Regulation Of Brown Algae Polysaccharides On The Gut Microbiota In High-fat Diet Mice And Its Specificity Analysis

In China,with the improvement of people's living standards,the prevalence of metabolic syndrome has increased year by year.Metabolic syndrome refers to an individual with multiple cardiovascular disease risk factors such as obesity,hypertension,hyperglycemia and dyslipidemia,which will bring heavy social burden and economic pressure to individuals and society.Previous studies have shown that polysaccharides as a dietary fiber have a variety of biological activities,such as anti-oxidation,immune regulation,anti-tumor,anti-coagulation,anti-virus,etc.,Polysaccharides can effectively improve the body's health and inhibit the occurrence and development of metabolic syndrome,but its regulation mechanism of metabolic syndrome induced by high-fat diet is not very clear.This paper first took high-fat diet mice as research objects,and the effects of brown algae polysaccharide(LJPs)on metabolic syndrome induced by high-fat diet and its mechanism were explored.Studies had shown that LJPs controlled the weight gain(~14.5%),alleviated organ damage and lipid metabolism disorders,repaired gut microbiota imbalance,reduced the abundance of Firmicutes phylum(~33.4%),and increased the level of Bacteroidetes phylum(~27.8%)in high-fat diet mice.The improvement of the gut microbiota by LJPs influenced the utilization of nutrients and regulated lipid metabolism by regulating the production of short-chain fatty acids.The results indicated that the intake of LJPs regulated lipid metabolism,restored microbiota imbalance,and thus improved metabolic syndrome and other intestinal diseases associated with obesity.LJPs inhibits obesity induced by high-fat diet,which is closely related to the regulation of gut microbiota.In this paper,the in vitro model was used to explore the effect of human digestive juice on the molecular structure of LJPs and the effect of LJPs on human gut microbiota.The results showed that LJPs avoided being digested by the upper digestive tract,improved the composition of the human gut microbiota and increased the relative abundance of Bacteroides(~22.1%).Through further isolation,identification and culture of Bacteroides,Bacteroides finegoldii was the dominant strain utilizing LJPs.In addition,some strains that could not utilize LJPs alone might use their decomposition products to promote growth,revealing the synergistic mutual help effect between Bacteroides strains in human gut microbiota ecosystems.The activity of polysaccharides is closely related to the dose,degree of polymerization and active group.In this study,a mice model constructed with high-fat diet was used as the research object,and the effect of low molecular weight brown algae polysaccharide(L-LJP-A)on metabolic syndrome induced by high-fat diet was systematically studied.The study showed that L-LJP-A could improve organ damage induced by high-fat diet and reduce lipid accumulation,which is closely related to the regulation of polysaccharides on gut microbiota.The intake of polysaccharides increased the level of "good bacteria",reduced the abundance of "harmful bacteria",and regulated the gene expression related to lipid metabolism by promoting the production of short-chain fatty acids,thus improved lipid metabolism disorders and alleviated inflammation.In addition,it could be seen from the experiment of fecal microbiota transfer that the gut microbiota improved by brown algae polysaccharides could regulate lipid metabolism.