TABLE 3.
Heat resistance of cold shock mutant strains of B. subtilisa
| Temp (°C) | Mean D ± SD for bacterial strain
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Wild type
|
CspB mutant
|
CspC mutant
|
CspD mutant
|
CspCD mutant
|
||||||
| Control | Cold shock | Control | Cold shock | Control | Cold shock | Control | Cold shock | Control | Cold shock | |
| 85 | 21.9 ± 1.7 | 28.3 ± 2.8 | 22.1 ± 1.8 | 27.6 ± 2.1 | 22.6 ± 1.7 | 29.1 ± 3.1 | 21.1 ± 2.6 | 26.5 ± 2.4 | 22.3 ± 2.0 | 26.3 ± 2.2 |
| 90 | 16.5 ± 1.4 | 18.7 ± 1.9 | 15.3 ± 1.3 | 19.2 ± 1.5 | 15.8 ± 1.3 | 19.8 ± 1.1 | 16.2 ± 1.8 | 19.5 ± 1.5 | 15.6 ± 1.1 | 18.6 ± 1.4 |
| 95 | 9.4 ± 0.6 | 3.7 ± 0.4 | 9.8 ± 0.8 | 4.0 ± 0.3 | 10.1 ± 0.9 | 3.8 ± 0.6 | 9.7 ± 0.8 | 4.1 ± 0.3 | 8.9 ± 0.7 | 3.6 ± 0.2 |
| 100 | 6.2 ± 0.3 | 1.8 ± 0.1 | 5.0 ± 0.3 | 1.6 ± 0.2 | 5.8 ± 0.4 | 1.9 ± 0.3 | 6.3 ± 0.5 | 2.1 ± 0.2 | 5.9 ± 0.4 | 1.6 ± 0.1 |
a
The effect of sublethal cold pretreatment (cold shock) of sporulating cells of wild type and cold shock mutants of B. subtilis on the heat resistance of spores formed subsequently was assessed at 85, 90, 95, and 100°C and compared to spores formed from control unpretreated cells. The results are from two independent experiments. As shown by analysis of variance, the cold shock pretreatment results are significantly different from the corresponding results for controls (P < 0.05 for all the heat kill temperatures tested).