(a) 16S ribosomal RNA sequences of fecal commensal microbiota from WT, Il17f−/− and Il17a−/− mice were analyzed, and proportions of major phyla in the whole microflora were presented (n=9/group). *, #, $: P<0.05. *P=0.0438, **P=0.0054, ***P=0.0009, #P=0.0342, ##P=0.0012, ###P=0.0007, $$P=0.0032.(b, c) Fresh feces from WT, Il17f−/− and Il17a−/− or Il17a−/−Il17f−/− mice were collected and the relative content of total commensal C. XIVa and C. XIVa sp. (b) or commensal Lactobacillus (c) was determined by qPCR (WT n=11, Il17f−/− n=10, Il17a−/− n=4in b; WT n=7, Il17f−/− n=6, Il17a−/−Il17f−/− n=6 in c). *, #: P<0.05.b, *P=0.0435, #P=0.0493, **P=0.0014, ##P=0.0017. c, *P=0.033, #P=0.0106, **P=0.0032. (d) Analysis in (a) were performed, and proportions of indicated species in C. XIVa in the whole microflora are shown. *, #, $: P<0.05. *P=0.028, **P=0.0062, ##P=0.0013, $$P=0.0041. (e) Il17f−/− mice were treated with antibiotics mixture VAMN or vancomycin only for 3 weeks, and fecal microbiota from vancomycin-treated mice were harvested and mixed with C. bolteae (JCM 12243) and C. clostridioforme (JCM 1291) and were transferred into VAMN-treated mice for 3 weeks. Clearance of C. XIVa in vancomycin-treated mouse feces were confirmed, and cLP Treg population in recipient mice after microbiota transfer was examined by flow cytometry (n=3/group). *, #, $, &: P<0.05. *P=0.0476, #P=0.0306, $P=0.0482, &P=0.0455. (f) SPF WT mice were orally administrated with a mixture of C. bolteae (JCM 12243) and C. clostridioforme (JCM 1291) or P. loescheii (JCM 12249) and P. shahii (JCM 12083) every 2 days for 2 weeks, and relative levels of indicated mRNA in the colon were determined by qPCR (n=4/group). *, #, $, &: P<0.05. *P=0.0251, **P=0.0052, #P=0.035, $P=0.0154, &P=0.0211. (g) Analysis in (a) were performed, and proportions of a part of C. IV species in the whole microflora are shown (n=9/group). Data in (b, e, f) are expressed as means ± SD, and measure of center in (a, c, d, g) is mean (for a-f, one-way ANOVA followed by Tukey’s multiple-comparisons test).