Repair of U.V. damages in Bacillus subtilis cultures competent for transformation: difference between competent and non-competent fractions.

The repair of U.V. damages to DNA in B. subtilis cultures competent for genetic transformation has been studied. The comparison of survival curves for competent and non competent fractions shows that: i) excision repair is more effective in competent than in non competent bacteria; ii) recombination repair is more effective in non competent than in competent bacteria. These facts support the hypothesis that metabolic conditions and, very likely, DNA replication play a role in the regulation of the efficiency of the two different mechanisms of repair.