Research on the Mutation Breeding of Avermectin High-producing Strain

[Objective] The aim was to breed the avermectins high-producing strain with high content of B1a component.[Method] Streptomyces avermitilis strain N-5-6 was treated by compound mutation of UV-LiCl and UV-NTG.[Result] The initial strain was treated by compound mutations of 1.00 ?mol/L LiCl combining with 60 s UV irradiation and 45 s UV irradiation combining with 0.8 ?mg/ml NTG.Thirteen mutants were screened out and compared with initial strains,their total titer enhanced more than 20%.HPLC detection showed that the contents of component B1a in 7 strains were relatively high,being all higher than 45%.The content of B1a in the strain H02180 reached 51.35%,compared with that in the initial strain N-56,it increased 65.1%.The content of B1a in the strain H02108 reached 51.26%, compared with that in the initial strain N-5-6,it increased 64.8%.[Conclusion] The 2 compound mutations of UV combining with LiCl and UV combining with NTG were available for breeding avermectins high-producing strain.