Abstract
Microbial fuel cell (MFC) technology is considered one of the renewable sources of energy for the production of bioelectricity from waste. Due to the depletion of fossil fuels and environmental considerations, MFC haa garnered increasing importance as it is a sustainable and environmentally-friendly method of generation of bioenergy. In MFC, electroactive bacteria (EAB) and biofilms are harnessed to convert organic substances to electrical energy. Extremophiles survive in extreme environments, and they have demonstrated potential applications in microbial electrical systems (MES) and MFC technology. The key limitations of MFC are the low power output and engineering constraints of the fuel cell. Hence, it is imperative to understand the genetics, key metabolic pathways, and molecular mechanisms of the EAB for enhancing the power generation in MFC. This chapter gives a brief overview of the scope and applications of extremophiles in wastewater treatment, bioelectricity, and biohydrogen production using MFC, eventually enhancing the functional efficiency of MFC.
TopBackground
MFCs are bioelectrochemical devices which consist of anode and cathode chambers which are physically separated by a proton exchange membrane (PEM). Microbial cells work as biocatalysts where they oxidize the organic substrates to generate electrons and protons in anode chamber (Rahimnejad et al.,2015; Yibrah Tekle & Addisu Demeke, 2015). Microorganism transfers the electrons to anode through which electrons then travel to the cathode with the help of an external circuit to produce electricity. General reactions at anode and cathode are as follows: (Chang et al., 2006; Yibrah Tekle & Addisu Demeke, 2015)
Anode oxidation reaction:
(1)Cathode reduction reaction:
(2) Key Terms in this Chapter
Reduction: Elimination of an oxygen atom, or more generally gain of electrons.
Metabolic Engineering: Process of modifying/optimizing the endogenous metabolic pathways in species.
Methanotrophs: Prokaryotic species, like bacteria or archaea, whose source of energy is via methane oxidation.
Nanowire: Conductive appendages/structures, a few nanometers wide and deep but with a longer length, produced by a number of bacteria.
Transposon: DNA sequences capable of moving to different locations within a genome.
Electroactive Bacteria (EAB): Bacterial species capable of transferring electrons from a microbial cell to an electrode.
Bioelectricity: Electric potentials or currents generated by or present within living cells, tissues, or organisms.
Biofilm: Complex microbiome where different bacterial colonies, embedded in extracellular polymeric substances, stick to each other, or a surface.
Gene Knockout: Mutating a DNA/gene in a way that its expression is permanently prevented.
Polymerase Chain Reaction (PCR): Method used to make millions to billions copies of specific DNA sequence.
Oxidation: Addition of an oxygen atom, or more generally loss of electrons.
Genetic Engineering: Process of altering the genetic makeup of an organism by using biotechnology/recombinant DNA technology.
Mutant: Any species where the DNA sequence has been modified, either during cell division or exposure to external stimuli like ionizing radiation or chemicals.