2 SMALL LINEAR PLASMIDS OF STREPTOMYCES-JUMONJINENSIS

In a survey of plasmids in a variety of beta-lactam antibiotic produci ng Streptomyces spp., two small linear plasmids (pSJL1 and pSJL2) of a pproximately 12 and 17.5 kb were detected within Streptomyces jumonjin ensis NRRL 5741, in addition to the previously reported giant linear p lasmids pSJL3 and pSJL4. Characterization of these plasmids by Souther n hybridization indicated that no significant homology exists between the S. jumonjinensis plasmids and plasmids detected in other beta-lact am antibiotic producing Streptomyces spp. Single and double restrictio n endonuclease digestions were performed to generate maps of the two p lasmids. The plasmids pSJL1 and pSJL2 have copy numbers of 21-27 and 1 5-20, respectively.