麦迪霉素产生菌生米卡链霉菌1748的质粒Psmyi及其特性的研究

从大环内酯类抗生索麦迪霉素的产生菌生米卡链霉菌1748(Streptomyces,mycarofa-ciens1748)中首次分离到质粒pSMYl DNA,通过琼脂糖凝胶电泳和电镜观察,测定pSMYl的分子量为7．17×10⁶道尔顿。用限制性内切酶EcoRI、PstI、XhoI、SalI和BamHl酶切该质粒DNA,构成了pSMYl的限制性内切酶酶切图谱。EcoRI、Pstl对该质粒均只有一个切点。pSMYI能转化到变青链霉菌1326(S.lividansl326)菌株中能稳定地存在,且具有形成麻点(pock)的特性。     

去甲基金霉素发酵的研究

我们在1971年用紫外光照射处理金霉素链霉菌(Streptomyces aureotaciens)38,获得颜色变株38-2,经鉴别证明此菌株除产生金霉素和四环素外,还产生去甲基金霉素。 同年开始进行去甲基金霉素试制研究,由38-2菌株的原始发酵单位100—150单位/毫升出发,通过一     

螺旋霉素发酵的研究

抗菌素是微生物的次级代谢产物,就大多数抗菌素的深层发酵而言,一般可划分为两个阶段,即菌丝生长阶段和抗菌素合成阶段。这二个阶段对营养的需求是有区别的。本文主要报道螺旋霉素合成期对碳源、氮源、磷源的需要,以及通过补加营养物质来提高螺旋霉素产量的研究结果。     

整合及游离状态的链霉菌质粒pLE1的研究

质拉pLEI以整合形式存在于宿主菌变青链霉菌染色体上,通过DNA转化宿主菌原生质体, 导 致了宿主染色体上的整合序列的环出而形成游离质粒DNA分子。初步探讨了质粒pLEI的理化特 性,确认pLEI与质粒PIJ101是同一系列。     

麦迪霉素产生菌生米卡链霉菌1748变株68的特性研究

A stable mutant No. 68 was obtained by treatment of S. mycarofaciens 1748 spores at high temperature. The electromicroscopic examination has shown that the mutant No. 68 and parent strain 1748 both have the spore chains of the spiratype. The spores of both strain are cylindrical in shape. The only difference is that the spores of the mutant No. 68 are of smooth surface, but the 1748 are of thorny. The physiological characteristics of both strains are also very similar with slight differences in utilization of few carbon sources and in cultural characters in few medium. Feeding experiment has shown that the mutant No. 68 was blocked in the formation of the macrolide lactone in the midecamycin biosynthetic pathway. This suggested that the mutant No. 68 might be a polyketide synthase genes deficient mutant. The ability of the mutant No. 68 to convert spiramycin into 4"-propionylspiramycin indicated that the mutant No. 68 contained the midecamycin 4"-propionyltransferase and could be used for microbial bioconversion of spiramycin into 4"-propionylspiramycin.