Optimization of the hydrolysis condition of pretreated corn stover using Trichoderma viride broth based on orthogonal design and principal component analysis

Abstract

A new strategy is described to optimize multiple closely related parameters that are involved in the degradation of lignocellulose. Exo-β-1,4-glucanase, endo-β-1,4-glucanase, and β-glucosidase contained in the broth of Trichoderma viride 3.3711 cultures were used as enzyme solution. Corn stover (CS) pretreated by a combination of H2O2 and lignin peroxidase was used as raw feedstock. A comprehensive hydrolysis index (CHI) of three enzymatic activities was constructed by principal component analysis (PCA). Corn stover (CS) was pretreated with a combination of H2O2 and lignin peroxidase. The accuracy of the CHI was demonstrated by a quadratic regression using the CHI as an independent variable and the yield of the total reducing sugar (Ytrs) as a dependent variable. The results showed that the CHI was closely post-correlated with Ytrs and could be used to optimize the fermentation medium components for T. viride cultures due to a highly significant correlation between CHI and Ytrs. Based on the CHI at 96 h, an optimal medium contained 0.6% fructose, 0.6% xylose, 0.3% bean pulp, 0.15% yeast extract, 0.12% KH2PO4, 0.004% CaCl2, 0.008% FeSO4, 0.006% ZnSO4, 0.012% glycine betaine, and 0.004% polyethylene glycol. The maximum actual Ytrs was very near to the theoretical Ytrs.