Entrapment of Xylanase within a Polyethylene Glycol Net-Cloth Grafted on Polypropylene Nonwoven Fabrics with Exceptional Operational Stability and Its Application for Hydrolysis of Corncob Hemicelluloses

Abstract

Enzyme immobilization is a core technique of enzymatic biochemical engineering because it can remarkably reduce the cost of enzymes and improve the enzyme recovery procedure. The most crucial issues for enzyme immobilization include (1) maintaining its activity, both in the immobilization process and in the batchwise catalyst course; (2) separating the immobilized enzyme from the reaction mixture; and (3) the readiness and cost of the immobilization process. Herein, we report a new strategy to immobilize xylanase within a hydrophilic and nonswelling polyethylene glycol (PEG) net-cloth grafted on a polypropylene nonwoven fabric (PPNWF) membrane by a visible light-induced surface graft cross-linking polymerization. The xylanase was in situ entrapped within the PEG net-cloth. The nonswelling PEG net-cloth can effectively maintain the xylanase without leakage in long-term operation. As for the hydrolysis of corncob hemicelluloses, the experimental results showed that the as-formed immobilized xylanase retained 80% of its original activity after being reused for 25 cycles and 60% after 50 cycles, which is far better than that of other immobilization methods by entrapment. Notably, this simple in situ entrapment of enzymes on routine polymeric matrix would lead to an easy industrial production at low cost, while the form of end-products as a sheet can be readily separated from the reaction mixture and reused for batchwise production. After immobilization, the xylanase showed no significant shift in pH or temperature optima as compared with its free form. These results suggest that the immobilization of xylanase within the PEG net-cloth grafted on PPNWF is promising for industrial applications because of its long-term operation stability and convenient recovery for reuse.