Experiment reconstructs cradle of life

The first life could have originated in alkaline hydrothermal vents of the ancient seas

This hydrothermal vent in the Pacific Lost City field spills hydrogen and methane in addition to mineral-rich water - similar vents could have been a cradle of life on the early Earth. © NOAA Ocean Explorer / URI-ILO, UW, IFE
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Looking back at the primordial soup: Important building blocks for the first life on earth could have arisen at the hydrothermal vents of the oceans. This shows an experiment in which researchers have recreated such primeval vents in the laboratory. In the presence of certain iron minerals, amino acids and lactate biomolecules for first life were formed in the warm water of this miniature primordial soup.

How and where did the first life on earth originate? This question is still unclear. Thus, researchers suspect the cradle of life in clay pits, in hot pools, in hydrothermal vents or in the pores of frozen lava from sea volcanoes. Even which biomolecules were the first building blocks of life is still in dispute. According to one theory, the RNA was still the DNA of the first cells before the DNA, whose building blocks could have been formed together with amino acids on sub-volcanoes, as experiments suggest.

Hydrothermal vent in miniature format

Researchers led by Laurie Barge of NASA's Jet Propulsion Laboratory have now carried out a new life-giving experiment. They wanted to know if alkaline hydrothermal vents are suitable as building sites for building blocks such as amino acids. "Understanding how much such biomolecules can only be formed from minerals and organic precursors is important to find out what kind of environment life can be in, " explains Barge.

Deep-sea vent in miniature: In the experiment, iron-containing minerals are released and lactic acid and amino acids are formed. NASA / JPL-Caltech / Flores

For their experiment, the researchers recreated the chemical-physical environment of one of these black smokers on a miniature scale. For this reason, they used iron-oxide mineral (FeO (OH)), which is often found on early earth, in slightly alkaline sea water heated to around 70 ° C. To this they added the organic compounds pyruvate and ammonia, which can be formed under such conditions at hydrothermal vents.

Spontaneous formation of amino acid and lactate

The result: Under the oxygen-poor conditions of the simulated uranium, the partially oxidized iron mineral reacted with the pyruvate and ammonia. The pyruvate received a nitrogen-containing amine group and was converted into the amino acid alanine. At the same time, lactate, the salt of lactic acid, was also produced. Both are important biomolecules for organisms, and hydrocarboxylic acids such as lactic acid are also regarded as precursors of other, complex components of life. display

"This shows that aqueous, partially reducing iron mineral systems, such as were common on early Earth, favored the synthesis and enrichment of prebiotic organic molecules could ", Barge and her team state. Another positive factor could be the geochemical gradients in the chimneys: the large differences in chemistry and temperature in a small space provide energy for chemical reactions and may have fueled the formation of increasingly complex molecules,

Help for searching for alien life

According to the researchers, their experiment provides another indication that alkaline hydrothermal vents could have been a suitable cradle of life on the primordial earth. At the same time, this could also reveal the conditions under which life could have originated on other celestial bodies. "We still have no evidence of alien life, but if we understand the conditions that are necessary for the creation of life, then we can narrow down the places, where we look for it, "says Barge.

At least two places in the solar system could actually have hydrothermal vents and thus potential cradles of life: The Saturn moon Enceladus has under its ice crust a subglacial ocean in which warm, alkaline water is likely to rise from the hot rock surface. Something similar could happen on Jupiter's moon Europa here too there is a liquid ocean under the ice crust. (Proceedings of the National Academy of Sciences, 2019; doi: 10.1073 / pnas.1812098116)

Source: NASA / JPL

- Nadja Podbregar