Efficient synthesis of N-acetyllactosamine using immobilized β-galactosidase on a novel 3D polymer support

A novel polymer support was prepared by curing of epoxy resin in ethanol solution in the macropores of a melamine sponge. The produced polymer gel could uniformly deposit on the surface of melamine in either porous or nonporous morphology. The composite sponge with porous coating can be used as a large-sized and well-mass transferred support for the immobilization of β-galactosidase from Bacillus circulans through method of adsorption and crosslinking, and a column reactor was made for the preparation of N-acetyllactosamine in a sealed circulation way. The porosity and specific surface area of the support were 91.6 % and 46 m²/g, respectively. The loading amount and the specific activity of immobilized β-galactosidase under the optimal immobilization conditions were 41.2 mg/g_support and 16.5 U/mg_protein, respectively. In the biosynthesis of N-acetyllactosamine lactose and N-acetylglucosamine were used as donor and acceptor, respectively. Under optimized conditions the N-acetyllactosamine yield reached 54 % within 150 min at 50 °C. After 10 cycles, the immobilized β-galactosidase retained 70 % of the original activity.