Table 1.
Results of Shewanella oneidensis survival experiments as a function of applied pressure stress at constant temperature (21°C).
| Previous pressure(s) experienced/MPa | Pressure/MPa | Survivor counts/CFU/ml | Average N/CFU/ml (SD) |
|---|---|---|---|
| None (WT) | 250 | 9, 10, 9 (×107) | 9.3 × 107 (60) |
| None (WT) | 500 | 150, 140, 155 (×102) | 1.5 × 104 (8) |
| None (WT) | 750 | 132, 130, 155 (×102) | 1.4 × 104 (14) |
| None (WT) | 1000 | 140, 927a | 5.2 × 102 |
| None (WT) | 1500 | 132, 132, 130a | 1.31 × 102 (1) |
| 250 | 500 | 25, 24, 24 (×105) | 2.4 × 106 (6) |
| 250 and 500 | 750 | 2, 2, 2 (×107) | 2.1 × 107 (11) |
| 250 and 500 and 750 | 1000 | 22 (×105) | 2.2 × 106 |
| 250 and 500 and 750 | 1500 | 5, 6, 3 (×105) | 4.6 × 105 (153) |
Starting average concentration for WT experiments was 108±0.5 cells/ml. The decadal exponent in brackets in the survivor counts column refers to the number of successive dilutions carried out. The value in parentheses following the mean average survivor count indicates 1 SD for the nine data points obtained for each sample. For two samples exposed to 1000 MPa insufficient count data were obtained to carry out a statistical test. Each experiment was held at pressure for a duration of 15 min. aThese CFU/ml values were determined via plate spreads followed by microscopic examination with no dilution factor.