The influence of prophage lambda on the mutagenic response of Escherichia coli to ultraviolet irradiation.

E. coli K-12 and its lambda-lysogenic derivative were used to study the influence of lysogenic induction on the induction of mutants (streptomycin sensitivity to streptomycin resistance) by UV irradiation. The lambda-lysogenic strain responded to UV irradiation with increased sensitivity and with a strong reduction of the absolute mutant quantity, recovered per UV dose, as compared with the non-lysogenic parental strain. However, similar mutant freqqencies per surviving bacterium exclude the possibility that the diminished mutant recovery results from a selective killing of mutant cells by simultaneous induction of the processes of mutation and lysis.