Lactose hydrolysis from milk/whey in batch and continuous processes by concanavalin A-Celite 545 immobilized Aspergillus oryzae beta galactosidase.

摘要

The present study deals with the immobilization of Aspergillus oryzae beta galactosidase on concanavalin A layered Celite 545 as bioaffinity support. The activity yield of crosslinked enzyme was 71%. Michaelis constant, K_m was 2.45 mM and 5.58 mM for soluble and crosslinked adsorbed beta galactosidase, respectively. V_max for soluble and crosslinked adsorbed enzyme was 0.52 mM/min and 0.38 mM/min, respectively. Moreover, the K_iapp value of crosslinked beta galactosidase was 366 x 10--6 M while its soluble counterpart exhibited lower K_iapp value, 181 x 10--6 M at 2% galactose concentration. Soluble and immobilized beta galactosidase exhibited same pH and temperature optima at pH 4.5 and 50 degrees C. The crosslinked adsorbed enzyme retained 90% activity after 1 month of storage at 4 degrees C and 71% activity after its seventh repeated use. Moreover, crosslinked beta galactosidase showed greater resistance to product inhibition mediated by glucose and galactose. Crosslinked Con A-Celite adsorbed beta galactosidase showed increased efficiency in hydrolyzing lactose from milk and whey in batch processes at 50 degrees C as compared to the adsorbed and soluble enzyme. The hydrolysis of lactose in the continuous reactors containing crosslinked beta galactosidase was 92% and 81% at flow rate of 20 mL h--1 and 30 mL h--1 after 1 month of operation, respectively.