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

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.

Key words:Gut microbiota, Lactic acid bacteria, Bifidobacterium, Specific primers, Single-molecule real-time sequencing technology (SMRT)