Modulation Of Oligosaccharides With Three Type Monosaccharide Composition On The Human Gut Microbiota

Oligosaccharides usually refer to carbohydrates with an average degree of polymerization between 2 and 20,which were divided into digestible oligosaccharides and non-digestible oligosaccharides according to physiological characteristics.Non-digestible oligosaccharides are resistant to enzymatic hydrolysis in the upper gastrointestinal tract and therefore reach the distal colon,where they are selectively fermented and have been linked to regulation of lipid metabolism and modulation of gut microbiota.Besides,non-digestible oligosaccharides also have the low sweet degree,the low quantity of heat,the good moisture and so on food processing characteristic,thus have received the widespread concern.In the previous studies,we successfully synthesize polygalactose,polydextrose and polymannose which was under the condition of microwave irradiation by using heteropolyacid as catalyst.Simulator of the Human Intestinal Microbial Ecosystem(SHIME)was used to study the modulation of polydextrose,polygalactose and polymannose on gut microbiota from human feces.At the end of 24 hours fermentation in vitro,gut microbiota was obtained for composition analysis by sequencing of bacterial 16 S rRNA genes,and the supernatant was separated for short-chain fatty acids(SCFAs)analysis.The main results of this study are as follow:1.In the 12-hour gastric-small intestine digestion experiment,only 35% of oligosaccharides were degraded into monosaccharides and disaccharides,indicating that all three oligosaccharides have good non-digestive properties.2.Polygalactose,polydextrose,and polymannose can significantly change the microbiota structure after in vitro colonic fermentation for 24 hours.However,these three oligosaccharides have different effects on the microbiota structure,and different oligosaccharide fermentations have different microbiota structures.3.Polygalactose,polydextrose,and polymannose change the composition of microbiota.None of the three oligosaccharides promoted the proliferation of Bacteroidetes,and the polymannose promoted the proliferation of Firmicutes.Polygalactose and Polydextrose increased the abundance of Actinobacteria.Both Polygalactose and Polydextrose exhibited excellent "bifidogenic" proliferation talents,which significantly increased the level of Bifidobacterium.Among them,Polygalactose had a stronger "bifidogenic" ability than polydextrose.Polymannose had a selective promotion effect on Bacteroides_thetaiotaomicron and Bacteroides_uniformis in Bacteroides,which may be related to its molecular structure.4.Polygalactose produced the most amounts of SCFAs in all three oligosaccharides,followed by Polydextrose,and Polymannose coming in third.Correlation analysis revealed that Bifidobacterium,Lactobacillus,etc.may be the backbone of the short-chain fatty acid production process.Through the above experimental results,it was found that polygalactose,polydextrose,and polymannose have good metabolic fermentation characteristics and have potential prebiotic activity.