Enhancement of enzyme hydrolysis by increasing the zeta potential to reduce non-productive cellulase adsorption on sugarcane bagasse treated with liquid hot water

Abstract

The enhancement of enzymatic hydrolysis is important for the biorefinery industry of lignocellulose. Changing the pH of hydrolysis is a simple and direct way to improve hydrolysis efficiencies. In this study, the enzymatic hydrolysis efficiencies of sugarcane bagasse (SCB) treated with liquid hot water (LHW) were 56.7% and 65.5% at pHs of 4.8 and 5.5, respectively. The result of cellulase adsorption on the LHW treated SCB showed that the non-productive adsorption was smaller at pH 5.5, which might tend to enhance hydrolysis. The surface hydrophobicity of lignin was larger at pH 5.5. This suggested that the hydrophobic interaction was not dominant because a strong hydrophobicity force can cause more non-productive adsorption of cellulase with lignin. At pH 5.5, the surface negative charges of lignin and cellulase increased. Therefore, the electrostatic repulsive force between lignin and cellulase increased, leading to less of the non-productive adsorption of cellulase on lignin. In addition, the cellulase desorption from the LHW treated SCB also increased at pH 5.5. This was beneficial in increasing the possibility of cellulase re-adsorption in new binding sites on cellulose and promoting enzyme hydrolysis efficiency.