FIG 8.

Frequencies of mutation to Rif^r. Cells of B. subtilis wild-type, aag, ywqL, and aag ywqL strains were sporulated in liquid DSM and treated with the LD₅₀ for each strain of either HNO₂ (A) or MMS (B) at 4.5 h after the onset of sporulation. The levels of Rif^r cells with (+) or without (−) treatment exposure were determined. Each bar represents the mean of data collected from three independent experiments, and error bars represent the standard error of the mean (SEM). *, P < 0.05; **, P < 0.01 (by the Mann-Whitney U test).