Hydrolysis Kinetics of Oil Palm Empty Fruit Bunch in Ionic Liquids and Cellulase Integrated System

Abstract

Ionic liquids (ILs) are developing as potential solvents in lignocellulose solvation, which enables cellulase accessibility into the substrate. Nevertheless, ILs could result in enzyme deactivation because of the high polarity. Therefore, developing a system of ILs-compatible cellulase (IL-E) to promote lignocellulose conversion into sugars is a challenge in ILs applications. This study used an IL-E to attain high conversion yield of sugars from oil palm empty fruit bunch (EFB). Cellulase (Tr-Cel) from Trichoderma reesei was stable in the ILs, 1-ethyl-3-methyl imidazolium diethyl phosphate [EMIM]DEP and choline acetate [Cho]OAc. The inhibition and deactivation of cellulase were evaluated using the model substrate, carboxymethyl cellulose (CMC) and EFB as a lignocellulosic material to assess the hydrolytic activity. The enzyme kinetics revealed that [Cho]OAc acted as a noncompetitive inhibitor. Additionally, [EMIM]DEP may not be considered as an inhibitor as it increases the Vmax and does not significantly affect the KM. In both cases, the study proved that IL did not result in a severe loss of cellulase activity, which is a promising outcome for one-pot hydrolysis of lignocellulosic materials.