A linear plasmid-like DNA was isolated by Agarose gel electrophoresis from a lysate of Streptomyces sp. 7434-AN4 which produces lankacidin group antibiotics. The DNA (pSLA2) with a molecular weight of 11.2×106 was cleaved into five and three fragments, respectively, with XmaI and BamNI on the definite sites from the end, but not digested by EcoRI and HindIII. Upon treatment of the strain with ethidium bromide, variants were obtained which have lost the ability to produce the antibiotics. These variants were found to have lost pSLA2. These results suggest that the linear plasmid-like DNA is involved in the production of lankacidin group antibiotics.
The Microbiology Research Foundation