Biotechnological Strategies for Enhanced Production of Biofuels from Lignocellulosic Biomass

Depleting fossil fuel reserves and increased climate changes have led the research community to look for sustainable and environment-friendly energy sources. Agricultural/forest feedstock has a tremendous potential to contribute for the production of biofuels and to reduce carbon dioxide emission. However, the biological transformation of lignocellulosic biomass is complicated due to their complex structure. Therefore, pretreatment, enzymatic hydrolysis, and fermentation technologies were being investigated for the conversion of lignocellulosic biomass into biofuels. Various factors that adversely affect ethanol production include presence of various fermentation inhibitors (furfurals, formic acid, and acetic acid) and presence of hexoses (glucose and mannose) that compete with or inhibit xylose utilization. This study compares and scrutinizes the various advanced biotechnological strategies applied on microbes such as strain adaptation, mutagenesis, genome shuffling, and metabolic engineering to enhance sugars and biofuel (bioethanol/biodiesel) production. Further, evaluation of BOLT-ON technology was carried out to study the impact of co-fermentation of sugars derived from molasses and lignocellulosics on ethanol production. Thus, it was concluded that co-utilization of hexoses and pentoses streams can be carried out by using advanced microbial strains that must be adapted to high sugars and ethanol concentration as well as fermentation inhibitors in future.