Breeding Of Strain With High Yield Of Spinosad And Optimization Of Fermentation Medium

Spinosyn is a class of macrolide antibiotics produced by the fermentation of the actinomycete Saccharopolyspora spinosa.It is a green broad-spectrum insecticide that has both the high efficiency of chemical pesticides and biological pesticides.safety.In this paper,with the goal of increasing the production of spinosyn,in-depth research has been conducted on the mutagenesis of strains of spinosyn fermentation,the optimization of medium components and culture conditions,etc.,which greatly increased the production of spinosyn The pilot scale-up experiment has laid a good foundation for the industrialization of spinosyn.The original strain was subjected to NTG mutagenesis at different doses and time,and high-throughput screening was performed to obtain 4 high-producing spinosyn strains with stable genetic traits,The yield of spinosyn was increased by 20.67%,21.25%,21.16%and 37.69%respectively compared with the original strain.The culture composition and culture conditions of spinosyn-producing bacteria were optimized through single-factor experiments.According to the experimental results,glucose,dextrin and cottonseed protein,which had a significant impact on spinosyn production,were selected for response surface experiments,and the spinosyn fermentation was finally determined.The optimal conditions are（g/L）:glucose 51.38,dextrin 21.43,cottonseed protein 21.52,Na Cl 3,K₂HPO₄ 1,Fe SO₄0.05,Ca CO₃ 1.After optimization,the yield of spinosyn reached 139μg/L,an increase of 37.93%.By exploring the effects of different cheap carbon and nitrogen sources on the fermentation yield of spinasides,the combination of sucrose and corn meal was determined to replace glucose as the optimal carbon source,and corn pulp was determined to replace cottonseed protein as the optimal nitrogen source.The results of the 50 L pilot fermentation experiment of spinosyn producing bacteria showed that the feeding amount was 15%-20%with sucrose and corn steep liquor as the carbon source and nitrogen source as the inducer,and the feeding was started when the reducing sugar concentration dropped to 0.5%.The concentration of reducing sugar in the fermentation process should be controlled at about 2.0%;the fermentation time should be controlled at 8d;the p H during fermentation should be controlled at 7.2;the dissolved oxygen value of the fermenter should be controlled at 20%-30%,under this condition,the yield of spinosyn reached the highest of 129.76μg/L.