Abstract
Summary: The isolation of a group of phages attacking the actinomycete Streptomyces coelicolor A3(2) is described. One of the phages, VP 11, has been characterized, with emphasis on the ways in which it might aid studies on the host organism. VP 11 is a virulent DNA phage with a wide host range. It has a latent period of 40 min at 30°C and an average burst size of about 40. The phage has been examined electron-micro-scopically and found to belong in group B of Bradley's morphological classification. It has also been shown to be host-cell reactivated after u.v.-irradiation. Two temperature-sensitive mutations have been shown to undergo recombination. The phage requires Ca2+ for stability and is very sensitive to chelating agents. Some of the difficulties encountered in using a mycelial organism as a host in phage studies are described and discussed.