Synergistic action of xylanase and mannanase improves the total hydrolysis of softwood

• Published in: Bioresource technology 2011-10, Vol.102 (19), p.9096-9104
• Main Authors: Várnai, Anikó, Huikko, Laura, Pere, Jaakko, Siika-aho, Matti, Viikari, Liisa
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biotechnology; Cellulase; Cellulase - metabolism; Cellulases - metabolism; Cellulose fibers; Endoglucanase; Enzymatic hydrolysis; Enzymes; Fundamental and applied biological sciences. Psychology; Hydrolysis; Lignin - metabolism; Lignocellulose; Mannanase; Mannans - metabolism; Polysaccharides; Polysaccharides - metabolism; Softwoods; Synergism; Wood - chemistry; Xylanase; Xylans - metabolism; Xylosidases - metabolism
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2011.06.059

► Linear correlation between solubilisation of cellulose and hemicelluloses. ► Hydrolysis of both hemicelluloses enhanced hydrolysis of cellulose synergistically. ► Hemicellulolytic enzymes increased also the hydrolysis of the other hemicellulose. ► Synergism observed suggests that cellulose, xylan and glucomannan are interlinked. ► Xylanolytic and mannanolytic enzymes necessary to obtain high yields on softwood. The impact of xylan and glucomannan hydrolysis on cellulose hydrolysis was studied on five pretreated softwood substrates with different xylan and glucomannan contents, both varying from 0.2% to 6.9%, using mixtures of purified enzymes. The supplementation of pure cellulase mixture with non-specific endoglucanase TrCel7B and xylanase TrXyn11 enhanced the hydrolysis of all substrates, except the steam pretreated spruce, by more than 50%. The addition of endo-β-mannanase increased the overall hydrolysis yield by 20–25%, liberating significantly more glucose than theoretically present in glucomannan. When supplemented together, xylanolytic and mannanolytic enzymes acted synergistically with cellulases. Moreover, a linear correlation was observed between the hydrolysis of polysaccharides, irrespective of the composition, indicating that glucomannan and xylan form a complex network of polysaccharides around the cellulosic fibres extending throughout the lignocellulosic matrix. Both hemicellulolytic enzymes are crucial as accessory enzymes when designing efficient mixtures for the total hydrolysis of lignocellulosic substrates containing both hemicelluloses.