ATP Production after ultraviolet irradiation inEscherichia coli

Doses of ultraviolet (UV) irradiation up to 40 Jm^–2 produce a continuous increase of both the level and the rate of ATP production in a RecA⁺ strain ofEscherichia coli growing in AB minimal medium with glucose as carbon source. At fluences higher than 40 Jm^–2, these two parameters increase at a constant rate independent of the dose. Furthermore, in the UV-irradiatedrecA13 mutant, the concentration of ATP is higher and its rate of production is faster than in the RecA⁺ strain. The same behavior as cited above was shown by both RecA⁺ and RecA^– cells when incubated in AB minimal medium without any carbon source both 60 min before and after UV irradiation.