Biofuel Cellulases Diversity, Distribution and Industrial Outlook

• Published in: Microbial Fermentation and Enzyme Technology pp. 283 - 298
• Main Authors: Jain, Lavika, Agrawal, Deepti
• Format: Book Chapter
• Language: English
• Published: CRC Press 2020
• Edition: 1
• Subjects: Cellulase Cocktails; GH; Lignin Peroxidase; Cellobiose Dehydrogenase; Trichoderma Reesei; Glycoside Hydrolase; GH3 Family; Cellulosic Ethanol; Acetyl Xylan Esterase; Exo Anomeric Effect; Soy Proteins; Tannase; Beta Renewables; GH Family; Manganese Peroxidase; TIM; GH48 Family; Moisture Content; Fermentation Technology; Ethanol Fermentation; CBHI
• ISBN: 0367183846; 9780367183844
• DOI: 10.1201/9780429061257-18

In the last twenty years, several innovations in the scientific know-how of enzymes have spurred the growth of biofuel and bio-based chemical industry from second generation feedstocks. These renewable feedstocks primarily comprises of forest and agricultural residues, non-food energy crops, including municipal, industrial waste etc. Biofuels, through this route, popularly termed as second generation biofuels are not only sustainable but they are expected to strengthen nation’s self-reliance in terms of energy security, reduce net carbon footprint, increase energy efficiency and eliminate the dilemma of food vs fuel. The major components of lignocellulosic biomass include cellulose, hemicellulose (xylan and galactomannan), pectic substances (galactouran and arabinogalactan) and polymeric lignin. Cellulose a homopolymer of glucose represents one of the most abundant imperishable carbon sources. Biotechnological production of fermentable sugars from cellulosic biomass essentially requires the use of enzymes specifically cellulases. Cellulases are complex group of synergistically acting enzymes namely endo b-1,4- glucanases cellobiohydrolyases or exo b-1,4, glucanases and β- glucosidase or cellobiase. A diverse group of microorganisms such as aerobic bacteria, fungi, yeast and actinomycetes have been reported to produce cellulases. However, most of the commercial cellulases belong to the fungal origin, predominantly Trichoderma reesei and Aspergillus niger.  The present book chapter provides an overview of biofuel cellulases derived from the microbial route. The chapter further discusses the global players of biofuel cellulases, the innovative platforms created to improve the efficacy of these enzymes and the current industrial scenario in the area of second-generation biofuels, more particularly cellulosic ethanol. This chapter discusses the global players of biofuel cellulases, the innovative platforms created to improve the efficacy of these enzymes and the current industrial scenario in the area of second-generation biofuels, more particularly cellulosic ethanol. Microbial cellulases exhibit two paradigms for depolymerizing cellulose, namely, complexed and non-complexed. Cellulases are multi-modular biocatalysts composed of structurally and functionally distinct units that are often folded independently. The discovery of Trichoderma reesei as the microbial factory for cellulases opened broad avenues for the researchers to develop novel cellulase cocktails which could lead to the techno-commercial success of second-generation biofuels. A dramatic shift in biofuel cellulase research was witnessed with the recent discovery of oxidoreductase enzymes belonging to AA9 family that stimulated enzymatic hydrolysis. The inclusion of these enzymes in cellulase cocktails has already led to a considerable reduction in operating costs of modern biorefineries.