Early life is presumed to have been autotrophs using the CO2 fixed metabolic system of the reduced acetyl-CoA pathway and the reverse Krebs cycle.However, no effective mechanism has been found to allow organic chemical reactions related to the CO2 fixation system to proceed in a deep-sea hydrothermal vent environment, and it is not known how organic compounds were produced.

　Meanwhile, in 2017, a research group at the University of Strasbourg in France reported that some reactions in the reverse citric acid cycle were promoted by pure metals. JAMSTEC had previously confirmed that an electric current is generated near the hydrothermal vent along the potential difference between hot water and seawater (hydrothermal power generation), and from this point, sulfurization, which is a typical constituent mineral of the hydrothermal vent. I thought of the possibility that the metal was metallized by electric reduction and the organic chemical reaction was promoted on the surface.

　Therefore, we reproduced the electrochemical reaction field that was presumed to have occurred in the hydrothermal vent environment at the initial ocean floor, and conducted a verification experiment.As a result, it was demonstrated that metals sulfide containing iron, copper, lead and silver change to each metal on a scale of several hours to several days.Furthermore, the complex of iron sulfide and metallic iron generated on the way acts as a reducing agent and a catalyst to promote multiple organic chemical reactions essential for life generation, including some reactions in the reverse Krebs cycle. I also found.

　At the early ocean floor, the metalation and organic chemical reactions shown in this experiment proceeded widely, which is thought to have greatly boosted the generation of life.It can be said that this result clarified a part of the environmental conditions that can produce life.

Paper information:[Science Advances] Metals likely promoted protometabolism in early ocean alkaline hydrothermal systems