MUC5AC and colitis: It has also been shown that the gut microbiota in the intestinal lumen is in close contact with mucin and has a profound regulatory effect on the mucus layer.30 In our study, 16S rRNA pyrosequencing analyses in the V4 regions of fecal samples indicated an abundance of variation of two major mucolytic bacteria, A. muciniphila and R. gnavus, which significantly decreased the relative abundance of A. muciniphila and R. gnavus in mice with DSS colitis (Figure 4(g)).