Breeding and fermentation study of a high-yield spinosad producing Saccharopolyspora spinosa strain

Saccharopolyspora spinosa parental strain CG-73 was exposed to cosmic radiation during a flight aboard a Shenzhou 9 spacecraft. 12,480 recovered colonies potentially harboring mutations were screened for increased spinosad production. Of these strains, 172 exhibited improved yields. The maximal spinosad yield of one strain in a shaking flask reached 573.8 mu g/mL which correspond to an improvement of 80.3% compared to that of the parental strain. The effects of S. spinosa biomass on the spinosad yield were also studied by shaking flask fermentation and in a 30-L fermentation tank. Using central composition design (CCD), the optimal medium formula for enhancing biomass was obtained with five important factors: glucose, peptonized milk, dextrin, cottonseed protein and soybean oil. Finally, the tank-based fermentation yield of spinosad reached 1156.8 mu g/mL by the fermentation process regulation.