| Due to its special structure,non-digestible oligosaccharides can "escape" the hydrolysis of digestive juices secreted by the stomach and small intestine and reach the colon,where they are fermented by microorganisms living in the colon,thus affecting the human gut microbiota.The metabolized short-chain fatty acid substances have beneficial effects on human health.In the study of structural-activity relationship of non-digestible oligosaccharides,the composition of monosaccharides,the degree of polymerization and the type of glycosidic linkage are important factors that affect the function of oligosaccharides.A large number of studies have also shown that oligosaccharides with different degrees of polymerization and changes in the composition of oligosaccharides affect their regulation of human gut microbiota.However,there is still a lack of research on the effect of linkage type on the regulation of human gut microbiota.Therefore,in this study,trehalose,kojibiose,maltose and isomaltose composed of two molecules of glucose by α-1,1,α-1,2,α-1,4 and α-1,6 glycosidic linkages were used as the subject,and the effects of glycosidic linkages on the regulation of human gut microbiota structure and intestinal microbial metabolites were studied by in vitro fermentation experiment of human gut microbiota.The results show that:(1)Trehalose,kojibiose,maltose and isomaltose can significantly change human gut microbiota structure through α-1,1,α-1,2,α-1,4 and α-1,6 glycosidic linkages.However,due to the influence of different gut microbiota donors,substrates with the same linkage type have different effects on gut microbiota structure from different sources.There are also differences in the regulation of different linkage substrates on the gut microbiota from the same source.(2)The effects of trehalose,kojibiose,maltose and isomaltose on the microflora structure of the three samples were different.In the fermentation process of gut microbiota of sample A,disaccharides composed of different glycosidic linkages all significantly increased the relative abundance of Bifidobacterium,indicating that all four disaccharides have a good ability to promote the proliferation of Bifidobacterium.Meanwhile,trehalose significantly increased the relative abundance of Streptococcus,while significantly decreased the relative abundance of Proteobacteria.Maltose had the most obvious effect on promoting the proliferation of bifidobacteria,and maltose significantly increased the relative abundance of Actinobacteria and significantly decreased the relative abundance of Firmicutes and Proteobacteria.In addition,kojibiose and isomaltose did not cause significant changes in the relative abundances of other fungi in sample A.In the fermentation process of sample B’s gut microbiota,trehalose significantly increased the relative abundance of Faecalibacterium and Parabacteroides,but significantly decreased the relative abundance of Bacteroides.Kojibiose significantly increased the relative abundance of Bacteroides;Maltose significantly increased the relative abundance of Prevotella;Isomaltose significantly increased the relative abundance of Prevotella and Blautia,and significantly decreased the relative abundance of Bacteroides.In the fermentation process of gut microbiota of sample C,trehalose significantly increased the relative abundance of Blaautia,and significantly decreased the relative abundance of Bacteroides and Megamonas.Maltose significantly increased the relative abundance of Bacteroides;Isomaltose significantly increased the relative abundance of Megamonas,while significantly decreased the relative abundance of Bacteroides.Kojibiose did not cause significant changes in the relative abundance of each phyla in sample C.(3)Trehalose,kojibiose,maltose and isomaltose all significantly increased the content of short chain fatty acids in fermentation broth.In the fermentation process of sample A gut microbiota,trehalose significantly increased the content of short-chain fatty acids,and the proportion of butyric acid was the highest.Maltose significantly increased the content of short chain fatty acids,and the proportion of acetic acid was the highest.Isomaltose significantly increased the content of short-chain fatty acids.At this time,sample A had the highest acid production,which was 81 m M.Kojibiose did not significantly increase the content of short chain fatty acids.In the fermentation process of sample B’s gut microbiota,trehalose significantly increased the content of short-chain fatty acids,and the acid yield of sample B was the highest,which was 57 m M.Maltose significantly increased the yield of short chain fatty acids,and acetic acid was the highest.Isomaltose significantly increased the yield of short-chain fatty acid,and the proportion of propionic acid was the highest.Kojibiose did not significantly increase acid production in sample B.In the fermentation process of gut microbiota of sample C,trehalose significantly increased the content of short-chain fatty acids,up to 94 m M;Maltose and isomaltose significantly increased the content of short chain fatty acids,and the proportion of propionic acid was the highest.Kojibiose did not significantly increase the content of short chain fatty acids.The results showed that the gut microbiota structure was affected by the oligosaccharide linkage type,and trehalose,maltose and isomaltose all had good fermentation characteristics,and significantly increased the yield of short-chain fatty acids. |
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