Research On The Strain Improvement, Culture Optimization For Spinosad Production

Spinosad is a new class of macrolide compounds produced by aerobicfermentation of the Gram-positive bacteria Saccharopolyspora spinosa. Spinosadis a new class of highly effective biological insecticide with low toxicity. The aim ofthis work is to increase the productivity of spinosad fermentation. After U.V. andNaNO2mutation with rational screening, medium composition and culture conditionoptimization, the spinosad productivity is increased greatly. This work providesreference for the industrialization of spinosad fermentation.According to the biosynthesis path of spinosad, a high yield strain S.spinosa4/26was obtained by rational breeding of the original wild strain ATCC49460with the U.V.and NaNO2mutation. Spinosad productivity of4/26was331.7mg/L, which was2-fold higher than that of ATCC49460.The optimiziation of the fermentation progress was studied. The effects ofinoculum level, seeding age, medium volume, the initial pH and various precursors onthe spinosad fermentation were studied in the shaking flasks.The seed medium andfermentation medium were also optimized. Several precursors such as short-chainalcohols, amino acids and methylating agents, which all could enhance spinosadbiosynthesis.The effect of the addition of various oils on the production spinosad by S.spinosaLU104was studied. The results indicated that the yield of spinosad was increased2.11-fold up to804.59mg/L when adding3%mixture oil at96h and1%corn steepliquor at96h and144h.The characteristic of the batch and fed-batch fermentation in the5L fermentorwere investigated.However, the productivity of spinosad in bioreactor was lower thanin shake flask. The kinetic models for biomass, substrate consumption and spinosadproduction were studied for the strain LU104by fed-batch fermentation. The modelsperformed well in simulating the cell, spinosad and glucose concentrations of bothwild strain and mutant strain with high accuracy. The result suggests that the kineticmodels can describe well the process of spinosad fermentation, and will be a basic forthe research of scaling up.