Effect of stepwise lignin removal on the enzymatic hydrolysis and cellulase adsorption

Abstract

Lignin can negatively impose on the enzymatic hydrolysis of pretreated lignocellulose through non-productive enzyme adsorption and/or steric hindrance. The effect of the residual lignin on enzymatic hydrolysis was evaluated with sugarcane bagasse (SCB) samples containing different lignin contents and their milled and enzymolytic lignins (MELs) retaining the intact protolignins. The results showed that the improvement of enzymatic hydrolysis of SCB would become insignificant when the lignin removal achieved above 64.0%, and the changes in chemical groups of lignin had slight impact on adsorbing enzymes. When the lignin retention in the pretreated SCB was less than 36.0%, the residual lignin would not significantly influence the enzymatic hydrolysis via enzyme adsorption and steric hindrance. The contributions of the residual lignins in pretreated SCB samples to the total enzyme adsorptions of pretreated SCB samples were only in the range of 9.6% to 15.5%, which were not predominant for the total enzyme adsorptions.