FIG. 3.

Frequencies of mutation to rifampin resistance. Shown are the median values (horizontal lines), 95% confidence intervals (rectangular boxes), and outliers (vertical lines) of mutation frequencies calculated from the ratio of cells that gained rifampin resistance in six independent cultures of each strain. *, significant increase of mutation frequency compared to the wild type (Student's t test; P < 0.05). wt, M. smegmatis wild-type strain; uvrB, uvrD1, and uvrB uvrD1, M. smegmatis NER mutant strains; recA, M. smegmatis recA mutant strain.