Optimization of temperature shift-based fermentation process for sophorolipids production using response surface methodology

Abstract

The present study aimed to optimize the fermentation process of sophorolipids production by using response surface methodology (RSM). The pre-fermentation temperature, temperature shift time and late fermentation temperature were selected as the 3 major considering-factors according to the results of preliminary experiment. Subsequently, response surface methodology was applied for the yield optimization of sophorolipids. The second-degree equation for the yield of sophorolipids had an extremely high coefficient of determination (0.9914) and the probability (P) value of the regression model was less than 0.001. The results showed the optimal conditions in the actual fermentative production of sophorolipids were pre-fermentation temperature of 26 °C, temperature shift time of 60 h and late fermentation temperature of 30 °C. Under these conditions, the yield of sophorolipids reached 99.08 g/L, which was 11.97% higher than that merely under constant temperature.