Chapter 20 - Electrochemically active bacteria as platform technology in microbial electrochemical system

Abstract

Microbial electrochemical technology (MET) is a combination of microbiology and electrochemistry is primarily based on bacterial interactions with insoluble electron donors and acceptors. The metabolic activity of electroactive bacteria on different kinds of chemical compounds led to the synthesis of chemicals, bioremediation of pollutant matrices, the treatment of contaminated soils, and power generation. Predominantly, in METs, microbes are used in two areas: one area focuses on bacteria which are capable of transfer electrons to anode also called as anode respiring bacteria and the other one focuses on bacteria or archea which are capable of oxidizing a cathode also called as electrode oxidizing bacteria. Extremophiles are ubiquitous and thrive well in very harsh environments. Among them, thermophiles play a pivotal role in microbial electrochemical systems because of their unique properties such as high metabolism, physically and chemically stable enzymes and low growth. Most of the thermophilic bacterial species are anoxic or anaerobes and use oxidized compounds, for instance, SO4−, Fe (III) oxides, NO3−, and Mn (IV) as their terminal electron acceptors and physiologically capable of growing on anodes at high temperature since thermophiles are ideal candidates in microbial electrochemical system research. So far a group of microorganisms that has been examined only to a limited extent in MFCs is the “extremophiles.” Extremes in pH, salinity, and temperature when combined with materials that operate best under such conditions would potentially result in more powerful MFCs. This chapter focuses on thermophilic bacteria that function optimally under extreme conditions because they may serve as more effective catalysts with higher activity, greater stability, and longer life in microbial fuel cells.