Reactivation of Ultra-Violet-Inactivated Bacteriophage by Visible Light

COLI-BACTERIOPHAGE of the `T' group¹ are inactivated at a logarithmic rate by ultra-violet light. Some of these phages can be reactivated inside bacteria that adsorb more than one inactive phage particle². I recently observed another type of reactivation of ultra-violet irradiated phage, namely, reactivation upon exposure to visible light in the presence of bacterial cells (photo-reactivation). Since this phenomenon may cause serious misinterpretations of results obtained in working with irradiated phage, it may be useful to report it at this early stage of its investigation.