Investigating lignin and hemicellulose in white rot fungus-pretreated wood that affect enzymatic hydrolysis

Selective delignification and hemicellulose removal were performed on white rot fungus-pretreated residues to investigate the effects of lignin and hemicellulose removal on enzymatic hydrolysis. 43.66 - 77% of lignin with small part of hemicellulose were degraded by chlorite treatment, while 79.97-95.09% of hemicellulose with little lignin were degraded by dilute acid treatment, indicating that cross effect between lignin and hemicellulose was minimized. In subsequent enzymatic digestion, regardless of the cellulase loading, residues from series-grade delignification released more glucose and xylose than that from hemicellulose removal, suggesting that lignin rather than hemicellulose in fungi-pretreated residues played a dominant role in hindering enzymatic hydrolysis. Based on the fundamental mechanisms of acidic/alkaline pretreatments in literature, it is proposed that fungal pretreatment prefers to integrate with alkaline pretreatment rather than acidic pretreatment to maximize the synergy. This indication would be helpful to optimize and renovate the integrated pretreatment. (C) 2013 Elsevier Ltd. All rights reserved.