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Asteroid-eating microbes could break down materials from space rocks

By Leah Crane

The bacterium Sphingomonas desiccabilis can extract minerals from basalt

UK Center for Astrobiology / University of Edinburgh

An experiment on the International Space Station (ISS) has shown that microbes can extract valuable or useful elements from rocks in zero gravity, suggesting that “biomining” may be key to using asteroids.

Microbes release elements from rocks by releasing compounds that accelerate chemical reactions, such as acids, that dissolve the rocks and allow the microbes to consume the elements they need to survive. Charles Cockell of the University of Edinburgh in the UK and his colleagues sent an experiment called BioRock to the ISS last year to see if this would work on the space station at low gravity.

“Microbes broken down stones because they have needed nutrients for billions of years,” says Cockell. “Much of the copper and gold on earth is mined today with microbes, so this method is not a piece of cake.”

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BioRock consisted of 36 small experiments, each involving a piece of basalt rock and a liquid medium that contained some additional nutrients that the microbes need. Some of the experiments also contained microbes that were allowed to feed on the rare earth elements in the rocks for three weeks.

When the researchers measured the amounts of these elements depleted by the microbes, they found that one – Sphingomonas desiccabilis – extracted rare earth elements just as well in zero gravity as it did on Earth. The other two microbes are not known to leach these elements on Earth, so it was no surprise they did not either on the ISS. All behaved the same with respect to earth gravity, microgravity and Mars gravity, which were simulated with a centrifuge.

“There was reason to believe that this would be different, but in fact we didn’t see any difference at all,” says Cockell. “This shows that experiments on Earth provide useful information that can be used in any gravity.” Finally, he says, biomining could be used to harvest useful materials for human settlements on the Moon or Mars so that they don’t have to be shipped off Earth.

Journal reference: Nature Communications, DOI: 10.1038 / s41467-020-19276-w

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