BACKGROUND Accumulating evidence is supporting the protective effect of whole grains against several chronic diseases. Simultaneously, our knowledge is increasing on the impact of gut microbiota on our health and on how diet can modify the composition of our bacterial cohabitants. Herein, we studied C57BL/6 J mice fed with diets enriched with rye bran and wheat aleurone, conventional and germ-free C57BL/6NTac mice on a basal diet, and the colonic fermentation of rye bran in an in vitro model of the human gastrointestinal system. We performed 16S rRNA gene sequencing and metabolomics on the study samples to determine the effect of bran-enriched diets on the gut microbial composition and the potential contribution of microbiota to the metabolism of a novel group of betainized compounds. RESULTS The bran-enriched study diets elevated the levels of betainized compounds in the colon contents of C57BL/6 J mice. The composition of microbiota changed, and the bran-enriched diets induced an increase in the relative abundance of several bacterial taxa, including Akkermansia, Bifidobacterium, Coriobacteriaceae, Lactobacillus, Parasutterella, and Ruminococcus, many of which are associated with improved health status or the metabolism of plant-based molecules. The levels of betainized compounds in the gut tissues of germ-free mice were significantly lower compared to conventional mice. In the in vitro model of the human gut, the production of betainized compounds was observed throughout the incubation, while the levels of glycine betaine decreased. In cereal samples, only low levels or trace amounts of other betaines than glycine betaine were observed. CONCLUSIONS Our findings provide evidence that the bacterial taxa increased in relative abundance by the bran-based diet are also involved in the metabolism of glycine betaine into other betainized compounds, adding another potential compound group acting as a mediator of the synergistic metabolic effect of diet and colonic microbiota.

中文翻译：

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肠道菌群对小鼠日粮甘氨酸甜菜碱代谢和体外结肠发酵的贡献。

背景技术越来越多的证据支持全谷物对几种慢性疾病的保护作用。同时，我们对肠道菌群对我们健康的影响以及饮食如何改变细菌同居者组成的知识的了解正在增加。在这里，我们研究了在人类胃肠道体外模型中饲喂富含黑麦麸和小麦糊粉的饮食的C57BL / 6 J小鼠，基础饮食中常规和无菌的C57BL / 6NTac小鼠以及黑麦麸的结肠发酵系统。我们对研究样品进行了16S rRNA基因测序和代谢组学研究，以确定富含麸皮的饮食对肠道微生物组成的影响以及微生物群对一组新型甜菜碱化合物代谢的潜在影响。结果富含麸质的研究饮食提高了C57BL / 6 J小鼠结肠内容物中甜菜碱化化合物的水平。微生物群的组成发生了变化，富含麸皮的饮食导致几种细菌类群的相对丰度增加，包括阿克曼菌，双歧杆菌，肠杆菌科，乳杆菌，副沙雷氏菌和Ruminococcus，其中许多与改善的健康状况或新陈代谢有关基于植物的分子。与常规小鼠相比，无菌小鼠肠道组织中的甜菜碱化合物水平显着降低。在人肠道的体外模型中，在整个培养过程中观察到了甜菜碱化合物的产生，而甘氨酸甜菜碱的水平却下降了。在谷物样品中 仅观察到甘氨酸甜菜碱含量低或痕量的其他甜菜碱。结论我们的发现提供了证据，表明麸皮饮食对细菌类群的相对丰度增加也参与了甘氨酸甜菜碱向其他甜菜碱化合物的代谢，从而增加了另一种潜在的化合物基团，其作为饮食与食物的协同代谢作用的介质。结肠菌群。