Resistance to Ultraviolet Light as an Index to the Reproduction of Bacteriophage

Infection of a susceptible bacterium by a single phage particle initiates a series of events climaxed, after a time called the latent period, by bursting of the cell and the release of a number (burst size) of replicas of the initial phage. We are here concerned primarily with the intervening process of phage replication which takes place behind the cloak of the cell wall. By prematurely disrupting infected cells, Doermann (1948) found that infective phage replicas are already present well before the time at which the bacterium bursts, i.e., about two-thirds of the way through the latent period. At earlier times, however, no plaque-forming particles are recovered, not even the initial phage. Our attention is, therefore, focused upon this "dark" period, during which the infecting phage must undergo some modification, and the key processes of phage reproduction come to pass.