Researchers have cultivated extremophilic microbes in a small piece of a Martian meteorite. This work demonstrated that life could potentially exist under ancient Martian conditions.
As you probably know, a mission is in preparation to bring back Martian samples put aside by the rover Perseverance . However, it is important to remember that we already have Martian rocks on Earth. The latter were dislodged by meteorite impacts, before traveling through the solar system to finally cross the road to our planet.
A small piece of this material was just used to grow microbes by researchers from the University of Vienna (Austria). The meteorite in question, named Martian Black Beauty, is a priceless stone formed from various pieces of Martian crust, some as old as 4.4 billion years , ejected millions of years ago from the surface of the red planet.
The goal:to determine whether or not a life form could survive and thrive under ancient Martian conditions.
The authors assumed that if life once existed on the red planet, then it probably resembled an extremophile. On Earth, these organisms are known to live in very hostile conditions .
In addition, we know that the atmosphere of ancient Mars was thick and rich in carbon dioxide. Here on Earth, organisms capable of fixing carbon dioxide and converting inorganic compounds (such as minerals) into energy are known as chemolithotrophs. So researchers have focused on this type of organisms. And on one species in particular:Metallosphaera sedula . This Archaean is known to evolve in hot and acidic volcanic springs.
As part of this work, the researchers placed these organisms on the Martian mineral. Then they put everything in a bioreactor that was carefully heated and gassed with air and carbon dioxide.
Under the microscope, the researchers were then able to observe the growth of these organisms which, visibly, have adapted to this Martian environment . Analyzes also assessed how these microbes transformed the material to "build" new cells, leaving behind biomineral deposits composed of complexed phosphates of iron, manganese and aluminum.
“ We also observed the intracellular formation of crystalline deposits of a very complex nature (Iron, Manganese oxides, mixed Manganese silicates) ” , note the researchers. " However, these are unique growth characteristics that we have not observed before when growing these microbes on terrestrial mineral springs " .
Ultimately, this work could provide invaluable data in the search for ancient life on Mars. As said above, Perseverance is expected to probe these extraterrestrial biosignatures. Now that astrobiologists know what crystal deposits of M. sedula look like , they could potentially identify similar traits in the rover samples.
