Layered Co-Immobilization of β-Glucosidase and Cellulase on Polymer Film by Visible-Light-Induced Graft Polymerization

Abstract

Exploring a suitable immobilization strategy to improve catalytic efficiency and reusability of cellulase is of great importance to lowering the cost and promoting the industrialization of cellulose-derived bioethanol. In this work, a layered structure with a thin PEG hydrogel as the inner layer and sodium polyacrylate (PAANa) brush as the outer layer was fabricated on low density polyethylene (LDPE) film by visible-light-induced graft polymerization. Two enzymes, β-glucosidase (BG) and cellulase, were separately coimmobilized onto this hierarchical film. As supplementary to cellulase for improving catalytic efficiency, BG was in situ entrapped into the inner PEG hydrogel layer during the graft polymerization from the LDPE surface. After graft polymerization of sodium acrylate on the PEG hydrogel layer was reinitiated, cellulase was covalently attached on the outer PAANa brush layer. Owing to the mild reaction condition (visible-light irradiation and room temperature), the immobilized BG could retain a high activity after the graft polymerization. The immobilization did not alter the optimal pH and temperature of BG or the optimal temperature of cellulase. However, the optimal pH of cellulase shifts to 5.0 after immobilization. Compared with the original activity of single cellulase system and isolated BG/cellulase immobilization system, the dual-enzyme system exhibited 82% and 20% increase in catalytic activity, respectively. The dual-enzyme system could maintain 93% of carboxymethylcellulose sodium salt (CMC) activity after repeating 10 cycles of hydrolysis and 89% of filter paper activity after 6 cycles relative to original activity, exhibiting excellent reusability. This layer coimmobilization system of BG and cellulase on the polymer film displays tremendous potential for practical application in a biorefinery.

Metal Affinity Immobilization of the Processive Endoglucanase EG5C-1 from Bacillus subtilis on a Recyclable pH-Responsive Polymer

“…8 Moreover, even though the magnetic nanoparticles could be uniquely collected by an external magnet, a loss of the catalyst is usually observed after one separation step from a thick broth with high solid concentrations. 7 The use of a stimuli-responsive polymer for cellulase immobilization has been suggested as a potential solution to the problems mentioned above. 10,13−15 The stimuli-responsive polymer is a special kind of organic material that can undergo soluble−insoluble changes in response to external stimuli such as pH and temperature.…”

Cellulose-deconstruction potential of nano-biocatalytic systems: A strategic drive from designing to sustainable applications of immobilized cellulases

“…The dual enzyme system showed the 82% and 20% enhanced enzymatic efficiency contrasting with the original activity of isolated BG/cellulase immobilization system and single cellulase system. The repeated experiments up to 10 cycles of CMC hydrolysis relative to original activity shows high stability and recyclability of enzyme after immobilization [60].…”

“…The production of cellulose-derived bioethanol was studied by cellulase enzyme immobilization to enhance the catalytic productivity and cellulase reusability [60]. The visible light induced graft polymerization on low-density polyethylene films, fabricated by a layered structure with a thin poly(ethylene glycol) gels as the inner layer and sodium polyacrylate (PAANa) brush as the outer layer.…”

Immobilization of Multi-Enzymes on Support Materials for Efficient Biocatalysis

“…A suitable polymer film was also exploited to co-immobilize β-glucosidase (BG) and cellulose for the production of glucose from cellulose, which was formed by visible-light-induced graft polymerization (Wang Y. et al, 2019 ). The layered polyethylene (LDPE) film consisted of a thin PEG hydrogel (as the inner layer) and a sodium polyacrylate (PAANa) brush (as the outer layer), where BG/cellulose was immobilized in/on the inner/outer layer, respectively.…”