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

- First report on biomass hydrolysis via synergism of T. asperellum crude and cellulose.
- T. asperellum USM SD4 hemicellulase is cellulase-free and composed mainly of xylanases.
- Enzyme activities were optimum at 50 °C; pH 5.3 and stable at 50 °C (1 h); pH 4.5-10.
- Crude enzyme showed xylanase activity up to 50% EtOH and MtOH concentration.
- Enzyme crude retained about 60% residual activity up to 50 mg/ml xylose concentration.
- 92% theoretical sugar yield was attained from co-hydrolysis of alkaline-treated OPEFB.

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-fruit-bunches (OPEFB). Hemicellulase complex was cellulase-free, but was dominated by β-1,4-xylanase and a few accessory enzymes such as β-xylosidase, α-arabinofuranosidase, acetyl xylan esterase and β-glucosidase. Based on xylanase assay, optimum enzyme activity was shown at 50 °C and pH 5.3; while thermal and pH stability were respectively at 50 °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 co-hydrolysis through synergism of hemicellulase crude by T. asperellum and commercial cellulase.

Hemicellulase sourced from T. asperellum was characterized and used to enhance cellulase performance for an efficient hydrolysis of alkaline-treated OPEFB.142