Immobilization and characterization of feruloyl esterase enzyme in calcium alginate

Enzymes are important biocatalysts for sustaining life and are widely used in many areas of industry. Enzyme immobilization is performed for the recovery and reusability of enzymes. In this study, immobilization of recombinant feruloyl esterase (FAE) enzyme in calcium alginate by the entrapment method was applied. Optimum conditions of free and immobilized feruloyl esterase were determined. These conditions are pH, temperature, kinetic parameters, thermal and storage stabilities and reuse stability of immobilized feruloyl esterase. Optimum pHs of free and immobilized feruloyl esterase were determined as 8.0 and 7.5, respectively, and optimum temperatures were determined as 40 °C for the both preparations. Storage stabilities of free and immobilized feruloyl esterase were investigated at certain time intervals for 15 days. Free feruloyl esterase maintained 86% of its initial activity at 5 °C for 15 days, while it maintained 49% of its activity at 25 °C. It was observed that immobilized feruloyl esterase retained 16% of its initial activity after 7 days at 5°C and 4% of its activity after 3 days at 25°C. Km value of free feruloyl esterase was calculated as 68.15 mM, Vmax value as 2.86 U/mg protein, Km value of immobilized feruloyl esterase was 34.96 mM, Vmax value as 21.79 U/mg protein. Thermal stabilities of free and immobilized feruloyl esterase were determined at different temperatures. It was determined that free feruloyl esterase retained 96% of its initial activity at 40°C and 22% at 50°C after 16 hours, while immobilized feruloyl esterase retained 47% of its initial activity at 40°C and 31% at 50ºC. The reusability of immobilized feruloyl esterase was investigated and it was observed that it retained its activity by 57% after the 4th use. As a result, calcium alginate was found to be a suitable immobilization method for feruloyl esterases. Keywords: Feruloyl esterase, Immobilization, Calcium alginate