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Effect of β-Mannanase and β-Mannosidase Supplementation on the Total Hydrolysis of Softwood Polysaccharides by the Talaromyces cellulolyticus Cellulase System
- Inoue, Hiroyuki, Yano, Shinichi, Sawayama, Shigeki
- Applied biochemistry and biotechnology 2015 v.176 no.6 pp. 1673-1686
- Aspergillus niger, Pseudotsuga menziesii, Talaromyces pinophilus, beta-mannosidase, carbon, cellulose, endo-1,4-beta-glucanase, feedstocks, fungi, glucomannans, hemicellulose, hydrolysis, lignocellulose, mannose, softwood
- Softwoods are promising lignocellulosic feedstock that provide numerous fermentable sugars via the hydrolysis of the components of cellulose and mannan-type hemicellulose such as galactoglucomannan (GGM). However, fungal cellulase systems are insufficient for the hydrolysis of softwood GGM due to the relatively low levels of mannan-degrading activities. To compensate for the deficient activities in the cellulase system, mannan-degrading enzymes were added to a cellulase preparation from Talaromyces cellulolyticus and the hydrolysis of a ball-milling-treated Douglas fir (BM-DF) was evaluated. The addition of a commercial enzyme derived from Aspergillus niger with high β-mannanase and β-mannosidase activities resulted in approximately 80 % mannose yield from BM-DF for a small protein loading amount (i.e., 1.4 mg/g substrate). Supplementation of β-mannanase and β-mannosidase purified from the commercial enzyme revealed that both enzymes were essential to improve the hydrolysis of BM-DF GGM by T. cellulolyticus cellulase. T. cellulolyticus produced inducible mannan-degrading enzymes using glucomannan as a carbon source. Supplementation of this enzyme preparation increased mannose yield from BM-DF to approximately 70 %. These results suggest that the enhancement of T. cellulolyticus β-mannosidase and β-mannanase productivity will be effective for the construction of cellulase system suitable for BM-DF hydrolysis.