Theoretical origin of life: very early chemical use (Introduction)

by David Turell , Friday, May 02, 2025, 21:11 (14 hours, 34 minutes ago) @ David Turell

Life without oxygen to burn:

https://www.sciencedaily.com/releases/2025/04/250430142248.htm

"Most likely, the earliest ancestor of all life on Earth liked warm conditions, lived off hydrogen, and produced methane. LMU researchers have come to this conclusion based on fossil evidence and metabolic reconstructions using genetic analyses. This relatively simple, primordial acetyl-CoA metabolic pathway has survived in many microorganisms to this day.

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"researchers led by Professor William Orsi from the Department of Earth and Environmental Sciences created laboratory simulations of the conditions on the young Earth some 4 to 3.6 billion years ago. These conditions had some similarities to those prevailing today in the hydrothermal vents on the ocean floor known as "black smokers," with a key difference being that the ancient oceans were full of dissolved iron.

"In the laboratory experiment, the researchers produced miniature versions of such "black smokers." As it happens naturally at the seafloor, iron and sulfur geochemical reactions took place at high temperatures, forming iron sulfide minerals such as mackinawite (FeS) and greigite (Fe3S4) in a process that produced hydrogen gas (H2). In these "chemical gardens," the single-celled archaean Methanocaldococcus jannaschii was not only able to thrive, but positively exceeded the expectations of the researchers: "As well as overexpressing some genes of the acetyl-CoA metabolism, the archaeans actually grew exponentially," explains Vanessa Helmbrecht, lead author of the study, which has now been published in the journal Nature Ecology & Evolution. "At the beginning, we expected only slight growth, as we did not add any extra nutrients, vitamins, or trace metals to the experiment." The single-celled organism thus proved highly adept at utilizing the hydrogen gas produced by the abiotic precipitation of iron sulfides as an energy source.

"Isolated from the sediment of hydrothermal vents on the ocean floor, the hyperthermophile microbe Methanocaldococcus jannaschii serves as a model organism for methanogenesis via the Acetyl-CoA metabolic pathway. It is an organism that is adapted to extreme conditions:

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"The researchers conclude from the study's results that chemical reactions during the precipitation of iron sulfide minerals around four billion years ago generated sufficient energy for the survival of the very first cells and thus laid the foundations for the hydrogen-dependent metabolism of the first microbes on the young Earth. Accordingly, this form of methanogenesis based on hydrogen produced inorganically through chemical reactions is the oldest known form of energy generation in evolutionary history."

Comment: this is the most solid research of its kind in early life.. Life has arrived, mechanism unknown, and it uses methanogenesis for energy. All confined to the Archaea. Philosophically, it must be conceded the universe arrived seeking, expecting life to appear.