FIG 1.

The ΔprrF1,2 mutant is defective for growth in low-iron medium and with heme as a sole iron source. (A to C) The indicated strains were grown for 4 h in M9 minimal medium with 60 μg/ml of tetracycline to deplete intracellular iron stores and diluted into fresh M9 medium with or without FeCl₃ (100 μM) or heme (5 μM) supplementation as indicated. Growth was monitored for 24 h in a Bioscreen C instrument. Significant differences in culture density of the wild type and ΔprrF1,2 mutant, as determined by two-tailed Student's t test, are indicated by a horizontal bar flanking the relevant time points. (D to F) The indicated strains were grown for 4 h in M9 minimal medium to deplete intracellular iron stores and then diluted into fresh M9 medium with or without FeCl₃ (100 μM) or heme (5 μM) supplementation, grown for an additional 8 h in M9 minimal media as indicated, and subsequently analyzed for iron content by ICP-MS analysis. Error bars indicate the standard deviations of three independent experiments. The indicated P values were obtained by two-tailed Student's t test.