Bacterial Metabolism–Coupled Energetics

Abstract Bacteria sustainably evolved through centuries in their diversified metabolism, yet in a close circuit to convert wide spectrum of carbonaceous substances to various energy forms depending on niche environment and biochemical network. The role of biochemical reaction associated with metabolism is to provide either structural or functional components or energy generation for its survival. The energy production is always associated with oxidation–reduction process where an electron donor is oxidized with simultaneous reduction of an electron acceptor along with a shift in free energy among components of reactants. Understanding the physicochemical process conditions along with higher energy–linked metabolic reactions would aid in development of devices or processes such as acidogenesis, methanogenesis, solventogenesis, biopolymers, etc. In this category, advancement has been made in utilization of bacterial molecular machinery to transfer electrons from microbial outer membrane to conductive electrode surfaces. This can be deployed in the development of bioelectrochemical devices such as microbial fuel cells and microbial electrolysis cells for generation of biofuels, bioelectricity, etc. using organic biomass in either solid or liquid form and with exoelectrogenic or electrogenic characteristics of microbes. As these processes are in infancy stage, larger scope is ahead for exploration and exploitation of its relative concerns as well as biochemical pathways toward improving the yields. A deeper understanding of pivotal microbial pathways concerning electroactive biofilm formation, microbe–metal surface interaction, electron transfer machinery, and environment to synthesis of specific redox proteins which involve in transfer of electrons is the most essential requirement for concept to commercialization. This chapter will provide a bird's eye view on microbial energy generation pathways of versatile microorganisms to exploit them for future bioenergy requirements.