Infectious transfer of a fertility factor inStreptomyces coelicolor

SUMMARYInitial Fertility (IF) strains ofStreptomyces coelicolorare able to convert recipient strains (UF) to the IF condition by contact, without concomitant transfer of chromosomal markers. The conversion is prevented by the presence of acridine orange in the medium of the mixed culture. Acridine orange is also moderately effective in inducing the formation of UF variants from IF-treated strains. No effect of the drug is observed on UF variant formation from Normal Fertility (NF) strains nor on the behaviour of the fertility factor in NF × UF mixed cultures. The hypothesis is put forward that the fertility factor works as an episome inS. coelicolor, fixed to the chromosome in the NF strain…