The lignin present in steam pretreated softwood binds enzymes and limits cellulose accessibility |
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Authors: | Kumar Linoj Arantes Valdeir Chandra Richard Saddler Jack |
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Institution: | Forest Products Biotechnology/Bio-energy Research Group, Forest Sciences Centre, University of British Columbia, 2424-Main Mall, Vancouver, BC, Canada, V6T1Z4 |
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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 (5 FPU/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. |
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Keywords: | BSA bovine Serum Albumin CBM carbohydrate Binding Module CBU cellobiase Units FPU filter Paper Unit SO2 sulphur dioxide SPDF Steam Pretreated Douglas-fir SPDF steam Pretreated Douglas-fir SPDF-CD Steam pretreated Douglas-fir that was completely delignified SPDF-D38/D30/D22/D11 steam pretreated Douglas-fir that was partially delignified to different lignin content SPDF-S41 steam pretreated Douglas-fir that was sulfonated WRV water Retention Value |
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