Biochemical characterization of a maize stover β-exoglucanase and its use in lignocellulose conversion

Plant is one of the important resources for glycosyl hydrolase production. A β-exoglucanase with molecular weight of 63.1 kDa was purified from fresh maize stover and subjected to enzymatic characterization. The optimal temperature and pH of the β-exoglucanase was 40 °C and 6.0, respectively. The β-exoglucanase was active against p-nitrophenyl-cellobiose (p-NPC), laminarin, cellotriose, cellotetraose, cellopentaose, Avicel, filter paper, and cotton cellulose. The analysis of hydrolytic mode suggested that the β-exoglucanase removed cellobiose from the ends of β-glucan. Kinetic parameters of the β-exoglucanase for laminarin and p-NPC were determined. The effects of metal ions and chemical reagents on the β-exoglucanase activity were also studied. The biochemical characterization of the β-exoglucanase makes it an appealing cellulase additive in converting lignocelluloses to ethanol through simultaneous saccharification and fermentation. The synergism of the β-exoglucanase or crude cell wall proteins of fresh maize stover with Trichoderma reesei cellulase was observed in ethanol production from lignocellulose.