Food Engineering Department, Ordu University, Ordu, Turkey
Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, Indiana, USA.
mSphere. 2020 May 6;5(3):e00180-20. doi: 10.1128/mSphere.00180-20.
The chemical structures of soluble fiber carbohydrates vary from source to source due to numerous possible linkage configurations among monomers. However, it has not been elucidated whether subtle structural variations might impact soluble fiber fermentation by colonic microbiota. In this study, we tested the hypothesis that subtle structural variations in a soluble polysaccharide govern the community structure and metabolic output of fermenting microbiota. We performed fecal fermentation studies using arabinoxylans (AXs) from different classes of wheat (hard red spring [AX], hard red winter [AX], and spring red winter [AX]) with identical initial microbiota. Carbohydrate analyses revealed that AX was characterized by a significantly shorter backbone and increased branching compared with those of the hard varieties. Amplicon sequencing demonstrated that fermentation of AX resulted in a distinct community structure of significantly higher richness and evenness than those of hard-AX-fermenting cultures. AX favored OTUs within , whereas AX and AX favored Accordingly, metabolic output varied between hard and soft varieties; higher propionate production was observed with AX and higher butyrate and acetate with AX and AX This study showed that subtle changes in the structure of a dietary fiber may strongly influence the composition and function of colonic microbiota, further suggesting that physiological functions of dietary fibers are highly structure dependent. Thus, studies focusing on interactions among dietary fiber, gut microbiota, and health outcomes should better characterize the structures of the carbohydrates employed. Diet, especially with respect to consumption of dietary fibers, is well recognized as one of the most important factors shaping the colonic microbiota composition. Accordingly, many studies have been conducted to explore dietary fiber types that could predictably manipulate the colonic microbiota for improved health. However, the majority of these studies underappreciate the vastness of fiber structures in terms of their microbial utilization and omit detailed carbohydrate structural analysis. In some cases, this causes conflicting results to arise between studies using (theoretically) the same fibers. In this investigation, by performing fecal fermentation studies using bran arabinoxylans obtained from different classes of wheat, we showed that even subtle changes in the structure of a dietary fiber result in divergent microbial communities and metabolic outputs. This underscores the need for much higher structural resolution in studies investigating interactions of dietary fibers with gut microbiota, both and .
由于单体之间存在多种可能的连接构型，因此可溶性纤维碳水化合物的化学结构因来源而异。然而，目前尚不清楚细微的结构变化是否会影响结肠微生物群对可溶性纤维的发酵。在这项研究中，我们检验了这样一个假设，即可溶性多糖的细微结构变化决定了发酵微生物群落结构和代谢产物。我们使用来自不同小麦品种（硬红春麦[AX]、硬红冬麦[AX]和春红冬麦[AX]）的阿拉伯木聚糖（AX）进行粪便发酵研究，这些 AX 具有相同的初始微生物群。碳水化合物分析表明，AX 的主链明显更短，分支增加，与硬品种相比。扩增子测序表明，AX 的发酵导致群落结构明显更丰富和均匀，与硬 AX 发酵培养物相比。AX 有利于 内的 OTU，而 AX 和 AX 则有利于 。相应地，代谢产物在硬品种和软品种之间有所不同；AX 产生更多的丙酸，AX 和 AX 产生更多的丁酸和乙酸。这项研究表明，膳食纤维结构的细微变化可能强烈影响结肠微生物群的组成和功能，进一步表明膳食纤维的生理功能高度依赖于结构。因此，专注于膳食纤维、肠道微生物群和健康结果之间相互作用的研究应该更好地描述所使用碳水化合物的结构。饮食，尤其是膳食纤维的摄入，被公认为是塑造结肠微生物群组成的最重要因素之一。因此，已经进行了许多研究来探索可预测地操纵结肠微生物群以改善健康的膳食纤维类型。然而，这些研究中的大多数都忽略了膳食纤维在微生物利用方面的巨大结构差异，并且省略了详细的碳水化合物结构分析。在某些情况下，这会导致使用（理论上）相同纤维的研究之间产生冲突的结果。在这项研究中，通过使用来自不同小麦品种的麦麸阿拉伯木聚糖进行粪便发酵研究，我们表明，膳食纤维结构的微小变化会导致不同的微生物群落和代谢产物。这强调了在研究膳食纤维与肠道微生物群相互作用时，需要更高的结构分辨率，无论是在 和 水平上。
