Abstract
Three intracellular forms of K phage DNA were identified by sucrose gradient centrifugation and EM: a form with sedimentation characteristics similar to mature phage DNA; a fast-sedimenting form (FSF) and a rapidly sedimenting complex (RSC). The FSF sedimented in a position intermediate between mature DNA and the RSC and comprised 1 genome length of phage DNA in association with a small mass of non-DNA material. Each RSC was associated with a discrete mass of non-DNA material about 3 times the size of that in the FSF and formed a large tangled structure containing up to 30 or more phage equivalents of DNA. The RSC was identified as the major replicative form.