Evaluation of the effects of isolated lignin on enzymatic hydrolysis of cellulose.

The different physical and chemical properties of lignin might have various effects on the enzymatic hydrolysis of lignocellulosic substrates. In this study, the influence of lignin on enzymatic digestibility of cellulose was assessed. Addition of 20% (4g/L) isolated enzymatic lignin (lignin 2 and 3) and kraft lignin (lignin 4) resulted in 5-20% drop of glucose yield, depending on lignin sources. The inhibitory effect of lignin was abated as the enzyme loading increased from 10 to 20FPU/g dry substrate. However, the increasing lignin amount to 40% (8g/L) did not appear to further decrease the cellulose hydrolysis efficiency. Ethanol lignin (lignin 1) and calcium lignosulfonate (lignin 5) had no negative effect on the enzymatic hydrolysis of cellulose at cellulase loading of 10 or 20FPU/g dry substrate, the increasing lignin content to 40% presented 6.2% increase of glucose yield. The results indicated that different lignin had significantly influence on the enzymatic hydrolysis, which was confirmed by analysis in chemical composition, elemental analysis, functionality, and thermogravimetry.