GIANT LINEAR PLASMIDS OF BETA-LACTAM ANTIBIOTIC-PRODUCING STREPTOMYCES

A survey of the total cellular DNA from five beta-lactam antibiotic-pr oducing Streptomyces spp, by pulsed field gel electrophoresis was cond ucted to investigate the presence of linear plasmids. Streptomyces cla vuligerus NRRL 3585 contained two giant linear plasmids of 120 and 430 kb, in addition to the well-characterized 11.7 kb linear plasmid. Str eptomyces griseus NRRL 3851 contained a single giant linear plasmid of 120 kb, and Streptomyces jumonjinensis NRRL 5741 contained two giant linear plasmids (220 and 280 kb), and two smaller linear plasmids. No plasmids were identified in Streptomyces cattleya NRRL 3841 or Strepto myces lipmannii NRRL 3584. Southern hybridization did not reveal any h omology shared by these plasmids, and beta-lactam antibiotic synthesis gene clusters were located on the chromosome.