β-Galactosidase from Aspergillus oryzae immobilized onto different magnetic supports: a comparative experimental and modelling study of the galactooligosaccharides production.

Abstract

β-Galactosidase from Aspergillus oryzae is an enzyme with a wide industrial application, mostly in the hydrolysis of lactose and, more recently, in the synthesis of oligosaccharides. Several advantages are associated with the application of immobilized enzymes on magnetic supports. In this work, β-galactosidase was covalently immobilised onto a Polysiloxane-Polyvinyl Alcohol Magnetic Composite (mPOS-PVA), Magnetic Polysiloxane with Polyaniline (mPOS-PANI), Magnetized Dacron (DACRON) and Magnetite with Polyaniline (MAG-PANI) using glutaraldehyde as activating agent being the synthesis of GOS evaluated and compared at different temperatures (30, 40, 50 and 60 oC) and various initial lactose concentration (50, 100, 200, 300, 400 and 500 g/L). The kinetic parameters obtained by fitting the experimental data were compared in order to determine the effect of the immobilization process with different supports on the synthesis of oligosaccharides. These results clearly demonstrate that all supports may be used for β-galactosidase immobilization as, besides improving the enzyme hydrolytic and GOS synthesis properties, its separation from the obtained reaction products is easy to accomplish