The study of Noachian Martian breccia, composed of ancient (about 4.5 billion years old) materials from the Earth’s crust of Mars, has provided a unique prototype of microbial life experimentally created from real Martian material.
Early Mars is considered to be the environment in which life could exist. There was a time in the geological history of the Red Planet when it could be very similar to Earth and had life. Unlike current conditions on Mars, bodies of water with liquid water, higher temperatures and higher atmospheric pressure may have existed in early history. Potential early life forms were supposed to get energy from inorganic mineral sources and convert CO2 to biomass. Such living things are microorganisms that feed on stones, called chemolithotrophs.
Scientists speculated that life forms like chemolithotrophs existed there during the early years of the Red Planet. Traces of this ancient life (biosignatures) could be preserved within the Noach territories with a moisture-rich ancient geological history and mineral springs that could have been colonized by chemolithotrophs. In order to correctly evaluate them, related to the Martian, it is extremely important to take into account the chemolithotrophs in the mineralogical environments corresponding to the Martian ones.
Researchers used true Noachian Martian breccias (a rock made of angular debris over 1 cm in size and cemented) to grow the extreme thermoacidophilus Metallosphaera sedula, an ancient terrestrial dweller. This sample of brecciated regolith is the oldest known Martian crust from the ancient crystallization period (about 4.5 billion years).
“This breccia is one of the rarest substances on Earth, formed by pieces of the Martian crust (some of them 4.42 ± 0.07 billion years old) and ejected millions of years ago from the surface of Mars. We had to take a bold approach to crushing a few grams of precious Martian stone to recreate the possible appearance of the earliest and simplest life on Mars.”Tatiana Miloevich, study author
As a result, the researchers observed how the dark, fine-grained bulk of the breccia was biotransformed and used to create microbial constituents in the form of biomineral deposits. Using a comprehensive suite of cutting edge techniques, the researchers studied unique microbial interactions with true Martian Noach breccias down to nanoscale and atomic resolution. M. sedula, which lives on the material of the Martian crust, has produced distinct mineralogical and metabolic imprints that may make it possible to trace the alleged processes of colonization of the Martian crust.
Growing up on the Martian crustal material, this microorganism has formed a strong mineral capsule, consisting of complex phosphates of iron, manganese and aluminum. In addition to massive incrustation on the cell surface, we observed the intracellular formation of crystalline deposits of a very complex nature (Fe, Mn oxides, mixed Mn silicates). These are the distinctive unique features of the growth of breccia, which scientists have not previously observed when cultivating this microbe on earth’s mineral springs and stony chondritic meteorite.
Observed multifaceted and complex models of breccia-grown M. sedula biomineralization show the rich, diverse mineralogy and multimetallic nature of this ancient Martian meteorite. The unique biomineralization patterns of M. sedula cells underscore the importance of experiments on genuine Martian materials for astrobiological research on Mars.