APPLICATION OF RESPONSE SURFACE METHODOLOGY TO OPTIMIZE DOCOSAHEXAENOIC ACID PRODUCTION BY SCHIZOCHYTRIUM sp. S31

The optimum concentrations of nutrients (glucose and yeast extract) and cultivation conditions (concentration of sodium chloride, pH and incubation time) on docosahexaenoic acid (DHA) production by Schizochytrium sp. S31 in flasks at 30C were studied. Experiment design employed fractional factorial design, path of steepest ascent, central composite design and response surface methodology (RSM). The empirical model developed by RSM was adequate to describe the relationships between the studied factors and the response of DHA production. Based on contour plots and canonical analysis, the optimal conditions for maximizing DHA production (516 mg/L) were at 27.98 g glucose/L, 4.52 g yeast extraction/L, 24.82 g sodium chloride/L, pH 6.96 and incubation for 4 days at 30C. Experimental verification of the optimal conditions resulted in about 97% of the predicted DHA production by the model.