关键词: 重组里氏木霉, 外切-b-葡聚糖酶, 转化子筛选, 玉米秸秆, 酶水解

Abstract: Increasing the activities of exo-β-glucanases, one of the important components of cellulase, is a key to strengthening the synergistic degradation of cellulase and reducing the cost of cellulolytic hydrolysis. The methods of MCC-agar plate screening and liquid culture medium of filter paper were used in this work respectively to screen Trichodermareesei transformants, obtaining 6 superior transformants with higher filter paper collapsing rate and growing rate on MCC-agar plates. Further screening experiment was conducted under shaking flask condition, obtaining the highly exo-b-glucanase (C₁)-producing transformant T.reesei ZU-101 whose C₁ activity was18.24 U·ml^-1 after 48 h liquid culture, 2.16-fold higher than the original strain. Analysis results demonstrated that filter paper activity (FPA) of the cellulase system of the transformant, representing total activity, increased by 61.9% as exo-β-glucanase activity ascended significantly, although endo-b-glucanase and cellobiase activities varied insignificantly from the original strain. The enzymatic hydrolysis yield of T.reesei ZU-101's cellulase in the hydrolysis of alkali pretreated corn stover was 94.4% when the enzyme dosage and hydrolysis time were 20 FPIU·(g substrate)^-1 and 48 h, respectively. The results of the present work have promising application prospects in the bioconversion and utilization of renewable cellulosic materials.

Key words: recombinant Trichoderma reesei, exo-b-glucanases, screening of transformants, corn stover, enzymatic hydrolysis