Immobilization of Glucoamylase by Plasma-Initiated Polymerization and Application to Bioreactor

Abstract

Glucoamylase was immobilized in highly crosslinked polyacrylamide gel by plasma-initiated polymerization, exposing the frozen aqueous monomer to a glow discharge for 90 seconds followed by postpolymerization at room temperature for several days. The polymer gel obtained was refrozen by liquid nitrogen and thawed. By this means, immobilization efficiency was increased drastically. Immobilization efficiency and half-life reached 65% and 520h respectively at a molar ratio of 0.1 and a monomer concentration of 0.20. The productivity of immobilized enzyme was 0.635 mol/g using 30% dextrin as substrate.
Glucose purity in the saccharificates exceeded 97% by a combination of continuous saccharification through the bioreactor using this enzyme with membrane separation by UF-membrane having a molecular cutoff of 1000.