title: The lignin present in steam pretreated softwood binds enzymes and limits cellulose accessibility.
abstract: The influence of cellulose accessibility and protein loading on the efficiency of enzymatic hydrolysis of steam pretreated Douglas-fir was assessed. It was apparent that the lignin component significantly influences the swelling/accessibility of cellulose as at low protein loadings (5FPU/g cellulose), only 16% of the cellulose present in the steam pretreated softwood was hydrolyzed while almost complete hydrolysis was achieved with the delignified substrate. When lignin (isolated from steam pretreated Douglas-fir) was added back in the same proportions it was originally found to the highly accessible and swollen, delignified steam pretreated softwood and to a cellulose control such as Avicel, the hydrolysis yields decreased by 9 and 46%, respectively. However, when higher enzyme loadings were employed, the greater availability of the enzyme could overcome the limitations imposed by both the lignin's restrictions on cellulose accessibility and direct binding of the enzymes, resulting in a near complete hydrolysis of the cellulose.
authors: Forest Products Biotechnology/Bio-energy Research Group, Forest Sciences Centre, University of British Columbia, 2424-Main Mall, Vancouver, BC, Canada, V6T1Z4.
authors: Linoj
authors: L
authors: Kumar
authors: Valdeir
authors: V
authors: Arantes
authors: Richard
authors: R
authors: Chandra
authors: Jack
authors: J
authors: Saddler
mesh_terms: D000818:Animals; D001709:Biotechnology / Q000379:methods*; D002417:Cattle; D002480:Cellulase / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D006868:Hydrolysis / Q000187:drug effects; D008031:Lignin / Q000302:isolation & purification / Q000378:metabolism*; D028224:Pseudotsuga / Q000378:metabolism*; D012710:Serum Albumin, Bovine; D013227:Steam; D013451:Sulfonic Acids / Q000494:pharmacology; D014934:Wood / Q000378:metabolism*
chemical_list: D013227:Steam; D013451:Sulfonic Acids; D012710:Serum Albumin, Bovine; D002482:Cellulose; D008031:Lignin; D002480:Cellulase