TABLE 4.
Transformation efficiencies of S. pneumoniae wild-type and ΔstkP mutant strains in the medium that did not allow natural competence development and after CSP treatmenta
| OD400 | S. pneumoniae strain | CSP inductionb | Total count (CFU ml−1 [107]) | Transformants (CFU ml−1 [104]) | Transformation efficiency (%) |
|---|---|---|---|---|---|
| 0.1 | CP1015 | No | 4.85 ± 0.52 | <0.003 | <6.22E-05 ± 0.71E-05 |
| Yes | 4.95 ± 0.54 | 102.00 ± 26.23 | 2.04 ± 0.32 | ||
| CP1015ΔstkP | No | 4.20 ± 0.38 | 4.50 ± 0.53 | 0.11 ± 0.01 | |
| Yes | 3.80 ± 0.68 | 9.25 ± 0.82 | 0.25 ± 0.04 | ||
| 0.4 | CP1015 | No | 14.53 ± 0.64 | <0.003 | <2.07E-05 ± 0.09E-05 |
| Yes | 11.58 ± 0.73 | 264.10 ± 17.15 | 2.29 ± 0.28 | ||
| CP1015ΔstkP | No | 10.00 ± 0.37 | 7.33 ± 0.49 | 0.07 ± 0.01 | |
| Yes | 11.91 ± 0.66 | 2.27 ± 0.38 | 0.02 ± 0.0 |
a
Transformation efficiencies were calculated as the ratio of the viable counts on plates with and without rifampin (see Materials and Methods). Results are expressed as the mean counts (±standard deviations) from three independent experiments.
b
Competence induction with CSP at 250 ng ml−1.