A new xylanase from a Trichoderma harzianum strain.

Area of Science:

• Biochemistry
• Enzymology
• Microbiology

Background:

• Xylanases are crucial enzymes in biomass degradation.
• Trichoderma harzianum is a known producer of industrially relevant enzymes.
• Optimizing pulp processing requires efficient and selective enzymes.

Purpose of the Study:

• To purify and characterize a novel xylanase (XYL2) from Trichoderma harzianum.
• To evaluate the biochemical properties and substrate specificity of XYL2.
• To assess the potential application of XYL2 in pulp delignification.

Main Methods:

• Solid-state fermentation of Trichoderma harzianum strain C.
• Enzyme purification using ultrafiltration and gel filtration.
• Biochemical characterization including pH/temperature optima, stability, and kinetic analysis (Km).
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular weight determination.
• Application testing on unbleached hardwood kraft pulp.

Main Results:

• A homogeneous xylanase, XYL2, with a molecular weight of 18 kDa was purified.
• XYL2 exhibited optimal activity at pH 5.0 and 45°C, with stability up to 50°C and pH 5.0 for 4 hours.
• The enzyme displayed a low Km for insoluble oat spelt xylan, indicating high substrate affinity.
• XYL2 showed a unique amino acid composition compared to other Trichoderma xylanases, with high glutamate/glutamine, phenylalanine, and cysteine content.
• Application of XYL2 significantly improved the delignification and selectivity of hardwood kraft pulp.

Conclusions:

• XYL2 is a novel, thermostable xylanase with favorable kinetic properties.
• Its unique amino acid profile may contribute to its specific activity and stability.
• XYL2 demonstrates significant potential as a biotechnological tool for enhancing pulp processing in the paper industry.