Preparation and Characterization of Polysaccharides From Grifola frondosa and Their Human Intestinal Flora‐modulating Effect

A novel and efficient hydrogen peroxide/ascorbic acid‐assisted extraction method for the preparation of Grifola frondosa polysaccharide (GFP) was developed, and two GFP fractions (GFP‐H and GFP‐L) with different molecular weights (Mws) were obtained by separation with ultrafiltration. Both high Mw component (GFP‐H, Mw 396.4 kDa) and low Mw component (GFP‐L, Mw 12.5 kDa) are possibly mainly comprised of →4)‐β‐Glc p ‐(1→, →6)‐α‐Glc p ‐(1→, →6)‐α‐Gal p ‐(1→, α‐T‐Glc p , →3,6)‐α‐Man p ‐(1→, and β‐D‐Glc p A‐(1→ units. The physicochemical properties of GFPs, such as surface morphology, rheological properties, and thermal stability, were also analyzed. Their modulatory effects on human gut microbiota were evaluated using a simulated human intestinal fermentation model in vitro. The results showed that GFPs could be degraded by intestinal microorganisms and promoted the production of short‐chain fatty acids such as acetic acid and butyric acid. Compared with GFP‐L, GFP‐H exhibited a better ability to increase the abundance of beneficial bacteria (e.g., Bifidobacterium , Megasphaera , and Lactobacillus ) and reduce the abundance of harmful bacteria (e.g., Escherichia / Shigella , and Lachnoclostridium ). This work revealed that Mw of GFP had a significant impact on the human gut microbiota‐regulating effect. This study provided valuable information about the relationship between the structure of GFPs and their regulatory effect on intestinal flora.