This new research explores how life formed on Earth
What's the story
A new study has revealed how hot springs may have contributed to the emergence of life on Earth. The research examined iron sulfides, minerals present in deep-sea hydrothermal vents as well as modern hot springs such as Yellowstone National Park's Grand Prismatic Spring. The minerals are thought to have enabled early chemical reactions that resulted in the formation of life, the study published in Nature Communications said.
Mineral significance
Iron sulfides and the genesis of life
Iron sulfides are created when dissolved iron reacts with hydrogen sulfide, a volcanic gas that gives hot springs their signature smell. The structure of these minerals closely resembles iron-sulfur clusters in enzymes and proteins necessary for carbon fixation, a process living organisms use to convert carbon dioxide (CO2) into organic molecules. This similarity has prompted scientists to propose that iron sulfides may have been key to early Earth's transition from geochemistry to biology.
Experimental setup
Simulating early Earth's hot springs
To delve deeper into this theory, the researchers designed a chamber to replicate ancient land-based hot springs. They placed synthesized iron sulfide samples in this environment, some pure and others combined with metals found in hot springs. The team then exposed these samples to carbon dioxide and hydrogen gas under varying light and temperature conditions to simulate early Earth's surface.
Findings
Iron sulfides facilitated carbon fixation in ancient hot springs
The experiments revealed that all iron sulfide samples were capable of producing methanol, a product of carbon fixation. Methanol production increased with visible light irradiation and at higher temperatures. These findings indicate that iron sulfides likely facilitated carbon fixation not only in deep-sea hydrothermal vents but also in land-based hot springs on early Earth, expanding the range of conditions where these minerals can aid in this process.
Ancient pathway
Methanol production and early form of carbon fixation
Further experiments and theoretical calculations revealed methanol production happened through a reverse water-gas shift, much like how some bacteria convert CO2 into food. This pathway, dubbed the "acetyl-CoA" or "Wood-Ljungdahl" pathway, is thought to be the first form of carbon fixation in early life. The study's findings bolster current scientific consensus that iron-sulfur clusters were key to life's emergence, be it on land or at sea bottom.