Enzymatic Pretreatment of Lignocellulosic Biomass for Bioethanol Production.

Concerns regarding the security and availability of crude oil as well as its negative environmental impacts have heightened the motivation to find renewable energy resources Bioenergy, in the form of bioethanol, is a viable potential source, but several limitations need to be overcome. Bioethanol can be prepared from sugars and starch, but this would not be practical from a socio-economic perspective because it competes for food sources. Lignocellulose, as one of the most abundant organic sources, has been considered as a potential raw material for bioenergy production. Lignocellulosic materials contain both cellulose and hemicellulose, present in a matrix of lignin. Both cellulose and hemicellulose are built up from long chain sugar monomers, which, after pretreatment and hydrolysis can be converted into bioethanol. Effective removal of lignin is often required at the pretreatment step for the subsequent hydrolysis to take place. Several pretreatment techniques have been used to open up and remove the lignocellulosic material, such as wet oxidation and steam explosion. These pretreatment methods are limited by loss of cellulose and hemicellulosic sugars, as well as by production of microbial inhibitors and environmentally undesirable chemicals. In this study, we aimed at the development of a novel approach to use lignolytic enzymes produced by white-rot fungi to pre-treat lignocellulosic material. Such an approach is inspired by the fact that white-rot fungi carry out natural degradation of lignin in the environment, which solubilizes and mineralizes lignin with the help of lignolytic enzymes. Such a pretreatment, using enzymes like laccase along with different mediators in different set of conditions, facilitates the degradation of lignin, hence making cellulose and hemicellulose available for subsequent hydrolysis. The use of enzymatic pretreatment will enhance sugar recovery and increase the overall efficiency of bioethanol production.