FIG 3.

The ΔpmtA mutant is defective in iron efflux and sensitive to oxidative stress. (A) The WT, ΔpmtA, and trans-complemented strains were grown in THY-C broth with (+) or without (−) 1 mM FeSO₄ to the mid-exponential phase of growth, and the intracellular metal content was measured by ICP-MS. n.s., not significant. (B) GAS strains were grown to mid-exponential phase in THY-C broth, incubated with 4 mM FeSO₄ for 15 min, and grown in THY broth in the presence or absence of 1 mM H₂O₂. Mean CFU recovered after the 6-h recovery period are shown, with P values (*, P < 0.0001) as determined by a t test. Triplicate cultures were grown under the indicated conditions, and each biological replicate was assessed in duplicate.