Enzymatic hydrolysis of oil palm empty fruit bunch and its kinetics

Abstract

Oil palm lignocellulosic biomass is a potential substrate for the production of renewable chemicals from agricultural wastes. Emptyfruit bunch (EFB) is one of the biomass waste aside from the trunk and frond from oil palm plantation. Bioconversion of oil palm lignocellulose using enzymes to fermentable sugar could be used for the production of bioethanol. However, the bioconversion is challenging due to the complex interactions between substrate and enzymes. In order to utilize EFB as the feedstock, it is important to understand the effect of enzyme concentration and substrate concentration on the bioconversion of EFB. In this study, we investigated the effect of enzyme loading and substrate loading for the maximum conversion of oil palm lignocellulose. The results show that as the enzyme loading increased, the rate of reaction and also the yield of reducing sugar (RS) and glucose initially increased and then plateaued. High enzyme loading might lead to enzyme in excess and enzyme layering around the substrate. Similar pattern was also observed on the reaction rate as the substrate loading increased. However, the yield of RS and glucosedecreased as the substrate loading increase. It could be explained by the substrate recalcitrance and product inhibition. The initial product formation rates were used to determine the kinetic parameters such as maximum rate constant Vmax and the half saturation constant Km. From this study, feasible amount of cellulase and EFB substrate could be identified for maximum conversion and facilitate bioethanol production.