Terrestrial bacterium revives hopes of finding life beneath the surface of Mars

Scientists hope to find life below the surface Mars during the investigation bacterium Earth: Deinococcus radiodurans.

According to a study by Michael Daley, an expert in genetics and radiobiology at the University of Maryland Armed Forces, published in the journal Astrobiology, this bacterium it can last up to 1.5 million years on the surface of Mars due to its resistance to radiation.

Conan bacterium

Deinococcus radiodurans It has been under study by scientists for years, who have even taken it to the International Space Station to test its resistance to microgravity.

In this latest study, Daley and colleagues dried and froze D. radiodurans and then they bombed bacterium with gamma radiation and proton radiation simulating cosmic radiation from deep space and solar radiation from the Sun.

They found that D. radiodurans dry and frozen, it could survive a staggering 140,000 grays of radiation, equivalent to a dose of 1.5 million years on the surface of Mars and 280 million years 10 meters below the surface, where the only radiation comes from radioactive decay within rocks and minerals.

But how do they survive in these conditions? Scientists note that, on the one hand, they retain “spare” copies of their genome for radiation-damaged fragments, and on the other hand, they accumulate large amounts of the antioxidant manganese, which captures harmful molecules created by radiation. . The capture of these molecules prevents damage to the proteins that repair the body’s DNA.

expects

bacterium it most likely evolved to withstand damage during dry periods, and radiation resistance is just a side effect of this evolution, the researchers suggest.

Such conditions should have affected any bacteria that might live in Marswhere it would have to develop in an environment without such protection, and would probably have to develop with a similar resistance to radiation.

Mars It hasn’t had widespread liquid water for 2 billion years, so even if ancient life did develop there, 280 million years is still too short to suggest there are many living things on the planet. bacteria waiting to come back to life. But because Mars Because of the very thin atmosphere, meteors regularly hit the planet’s surface, Daly said. The heat and liquid water released by these impacts could potentially awaken bacteria dormant in the depths and allow life to flourish temporarily.

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