C. difficile spore germination in the presence of taurocholate and glycine mixtures. (A) C. difficile spores were incubated with 8 mM taurocholate and titrated with 8 (•), 9 (○), 10 (▪), 13 (□), and 16 (⧫) mM glycine concentrations. (B) C. difficile spores were incubated with 8 mM glycine and titrated with 6 (•), 7 (○), 9 (▪), 12 (□), and 15 (⧫) mM taurocholate concentrations.