Microbial resources for bioconversion of lignocellulose to ethanol

The bioethanol as a renewable transport fuel is one of the potent alternatives for the problem of energy security to the future generations. The lignocellulose is a potential feedstock for the production of bioethanol. Every year, a huge amount of lignocellulosic waste is generated around the globe from different sources. These lignocellulosic wastes can be converted into ethanol, also known as cellulosic ethanol or second generation ethanol. The biochemical process for the conversion of lignocellulose to ethanol is a multiple-step process. The microbial systems play a vital role in this process. The recalcitrant lignocellulose structure is made digestible using microbial lignolytic enzymes. The carbohydrate polymers locked in the biomass are hydrolyzed to fermentable sugars in the saccharification step, in which microbial (hemi)-cellulolytic enzymes are major players. Once sugars are obtained in the hydrolysate after biomass hydrolysis, a different group of microorganisms, the ethanologens, finish the fermentation step yielding bioethanol as the major product. In order to make the cellulosic ethanol production process economically successful, various mutant and genetically modified strains are employed at different steps, and many microorganisms are utilized efficiently in integrated approaches of fermentation.