MAFF system functions in colonic mucus of mice and humans with complex microbiota. (A) Heat map analyses of BTWT and BTΔMAFF gene expression in indicated gnotobiotic conditions compared with monocolonization were performed with a likelihood ratio test. Each line shows the mean value of each group (n = 2–4 mice per group). The genes with a P-value adjusted <0.05 are shown. A full annotation of the heat map is shown in Table S3. (B) Cecal weight measured at the point of dissection of gnotobiotic mice. Each point represents an individual animal (n = 3–6 mice for each group). (C) qPCR analysis of B. theta maffC expression in large intestinal content and mucus collected from mono-colonized or gnotobiotic mice. Each point is data from an individual animal (n = 3–6 mice). (D) B. theta maffC expression in human feces, mucosal wash, and tissue biopsy samples from the large intestine. Each dot represents matched samples from one donor (n = 10 donors). Statistical analysis was performed with unpaired Student’s t tests (B), one-way ANOVA with Tukey’s multiple comparison test (C), and Kruskal-Wallis test with Dunn’s multiple comparison tests (D). **P < 0.01, ***P < 0.001. Error bars represent SEM.