产生变活霉素的变株的分离与初步鉴别

ISOLATION AND CHARACTERIZATION OF MUTACTIMYCINPRODUCING MUTANT

对天然无抗菌活性的链霉菌1254菌株进行诱变,获得了二株有抗菌话性的变株。变株113产生的抗生素为一组新蒽环类化合物,有抗病毒活性,定名为变活霉素。变株2-6产生碱性水溶性物质。初步实验结果表明,原株1254及变株2-6均是胞壁类型Ⅰ,为链霉菌属。变株113为胞壁类型Ⅳ,不含有枝菌酸。原株1254与变株113的阻断变株共合成的产物与变活霉素相同,以放线紫红素聚酮合成酶基因 actI 为探针与原株1254的总 DNA 进行Southern 杂交为阳性。根据这二个实验的结果推断,在1254菌株中可能存在一条变活霉素的合成途径,但有的基因处于未表达状态,诱发突变使其被活化。

Natural non-antibiotic producing Streptomyces sp.1254 was mutagenized by UV irradiationand two active mutants were isolated.Mutant 113 produced novel anthracycline compounds de-signated mutactimycins.Mutactimycin A was active against the bacteriophage of Bac.subtilis andsome viruses in tissue culture.The mutant 2-6 synthesized a basic water-soluble antimicrobialantibiotic.Chemical analysis of the whole cell hydrolysate and the morphological characterization sho-wed that the strain 1254 and its mutant 2-6 were of chemotype Ⅰ,belonging to the genus ofStreptomyces,and the mutant 113 was of chemotype Ⅳ without mycolic acid.Co-synthesis test of strain 1254 and a blocked mutant of strain 113 gave the active com-pounds identical with mutactimycins.Using the act(?) gene as a probe,the Southern hybridizationrevealed homology between the actinorhodin polyketide biosynthase gene and the total DNA ofthe strain 1254.Based on these data it was deduced that Streptomyces sp.1254 should have a bio-synthesis pathway for mutactimycin,but some of its genes might fail in expression and mutage-nesis would make the silent gene(s)active.