Study on rational breeding of high-yield avermectin industrial strain

[Objective] Strain Biok Av-023 used as the control was employed on screening of high-avermectin yield mutants by rational screening. [Method] With Biok Av-023 as the original strain, the positive mutation strain was firstly screened by routine UV mutagenesis, and then the high-yield avermectin producing strain was selected by the breeding way inferred by L-Ile induction. [Result] UV mutation and L-Ile directional screening had showed that the best L-Ile screening concentration was 0.5%, and the high-yield mutation strain AV60s-32 after re-screening reached the highest titer of 4520 IU/ml, which increased by 23.4% compared with the original strain. [Conclusion] The production of avermectin can be effectively enhanced by the combined way of UV mutation and L-Ile rational breeding.