FIG 4.

Bacterial oxygen consumption. (A) E. coli MG1655 and hemA strains were grown in LB supplemented or not with 5 μM heme (H). (B) E. coli WT and hemA strains were grown in LB. The hemA strain was also grown in LB supplemented with the indicated concentrations of δ-aminolevulinic acid (ALA) (micromolar). (C) WT and hemA E. coli strains were grown in LB or in 90% murine cecum containing 10% of a 10×-concentrated LB medium. (D) C. scindens and E. coli WT and hemA control strains were compared for their capacity to consume oxygen. See Text S1 in the supplemental material for protocols. Dissolved oxygen (milligrams per liter) is normalized to 100% for all samples at T₀.