Effects of Flammulina velutipes polysaccharide on immune response and intestinal microbiota in mice

[Display omitted] •The polysaccharide from Flammulina velutipes named FVP were extracted and analyzed to assess its characters.•By animal experiment, FVP can reduce the pH value and increase the content of SCFAs in mice intestinal lumen.•FVP can change the mice fecal microbe diversity became richness, the composition of fecal microbe was significantly altered.•FVP can increase the immunoglobulin and immune factors in mice serum. A crude polysaccharide derived from Flammulina velutipes (FVP), mainly consisting of glucose linked with β-glycosidic bonds, was administered to 6 week-old male ICR mice by gavage for five weeks, to investigate the effects on mice intestinal microbiota and immune response. The pH of the intestinal compartments decreased while short chain fatty acids concentrations increased in FVP-fed groups, in a dose dependent manner. High throughput sequencing revealed the enrichment in the diversity and an alteration in the composition of the fecal microbiota in the FVP fed mice. A significant decrease in the Firmicutes/Bacteroidetes ratio, relative abundances of Lactobacillus and Akkermansia were related to the energy absorption. The relative abundances of Porphyromonadaceae and Bacteroidaceae positively correlated with an increase in serum immunoglobulin and cytokines. This study indicated that this crude polysaccharide from F. velutipes could modulate the gut microbiota and represented a potential capacity of obesity suppression and immune regulation.