Microbial electrosynthesis

Microbial electrosynthesis (MES) is a form of microbial electrocatalysis in which electrons are supplied to living microorganisms via a cathode in an electrochemical cell by applying an electric current. The electrons are then used by the microorganisms to reduce carbon dioxide to yield industrially relevant products. The electric current would ideally be produced by a renewable source of power.<ref name="pmid20714445">Nevin KP, Woodard TL, Franks AE, Summers ZM, Lovley DR (May 2010). "Microbial electrosynthesis: feeding microbes electricity to convert carbon dioxide and water to multicarbon extracellular organic compounds". mBio. 1 (2). doi:10.1128/mBio.00103-10. PMC 2921159. PMID 20714445.</ref> This process is the opposite to that employed in a microbial fuel cell, in which microorganisms transfer electrons from the oxidation of compounds to an anode to generate an electric current.

Comparison to microbial electrolysis cells

Microbial electrosynthesis (MES) is related to microbial electrolysis cells (MEC). Both use the interactions of microorganisms with a cathode to reduce chemical compounds. In MECs, an electrical power source is used to augment the electrical potential produced by the microorganisms consuming a source of chemical energy such as acetic acid. The combined potential provided by the power source and the microorganisms is then sufficient to reduce hydrogen ions to molecular hydrogen.<ref>"Microbial Electrolysis Cell - Turning Bacteria Into Hydrogen Machines". Scientific Blogging. 13 November 2007.</ref> The mechanism of MES is not well understood, but the potential products include alcohols and organic acids.<ref>Moscoviz R, Trably E, Bernet N, Carrère H (2018-07-16). "The environmental biorefinery: state-of-the-art on the production of hydrogen and value-added biomolecules in mixed-culture fermentation". Green Chemistry. 20 (14): 3159–3179. doi:10.1039/C8GC00572A.</ref> MES can be combined with MEC in a single reaction vessel, where substrate consumed by the microorganisms provides a voltage potential that is lowered as the microbe ages.<ref>Tian JH, Lacroix R, Desmond-Le Quéméner E, Bureau C, Midoux C, Bouchez T (16 April 2019). "Upscaling of Microbial Electrolysis Cell Integrating Microbial Electrosynthesis: Insights, Challenges and Perspectives". bioRxiv. doi:10.1101/609909.</ref> "MES has gained increasing attention as it promises to use renewable (electric) energy and biogenic feedstock for a bio-based economy."<ref>Schmitz S, Nies S, Wierckx N, Blank LM, Rosenbaum MA (2015). "Engineering mediator-based electroactivity in the obligate aerobic bacterium Pseudomonas putida KT2440". Frontiers in Microbiology. 6: 284. doi:10.3389/fmicb.2015.00284. PMC 4392322. PMID 25914687.</ref>

Applications

Microbial electrosynthesis may be used to produce fuel from carbon dioxide using electrical energy generated by either traditional power stations or renewable electricity generation. It may also be used to produce speciality chemicals such as drug precursors through microbially assisted electrocatalysis.<ref name="pmid20844557">Rabaey K, Rozendal RA (October 2010). "Microbial electrosynthesis - revisiting the electrical route for microbial production". Nature Reviews. Microbiology. 8 (10): 706–16. doi:10.1038/nrmicro2422. PMID 20844557. S2CID 11417035.</ref>

Microbial electrosynthesis can also be used to "power" plants. Plants can then be grown without sunlight.<ref>Strik DP (May 29, 2017). "Open Mind Award for a revolutionary idea". Wageningen University & Research.</ref><ref>"David Strik's "dark photosynthesis" idea receiving Open Mind Award". NWO.</ref><ref>Sikkema A (November 29, 2016). "Producing food without sunlight". Resource. Wageningen University & Research.</ref>

See also

• Electrofuels
• Electrohydrogenesis
• Electromethanogenesis
• Glossary of fuel cell terms
• Microbial fuel cell