Figure 7

FlaR facilitates S. pneumoniae growth under oxidative stress. The WU2 WT, WU2ΔflaR ^Erm and complemented strains WU2ΔflaR ^flaR/^Erm/Kan plasmid and WU2ΔflaR ^flaR/Erm/Kan chromosome were inoculated into 20 ml of THY at initial OD₆₂₀ = 0.05 and grown to OD₆₂₀ = 0.35 under anaerobic conditions. Then, bacteria were harvested, resuspended in PBS and incubated with equal volumes of either PBS (control) or H₂O₂, at final concentration of 20 mM. The WU2ΔflaR ^Erm mutant and, to a lesser extent, WU2ΔflaR ^flaR/Erm/Kan chromosome strain exhibited significant susceptibility to the oxidative stress, relative to the WU2 WT. The results presented are the mean of three different experiments, each performed in triplicates (one way ANOVA with Dunnett’s post hoc multiple comparisons test, n = 3 in each group, ** p = 0.0011; ****p = 0.0001).