Optimization of inulinase production by Kluyveromyces marxianus using factorial design

Factorial design and response surface techniques were used to optimize the culture medium for the production of inulinase by Kluyveromyces marxianus. Sucrose was used as the carbon source instead of inulin. Initially, a fract ional factorial design (2(5-1)) was used in order to determine the most rel evant variables for enzyme production. Five parameters were studied (sucros e, peptone, yeast extract, pH, and K2HPO4), and all were shown to be signif icant. Sucrose concentration and pH had negative effects on inulinase produ ction, whereas peptone, yeast extract, and K2HPO4 had positive ones. The pH was shown to be the most significant variable and should be preferentially maintained at 3.5. According to the results from the first factorial desig n, sucrose, peptone, and yeast extract concentrations were selected to be u tilized in a full factorial design. The optimum conditions for a higher enz ymatic activity were then determined: 14 g/L of sucrose, 10 g/L of yeast ex tract, 20 g/L of peptone, 1 g/L of K2HPO4. The enzymatic activity in the cu lture conditions was 127 U/mL, about six times higher than before the optim ization.