Chapter 8 - Overcome saccharification barrier: Advances in hydrolysis technology

Abstract

The production of biofuels from ligno-cellulosic biomass consists of three main stages, starting with a pretreatment, followed by the saccharification step where fermentable sugars are generated for the final fermentation process. Hydrolysis is an essential step in the biofuels production industry. However, there are some barriers in this process, such as low enzyme production, low hydrolysis efficiency, and high production cost, which hinder the economic feasibility of converting ligno-cellulose into biofuels. Different strategies have been studied to overcome these barriers including enhancing enzymes production by screening of high-efficiency wild-type strains, modifying cellulolytic enzymes and their coding genes via molecular means and optimizing enzymes optimal production conditions, improving enzymatic hydrolysis efficiency by optimizing enzymes optimal hydrolysis conditions to reduce inhibition and deactivation of enzymes, adding additives to inhibit the irreversible adsorption of cellulolytic enzymes on ligno-cellulose and optimizing bioreactor design for enzymatic hydrolysis, and increasing the economics of enzymatic hydrolysis by combining saccharification and fermentation processes together with multienzymatic hydrolysis synergy, on-site enzyme production, enzyme recycling, and high solids loading hydrolysis. Therefore, this chapter will address the factors affecting enzymatic hydrolysis and elaborate the strategies to overcome ligno-cellulose saccharification barriers from three aspects: enhancing enzymes production, improving enzymatic hydrolysis efficiency, and increasing enzymatic hydrolysis economics.