复合诱变筛选avermectins高产菌株

Screening of high-yield avermectins producing strain by complex mutation

由Streptomycesavermitilis初始菌株经过自然分离可以得到三种不同类型的菌株,即灰色粉末型、白色和光秃型。其中灰色粉末型产素水平最高,摇瓶发酵效价达到6835.1μg/ml,B1组分达到56.3%。经过紫外线和亚硝基胍对初始菌株的孢子的诱变及对其原生质体的诱变再生,并且经过异亮氨酸和链霉素的定向筛选,得到的高产菌株摇瓶发酵效价达到8542.9μg/ml,B1组分达到64.9%;同时通过对高产菌株进行传代培养检验其传代稳定性,结果表明,传代3代后,菌株开始退化,并且其发酵效价有比较显著的下降。

Three types of colony, powdery gray, white and bald, were naturally isolated from Streptomyces avermitilis initial strain. Among them, the powdery grey one produces the highest level of avermectins, and its total titer reaches 6835.1μg/ml in shaking flask with B 1component accounting for 56.3%. After muta-ted with UV and NTG on spores and protoplast (mutated protoplast need to be regenerated before selection), then induced and selected by Ile and Streptomycin, an avermectins high-yielding strain was selected with total titer 8542.9μg/ml and B 1component 64.9%. The stability of the high-yielding mutant was tested, the result showed that after passing 3 generations, the strain began to retrogress and the total titer had a substantial decline.