Source of gut microbiota determines oat β-glucan degradation and short chain fatty acid-producing pathway

Abstract

β-Glucan in grains has been included in almost every diet, however, biological mechanism and affecting factor of β-glucan metabolism in the gut remain unclear. In this study, we performed an in vitro fermentation experiment that was aimed at investigating the effect of gut microbial source on oat β-glucan metabolism by using mice and human fecal microbiota. It was found that, in both cases, acetate, propionate, and butyrate were the main end products from gut microbial fermentation of β-glucan. Notably, butyrate was the main product from the mice group while propionate was considered particularly enriched in the human group. β-Glucan contents at different time points were analyzed and results showed that β-glucan was nearly undetectable in the human group after 12 h of fermentation while a small amount of β-glucan was still detectable in mice group until the end of the fermentation. Further analysis of gut microbiota composition revealed that, at the genus level, Barnesiella, Holdemanella, Lactobacillus, Olsenella and Escherichia/Shigella were significantly enriched in the mice group whereas Bacteroides, Prevotella, Megamonas, Faecalibacterium and Collinsella were significantly enriched in the human group (p < 0.05). Moreover, a probable catabolic process of β-glucan was proposed. Overall, our data suggested that β-glucan could be completely hydrolyzed by human fecal microbiota but not thoroughly degraded by mice fecal microbiota. The notion shed some light on the effect of gut microbial source on β-glucan degradation, providing new information for the relationship between β-glucan metabolism and gut microbiota.