【摘要】 吸水链霉菌应城亚种１０－２２对外源载体ＤＮＡ显示强烈的限制性，来自变铅青链霉菌高拷贝质粒ｐＩＪ１０１的衍生载体ｐＩＪ７０２，能以较低频率转化吸水链霉菌应城亚种１０－２２的衍生菌株Ｑ１５１０。本研究先用质粒ＤＮＡ转化Ｑ１５１０，以获得一些硫链丝菌素的抗性转化子，再对这些混合转化子进行亚硝基胍和吖啶橙的多轮诱变。从经诱变后的单菌落群体中筛选获得６株对Ｃ３１敏感的个体，经鉴定均为限制和修饰基因的双突变子（Ｒ－Ｍ－）。进一步的研究证明，某些本不能转化出发菌株的质粒载体可以转化这些菌株，Ｃ３１能以高频率感染这些衍生菌株；另一个不能感染出发菌株的链霉菌噬菌体Ｒ４，也可以高频率感染这些衍生菌株；Ｃ３１和Ｒ４的ＤＮＡ以及以原始菌株１０－２２为指示菌，从土壤中筛选的但不能转染１０－２２的两株噬菌体ＨＡＵ３和ＨＡＵ４的ＤＮＡ，均能转染限制性缺陷菌株。更多还原

【Abstract】 Streptomyces hygroscopicus subsp.yingchengensis Q1510 is a producer for at least three agriculturally important antibiotics,which can not be infected or transfected by actinophage C31 and its derivatives,and can not be transformed by some plasmids,but its derivative Q1510 can be transformed by pIJ702 derived from high copy number plasmid pIJ101 at low frequency(c.transformants 10/μg DNA)when DNA is isolated from S.lividans.DNA of pIJ702 was thus used to transform Q1510,many thiostrepton resistant transformants were obtained.The mixture of trnasformants were sequencially mutagenized by NTG and acridine orange for several times.6 mutants were obtained after an intensive screening for a single colony sensitive to C31 from a population of mutagenized spores,normally showing resistance to C31.All of them were characterized as restriction deficient(r-)and modification deficient(m-)double mutants(r-m-).Some of the mutants can be transformed by some plasmid vectors which were unable to transform parental strains of the mutants.They can be infected not only by actinophage 3l,but also by R4(another actinophage unrelated to C31).The DNA of C31 and R4,together with DNA of HAU3 and HAU4 can all be introduced into mutant strains by transfection.while C31 and R4 are highly developed known phages,HAU3 and HAU4 are newly isolated phages from soil using S.hygroscopicus subsp.yingchengensis 10-22 as indicator strain.更多还原