Isolation and characterization of plasmids isolated from streptomyces spp. and construction of recombinant plasmids

Streptomyces 속으로 부터 분리한 플라스미드의 특성 및 재조합 유도체의 제조

Five independent Actinomycetes harboring plasmids were isolated from soil. Molecular weight of these plasmids was 55kb, 6.2kb, 4.4kb, 55kb and 7.0kb, respectively. Among them small and apprent high copy number plasmids, pJY501 of 4.4kb and pHY711 of 7.0kb, were selected. The plasmids purified by CsCl-EtBr density gradient centrifugation preserved the conformation of supercoiled covalently closed circular molecule, and an apparent copy number was estivated about 150 and about 35 per chromosome. The isolates carrying plasmids were assigned to the genus Streptomyces. For the purpose of introducing selection markers into the isolated plasmids, the tsr fragmemt of pIJ702 was inserted into the BclI site of pJY 501 and pJY711. And the recombinant plasmids constructed designated as pJY502 and pJY712 respectively.