FIGURE 4.

The permease FetM is required for growth of E. coli strain ECA458 (ΔentC ΔfecABCDE ΔfeoABC ΔmntH ΔzupT) in the presence of the iron chelator CDTA. The fetMP operon, fetM, fetP, or empty vector control was inserted into the chromosome of strain ECA458, resulting in strains ECA612 (glmS-fetMP) (●), ECA613 (glmS-fetM) (■), ECA614 (glmS-fetP) (▴), and ECA611 (glmS-Gm) (○). Iron-limited cultures of these four E. coli strains were diluted 400-fold into TMM containing no iron but 1 μm CDTA. The cultures were cultivated at 37 °C with shaking, and the turbidity was measured as Klett units. Shown are averages of four independent experiments.