Hydrothermal vents, releasing hydrogen in the deep sea, provided the early Earth's life forms with the necessary energy through the chemical reaction of hydrogen with carbon dioxide. This mechanism, essential for the synthesis of life's molecules, allowed the first cells to thrive in complete darkness in eerie, life-originating settings such as deep-sea vents and subterranean rock formations.

The study, published in the Proceedings of the National Academy of Sciences (PNAS), was led by William F. Martin of the University of Dusseldorf and Martina Preiner of the Max Planck Institute for Terrestrial Microbiology, with international collaboration.

It introduces a novel understanding of how the earliest cells utilized hydrogen for energy before the advent of complex enzymes and metabolic pathways. Specifically, it details a process known as electron bifurcation, where cells distribute electrons from hydrogen through two different paths, a mechanism discovered only a decade and a half ago by Wolfgang Buckel and Rolf Thauer.

Remarkably, at a pH of 8.5, typical for naturally alkaline hydrothermal vents, this study reveals that no proteins are needed for the initial stages of this process. Hydrogen molecules directly interact with iron surfaces, facilitating the transfer of electrons to an ancient biological electron carrier, ferredoxin, without the requirement of complex proteins.

This insight into the pre-enzymatic use of hydrogen at life's inception not only provides a simpler explanation for the energy transactions in the earliest life forms but also emphasizes the role of metals and environmental hydrogen production in these primordial processes. The research highlights the unique conditions of hydrothermal vents that were conducive to life's emergence, with the interaction of water and iron-rich minerals naturally producing hydrogen.

The discovery that iron, under the conditions found in specific hydrothermal vents, could facilitate the upward movement of electrons to ferredoxin opens new doors to understanding the origins of life. This aligns with theories that life began in such alkaline hydrothermal vent environments, offering a tangible link between the chemistry of the early Earth and the metabolic processes observed in contemporary microbes.

This research not only fills a crucial gap in our comprehension of life's origins but also demonstrates the enduring relevance of hydrogen as an energy source, from the earliest cells on Earth to future green technologies.

Research Report:Ferredoxin reduction by hydrogen with iron functions as an evolutionary precursor of flavin-based electron bifurcation

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