Fig. 3: Generation of ROS.

a Survival of stationary phase cells under anaerobic conditions in the absence or presence of 100 µM valinomycin. The addition of 1 % DMSO was used as control. Viable counts were determined after 0 and 10 h incubation. Data reflect mean ± SD of three biological replicates. b Survival curves of stationary phase wild type (wt), ΔrecA and Δspx cells in the presence of 100 µM valinomycin (val) or 1 % DMSO. Data shown reflect mean ± SD of three biological replicates. The viable counts of ΔrecA and Δspx cells in the presence of 1 % DMSO were similar to that of wild-type cells and are not indicated here. c ROS production in stationary phase cells measured by the fluorescent ROS probe H2DCFDA. Cells were treated with either 100 µM valinomycin, 1 mM paraquat, or 1 % DMSO for 2 and 4 h. The fluorescence intensities of 120 cells were measured microscopically and plotted. Three biological replicates were performed to ensure repeatability.