Mutagenesis of free and intracellular cyanophage AS-1 by ultraviolet, N-methanyl-N'-nitro-N-nitrosoguanidine and acriflavine.

Mutagenic actions of ultraviolet irradiation (UV), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and acriflavine (photodynamic) were tested in free and intracellular phage AS-1 infecting Anacystis nidulans IU625. Spontaneous and induced mutations with particular reference to host range (h) and minute plaque formation (m) were investigated. The spontaneous mutation frequencies varied from 10(-9) to 10(-8) and from 2 X 10(-5) to 2 X 10(-4) for h and m mutants respectively. UV was efficient in inducing h and m markers in free phage particles as well as intracellular phage; MNNG induced both markers in intracellular phage only, and acriflavine induced m mutants only in free as well as in infecting phages. UV-induced mutations in free phage were photo-reactivable by visible light. With all the mutagens used, maximal induction of both markers was observed with treatment of 2-h complexes.