I will survive: protecting and repairing spore DNA.

an actively metabolizing cell. The end product of sporulation is an endospore with no detectable metabolism, which lacks most common high-energy compounds, including ATP and other nucleoside triphosphates (28). However, this dormant spore can survive for long periods of time even in a hydrated state, as there are reports of spores which may have survived several thousand years (33). While there are no direct experimental measurements of the percentage of spores which survive over such extended periods, observation of >50% survival of spores stored in water at 6 to 10°C for at least a year is not uncommon. Clearly, in order for spores to survive during these long periods of dormancy, mechanisms must be operating to prevent accumulation of potentially lethal damage in spore DNA. Although damage to essential proteins (e.g., RNA polymerase) could result in spore killing, if a spore has a thousand molecules of such a protein almost all would have to be inactivated to cause spore death. In contrast, a spore with its single chromosome can acquire