Response surface optimization of Bacillus cereus CGMCC4348 fermentation

The optimum conditions of cultivation of Bacillus cereus were studied by the response surface analysis to the OD600(1/50).Based on the Plackett-Burman experimental design,the independent variables of the temperature,pH,and CaCO3 dosage were determined,and a quadratic regression model of optimized culture conditions was established by Design-Expert center combination experiments.The results of response surface analysis showed that temperature of 34.36 ℃,pH of 7.37,CaCO3 dosage of 2.4 g/L were the optimal conditions.The predicted maximal OD600 was(1/50) average of 0.652.A set of parallel tests was made under optimal culture conditions,and the average OD600(1/50) was 0.649,indicating that the actual experimental values and model prediction ones were basically the same.Results showed that the response surface methodology using central composite design could improve the yield of Bacillus cereus,the number of viable cells in the culture medium could be 2.48×1010 cfu/mL.