Department of Food Science and Technology, University of California, Davis, California, USA.
Foods for Health Institute, University of California, Davis, California, USA.
Appl Environ Microbiol. 2024 Aug 21;90(8):e0096424. doi: 10.1128/aem.00964-24. Epub 2024 Jul 15.
Members of the mammalian gut microbiota metabolize diverse complex carbohydrates that are not digested by the host, which are collectively labeled "dietary fiber." While the enzymes and transporters that each strain uses to establish a nutrient niche in the gut are often exquisitely specific, the relationship between carbohydrate structure and microbial ecology is imperfectly understood. The present study takes advantage of recent advances in complex carbohydrate structure determination to test the effects of fiber monosaccharide composition on microbial fermentation. Fifty-five fibers with varied monosaccharide composition were fermented by a pooled feline fecal inoculum in a modified MiniBioReactor array system over a period of 72 hours. The content of the monosaccharides glucose and xylose was significantly associated with the reduction of pH during fermentation, which was also predictable from the concentrations of the short-chain fatty acids lactic acid, propionic acid, and the signaling molecule indole-3-acetic acid. Microbiome diversity and composition were also predictable from monosaccharide content and SCFA concentration. In particular, the concentrations of lactic acid and propionic acid correlated with final alpha diversity and were significantly associated with the relative abundance of several of the genera, including and . Our results suggest that monosaccharide composition offers a generalizable method to compare any dietary fiber of interest and uncover links between diet, gut microbiota, and metabolite production.
The survival of a microbial species in the gut depends on the availability of the nutrients necessary for that species to survive. Carbohydrates in the form of non-host digestible fiber are of particular importance, and the set of genes possessed by each species for carbohydrate consumption can vary considerably. Here, differences in the monosaccharides that are the building blocks of fiber are considered for their impact on both the survival of different species of microbes and on the levels of microbial fermentation products produced. This work demonstrates that foods with similar monosaccharide content will have consistent effects on the survival of microbial species and on the production of microbial fermentation products.
哺乳动物肠道微生物群代谢宿主无法消化的各种复杂碳水化合物，这些碳水化合物统称为“膳食纤维”。虽然每种菌株用于在肠道中建立营养生态位的酶和转运蛋白通常非常特异，但碳水化合物结构与微生物生态学之间的关系还不完全清楚。本研究利用复杂碳水化合物结构测定的最新进展，测试纤维单糖组成对微生物发酵的影响。55 种具有不同单糖组成的纤维在改良的 MiniBioReactor 阵列系统中，由猫粪便接种物混合进行发酵，发酵时间为 72 小时。发酵过程中 pH 值降低与单糖葡萄糖和木糖的含量显著相关，短链脂肪酸（如乳酸、丙酸和信号分子吲哚-3-乙酸）的浓度也可以预测 pH 值降低。微生物组的多样性和组成也可以从单糖含量和 SCFA 浓度来预测。特别是，乳酸和丙酸的浓度与最终的 alpha 多样性相关，与包括 和 在内的几个属的相对丰度显著相关。我们的结果表明，单糖组成提供了一种可用于比较任何感兴趣的膳食纤维的通用方法，并揭示了饮食、肠道微生物群和代谢产物产生之间的联系。
微生物物种在肠道中的存活取决于该物种生存所需的营养物质的可用性。以非宿主可消化纤维形式存在的碳水化合物尤其重要，每种物种用于碳水化合物消耗的基因集合可能有很大差异。在这里，考虑了纤维的组成单糖的差异对不同微生物物种的存活以及微生物发酵产物产生水平的影响。这项工作表明，具有相似单糖含量的食物将对微生物物种的存活和微生物发酵产物的产生产生一致的影响。
