[en] Mutants obtained from N - methyl -N' - nitro - N - nitrosoguanidine (MNNG) treatment of the W₅ strain or Staphylococcus epidermidis and selected for their increased UV - sensitivity were characterized according to their capacity to repair DNA damage. The original W₅ parental strain as well as several phenotypically defined strains of Escherichia coli, described in the literature, were used as a reference. The study included: the verification of cellular UVV - and MNNG - sensitivities; the determination of the bacterial potential for phage-reactivation by constitutive enzymatic mechanisms (host cell reactivation), as well as by the action of inducible repair systems (W-reactivation); the assessment of the UV-inductibility of prophage in the lysogenic hosts. (author)