Digestive Characteristics of Hericium erinaceus Polysaccharides and Their Positive Effects on Fecal Microbiota of Male and Female Volunteers During in vitro Fermentation

Abstract

<i>Hericium erinaceus</i> polysaccharides (HEPs) have attracted widespread attention in regulating gut microbiota (GM). To investigate digestibility and fermentation of HEPs and their effects on GM composition, three polysaccharide fractions, namely, HEP-30, HEP-50, and HEP-70, were fractionally precipitated with 30%, 50%, and 70% ethanol concentrations (v/v) from hot water-soluble extracts of <i>Hericium erinaceus</i>, respectively. Three kinds of prepared HEPs were structurally characterized and simulated gastrointestinal digestion, and their effects on human fecal microbiota fermentations of male and female and short-chain fatty acid (SCFA) production <i>in vitro</i> were clarified. Under digestive conditions simulating saliva, stomach, and small intestine, HEPs were not significantly influenced and safely reached the distal intestine. After 24 h of <i>in vitro</i> fermentation, the content of SCFAs was significantly enhanced (<i>p</i> < 0.05), and the retention rates of total and reducing sugars and pH value were significantly decreased (<i>p</i> < 0.05). Thus, HEPs could be utilized by GM, especially HEP-50, and enhanced the relative abundance of SCFA-producing bacteria, e.g., <i>Bifidobacterium</i>, <i>Faecalibacterium</i>, <i>Blautia</i>, <i>Butyricicoccus</i>, and <i>Lactobacillus</i>. Furthermore, HEPs reduced the relative abundances of opportunistic pathogenic bacteria, e.g., <i>Escherichia-Shigella</i>, <i>Klebsiella</i>, and <i>Enterobacter</i>. This study suggests that gradual ethanol precipitation is available for the preparation of polysaccharides from <i>Hericium erinaceus</i>, and the extracted polysaccharide could be developed as functional foods with great development value.