Abstract
► The paper summarizes the preparation of a bioaffinity support, concanavalin A layered Celite 545 for the immobilization of Aspergillus oryzae β galactosidase. ► The crosslinked adsorbed β galactosidase exhibited greater stability against various physical and chemical denaturants as compared to the soluble and adsorbed enzyme. ► Moreover, the crosslinked β galactosidase hydrolyzed greater percentage of lactose from milk and whey in batch processes at 50°C and in continuous reactors at different flow rates.
The present study deals with the immobilization of Aspergillus oryzae β galactosidase on concanavalin A layered Celite 545 as bioaffinity support. The activity yield of crosslinked enzyme was 71%. Michaelis constant, Km was 2.45mM and 5.58mM for soluble and crosslinked adsorbed β galactosidase, respectively. Vmax for soluble and crosslinked adsorbed enzyme was 0.52mM/min and 0.38mM/min, respectively. Moreover, Kiapp value of crosslinked β galactosidase was 366×10−6M while its soluble counterpart exhibited lower Kiapp value, 181×10−6M at 2% galactose concentration. Soluble and immobilized β galactosidase exhibited same pH and temperature optima at pH 4.5 and 50°C. The crosslinked adsorbed enzyme retained 90% activity after 1 month of storage at 4°C and 71% activity after its seventh repeated use. Moreover, crosslinked β galactosidase showed greater resistance to product inhibition mediated by glucose and galactose. Crosslinked Con A-Celite adsorbed β galactosidase showed increased efficiency in hydrolyzing lactose from milk and whey in batch processes at 50°C as compared to the adsorbed and soluble enzyme. The hydrolysis of lactose in the continuous reactors containing crosslinked β galactosidase was 92% and 81% at flow rate of 20mLh−1 and 30mLh−1 after 1 month of operation, respectively.