Enhancing the enzymatic hydrolysis efficiency of lignocellulose assisted by artificial fusion enzyme of swollenin-xylanase

Abstract

Low enzymatic hydrolysis efficiency prevents the economic biotechnological conversion of lignocellulose to valuable products. To improve the lignocellulose degradation, artificial fusion enzymes of swollenin (SWOI) and xylanase (XYNⅡ) from Trichoderma reesei were constructed and utilized in lignocellulose hydrolysis. Different connection modes between swo1 and xyn2 were shown to have a significant effect on the activity of the fusion enzyme. Xylanase activity of fusion enzyme SWOI-XYNⅡ (S-X) obtained by connecting C-terminal of SWOI and N-terminal of XYNII increased, while that of XYNⅡ-SWOI (X-S) decreased. Xylanase activity of SWOI-(GGGGS)2-XYNⅡ (S-2X) with a connecting peptide (GlyGlyGlyGlySer)2 between SWOI and XYNII was further improved comparing to that of S-X. Compared with XYNII, S-2X improved the production of reducing sugar from alkali-treated corn (Zea mays L.) cob by 42 %. When acting on alkali-treated corn cob together with endoglucanase EGII, S-2X increased the yield of reducing sugar by 58 % comparing with XYNII. The swollenin-xylanase fusion enzyme was proved to be conducive to plant cell wall decomposition and could be a promising candidate to enhance the efficiency of enzyme cocktails for lignocellulose degradation.