[Mutagenesis of synchronous populations of Escherichia coli with normal and defective reparative enzymes under the influence of hydroxylamine].

Bacterial populations of E. coli K12 uvr+ and E. coli K12 uvr- were preliminary synchronized on membrane nitrocellulose filtres and then treated with 1 M hydroxylamine for different times; the frequency of mutants failing to assimilate glucose was estimated. Kinetics of mutagenesis in the cells of both strains was almost the same and indicated that lesions induced by hydroxylamine were not repaired. It is for the first time that the maximum mutation frequency was registered in experiments with hydroxylamine; this suggests that the repair hypothesis of attaining the maximum mutation frequency is not universal.