Fermentation Characteristics Of Polysaccharides From Termitomyces Albuminosus And Its Alleviating Effect On Ulcerative Colitis

Termitomyces albuminosus is a kind of wild edible fungus,which is delicious and rich in nutrients and bioactive polysaccharides.Inflammatory bowel disease(IBD)is a non-specific chronic intestinal inflammatory disease,which is closely related to the disorder of intestinal flora.The research shows that edible fungus polysaccharides have positive alleviatons on IBD.However,the characteristics of polysaccharide from T.albuminosus(TAP)in gastrointestinal tract and its influencial mechanism on intestinal flora have not been clarified.And the intervention of TAP on IBD lacks sufficient theoretical support.In this study,different extraction methods(water,acid,and alkali extraction)were used to extract TAP,and its structure was characterized.At the same time,its gastrointestinal digestion and colonic fermentation characteristics in vitro were explored.The IBD mouse model induced by dextran sulfate sodium(DSS)was established to explore the effect of TAP on intestinal flora of colitis mice in vitro and in vivo.This topic aimed to clarify the effect of TAP on intestinal flora and IBD,and to provide further theoretical support for the development and utilization of T.albuminosus.The main results are as follows:(1)Hot water extraction polysaccharide(HWEP),hydrochloric acid extract polysaccharide(HAEP)and alkali extract polysaccharide(SHEP)were obtained from the fruiting body of T.albuminosus by continuous extraction.The yields were3.90±0.51%,2.70±0.36%,3.34±0.42%,respectively.The contents of total sugar were 57.57±4.30%,48.98±1.12% and 40±5.10%,respectively.Monosaccharides were composed of Rha,Fuc,Ara,Xyl,Man,Gal and Glc with different molar ratios.(2)By simulating digestion and colonic fermentation model in vitro,the characteristics of digestion and colonic fermentation of TAP and its effect on intestinal flora were studied.The results of in vitro digestion showed that HWEP,HAEP and SHEP were hardly degraded by oral,gastric,and intestinal digestive enzymes.During fermentation in vitro,HWEP,HAEP and SHEP could be effectively utilized by intestinal flora,and the total sugar and monosaccharide content was decreased.At the same time,TAP promoted the production of short chain fatty acids(SCFAs),especially propionic acid and butyric acid.At the phylum level,TAP significantly increased the relative abundance of Bacteroidetes and decreased the relative abundance of Actinobacteriota,Fusobacteria and Firmicutes.At the genus level,the TAP decreased the relative abundance of Escherichia Shigella,Fusobacterium,lachnoclostridium and Sutterella.HAEP increased the relative abundance of Dialist and Prevotella and decreased the relative abundance of Parabacteroides.The relative abundance of Bacteroides was increased in HWEP group.SHEP group decreased the relative abundance of Parabacteroides and Sutterella.The above results showed that TAP could promote the growth of beneficial bacteria,and inhibit the growth of harmful bacteria and promote the production of SCFAs.(3)The mouse IBD model was established by DSS induction to explore the in vivo intervention effect of TAP on IBD mice.The mouse model(C57BL/6J)was constructed in two stages(12 days and 14 days).They were free to drink 1.9% and 2.3% DSS solution for 12 days in each stage.The IBD mice were gave with 50 mg/kg/d of HWEP,HAEP and SHEP.The results showed that TAP had alleviation on weight loss,bloody stool and loose stool in IBD mice.At the same time,it could significantly reduce the m RNA expression of IL-1β and TNF-α.In addition,TAP increased the production of SCFAs in intestinal.The levels of acetic acid,propionic acid,butyric acid,isobutyric acid and isovaleric acid were significantly increased in HAEP group.HWEP significantly increased the levels of isobutyric acid,isovaleric acid and valeric acid.SHEP group significantly increased the levels of propionic acid and valeric acid.At the same time,TAP improved the intestinal flora composition of IBD mice.At the phylum level,it increased the relative abundance of Bacteroidetes in the intestine and significantly reduced the ratio of Firmicutes to Bacteroidetes.At the genus level,relative abundance of Lactobacillus and uncultured＿bacterium＿f＿Muribaculaceae were increased.From the overall intervention results,HAEP had a better effect.(4)By simulating the cecal fermentation model of mice in vitro,the fermentation characteristics of TAP in intestinal tract of IBD mice and their regulatory effects on intestinal flora were investigated.The results showed that the contents of total sugar and monosaccharide(Man,Gal and Glc)in HWEP group,HAEP group and SHEP group decreased with the extension of fermentation time.The crude TAP improved the intestinal microbiome composition.At the phylum level,it increased the relative abundance of Proteobacteria and decreased the relative abundance of Firmicutes and Bacteroidetes.At the genus level,TAP significantly increased the relative abundance of Enterbacter and decreased the relative abundance of Ligilactobacillus,unclassified＿Lachnospiraceae,Alistipes,Rikenellaceae＿RC9＿gut＿group.In conclusion,TAP could improve the disorder of intestinal flora in IBD mice mainly by inhibiting some harmful intestinal bacteria.In conclusion,the TAP was mainly composed of Rha,Fuc,Ara,Xyl,Man,Gal and Glc.TAP could not be degraded by digestive enzymes,but could be degraded by intestinal flora in the colon.Both in vitro and in vivo experiments showed that it could regulate the structure and abundance of intestinal flora and promote the production of SCFAs.In addition,TAP could upregulate the relative abundance of anti-inflammatory flora,downregulates IL-1β and TNF-αThe expression of pro-inflammatory factors,regulating the TNF signaling pathway and thereby play an alleviative role on DSS induced colonic inflammation as well as damage,etc.,in IBD mice.It can be seen that the TAP is of great significance in maintaining intestinal homeostasis and may be a potential natural agent for the prevention or treatment of IBD.