TABLE 3.
Survival of strains AP1 and SR301 at different time points following peroxide challenge
| Strain (growth condition)b | CFU/ml at time (min)a:
|
||||
|---|---|---|---|---|---|
| 0 | 15 | 30 | 60 | 90 | |
| AP1 (CO2) | 2.5 × 108 ± 7.7 × 107 | 3.8 × 107 ± 3.6 × 107 | 1.5 × 107 ± 7.9 × 106 | 5.1 × 106 ± 4.2 × 106 | 1.2 × 106 ± 1 × 106 |
| SR301 (CO2) | 2.9 × 108 ± 1 × 108 | 2.7 × 108 ± 9.7 × 107 | 2.1 × 108 ± 9.5 × 107 | 7.3 × 107 ± 3.3 × 107 | 1.8 × 107 ± 1.5 × 107 |
| AP1 (O2) | 1.1 × 108 ± 8.6 × 107 | 1.6 × 108 ± 1.5 × 108 | 7.4 × 107 ± 6.4 × 107 | 7.3 × 107 ± 5.6 × 107 | 3.2 × 107 ± 2.2 × 107 |
| SR301 (O2) | 1.1 × 108 ± 6.9 × 107 | 9 × 107 ± 7.9 × 107 | 5.5 × 107 ± 3.9 × 107 | 4.8 × 107 ± 5 × 107 | 2.5 × 107 ± 3.1 × 107 |
a
CFU per milliliter of AP1 (wild type) and SR301 (perR) bacteria surviving H2O2 challenge. Bacterial dilutions were plated onto THY plates 0, 15, 30, 60, and 90 min after the addition of 5 mM H2O2. Results are expressed as means ± SD of four to five independent assays.
b
AP1 and SR301 strains were grown either under aerobic conditions (O2) or in the presence of 5% CO2 prior to challenge with H2O2.