菌菌种相对含量存在显著差异(p<0.05)。对样品中的优势乳酸菌和双歧杆菌进行Spearman相关性分析发现，乳酸菌和双歧杆菌彼此之间相关性较为密切，不同菌种间相关性不尽相同，与具体的菌种有关。【结论】首次采用PacBio SMRT测序技术在种的水平揭示了健康蒙古族人肠道中乳酸菌和双歧杆菌菌种多样性，为在种水平上解析肠道中乳酸菌和双歧杆菌多样性提供了新的研究思路和实施方案。

Abstract:

[Background] Intestinal flora performs a crucial role in human health and its imbalance may cause numerous pathological changes. Lactobacillus and Bifidobacterium are the main beneficial bacteria, which to some extent reflect the health status of the intestinal tract. However, the community structure of intestinal flora was different in different populations. [Objective] To analyze the diversity of lactic acid bacteria (LAB) and Bifidobacterium in the intestine of healthy Mongolians at the species level. [Methods] We studied the abundance and diversity of LAB and Bifidobacterium in 27 healthy Mongolians from Inner Mongolia Autonomous Region of China and Mongolia by using laboratory-designed LAB primers and Bifidobacterium-specific primers. This work also aimed to discuss the influence of gender, body mass index (BMI) and location on the quantities of these two bacterial groups, and to analyze the correlation between dominant strain. [Results] At the species level, a total of 68 LAB species and 11 Bifidobacterium species were detected in the intestine of 27 healthy Mongolians. Among them, eight LAB species were the most abundant species with relative abundances >1.0%, including Streptococcus salivarius (36.41%), Lactobacillus ruminis (17.94%), Lactobacillus delbrueckii (3.11%), Lactobacillus rogosae (2.23%), Streptococcus mitis (2.18%), Lactobacillus vaginalis (2.02%), Weissella confuse (1.54%) and Lactobacillus rhamnosus (1.09%). Meanwhile, Bifidobacterium adolescentis (39.88%), Bifidobacterium longum (27.15%), Bifidobacterium catenulatum (26.30%), Bifidobacterium bifidum (3.92%) and Bifidobacterium angulatum (1.71%) were the most abundant Bifidobacterium species with relative abundances>1.0%, and volunteers can be divided into two different groups (B. catenulatum group and B. adolescentis group) according to the composition of bifidobacteria by the cluster analysis. The results showed that the community structure of LAB and Bifidobacterium has no significantly correlation with gender, BMI value and region, and the community structure of LAB also no significantly correlation with BMI value, but there are significant differences in the relative abundances of several LAB species between men and women, between in Inner Mongolia and the Mongolian volunteers (P<0.05). This study also found significant correlations between dominant LAB and Bifidobacterium, and the correlation between different species was different and related to specific strains. [Conclusion] This is the first report on the use of PacBio SMRT sequencing technology to evaluate the diversity of lactic acid bacteria (LAB) and Bifidobacterium in the intestine of healthy Mongolians at the species level. Based on these data of intestinal flora, it is beneficial to achieve targeted regulation of intestinal flora and accurate medical treatment. In addition, our study could serve as good reference for other studies on the diversity of LAB and Bifidobacterium in the intestinal tract at the species level.