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Abstract
Bacillus licheniformis CGMCC 2876, an aerobic spore-forming bacterium, produces a polysaccharide bioflocculant that is biodegradable and harmless. The present study determined that β-glucosidase played a negative role in bioflocculant synthesis. The gene encoding β-glucosidase was cloned and expressed in Escherichia coli BL21. This gene consists of 1437 bp and encodes 478 amino acid residues. The recombinant β-glucosidase (Bgl.bli1) was purified and showed a molecular mass of 53.4 kDa by SDS-PAGE. The expression and reaction conditions of Bgl.bli1 were optimized; the activity of β-glucosidase reached a maximum at 45.44 U/mL. Glucose clearly inhibited the activity of β-glucosidase. The purified recombinant Bgl.bli1 hydrolysed polysaccharide bioflocculant in vitro and synergised with other cellulases. The ability of Bgl.bli1 to hydrolyse polysaccharide bioflocculant was the reason for the decrease in flocculating activity and indicated the utility of this enzyme for diverse industrial processes.
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1 Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, People’s Republic of China; College of Life Sciences, Xinyang Normal University, Xinyang, Henan, China
2 Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, People’s Republic of China
3 Guangxi State Farms Sugar Industrial Group Company Limited, Guangxi Sugarcane Industry R&D Center, Nanning, Guangxi, People’s Republic of China; Guangdong Key Lab of Sugarcane Improvement and Biorefinery, Guangzhou Sugarcane Industry Research Institute, Guangzhou, Guangdong, People’s Republic of China