土壤放线菌分离及无抗菌活性株的激活

从广州的稻田土里分离出三支菌，其中一株（２０号）产生的抗生物质不仅可抑制多种细菌，而且也可抑制白色念珠菌，经初步鉴定为诺卡氏菌属放线菌；另外两支为天然无抗生活性的放线菌，属拟诺卡氏菌。对两株无活性的菌进行紫外照射，然后用四环素和盐酸羟胺复合诱变，经初筛后发现三支激活株，其中一支产生了较明显的抗真菌活力。最后对激活株和２０号菌所产生的抗生物质进行初步研究，证明可能是一种非多烯大环内酯类抗真菌抗生素。实验结果表明这几支天然无活性的供试菌中均含有可被激活的沉默基因，这些基因和抗生素合成有关。

ISOLATION OF SOIL ACTINOMYCETES AND ACTIVATION OF STRAINS WITHOUT ANTIBIOTIC

Three strains were isolated from soil of rice fields in Guangzhou.One,No.20,produces the antibiotics which can inhibit some bacteria and C.albicans .The strain was identified as Nocardia .The other two strains,No.12 and No.38,cannot produce any antibiotic substance,and were identified as Nocardiopsis .The two strains were irradiated with UV rays and mutated by tetracycline,hydrooxylamine chloride,and three active mutants were isolated.The antibiotics secreted from one of the three mutants can obviously inhibit C.albicans .The antifungal antibiotics produced by two strains,active mutant and No.20,were primarily studied,the results show they are not polyene macrolide antibiotics,and some silent genes exist in the strains without antibiotic activity in the test,the genes can be activated and related to the formation of antibiotics.