TABLE 2.
Mutability of the dnaQ991 mutant and related strainsa
| Genotype | Total no. of cells (109/ml) | No. of Rifr mutants/ml | No. of mutants/106 cells |
|---|---|---|---|
| dnaQ+ | 8.4 | 50 | 0.006 |
| dnaQ991 | 0.49 | 55,200 | 111 |
| dnaQ991 spq-2 | 3.0 | 244,000 | 82 |
| dnaQ903::tet | 0.15 | 14,640 | 99 |
| dnaQ903::tet spq-2 | 1.8 | 199,600 | 109 |
a
All strains are derivatives of MG1655. The dnaQ991 strains were prepared as described in the text by using either MG1655 or its spq-2 derivative. The dnaQ903::tet strains were prepared by transduction of the dnaQ903::tet/dnaQ+ heterodiploid configuration (donor provided by R. Maurer) into MG1655 and its spq-2 derivative, followed by segregation of dnaQ903 haploids as described previously (20). Strains were grown at 37°C.