ABSTRACT
Butanol is amajorchemicalprecursor for the manufacture of paints, polymers, and plastics. Recently, it also has been considered as a possible alternative fuel for transport that can replace gasoline. Due to its physicochemical properties is considered the biofuel with greater similarity to gasoline compared to other biofuels (hydrogen, biodiesel, and ethanol). Compared to ethanol, butanol can be burned directly in current gasoline engines, generating 25% more energy and lower gas emissions to the environment. Currently, butanol is mainly produced from crude oil through a petrochemical reaction. However, its production costs are linked to the propylene production market, which is strongly related 204to the price of crude oil. Therefore another alternative independent to petroleum derivatives is the biotechnological pathway, known as ABE (acetone, butanol, ethanol). Simple sugars such as glucose are fermented by solventogenic strains (mainly of the genus Clostridium) producing ABE at a 3:6:1 ratio, respectively. Few countries, such as China, have maintained the production of butanol by fermentation from corn and sugarcane for decades. Sugarcane and corn starch are the raw materials commonly reported in several studies as the preferred substrate to produce butanol. However, the additional demand for these raw materials to produce biofuels can cause food security issues. In the butanol production process via fermentation, 75% of the final cost is directly related to feedstock prices. Due to its decisive role in the final product cost, the search for low-cost substrates is a persistent pursuit in the bioenergy industry. The abundance of lignocellulosic biomass and its low cost have outlined it as a potential alternative. However, its recalcitrant nature and the high costs of hydrolyzing cellulose have meant that there are no more plants on an industrial scale. This chapter describes recent advances in butanol production from lignocellulosic biomass with special emphasis on the processes known as consolidated bioprocessing.
