Insights on biomass pretreatment and bioconversion to bioethanol and biobutanol

Lignocellulosic biomass is a sustainable feedstock for producing alcohol-based biofuels such as bioethanol and biobutanol that can substitute petroleum-based fuels. However, to reduce the crystallinity of cellulose fibers and eliminate lignin from biomass during the conversion process, it is essential to employ an effective pretreatment method or a series of pretreatment methods before enzymatic hydrolysis and fermentation. The primary obstacles to the profitable production of bioethanol and biobutanol are proper pretreatment methods for lignocellulosic biomass, cost-effective cellulolytic enzyme production, and efficient fermentation of sugars (glucose and xylose). Although novel xylose-fermenting strains are being developed, they frequently lack resistance to inhibitory substances found in biomass hydrolysates. This chapter presents a comprehensive overview of the biological conversion route for the production of lignocellulosic bioethanol and biobutanol, concentrating on the most popular pretreatment techniques and important effective factors for enzymatic hydrolysis and fermentation taking into account sugar and ethanol yields.