Effect Of β-glucan From Lyophyllum Decastes (Fr.) Singer On Gut Microbiota

Based on the low fat,high protein and high dietary fiber content of edible mushrooms,as a large edible mushroom,the application of Lyophyllum decastes(Fr.)Singer is becoming more and more widespread,attracting the attention of domestic and foreign researchers.Polysaccharide is one of the main active components of edible mushrooms,which has various biological activities such as antioxidant,immunomodulatory,tumor suppression,anti-inflammatory and antibacterial,etc.It has also been revealed that edible mushroom polysaccharide has a moderating effect on the composition of intestinal flora.The structural effects ofβ-glucan with different molecular weights,glycosidic bonds and branching degrees on intestinal flora have not been fully studied.It has been found that polysaccharides from Lyophyllum decastes(Fr.)Singer have various biological activities,but scholars at home and abroad have mainly focused on the extraction of intra-and extracellular polysaccharides,antioxidant activity,antitumor activity and immunomodulatory activity,but there are few reports on the activity ofβ-glucan from Lyophyllum decastes(Fr.)Singer,especially on intestinal flora and intestinal flora metabolites.The present study aims to identify the effects of antler mushroom polysaccharides on the intestinal flora and intestinal metabolites.In this study,we aimed to identify the main components of the probiotic capacity of antler mushroom polysaccharide,to explain the mechanism ofβ-glucan structure on the regulation of intestinal flora,and to evaluate the intervention effect of antler mushroomβ-glucan on lipid metabolism and intestinal flora disorders in mice on high-fat diet.(1)Water extract of Lyophyllum decastes(Fr.)Singer(LDW),crude polysaccharide of Lyophyllum decastes(Fr.)Singer(LDP)andβ-glucan of Lyophyllum decastes(Fr.)Singer(LDB)were extracted,isolated and purified from deer antler mushroom seeds by hot water extraction,and the digestive characteristics of the three deer antler mushroom polysaccharide fractions were investigated by simulating saliva-gastrointestinal digestion model in vitro.The results showed that LDB was 88.51%of antler mushroomβ-glucan with a heavy average molecular weight of 7.916×10~6 Da,which was partially degraded and not completely digested and absorbed in the upper gastrointestinal tract and had good anti-digestive properties.(2)The in vitro fermentation of LDB was investigated using an in vitro fecal flora anaerobic fermentation model with oatβ-glucan(OATB)as a positive control;16S r DNA sequencing was used to reveal the ability of different structures ofβ-glucan to regulate the intestinal flora and the quantitative-effect relationship of their effects on the intestinal flora.After 24 h of in vitro fermentation,the significant decreases in total carbohydrates and p H in the LDB medium indicated that it could be degraded and utilized by the intestinal flora for conversion to propionic acid and n-butyric acid;LDB significantly(p<0.05)promoted the increase in the abundance of butyric acid-producing bacteria Blautia,Roseburia and Bacteroides and Prevotella,while the OATB The dominant groups were Ruminococcus＿gauvrcauii＿group and Klebsiella;additional addition of LDB significantly promoted the n-butyric acid content and the relative abundance of Lactobacillus in the medium in a dose-dependent manner.(3)A high-fat diet was used to induce a C57BL/6 obesity model with OATB as a control to investigate the modulation of obesity phenotype and intestinal flora disorders by dietary intervention with LDB on high-fat diet.After 6 weeks of feeding,dietary interventions of OATB,LDP and LDB improved the significant increase in body weight,body fat percentage and abnormal organ index,elevated plasma lipid levels and disturbed leptin levels in mice caused by high-fat diet;effectively improved the pathological degeneration of liver,adipose and colonic tissues and tissue inflammation levels in obese mice;reversed the reduction of species richness and diversity,and reduction in relative abundance of Bacteroidota and decrease in B/F ratio caused by high-fat diet.,suppression of relative abundance of obesogenic bacteria Erysipelotrichaceae;up-regulation of acetate,butyric acid and total acid levels;correlation analysis showed that LDB could up-regulate Lactobacillus,Ruminococcus and Clostridium＿sensu＿stricto＿1 and downregulating Roseburia to ameliorate the abnormal lipid and inflammation levels.In conclusion,LDB has anti-digestion properties,and can be decomposed and utilized by intestinal flora in vitro fermentation models to promote the abundance of butyric acid producing flora and the increase of n-butyric acid,in addition,LDB intervention can improve lipid metabolism and inflammation in obese mice by regulating the structure of intestinal flora,indicating that LDB can be used as a potential prebiotic to promote body health.