NASA astrobiologists at the Jet Propulsion Laboratory in Pasadena have recreated the conditions suitable for the first living organisms to appear underwater without the sunlight needed for photosynthesis. An article by scientists was published in the journal Proceedings of the National Academy of Sciences.
During the experiment, the researchers reproduced in test tubes the chemical processes that could take place at the bottom of the primary seas of the Earth. In the first case, the deposition of iron oxyhydroxides on the bottom was simulated, in the second case, the activity of hydrothermal springs releasing iron hydroxides into water. These compounds reacted with ammonium (NH4Cl) and pyruvate, which plays a key role in the metabolism of living organisms.
Pyruvate, or pyruvic acid (C3H4O3), is a simple organic substance that may have formed spontaneously in hydrothermal systems. Scientists have found that under simulated conditions in the presence of iron oxides, pyruvate undergoes reductive amination, that is, its carbonyl group (C = O) is replaced by an amine. The result is the simplest amino acid - alanine (one of the components of proteins). In this case, the maximum amount of alanine is produced when the medium is alkaline, and the iron oxyhydroxide minerals contain equal amounts of ferrous and ferric iron.
Similar conditions are found in iron-rich rocks near high alkalinity hydrothermal vents. In this case, the water temperature should reach 70 degrees Celsius. At the same time, chemical reactions produce not only alanine, but also other compounds that can become the basis for more complex organics. Thus, at the bottom of the oceans, chemosynthetic organisms may appear, which receive energy through the oxidation of inorganic substances.
The results increase the likelihood of life on space objects such as Enceladus (the moon of Saturn) and Europa (the moon of Jupiter), which have subglacial oceans and are geologically active due to the tidal forces of the gas giants, the researchers said.
