Abstract
It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy. However, the presence of such primordial ingredients in early Earth habitats has not yet been demonstrated. Here we report the existence of indigenous organic molecules and gases in primary fluid inclusions in c. 3.5-billion-year-old barites (Dresser Formation, Pilbara Craton, Western Australia). The compounds identified (e.g., H2S, COS, CS2, CH4, acetic acid, organic (poly-)sulfanes, thiols) may have formed important substrates for purported ancestral sulfur and methanogenic metabolisms. They also include stable building blocks of methyl thioacetate (methanethiol, acetic acid) – a putative key agent in primordial energy metabolism and thus the emergence of life. Delivered by hydrothermal fluids, some of these compounds may have fuelled microbial communities associated with the barite deposits. Our findings demonstrate that early Archaean hydrothermal fluids contained essential primordial ingredients that provided fertile substrates for earliest life on our planet.
Highlights
It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy
Primeval microbes likely required small organic molecules to act as building blocks for biomass and as catabolic substrates for heterotrophic metabolism
Experiments have shown that organic molecules relevant for primordial life can be formed by synthesising organic compounds from inorganic atmospheric gases[4,5]
Summary
It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy. The compounds identified (e.g., H2S, COS, CS2, CH4, acetic acid, organic (poly-)sulfanes, thiols) may have formed important substrates for purported ancestral sulfur and methanogenic metabolisms They include stable building blocks of methyl thioacetate (methanethiol, acetic acid) – a putative key agent in primordial energy metabolism and the emergence of life. A primordial carbon fixation mechanism involving the reaction of CO with methanethiol (CH3SH) on catalytic metal (Ni-/Fe-) sulfide surfaces could be demonstrated in the laboratory under hydrothermal conditions This experiment produced an activated form of acetic acid that represents a plausible building block for further organic synthesis, for example, into acyl lipids[15]. The content of organic molecules, potential key ingredients for early life, is as yet unknown
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