Characteristics of the developmental cycle of actinophage phi C31.

Some characteristics of the lytic development of the temperate phage phi C31 in Streptomyces coelicolor A3(2) were studied using a thermoinducible lysogen. The physiological state of the host and the culture medium influenced the production of progeny virus after induction. The latent period lasted 45 min and the rise period 20-30 min. RNA synthesis in induced cultures was reduced with respect to controls. This reduction was restricted to cellular transcription as evidenced by: no stable RNA being synthesized in induced cultures, and the proportion of phage specific RNA increasing from 0.5% before induction to more than 30% in induced cultures. Host RNA synthesis proceeded throughout the lytic cycle. Protein synthesis was also reduced in induced cultures, although to a lesser extent than RNA synthesis. Phage DNA synthesis started at around 10 min postinduction, marking the division between the early and late periods of phage development. Host DNA synthesis occurred during the first 20 min after induction, and gradually decreased later.