title: Synergistic killing of Escherichia coli by near-UV radiation and hydrogen peroxide: distinction between recA-repairable and recA-nonrepairable damage.
abstract: Wild-type cells and six DNA repair-deficient mutants (lexA, recA, recB, recA, recB, polA1, and uvrA) of Escherichia coli K-12 were treated with near-ultraviolet radiation plus hydrogen peroxide (H2O2). At low H2O2 concentrations (6 X 10(-6) to 6 X 10(-4) M), synergistic killing occurred in all strains except those containing a mutation in recA. This RecA-repairable damage was absent from stationary-phase cells but increased in logarithmic cells as a function of growth rate. At higher H2O2 concentrations (above 6 X 10(-4) M) plus near-ultraviolet radiation, all strains, including those with a mutation in recA, were synergistically killed; thus, at high H2O2 concentrations, the damage was not RecA repairable.
mesh_terms: D004260:DNA Repair; D004926:Escherichia coli / Q000187:drug effects* / Q000528:radiation effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D009154:Mutation; D011995:Recombination, Genetic; D014466:Ultraviolet Rays
chemical_list: D006861:Hydrogen Peroxide