Table 1.
Mutant frequencies (mutants per 108 cells) for resistance to rifampicin (Rifr) and nalidixic-acid (Nalr) for wild-type (polA+) and polAexo strains in various backgrounds.
| Experiment | Strain | Rifr | Nalr |
|---|---|---|---|
| 1 | mutL+ polA+ | 1.9 | 0.03 |
| mutL+ polAexo | 3.4 (1.8×) | 0.27 (9.0×) | |
| 2 | mutL polA+ | 311 | 83 |
| mutL polAexo | 321 (1.0×) | 85 (1.0×) | |
| mutL dnaE915 polA+ | 81 | ND | |
| mutL dnaE915 polAexo | 121 (1.5×) | ND |
Values within parentheses indicate the increase compared to the corresponding polA+ strain (mutator effect). Frequencies are the averages for 20–30 independent cultures (see Section 2). Bold numbers indicate statistically significant differences (p < 0.05, see Section 2). ND = not done.