title: Novel Aspergillus hemicellulases enhance performance of commercial cellulases in lignocellulose hydrolysis.
abstract: A novel hemicellulase-producing fungal strain was isolated from a local soil sample. The organism is identified as Aspergillus fumigatus based on ribosomal RNA analyses. The Aspergillus strain, designated as 2NB, produces both enzymes acting on xylan backbone (xylanase and β-xylosidase), and those acting on side chains (or accessory enzymes) notably α-arabinofuranosidase and acetyl-xylan esterase. The Asperigillus hemicellulases are characterized as having relatively low xylanase and β-xylosidase activities but high side chain removal activities. The activity ratio of side-chain acting enzymes to xylanase is higher than that of the Multifect enzyme, a commercial hemicellulase product. The potential of the novel hemicellulases in lignocelluloses bioprocessing was demonstrated with alkaline-pretreated switchgrass as lignocellulose substrate with hemicellulase supplemented with a ratio of xylanase activity to filter paper unit of 2:1. Supplement of Aspergillus hemicellulases to commercial cellulases significantly enhanced the hydrolysis of lignocellulose, achieving a 94% hydrolysis yield based on reducing sugar measurement, compared to 60% when no hemicellulase or 75% when Multifect enzyme was used under otherwise identical conditions. The significant improvement resulting from supplementing a hemicellulase mix with high side-chain removal activities suggests the importance of accessory hemicellulases in lignocellulose processing.
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Hyun-Dong
authors.initials: HD
authors.lastname: Shin
authors.forename: Trinh
authors.initials: T
authors.lastname: Vo
authors.forename: Rachel
authors.initials: R
authors.lastname: Chen
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D044602:Cellulases / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D007218:Industrial Microbiology / Q000379:methods*; D008031:Lignin / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: C036909:lignocellulose; D008031:Lignin; D044602:Cellulases; D006026:Glycoside Hydrolases; C023305:hemicellulase