Characterization of novel Trichoderma hemicellulase and its use to enhance downstream processing of lignocellulosic biomass to simple fermentable sugars

Crude hemicellulase by novel mycoparasitic Trichoderma asperellum (GenBank accession nos. KU878976) was characterized and used in synergy with commercial cellulase to enhance the hydrolysis of Oil-palm-empty-fruitbunches (OPEFB). Hemicellulase complex was cellulase-free, but was dominated by beta-1,4-xylanase and a few accessory enzymes such as beta-xylosidase, a-arabinofuranosidase, acetyl xylan esterase and beta-glucosidase. Based on xylanase assay, optimum enzyme activity was shown at 50 degrees C and pH 5.3; while thermal and pH stability were respectively at 50 degrees C (1 h) and pH 4.8-10. Moreover, the crude hemicellulase from T. asperellum could withstand up to 50% selected hydrolytic and fermentation inhibitors. Supplement of hemicellulase crude to Celluclast 1.5 L at 1FPU: 5U enhanced the hydrolysis of alkaline-treated OPEFB biomass achieving a 91.7% saccharification yield, higher than 77.9% yield or 12.2% yield when no hemicellulase was used or used without addition of cellulase respectively. The high saccharification yield, which has not been attained in any previous report on OPEFB, demonstrates the potential of T. asperellum for the development of efficient enzyme system for lignocellulosic bio-conversion. As far as we know, this is the first report on enhancement of lignocellulosic cohydrolysis through synergism of hemicellulase crude by T. asperellum and commercial cellulase.