Improvement of biomass production and glucoamylase activity by Candida famata using factorial design

To improve biomass production and glucoamylase activity (GA) by Candida famata , culture conditions were optimized. A 2 3 full factorial design (FFD) with a response surface model was used to evaluate the effects and interactions of pH ( X 1 ), time of cultivation ( X 2 ), and starch concentration ( X 3 ) on the biomass production and enzyme activity. A total of 16 experiments were conducted toward the construction of an empiric model and a first‐order equation. It was found that all factors ( X 1 , X 2 , and X 3 ) and their interactions were significant at a certain confidence level ( P < 0.05). Using this methodology, the optimum values of the three tested parameters were obtained as follows: pH 6; time of cultivation 24 H and starch concentration 7 g/L, respectively. Our results showed that the starch concentration (X3) has significantly influenced both dependent variables, biomass production and GA of C. famata . Under this optimized medium, the experimental biomass production and GA obtained were 1.8 ± 0.54 g/L and 0.078 ± 0.012 µmol/L/Min, about 1.5‐ and 1.8‐fold, respectively, higher than those in basal medium. The ( R 2 ) coefficients obtained were 0.997 and 0.990, indicating an adequate degree of reliability in the model. Approximately 99% of validity of the predicted value was achieved.