The emergence of life necessitated the creation of membrane-bound compartments to separate and concentrate internal biochemistry from the external environment, establishing energy-harnessing ion gradients. Long-chain amphiphilic molecules, like fatty acids, are considered strong candidates for forming the first cell membranes. However, the exact processes leading to their initial generation still need to be determined.
Funded by the UK’s Natural Environmental Research Council, a research team explored the origins of the first living systems on Earth over 3.5 billion years ago from inert geological materials. Scientists at Newcastle University discovered that by combining hydrogen, bicarbonate, and iron-rich magnetite under conditions simulating relatively mild hydrothermal vents, a variety of organic molecules, notably fatty acids extending up to 18 carbon atoms, were formed.
The findings shed light on how some crucial elements- essential to form life- formed from inorganic chemicals. The study is a path toward understanding how life began on the Earth billions of years ago.
Fatty acids, long organic molecules with water-attracting and water-repelling regions, naturally form cell-like compartments in water. These molecules are considered potential candidates for creating the first cell membranes. Despite their significance, how these fatty acids originated in the early stages of life was still being determined. One hypothesis is that they could have been created in hydrothermal vents, where hot water mixed with hydrogen-rich fluids from underwater vents, interacting with seawater containing CO2.
The research team replicated critical aspects of the chemical conditions in early Earth’s oceans, simulating the mixing of hot alkaline water from specific hydrothermal vents in their laboratory. They observed that when hot hydrogen-rich fluids mixed with carbon dioxide-rich water in the presence of iron-based minerals found on early Earth, molecules that were essential for forming primitive cell membranes were created.
Lead author Dr Graham Purvis conducted the study at Newcastle University and is currently a Postdoctoral Research Associate at Durham University.
He said: “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 beginning of life. This process engendered various 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 researchers propose that similar membrane-forming reactions could be occurring in the oceans beneath the icy surfaces of moons in our solar system today. This opens up the intriguing possibility of alternative origins of life in these distant celestial bodies.
Journal Reference:
- Purvis, G., Šiller, 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). DOI: 10.1038/s43247-023-01196-4