Structural Characterization of Β-Glucan in Hericium Erinaceus Pretreated by Steam Explosion and its Effects on Human Gut Microbiota in Vitro

To investigate the impact of steam explosion on the structure of β-glucan and its regulation human gut microbiota (GM), two polysaccharides were prepared from Hericium erinaceus fruit bodies treated by steam explosion and conventional crushing, respectively. Structural analysis indicated that both two fractions were identified as β-(1→3)-glucan with different branching ratios attached at O-6 position. Compared with W20E obtained by conventional crushing, Q5E obtained by steam explosion possessed lower molecular weight (Mw, 2.158×106 g/mol) and lower branching ratio of 2:7, which influenced its effects on the diversity and metabolites of GM. W20E (Mw, 6.944×106 g/mol, branching ratio of 1:3) could promote n-butyrate production by increasing the abundance of Prevotellaceae_NK3B31_group, Lachnospira and Faecalibacterium. Q5E tended to improve the abundance of Lactococcus and Megamonas, as well as the total production of short chain fatty acids (especially acetic and propionic acids). These findings provide reference for further development of β-glucan in healthy food.