Adaptive response and enhancement of N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis by chloramphenicol in Streptomyces fradiae

Streptomyces fradiae expressed an adaptive response to treatment with small doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) that caused a reduction in mutagenesis by treatment with larger doses of MNNG. Treatment of S. fradiae with high levels of MNNG in the presence of chloramphenicol caused enhancement of mutagenesis, independent of the adaptive response.