Expression of Trichoderma reesei β-Xylanase in Escherichia coli and its function in degradation of Juncao holocellulose

摘要

In this study, the xyn2 gene, which encodes an endo-(3-l,4-xylanase, was isolated with holocellulose extracted from Juncao Miscanthus floridulu as an inducer. The xyn2 gene expressed in Escherichia coli, with the estimated yield of 349 U-mL"1. Zymogram analysis showed that the purified Xyn2 had only one band on SDS-PAGE with an estimated molecular mass of 28 kDa. Enzymology analysis demonstrated that its optimum activity was at pH 6.0 and 60°C, with stability at pH range 4.0-7.0 and temperature up to 50°C. The metal ions Cu~(2+) and Mg~(2+) showed some inhibition effects, while Fe~(2+) and Fe~(3+) had small stimulating effects. Its values of Km and Vmax are 2.85 mM and 50.2 mM/min, respectively. Based on our results, we propose a novel way to convert Juncao biomass into energy and other useful products.