转座子Tn5096对刺孢吸水链霉菌北京变种PR220转座的诱变

用大肠杆菌／链霉菌穿梭质粒ｐＣＺＡ１６８多次转化农抗１２０产生菌刺孢吸水链霉菌北京变种ＲＦ２２０的原生质体，均未得到转化子。来自吸水链霉菌应城变种１０－２２突变株的链霉菌质粒ｐＩＪ７０２可以转化ＲＦ２２０，但转化频率只有数十个转化子／μｇＤＮＡ。用来自ＲＦ２２０本身的ｐＩＪ７０２对消除ｐＩＪ７０２后的ＲＦ２２０的原生质体进行了再转化，转化率没有明显的提高。用氨苄青霉素和甘氨酸协同处理ＲＦ２２０的菌

Transposition of Tn5096 in a agricultural antibiotic 120 roducer Streptomyces hygrospinocus var. beijingensis RF220]

No transformant was obtained when pCZA168(bla, tsr, Tn5096, ColEI rep. Strep repts) was used to transform S. hygropinocus RF220. pIJ702 isolated from S. hygroscopicus N103 was transformed into RF220 at a low frequency. pIJ702 plasmid was cured in RF220 transformant and it was re-transformed into its cured FR220 strain, but the transformation frequency was not increased significantly, suggesting that restriction-modification system in FR220 was existent and complicated. Four transformants containing pCZA168 were obtained, when the RF220 strain was grown in medium with ampicillin, glycine and the protoplast was stored at -70 degrees C. Restriction analysis of plasmid from transformants indicated that the DNA fragment from E. coli in pCZA168 was deleted. With transposition of Tn5096, two mutants blocked in antibiotic biosynthesis of 120 and some mutants with variation in antibiotic level were obtained, this showed that the Tn5096 transposed in different positions of chromosomal DNA in RF220 and resulted in the production of 120 in different level.