FIG 6.

Minimizing the interplay between iron and H₂O₂ is critical in the protection of NTHI strain 86-028NP from H₂O₂-induced oxidative stress. A strain of 86-028NP that lacked dps was grown exponentially and then treated with (+) or without (−) 500 μM H₂O₂ for 10 min. The treatment with H₂O₂ was carried out in the presence (+) or absence (−) of the iron chelator 2,2′-bipyridine. The cells were harvested and plated to assess viability. The dps mutant exhibited a loss of viability in the absence of iron chelation. In contrast, iron chelation protected the dps mutant from the effects of H₂O₂. Complementation of the dps mutation restored the parental phenotype under all conditions tested (data not shown). Error bars show standard errors of the means. ***, P ≤ 0.001 (n = 6).