Table 2.
Persister deficiency of the identified mutants in exposure to different stress conditions.
| Genes | No. of bacteria (Log CFU/ml, mean ± SD) | |||||||
|---|---|---|---|---|---|---|---|---|
| pH 3.0 | 57°C | |||||||
| Start | 1 d | 2 d | 3 d | 0.5 h | 1.0 h | 1.5 h | 2.0 h | |
| USA500 | 9.7 ± 0.15 | 7.8 ± 0.17 | 7.0 ± 0.22 | 4.8 ± 0.16 | 7.4 ± 0.23 | 5.7 ± 0.24 | 4.7 ± 0.19 | 4.1 ± 0.17 |
| ureG | 9.4 ± 0.15 | 6.2 ± 0.28* | 2.8 ± 0.17* | 1.0 ± 0.15* | 6.0 ± 0.22* | 3.6 ± 0.20* | 2.6 ± 0.27* | 2.0 ± 0.17* |
| sdhA | 9.6 ± 0.18 | 6.8 ± 0.22* | 5.5 ± 0.18* | 1.4 ± 0.22* | 6.9 ± 0.27 | 5.7 ± 0.13 | 4.6 ± 0.15 | 3.5 ± 0.13* |
| sdhB | 9.3 ± 0.16 | 6.3 ± 0.23* | 3.7 ± 0.22* | 1.0 ± 0.14* | 6.3 ± 0.19* | 4.6 ± 0.16* | 3.2 ± 0.19* | 2.0 ± 0.17* |
| ctaB | 9.4 ± 0.27 | 6.1 ± 0.12* | 2.7 ± 0.16* | 1.0 ± 0.15* | 5.4 ± 0.13* | 4.7 ± 0.17* | 4.2 ± 0.31 | 2.9 ± 0.17* |
| fbaA | 9.6 ± 0.12 | 8.1 ± 0.17 | 7.5 ± 0.16 | 6.0 ± 0.14 | 6.7 ± 0.25 | 6.1 ± 0.19 | 5.2 ± 0.13 | 4.0 ± 0.16 |
| clpX | 9.4 ± 0.17 | 7.5 ± 0.25 | 6.5 ± 0.17 | 4.8 ± 0.17 | 6.4 ± 0.17 | 5.1 ± 0.20 | 3.3 ± 0.32* | 2.1 ± 0.27* |
| mnhG1 | 9.4 ± 0.25 | 7.5 ± 0.24 | 6.6 ± 0.15 | 5.1 ± 0.19 | 7.3 ± 0.13 | 5.6 ± 0.13 | 3.9 ± 0.15* | 3.1 ± 0.19* |
| parE | 9.6 ± 0.17 | 7.8 ± 0.26 | 6.8 ± 0.11 | 5.7 ± 0.16 | 7.1 ± 0.16 | 5.1 ± 0.18 | 3.9 ± 0.29* | 3.5 ± 0.20* |
| HOU_0223 | 9.5 ± 0.16 | 7.5 ± 0.21 | 6.1 ± 0.21 | 4.2 ± 0.18 | 6.7 ± 0.20 | 6.3 ± 0.13 | 5.6 ± 0.16 | 3.9 ± 0.19 |
| HOU_0587 | 9.6 ± 0.14 | 6.3 ± 0.15* | 2.5 ± 0.64* | 1.0 ± 0.17* | 6.5 ± 0.13 | 5.3 ± 0.20 | 4.5 ± 0.26 | 4.2 ± 0.21 |
| HOU_2091 | 9.7 ± 0.12 | 7.6 ± 0.38 | 7.3 ± 0.17 | 6.6 ± 0.16 | 7.4 ± 0.14 | 5.7 ± 0.12 | 4.1 ± 0.12* | 3.4 ± 0.14* |
| HOU_2315 | 9.4 ± 0.13 | 7.5 ± 0.17 | 6.9 ± 0.20 | 5.8 ± 0.18 | 7.3 ± 0.14 | 5.6 ± 0.12 | 4.7 ± 0.13 | 3.9 ± 0.21 |
| HOU_2346 | 9.5 ± 0.16 | 7.8 ± 0.23 | 6.9 ± 0.28 | 5.8 ± 0.16 | 6.6 ± 0.27 | 5.5 ± 0.17 | 4.8 ± 0.18 | 4.2 ± 0.21 |
Stationary-phase cultures of insertion mutants were evaluated for susceptibility to heat and acidity compared with the parent strain. For acid stress, cultures were harvested, washed, and then resuspended in TSB medium at pH 3.0. For heat stress, cultures were directly incubated at 57°C for various times. The number of CFU was determined by plating serial dilutions of bacteria on TSA plates.
*
indicates significant differences in comparison to the parent strain (Student's t-test, P-value < 0.05).