Enhancement of Enzymatic Saccharification of Sugar Cane Bagasse by Extractive Removal of Phytochemicals: An Experimental and Molecular Simulations Study

Abstract

This study has investigated the effect of the removal of phytochemicals from sugar cane bagasse (after acid/alkali pretreatment) on the yield of enzymatic hydrolysis. Hydrolysis experiments were conducted at preoptimized conditions using a mixture of endoglucanase and β-glucosidase. Two biomasses were used: (1) acid/alkali pretreated sugar cane bagasse (ApSCB) and (2) ApSCB after extraction of phytochemicals using acetonitrile and methanol (ApSCBx). Hydrolysis of ApSCB and ApSCBx yielded 17 and 21.2 g of total reducing sugar (TRS) per 100 g of raw biomass, respectively. Molecular docking simulations were conducted for the complexation of phytochemicals with hydrolyzing enzymes. Many phytochemicals, viz., chlorogenic acid, luteolin, tricin, and diosmetin, have smaller binding energies and inhibition constants for complexation with endoglucanase and β-glucosidase enzymes than their substrates. Molecular dynamics simulations revealed that phytochemicals formed stable complexes with both enzymes, intensifying the inhibitory effects. Molecular simulations indicated a higher susceptibility of β-glucosidase to inhibition by phytochemicals. Removal of phytochemicals through solvent extraction before enzymatic hydrolysis enhanced TRS yield by ∼25%.