Fig. 3. Host-derived electron acceptors license E. coli choline catabolism in vivo.

Mice were reared and maintained on a low-fat diet supplemented with 1% choline or a high-fat diet supplemented with 1% choline unless indicated otherwise. (A) Mice (C57BL/6J) were inoculated with E. coli strain MS 200-1 (wt) or an isogenic cydA napA narG narZ mutant, and CFU of E. coli in the feces were determined. (B and C) Mice (C57BL/6J) were inoculated with the indicated E. coli MS 200-1 strain mixtures, and the CI in the feces was determined 14 (B) or 7 (C) days later. (D) Mice (C57BL/6J) were inoculated with E. coli strain MS 200-1 (wt) or an isogenic cutC mutant, and CFU of E. coli in the feces were determined. (E and F) Mice (C57BL/6J) were mock-treated or received drinking water supplemented with the iNOS-inhibitor aminoguanidine (AG). (E) Nitrate concentrations were determined in colonic mucus. (F) Mice were inoculated with a 1:1 mixture of E. coli strain MS 200-1 (wt); an isogenic cutC mutant and CFU of each E. coli strain in the feces were determined to calculate the CI. (G) Germ-free (Swiss Webster) mice were mono-associated with the indicated E. coli strains, and TMAO levels in the plasma were determined 28 days later. (H) Germ-free (Swiss Webster) mice were engrafted with a defined microbial community containing either E. coli strain MS 200-1 or an isogenic cutC mutant. TMAO levels in the plasma were determined 28 days later. (I) Conventional (C57BL/6J) mice were engrafted with E. coli strain MS 200-1 and maintained on the indicated diet. TMAO levels in the plasma were determined 14 days later. (A to I) Each dot represents data from one animal (biological replicate). *P < 0.05; **P < 0.01; ***P < 0.001 using an unpaired two-tailed Student’s t test [(A) to (F), (H), and (I)] or a one-way ANOVA followed by Tukey’s HSD test (G).