Biofuel Synthesis by Extremophilic Microorganisms

Abstract

Microbial biofuel production has gained great interest over the last 3 decades due to an increase in global energy demand. Fossil fuels are not considered good as they release large volumes of greenhouse gas into the environment and ultimately cause global warming. Microorganisms from extreme environments are especially important because they have enzymes and proteins that can work properly in extreme environmental conditions, such as, extreme temperatures, pH, salinity, drought, and pressure. These microorganisms can be used in different biotechnological applications, providing great momentum for biofuel production. Extremophilic microorganisms including thermophiles, psychrophiles, halophiles, alkaliphiles, and acidophiles have the ability to produce biofuels, such as bioethanol, biobutanol, biodiesel, and biogas or methane, by using various starting materials, such as sugars, starch crops, plant seeds, lignocellulosic agricultural waste, and animal waste, under extreme environments. With progress being made with bioinformatics and gene-editing tools, microorganisms such as Saccharomyces cerevisiae, Escherichia coli, Clostridium thermocellum, Pyrobaculum calidifontis, and Thermococcus kodakarensis have been genetically engineered to upscale biofuel production. This chapter provides an overview of the various types of biofuels produced by extremophiles, their commercial scale production, and research conducted to improve current technologies. Biofuel production by thermophiles, psychrophiles, halophiles, alkaliphiles, and acidophiles is explained thoroughly. Finally, we discuss the metabolic engineering of extremophiles for upscaling biofuel production.