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KMID : 1094720140190050829
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Biotechnology and Bioprocess Engineering
2014 Volume.19 No. 5 p.829 ~ p.837
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Biodegradation of cellulose by β-glucosidase and cellulase immobilized on a pH-responsive copolymer
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Liu Jingjing
Cao Xuejun
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Abstract
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Biodegradation of cellulose involves synergistic action of the endoglucanases, exoglucanases and β-glucosidases in cellulase. However, the yield of glucose is limited by the lack of β-glucosidase to hydrolyze cellobiose into glucose. In this study, β-glucosidase as a supplemental enzyme along with cellulase are co-immobilized on a pHresponsive copolymer, poly (MAA-co-DMAEMA-co-BMA) (abbreviated PMDB, where MAA is α-methacrylic acid, DMAEMA is 2-dimethylaminoethyl methacrylate and BMA is butyl methacrylate). The thermal and storage stabilities of PMDB with immobilized enzymes are improved greatly, compared with those of free cellulase. Biodegradation of cellulose is carried out in a pH-responsive recyclable aqueous two-phase system composed of poly (AA-co- DMAEMA-co-BMA) (abbreviated PADB 3.8, where AA is acrylic acid) and PMDB. Insoluble substrate and PMDB with immobilized cellulase and β-glucosidase (Celluclast 1.5L FG and Novozyme 188, respectively) were biased to the bottom phase, while the product was partitioned to the top phase in the presence of 40 mM (NH4)2SO4. When the degradation reaction of cellulose is carried out with PMDB containing immobilized cellulase and β-glucosidase, the concentration of glucose reaches 4.331 mg/mL after 108 h. The yield of glucose is 50.25% after PMDB containing the immobilized enzymes is recycled five times.
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KEYWORD
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cellulase, β-glucosidase, water-soluble immobilized enzyme, pH-responsive copolymer, aqueous two-phase system
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