Possible origin of life in ancient hot springs

Newcastle University research turns to ancient hot springs to explore the origins of life on Earth. Funded by the UK's Natural Environment Research Council, the research team investigated how the first living systems emerged from inert geological material on Earth 3.5 billion years ago.

By mixing hydrogen, bicarbonate and iron-rich magnetite to mimic a relatively mild hydrothermal vent, scientists at the University of Newcastle formed a spectrum of organic molecules, notably fatty acids up to 18 carbon atoms long.

Published in the journal Nature Communications Earth & Environment, their findings reveal how some of the key molecules needed for life production are made from inorganic chemicals, a key step in understanding how life evolved on Earth billions of years ago. Their results may provide a plausible look at the organic molecules that make up ancient cell membranes, which may have been selected by early biochemical processes on the primitive Earth.

Fatty acids in the early stage of life

Fatty acids are long organic molecules that have water-attracting and water-repelling regions that naturally form cell-like compartments in water, and these types of molecules can form the first cell membranes. However, despite their importance, it is uncertain where these fatty acids came from in the early stages of life. One idea is that they may have formed in hydrothermal vents where hot water mixed with hydrogen-rich fluids from underwater vents mixed with CO2-rich seawater.

In their laboratory, the team replicates important aspects of the chemical environment found in early Earth's oceans and the mixing of hot alkaline water from certain types of hydrothermal vents. When hot hydrogen-rich fluids mixed with carbon dioxide-rich water in the presence of iron-based minerals on early Earth, it created the types of molecules needed to build primitive cell membranes.

Representative comparison of one of three replicate total ion chromatograms obtained by reacting the magnet with HCO3− and H2 at 90°C and 16 bar total pressure for 16 h at 16 bar total pressure. (a) Organic molecules formed using magnetite with H2 and HCO3−. (b) Control sample using magnet with H2 (c) Control sample using quartz with H2 and HCO3- (d) Control sample using quartz with H2. B Magnification of the chromatogram area defined by the broken dashed box in (A). Peaks with a signal:noise ratio <5:1 or an inverse fit factor <65.0 for the NIST20 library were not labeled (Supplementary Data 3 for peak identities obtained from the NIST20 library).

The lead author, Dr Graham Purvis, carried out the study at Newcastle University and is currently a Postgraduate Research Associate at Durham University.

He said: „Centre from the beginning of life are cellular compartments, critical for isolating internal chemistry from the external environment. By concentrating chemicals and facilitating energy production, these compartments were instrumental in developing survival reactions that would serve as cornerstones of life's earliest moments.

The results suggest that the amalgamation of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters in iron-based minerals may have precipitated the basement membranes of early cells early in life. This process may have given rise to a diversity of membrane types, some serving as cradles of life when life first began. Furthermore, this metamorphic process may have contributed to the formation of specific acids found in the elemental composition of meteorites.”

Dr John Delling, Reader Principal Investigator in Biogeochemistry in the School of Natural Environmental Sciences, added:

„We think this research may provide a first step toward understanding how life originated on our planet. Research in our lab now continues to determine the second major step; how these organic molecules initially 'trapped' on mineral surfaces can form spherical membrane-bound cell-like compartments; the first possible 'protocells'. ' created the first cellular life.”

Interestingly, the researchers also suggest that similar membrane-forming reactions may occur in oceans beneath the surfaces of icy moons in our solar system today. This raises the possibility of the origin of alternative life on these distant worlds.

Note

Purvis, G., Schiller, L., Crosskey, A. and many others. Formation 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 (Open Access)

Astrophysics