[Mutagenic effect of o-methylhydroxylamine on the prophage and extracellular phage lambda].

Induction of c-mutations in extracellular bacteriophage and prophage lambda cI857 ind-treated with 1 M O-methylhydroxylamine (OMHA) at 32 degrees and pH 5.6 has been studied. The frequency of c-mutations increases proportionally to the time of treatment of extracellular phage and does not depend on cellular recA+ or polA+ functions and on induction of SOS-repair system caused by UV-irradiation of host cells. Prophage is inactivated and mutagenized approximately 10-fold faster than extracellular phage immediately after treatment of lysogenic cells during prophage induction. Thus, prophage survival does not depend on repair functions of the host cells, and the frequency of c-mutations in recA and, especially, in polA lysogens is significantly lower, than in the wild-type cells. Delayed thermoinduction (90 min) of prophage causes significant enhancement of survival and decreases the frequency of c-mutations in all strains studied. Preliminary treatment of non-lysogens with OMHA does not increase the frequency of c-mutations in undamaged phage or in phage treated with OMHA in vitro.