Figure 5.

Hypersensitivity to hydrogen peroxide (H₂O₂). (A) The H₂O₂ sensibility was tested by disk diffusion assay. PXO99A, RR35, and cRR35 were cultured in XOM2 broth medium to OD₆₀₀ = 1.0 and then mixed with soft PSA medium containing appropriate antibiotics for each strain. Paper disks loaded with 1 mM H₂O₂ or 10 mM H₂O₂ were placed in the middle of the plate, which was incubated at 28 °C for three days, and the diameters of inhibitory zone of strains were observed. (B) Inhibition zone diameters from the disk diffusion assays shown in (A). The experiment was performed as two/three independent biological replicates. Data with p-value < 0.001 are indicated with two asterisks, whereas data of p-value between 0.01 and 0.001 are indicated with an asterisk. Typical survival of PXO99A, RR35, and cRR35 grown in XOM2 broth media treated with 0 mM H₂O₂, 1 mM H₂O₂ (C), and 10 mM H₂O₂ (D) for 6 h. All experiments were repeated at least three times with consistent results.