Biofuels and Bioproducts Produced through Microbial Conversion of Biomass

Lignocellulose is a complex polymer composed of intertwined cellulose, hemicelluloses and lignin substances. Research on conversion of lignocellulosic biomass into biofuels and other bioproducts is on the increase recently. Significant advances have been made toward the development of various technologies for pretreatment of the lignocellulosic biomass. The conversion of lignocellulose, therefore, could offer the advantage of cheaper fermentable sugars for the production of biofuels and chemicals. However, due to the complex structure of lignocellulose biomass, development of an efficient and cost-effective pretreatment process is necessary. Also, efficient enzyme hydrolysis of carbohydrates into simple sugars allows higher reaction rates and increased yields of accessible sugars (hexoses and pentoses). Furthermore, an efficient microorganism, capable of degrading biomass efficiently and in high yields, is necessary to facilitate a sustainable and economically viable manufacturing of biofuels and bioproducts from lignocellulosic raw materials. Currently, a number of pretreatment methods have been developed, with only a few being optimized on an industrial scale. This review provides practical examples and gives a broad overview of the current status of biofuels and bioproducts produced through microbial conversion of lignocellulosic biomass. Both biological and nonbiological pretreatments of biomass, prior to hydrolysis, and different processes of microbial-mediated biomass conversion have been discussed. Furthermore, the development of novel microorganism strains, through genetic engineering, for biomass conversion and the pros and cons of commonly used microorganisms in biomass conversion have also been discussed.