Optimization of Candida rugosa lipase immobilization parameters on magnetic silica aerogel using adsorption method

Magnetic silica aerogel in hydrophobic and hydrophilic forms were used as support to immobilize Candida rugosa lipase by adsorption method. Response surface methodology (RSM) was employed to study the effects of the three most important immobilization parameters, namely enzyme/support ratio (0.3-0.5, w/w), immobilization time (60-120 min) and alcohol percentage (20-40, %v/v) on the specific activity of immobilized lipase on the hydrophobic supports. For hydrophilic supports, alcohol percentage was removed as there was no need for pre-wetting step in enzyme immobilization process. Second order regression models with high coefficient determination (R2) values of higher than 0.98 were fitted to predict the response as function of immobilization parameters. The results indicated that for hydrophobic supports, optimum values for enzyme/support ratio, immobilization time and alcohol percentage were obtained at 0.45 (w/w), 94.27 min and 38.81 %, respectively, in which specific activity were predicted at 15.32 U/mg-protein. For hydrophilic supports, the optimum enzyme/support ratio and immobilization time were predicted at 0.47 (w/w) and 83.47 min, respectively. Specific activity in these conditions were obtained 11.21 U/mg-protein. As the difference between the experimental and predicted values was showed as non-significant, the response surface models employed could be considered as adequate.