ABSTRACT
Isolated free enzymes, immobilized enzymes, and wild whole-cells of bacteria, fungi, microalgae, plants, and others are employed as catalysts for biofuel production and a surfeit of chemicals for more than 100 years. Natural enzymes and wild whole-cell catalysts have permitted the growth of several industries, such as foods, beverages, pharmaceuticals, chemical, and energy sector growth. Still, a few important factors, i.e., cost-effectiveness, environmental issues, etc., act as a bottleneck for the growth of the sector dealing with energy and biofuel production from cheap feedstock using natural enzymes and whole-cells. With the advancement of technology in the field of metabolic engineering, synthetic biology, computational tools, molecular biology, computational tools, and metabolic engineering, progress has been made in the field of a rational design of enzyme and whole-cell biocatalysts, which has thus brought a revolution in the energy sector for biofuel production. The design and engineering of whole-cell catalytic cascades is the latest research for the valorization of fatty acids. The use of designed whole-cell catalysts has several advantages; it allows high enantioselectivity followed by a moderate or ambient range of reaction conditions, making it 356a preferable system. In addition, the process has no/lower toxicity levels and the possibility of recycling and production of eco-friendly wastes. The whole-cell system has the power to bestow an instinctive environment to the enzymes, arresting conformational orientation in the protein structure so that enzyme activity will be retained in the non-conventional medium. Cofactor regeneration will be attained without any deterioration. This book chapter presents a critical review of recent developments in whole-cell biocatalysts, with a close look at strategies undertaken in designing and optimizing the organisms which have been modified to an extent for realizing efficient production of biofuel, the role of the whole catalyst in biofuel production, design, and engineering of whole-cell biocatalytic cascades, future perspective, and challenges.
