Abstract
Prophages were induced from Bacillus subtilis spores lysogenic with SPO2 by ultraviolet (160 nm to 240 nm) irradiation from synchrotron orbital radiation (SR UV). SR UV at around 220 nm was most effective in the inactivation of spores and prophage induction from lysogenic spores, suggesting that the lesions are produced on the DNA molecule which eventually induces signals to inactivate the phage repressor.