The Optimization Of Fermentation Medium And Process Of Spinosad By Saccharopolyspora Spinosa

Spinosyns, a kind of macrolide insecticide, is produced by Saccharopolyspora spinosa. Spinosyns have a strong toxic effect on economic pests, and are safe to birds, fish and most of the other beneficial insects. Due to its unique chemical structure and mechanism, spinosyns degrade quickly,is friendly to environment without residue.In order to improve the spinosad yield, the fermentation medium and fermentation conditions were optimized. Optimization the fermentation medium and fermentation conditions are the most commonly used and efficient way to improve the microorganism fermentation production. Based on artificial neural network and genetic algorithm, the optimization of spinosad fermentation medium was studied by taking effective measures:Firstly, optimization of the spinosad fermentation medium was performed by using Plackett-Burman design and the contribution degrees of various factors on the fermentation results were determined; Secondly, artificial neural network was built by using the medium composition as the input variable and the corresponding production of spinosad as the output variable. Subsequently, the formula of culture medium was corresponded to the fermentation potency by using "black-box" model. Thirdly, the best formula of culture medium was achieved by using Genetic Algorithm and the optimal fermentation medium were determined as follows:glucose 85.28 g/L,starch 12.38 g/L,corn steep liquor 9.70 g/L, soybean powder 3.00 g/L,cotton seed powder 27.37 g/L, yeast powder 4.56 g/L, methyloleate 9.08 g/L, KH2PO40.618 g/L, CaCO38.00 g/L and initial pH 7.6. Cultured for 10 days under the conditions of this medium for fermentation, the culture temperature was 30℃, stirring speed was 280 r/min, the spinosad fermentation yield increased from 187.86 mg/L to 301.96 mg/L, which increased by 60.74%.The results shows that the network algorithm combined with genetic algorithm can effectively improve the yield of spinosad in fermentation process. Therefore, this method has a certain application value in biological fermentation region.Fed-batch fermentation is a complex, nonlinear, time-varying process. It is impossible to establish an effective model by traditional experimental methods. The results show that corn syrup plays a key role in fermentation process, and it can improve the yield of spinosad during Saccharopolyspora Spinosa fermentation by feeding corn syrup liquid.The impact on spinosad production with the addition of corn syrup in different stages was studied by single factor experiments. The results showed that the yield of spinosad was effectively improved by feeding the corn syrup during the early fermentation. But the adverse result achieved when feeding the corn syrup in the late fermentation. The reason is that higher concentration of corn syrup makes the bacterial fermentation towards the direction of cell growth and leads to decrease the fermentation yield. The neural network model was built by using feeding corn syrup concentration in each time as input and the corresponding spinosad fermentation yield as output, and the model was trained to adapt to the feeding process in the fermentation. Then, the amount of appropriate supplemental corn syrup was explored in each time scale by using Genetic Algorithm, and the optimal scheme for feed was determined. That was on the 3,5,7,9 days of the fermentation process were supplemented with corn steep liquor of 31.0 g/L,22.3 g/L, 2.5 g/L, and 2.0 g/L, the test showed the result of spinosad fed-batch fermentation process was good, with the spinosad fermentation yield increased from 187.86 mg/L to 236.73 mg/L. the production increases by 26% which means a good application value. The results show that this method can effectively improve the production of spinosad in fermentation process.The results show that the network algorithm combined with genetic algorithm can remarkably improve the fermentation medium of spinosad and the feeding process in the fermentation. Furthermore, the optimal method can effectively improve the yield of spinosad in fermentation process. Therefore, this method has a certain applicaton value and prospect in biological fermentation region.