electroautotrophy

Electroautotrophy is a metabolic strategy in which microorganisms derive energy from an external electrical current and fixation of inorganic carbon, typically carbon dioxide, to produce organic compounds. In this process, electrons are supplied directly to the microbial cells through electrochemical interfaces such as electrodes, or via soluble redox mediators. The electrons are transferred to respiratory or photosynthetic-like pathways within the organism, generating a proton motive force or reducing equivalents that are used for CO₂ fixation through pathways such as the Calvin cycle, the ribulose monophosphate pathway, or other autotrophic pathways.

Microorganisms capable of electroautotrophy include a variety of bacteria and archaea, notably members of the classes Desulfovibrionia, Thermotogales, and some methanogens. In laboratory settings, Shewanella species, Geobacter species, and the hydrogenotrophic archaeon Methanosarcina have been employed to demonstrate current-driven CO₂ reduction to acetate, ethanol, or methane. Electrochemical reactors known as microbial electrolysis cells or microbial electrosynthesis setups provide controlled potentials that enable these organisms to convert electrical energy into chemical energy with high conversion efficiencies.

The significance of electroautotrophy lies in its potential to transform renewable electricity—produced from solar or wind sources—into chemical fuels and commodity chemicals, offering a sustainable technology for carbon capture and utilization. Ongoing research explores engineering strategies for improving electron uptake rates, expanding product portfolios, and integrating electroautotrophic systems with existing bioenergy and bioprocess infrastructure.