Effects Of Sialylated Lactulose On The Mouse Intestinal Microbiome

Sialylated oligosaccharides,with oligosaccharide as receptor and sialic acid as donor material,are synthesized by chemical or enzymatic methods,which have effects of promoting increased bifidobacteria,reducing blood endotoxin levels,and enhancing the body's immune system via blood ammonia levels.Given their biological roles,the synthesis and modification of sialylated oligosaccharides have become research focuses in the fields of chemistry and biology.However,there are few reports about the effects of sialylated oligosaccharides on the intestinal microbiota in vivo.In view of this,Illumina high-throughput sequencing was used to analyze the effect of sialylated lactulose on the intestinal microbiota and to explore the effects of changes in intestinal microbiota on host's health after treatment with sialylated lactulose in order to provide reference for its application in food and medicine industry.The main research contents and results are as follows:(1)Effect of sialylated lactuloses on structure in the intestinal microbiota of miceThe structural changes of intestinal microbiota of mice at the level of phylum,class,order,family and genus were compared through taxonomic analysis and species composition analysis to analyze the effects of four kinds of sialylated lactuloses on structure in the intestinal microbiota of mice.The results showed that there was little difference in the number and average length of the optimized sequence among the treatment groups,and the length of the optimized sequence was mainly 421-460 bp.The intervention of sialylated lactuloses could enrich the intestinal microbiota of mice to a certain extent.The community abundance of Clostridiales and Lachnospiraceae were significantly decreased,while Bacilli,Bacillales,Staphylococcaceae and Staphylococcus were significantly increased in the Kdn-?2,3-lactulose group compared with the normal control group.There was no significant difference in the community abundance of dominant bacteria in the Kdn-?2,6-lactulose group,Neu5Ac-?2,3-lactulose group and Neu5Ac-?2,6-lactulose group compared with the normal control group.(2)Effect of sialylated lactuloses on diversity in the intestinal microbiota of miceThe Alpha and Beta diversity of intestinal microbiota of mice were compared through mothur and FastUniFrac software to analyze the effects of four kinds of sialylated lactuloses on diversity in the intestinal microbiota of mice.Alpha diversity analysis results show that the Chao and Ace indices in thesialylated lactulose groups were higher than that the normal control group.Both the Shannon and Simpson indices in the group Kdn-?2,6-lactulose,Neu5Ac-?2,3-lactulose group and Neu5Ac-?2,3-lactulose were superior to the normal control group.In addition,The span of Kdn-?2,6-lactulose group and Neu5Ac-?2,3-lactulose group on the Rank-Abundance curve was wider and the trend was flatter compared with the normal control group,indicating that Kdn-?2,6-lactulose group and Neu5Ac-?2,3-lactulose group had a better community richness and community evenness.And the results of Beta diversity analysis showed that the inter-group community difference between the normal control group and the Kdn-?2,3-lactulose group was the greatest,while the inter-group difference among the normal control group and other groups was not significant.(3)Effect of sialylated lactuloses on metabolic function and the key differential species in the intestinal microbiota of miceBased on 16 S rDNA high-throughput sequencing results,the metabolic function of intestinal microbiota of mice were analyzed through PICRUSt software,and the species with significant differences in abundance wre counted by LEfSe cladogram and linear discriminant analysis(LDA).The results showed that Kdn-?2,3-lactulose significantly reduced the function of intestinal microbiota metabolism of mice,while Kdn-?2,6-lactulose,Neu5Ac-?2,3-lactulose and Neu5Ac-?2,6-lactulose had no significant effect.The results of LEfSe cladogram and LDA showed that there were significant differences in some species of intestinal microbiota of mice before and after the intervention of sialylated lactuloses.And the number of corresponding harmful bacteria in the sialylated lactuloses groups decreased,while the beneficial bacteria increased.(4)Correlation analysis of intestinal microbiota and immune index in miceAccording to the growth characteristics and changes of immune index of mice before and after the intervention of four kinds of sialylated lactuloses,the correlation between intestinal microbiota and immune index of mice was explored through the spearman correlation factor analysis.The results showed that the change of immune index may be related to the abundance of intestinal microbiota after the intervention of sialylated lactuloses.The above studies showed that sialylated lactuloses had a positive effect on regulating the intestinal microbiota of mice,and could effectively reduce the number of some intestinal harmful bacteriaand promote the proliferation of beneficial bacteria.In addition,there may be some interaction mechanism between changes of intestinal microbiota and immune function of mice,and the mechanism of action needs to be further explored.