DETECTION OF FOUR PLASM1DS IN STREPTOMYCES HYGROSCOPICUS VAR. YINGCHENGENSIS 10-22 AND THEIR STEPWISE ELIMINATIONS
吸水链霉菌应城变种的四个内源质粒及其逐个消除的研究

Four indigenous piasmids were detected with the medified method of plasmid DNA isolation in Streptomyces hygroscopicus var. yingchengensis 10-22, which produces three different effective antibiotics against plant diseases. Two dimentional agarose get electrophoresis revealed that all of them were Ccc molecales. By parallel electrophoresis with plasmids of known sizes, the four plasmds were estimated 10 be approximately 6' kb, 4. 7 kb, 4. 1 kb and 3. 3 kb in size, which were designated pHZ1 pHZ2. pHZ3 and pHZ4, respectively. Based on the assumption that conjugative plasmids would form "pocks" on the lawn of strains lacking corresponding plasmids, we isolated and characterized several 10-22 derivatives which had lose 13 plasmas, and confirmed tive types of pocks under light microscope.