FIG 5.

The absence of translesion DNA polymerases reduces, but does not completely inhibit, H₂O₂-induced mutagenesis in the presence of manganese. (A) Wild-type cultures and polB, dinB, and umuDC mutant cultures grown in medium supplemented with manganese or no metals were treated with 10 mM H₂O₂ for 5 min and examined for the number of rifampin-resistant (Rif^r) colonies that appeared after overnight incubation. (B) Wild-type cultures and polB, dinB, and umuDC mutant cultures grown in medium supplemented with manganese or no metals were treated with 27 J/m² UV and examined for the number of rifampin-resistant colonies that appeared after overnight incubation. (C) Cultures of polB, dinB, and umuDC mutants grown in medium supplemented with manganese or no metals were treated with 10 mM H₂O₂ for 5 min and examined for the number of rifampin-resistant colonies that appeared after overnight incubation. (D) mutD cultures were grown in the presence or absence of manganese and treated with 10 mM H₂O₂ for 5 min, then examined for the number of rifampin-resistant colonies after overnight incubation. The number of rifampin-resistant colonies per 10⁹ surviving cells is plotted for each treatment. Graphs represent averages from six independent experiments. Error bars represent one standard error of the mean. P values represent the likelihood the observed difference could arise by chance, as determined by two-way ANOVA.