Extremeophiles and Extreme Environments

Current Understanding Of Electroautotrophy And Its Relevance In Astrobiology-related Research

By Keith Cowing

Status Report

mLife

October 28, 2025

Filed under autotroph, biochemistry, Electroautotrophy, extremophile, genomics, Metabolism, microbiology, mLife

Current Understanding Of Electroautotrophy And Its Relevance In Astrobiology-related Research — Summary of different extracellular electron transfer (EET) pathways. While it is common to classify EET based on the nature and function of the mediators, here the emphasis is on the means of electron transport. (A) Electrons are transported between cells via direct interspecies electron transfer (DIET) through (1) direct contact via conductive pili and/or nanowires, (2) conductive particles smaller than the cells (e.g., magnetite), and (3) conductive particles larger than the cells (e.g., activated carbon). (B) Electrons are exported from cells to the solid surface via outward EET through (1), (4) direct contact via redox-active proteins, (5) diffusive soluble electron shuttles, and (6) redox mediators or enzymes. (C) Electrons are taken up by cells from the solid surface via inward EET or extracellular electron uptake (EEU) through (1), (4)–(6). Asterisks denote that not the exact same mechanism is employed by outward EET and inward EET when redox-active proteins are involved. — mLife

Electroautotrophy—the use of extracellular electrons as the primary energy source for autotrophic metabolism—remains understudied compared to photoautotrophy and chemoautotrophy.

Its occurrence in deep-earth and deep-sea environments suggests profound implications for astrobiology, yet electroautotrophic microorganisms remain poorly explored. This review synthesizes the discovery of electroautotrophs and current knowledge from laboratory and field studies, including insights from the deep biosphere.

We evaluate their ecological roles on Earth and discuss their potential significance in possible life-supporting ecosystems elsewhere and in life-detection strategies.

Finally, we propose six key research priorities to advance the study of electroautotrophy in astrobiological contexts.

Current understanding of electroautotrophy and its relevance in astrobiology-related research, mLife (open access)

Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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