Figure 5. The ΔfslA ΔfeoB′ strain requires F. tularensis siderophore for growth.

A and B, LVS, ΔfslA, ΔfeoB′, and ΔfslA ΔfeoB′ strains grown on MHA+ agar plates were resuspended and brought to an OD₆₀₀ of 1 in che-CDM. Strains were further serially diluted and spotted on MHA+ and MHA- plates. The order of ΔfslA and ΔfeoB′ spots was switched in A and B. C, ten-fold serial dilutions of the mutant ΔfslA ΔfeoB′ were spotted near dense streaks of LVS or ΔfslA strains on an MHA+ plate and grown for two days under aerobic 37°C conditions. D, ten-fold serial dilutions of the ΔfslA ΔfeoB′ strain were spotted with (top) or without (bottom) 5 μL of 1.5 mM F. tularensis siderophore and grown for two days under aerobic 37°C conditions.