Molecular genetics of electricity production in bacteria: A review

As the number of population around the world increases, the search for new energy sources has become a necessity. Much research has been conducted on renewable energy sources that may substitute traditional energy sources, these include solar energy, wind energy, and wave power. Microbes play an important role in producing energy by generating electrical conductivity through transporting electrons generated from their metabolism. Such bacteria are known as Electro-active bacteria and are used in microbial fuel cells where microbes are used to generate electric energy from the degradation of organic compounds. The role of microbial fuel cells are not only important in generating electricity, but also in reducing organic contaminants from the environment. Microbial fuel cells are also important in producing electricity in locations where it is costly to maintain batteries periodically such as the bottom of the oceans. One of the best-known electro-active bacteria is Geobacter, which has the ability to transfer electrons outside its membrane. Researchers have developed a genetic system that functions in Geobacter in order to construct mutants and study gene knockout strains and they found that this bacterium uses multiple c-type cytochromes to iron oxides by direct contact. In the past few decades, Shewanella has gained the attention of scientists due to its respiratory adaptability. This bacterium can respire different inorganic compounds as electron acceptors, including, thiosulfate, nitrate, arsenate, elemental sulfur, and fumarate. This ability came from its unique electron-transport pathways which helped to adapt changes in electron acceptor availability which fluctuate according to environmental conditions.