Chloramphenicol enhanced the bactericidal activity of H
. The wild type E. coli (WT) and the ΔarcA mutant E. coli (ΔarcA) were incubated in M9 minimal medium containing 1.5 mM H2O2 for 6 hours at 37°C. The survival of bacteria was determined by plating. Bacterial concentration following each treatment (open bars, no treatment; diagonally-hatched bars, H2O2; vertically-hatched bars, 25 μg ml-1 of chloramphenicol; cross-hatched bars, H2O2 and 25 μg ml-1 of chloramphenicol; dotted line-hatched bars, 50 μg ml-1 ampicillin and horizontally-hatched bars, H2O2 and 50 μg ml-1 ampicillin) was plotted on the graph. The horizontal dashed line indicates the starting concentration of bacteria.