Figure 4

H ₂ O ₂ sensitivity assays for 1529 Δspy1236 and MDYK Δspy1236 strains. H₂O₂ sensitivity assays were performed for wild-type 1529 and 1529Δ spy1236 strains (a), 1529Δ spy1236 (pLZ-spy1236) and 1529Δ spy1236 (pLZ-12-Km2) strains (b), or wild-type MDYK and MDYKΔ spy1236 strains (c). 1529Δspy1236 (pLZ-spy1236) and 1529Δspy1236 (pLZ-12-Km2) strains were grown in broth supplemented with 62.5 mg/mL kanamycin. H₂O₂ (61 mM) was added to 1-mL aliquots of culture grown to an OD₆₆₀ of ~0.3. After 15 min at room temperature (~22°C), viable counts were performed on BHI-Y and sheep blood agar plates before and after the addition of peroxide, and the percentages of survival were calculated. The BHI-Y agar plates were supplemented with 125 mg/mL kanamycin for the 1529Δspy1236 (pLZ-spy1236) and 1529Δspy1236 (pLZ-12-Km2) strains. Values expressed are the means (± SEM) of three independent experiments.