TABLE 2.
Spontaneous-mutation frequencies of wild-type, exoA, nfo, and exoA nfo strainsa
| Strain (genotype) | Frequency of Rifr mutants (10−9)b
|
|
|---|---|---|
| Expt 1 | Expt 2 | |
| PS832 (wild type) | 1.2 ± 0.30 | 1.3 ± 0.13 |
| PERM 452 (exoA) | 1.6 ± 0.32 | 1.24 ± 0.32 |
| PERM 453 (nfo) | 1.1 ± 0.05 | 1.2 ± 0.16 |
| PERM 454 (exoA nfo) | 1.15 ± 0.25 | 1.92 ± 0.70 |
| PS3677 (mutM yfhQ) | 322 ± 26 | 284 ± 16 |
a
The mutation frequencies in growing cells were measured as described in Materials and Methods.
b
Average of six different selection plates ± standard deviations.