FIG 4.

Expression of DnaE2 in persisters promotes enhanced rates of emergence of resistance to different antibiotics. Ten replicate cultures of M. smegmatis wild-type, ΔdnaE2, and ΔdnaE2::dnaE2 strains were subjected to either Cip or Rif to generate persisters along with untreated controls. The persisters from Cip and Rif were recovered in 7H9A medium, and the mutation frequency was determined by the ratio of the number of mutants to the viable count for each replicate. (A to C) Mutation frequencies for ciprofloxacin; (D to F) mutation frequencies for streptomycin. Under conditions where no mutant colonies were obtained, the frequency was calculated to be zero, and the values were not plotted. The individual values were plotted on a scatterplot using GraphPad Prism software v8, and the corresponding median value for each set is indicated above the plot (*, P value of <0.05; **, P value of <0.01).