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Scientists at Newcastle University found that mixing hydrogen, bicarbonate, and iron-rich magnetite under conditions mimicking relatively mild hydrothermal vent results in the formation of a spectrum of organic molecules, most notably including fatty acids stretching up to 18 carbon atoms in length. The Natural Environmental Research Council of the United Kingdom provided funding for the research team, which examined how the Earth's first life systems formed from inert geological components over 3.5 billion years ago.



Their discoveries, which were published in the journal Nature Communications Earth & Environment, may clarify how some important molecules required to generate life are derived from inorganic substances. This knowledge is crucial for comprehending an important phase in the formation of life on Earth billions of years ago. Their research could offer a believable explanation for the origin of the organic molecules that make up ancient cell membranes, which were possibly picked at random by early biochemical processes on the primordial Earth.



Dr Graham Purvis, the study's lead author, is a postdoctoral research associate at Durham University and carried out the research at Newcastle University. He said, "The results suggest that the convergence of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the rudimentary membranes of early cells at the very beginning of life."



Fatty acids in the early stages of life

Long chemical molecules called fatty acids have sections that both attract and repel water. As a result, these molecules would naturally form cell-like compartments in water, and these molecules may be the source of the first cell membranes. However, in the early stages of life, the origin of these fatty acids remained unknown, despite their significance. One theory is that they may have developed at the hydrothermal vents, which are areas where hot water and hydrogen-rich fluids from underwater vents combine with CO2-containing seawater.



The group replicated critical components of the chemical environment present in early Earth's oceans and the mixing of the hot alkaline water from around specific kinds of hydrothermal vents in their laboratory. They found that the kinds of molecules required to build primitive cell membranes were produced when hot, hydrogen-rich fluids were combined with carbon dioxide-rich water in the presence of iron-based minerals that were present on early Earth.



Dr Purvis added, "Central to life's inception are cellular compartments, crucial for isolating internal chemistry from the external environment. These compartments were instrumental in fostering life-sustaining reactions by concentrating chemicals and facilitating energy production, potentially serving as the cornerstone of life's earliest moments. The results suggest that the convergence of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the rudimentary membranes of early cells at the very beginning of life. This process might have engendered a diversity of membrane types, some potentially serving as life's cradle when life first started. Moreover, this transformative process might have contributed to the genesis of specific acids found in the elemental composition of meteorites."



Principal Investigator Dr Jon Telling, Reader in Biogeochemistry, at the School of Natural Environmental Sciences, added, "We think that this research may provide the first step in how life originated on our planet. Research in our laboratory now continues determining the second key step; how these organic molecules which are initially 'stuck' to the mineral surfaces can lift off to form spherical membrane-bounded cell-like compartments; the first potential 'protocells' that went on to form the first cellular life."



Interestingly, the scientists also suggest that membrane-forming processes like these might still be occurring in the oceans beneath the ice moons in our solar system today. This suggests that these far-off worlds may have different life origins.



Reference

Purvis, G., Å iller, L., Crosskey, A. et al. Generation of long-chain fatty acids by hydrogen-driven bicarbonate reduction in ancient alkaline hydrothermal vents. Commun Earth Environ 5, 30 (2024). https://doi.org/10.1038/s43247-023-01196-4