Agarose Hydrogel Beads: An Effective Approach to Improve the Catalytic Activity, Stability and Reusability of Fungal Amyloglucosidase of GH15 Family

摘要

This study deals with the immobilization of amyloglucosidase within agarose using method of entrapment. Enzyme was produced from Aspergillus fumigatus KIBGE-IB33 and then partially purified using 40% ammonium sulphate saturation. Using 40 gl(-1) concentration of agarose and adjusting 3.0 mm size of hydrogels, maximum entrapment yield (78%) was obtained. The kinetic behavior was slightly changed after immobilization as reaction time and reaction temperature increases from 5.0 min (soluble) to 10.0 min (immobilized) and 60 A degrees C (soluble) to 65 A degrees C (immobilized), respectively while, pH optima remained same (pH 5.0). Substrate saturation kinetics revealed that K (m) was increased from 1.47 to 4.215 mg ml(-1) while, the value of V-max decreased from 947 to 611 kU mg(-1) for soluble and entrapped amyloglucosidase, respectively. The stability profile of amyloglucosidase also significantly improved after entrapment in agarose hydrogels at 50, 60 and 70 A degrees C for 120 min with retention of 77, 59 and 25% residual activity, respectively. Furthermore, the t(1/2) of soluble and immobilized amyloglucosidase at 60 A degrees C was 167 and 375 min respectively. Due to increase in reusability for various subsequent cycles of entrapped amyloglucosidase, about 8.73 mg ml(-1) increase in glucose production was observed as compared to soluble enzyme.