ABSTRACT
The present scenario of biofuels is found to be most effective and is alternative source to fossil-based fuels and natural gases. Biofuels have become an innovative alternative that offers a wide variety of exceptional benefits. Biofuels are making resurgence due to increasing oil prices and dwindling fossil fuel reserves, as these are eco-friendly, renewable, and a reliable source of energy. There are four generations of biofuels: first-, second-, third-, and fourth-generation biofuels. They are categorized by their sources of biomass, their limitations as a renewable source of energy, and their technological requirement. The main limitation of first-generation biofuels is that they are produced from biomasses which are also used for food purpose. In future, its production will impose problems during shortage of food production to the growing population. Second-generation biofuels are produced from nonfood biomass, but the land utilized for food production is diverted for this purpose. Third-generation biofuels are a good alternative source because algal biomass is used as feedstock for biofuel production. In fourth-generation biofuels, the feedstock is tailored not only to improve the processing efficiency, but it is also designed to capture more carbon dioxide, as the crop grows in cultivation. Fourth-generation biofuels are found to be carbon neutral or even carbon negative compared to the other generation biofuels and result in reducing 300greenhouse gas emissions. Biofuels such as bioethanol and biohydrogen can be produced by fermentation process of sugars obtained from cellulosic agricultural and industrial wastes. In the recent years, significant improvement has been made with the help of biotechnological and molecular approaches so as to improve microbial activity and enzymes. The use of genetically modified organisms is considered to be the most efficient and quick method for efficient conversion of lignocellulosic biomass to biofuels. Lignocellulosic biomasses contain cellulose (30%-50%), hemicellulose (20%-40%), and lignin (20%-30%). Hence, in the present study, major attention is focused on improvement of cellulase enzyme production for biofuel industry via genetic modification and its utilization for biofuel production by employing thermostable cellulase enzymes via genetic modification and characterization and optimization of thermostable cellulase enzymes for biofuel production.
