FIGURE 2.

Requirement of feoA and feoB for aerobic growth with ferric iron in the growth medium over a wide concentration range of iron. Growth medium was inoculated with 1 × 10⁶ cells/ml of the wild type (green, closed circles), feoB (magenta, open circles), feoA (blue, closed diamonds), feoB(Y454term) (black, crosses), and feoA(E40K) (red, open triangles) strains. Strains were grown in minimal medium supplemented with either no added iron (A), 5 μm FeCl₃ (B), 50 μm FeCl₃ (C), 500 μm FeCl₃ (D), or 0.5 μm heme (E). Aliquots were taken at the indicated time points, and the optical density was measured at 540 nm (A₅₄₀).