Figure 7
Effect of catalase on L medium sensitivity in ΔrecA306 polA25 cells. (a) Effect of catalase in ΔrecA306 polA25 cells growing on plate medium. TK1230 (ΔrecA306 polA pvec) or TK1224 (ΔrecA306 polA pEXsrpC) cells were fully grown in M9GCAA medium and subsequently diluted with M9B to contain the indicated number of cell particles. Then, 2 μL of diluted cells were spotted on L plates and incubated at 30 °C for 30 h. The images are shown from top to bottom: M9GCAA and L plate medium; right to left: no catalase and 1000 U/mL, respectively, at 30 °C. (b) Effect of catalase on ROS accumulation in ΔrecA polA cells. The cells shown in (a) were recovered and stained with SYBR Green I and CellRox Deep Red. Nucleic acid-containing E. coli particles were selected from the double-stained samples and analysed using histograms. Each histogram was as follows: blue, M9GCAA without catalase; green, M9GCAA with catalase; red, L without catalase; orange, L with catalase. Each bar represents the mean ± SEM (n ≥ 4). Double asterisks indicate significant differences (p < 0.01) as analysed using Welch’s t tests (n = 6).
