FIG. 7.

Growth of Y. pestis KIM6+ derivatives in PMH-EDDA with increasing concentrations of hemoglobin. Iron-depleted cells (described in Materials and Methods) were transferred to PMH–50 μM EDDA containing 1.25, 2.5, 5, 10, or 20 μM hemoglobin (Hb). The Y. pestis strains used in these experiments include KIM6+ (Hmu⁺ parent strain) (A), KIM6-2060.1+ (ΔhmuP′RSTUV-2060.1) (B), and KIM6-2063.1+ (hmuT::cat-2063.1) (C). The cells were grown at 37°C, and growth was monitored by measuring the optical density of each culture at 620 nm (OD₆₂₀). These graphs depict one of two separate experiments.