Spark of Life: Role of electrotrophy in the emergence of Life

Funken des Lebens

During the last decade, studies have shown the presence of a natural electrical current across the chimney walls of modern hydrothermal vents. This phenomenon occurs by the oxidation of H2S from the hydrothermal fluid on the internal side of the chimney made of conductive pyrite, coupled with the reduction of oxygen outside from the surrounding seawater. Since few years, we made the hypothesis that this electrical current could have been the first energy source for the emergence of Life in hydrothermal context during the Hadean. We notably succeeded to enrich modern deep-branching archaea from hydrothermal communities using only electricity and CO2, as proof of the favorable thermodynamic of such metabolism. However, during the Hadean, the O2 required for this natural electrical current was not available, as it appeared after the great oxygenation event. In this project, we aim to reproduce similar conditions and characterize the different steps of this theory to assess its possibility. We first entail to show that a similar electrical current reaction could have occurred by the reduction of Nitrate produced by lightning in the atmosphere and can lead to the electroreduction of CO2 into short chain fatty acids.