Conditions on our closest celestial bodies today are far from suitable for humans, but some terrestrial organisms have survived for millions of years. And now tiny bacteria found in the driest desert on our planet can help humans turn the Moon and Mars into habitable worlds.
The Atacama Desert is one of the driest and most inhospitable places on Earth, but the cyanobacterium Chroococcidiopsis, found in local gypsum samples, can extract the water and minerals it needs directly from the surrounding rocks. To detect these tiny lumps of life, researchers from Johns Hopkins University (USA) had to track not even the cells themselves, and traces of their presence in the gypsum.
Scientists already knew that the cells of cyanobacteria in the process of life gradually extracts water from gypsum, turning it into anhydrous calcium sulfate. But the mechanism by which the microorganisms provide themselves with another essential substance - iron - has remained unclear until now. Now, finally, the researchers were able to trace this process by populating desert cyanobacteria with special substrates of crumbled magnetite, a common iron oxide on Earth.
After studying magnetite samples under an electron microscope, the authors of the new work noted that the mineral particles covered by the bacterial film had markedly reduced in size. At the same time, traces of hematite - another iron-containing mineral that can be called "rusty magnetite" - were found on the substrates. It turned out that bacteria dissolve magnetite, after which they release siderophores - special molecules that bind iron and store it for later use by the microorganism.
After observing the inconspicuous life of cyanobacteria in their desert home, scientists thought of new mining methods in which ore processing would not require sophisticated machinery, high temperatures and massive energy costs, but rather repopulation of the crushed rock with suitable microorganisms and incubation at room temperature.
Since Atacama desert conditions are among the harshest on the planet, perhaps microbial "miners" will be able to survive beyond Earth, becoming the first "colonists" on the Moon and Mars. Not requiring free water, capable of extracting minerals from rocks and releasing oxygen through photosynthesis, they could serve to terraform other bodies of the solar system and prepare them for the arrival of the first humans.
