A) Schematic of competition experiments. Mice were gavaged with 1:1 mixtures of WT and each commensalism mutant, strain abundance in feces was monitored for ≥25-days using qPCR. B-G) Results for: (B) WT (ySN226) vs. efg1 (ySN119), (C) WT (ySN425) vs. brg1 (ySN1180), (D) WT (ySN250) vs. rob1 (ySN1440), (E) WT (ySN250) vs. tec1 (ySN1442), (F) WT (ySN250) vs. ume6 (ySN1479), (G) WT (ySN1556) vs. UME6OE (ySN1558). Bars represent the mean. Significance was determined using the paired student’s t-test: n.s. not significant, *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. Additional results are presented in Figures S1, S2, and S3.