Gardening Life on Mars

Bacteria could detoxify the soil of the Red Planet

By Bart Braun

There’s a definite problem for anyone hoping to grow anything on Mars: the soil is toxic. A team of Leiden students hopes to solve the problem using biotechnology.

(De orginele Nederlandstalige versie staat hier)

“Mars is a fixer-upper of a planet”, entrepeneur Elon Musk said once. “But we could make it work.” Musk is the founder of PayPal, Tesla Motors and SpaceX, a spaceflight company that, if it were up to him, will put man on Mars. But for now, robots make up the entire population of Mars and there is plenty to do before anything else can take up residence there. It involves plenty of both very minor and very major problems and to find out about one of them, we must turn our attention away from from Mars and Musk’s Silicon Valley and towards Leiden’s Sylvius Building.

“We are the first Leiden-only team to take part in this international biotechnology competition, iGEM”, explains Biology student Valentijn Broeken. “The objective is to think up a challenge and solve it using biotechnology.”
“Mars is a hot topic right now”, his team mate and fellow Biology student Lisanne van Oosterhoud adds. “We want to solve a problem on that planet. Microbiologist Dennis Claessen, the researcher who is working with us, was very excited about it.”

Broeken continues: “If you want to grow plants in greenhouses on Mars like they do in The Martian (a science-fiction story by American author Andy Weir – ed.), you have a problem. Relatively speaking, there is quite a lot of poisonous perchlorate in the soil. Plants absorb it and become poisonous too. It’s a problem on Earth too, in some places. We don’t have any means of solving it on Mars yet.

Perchlorate has the chemical formula CIO4-, which means that the chemical agents can be converted into relatively harmless chloride ions (CI-, the stuff we eat as cooking salt) and oxygen (O2, the stuff we breathe). There are a few microorganisms that do it for us: the bacterium Dechloromonas agitata is the one we know the most about. Van Oosterhoud: “We want to transfer the bacterium responsible for breaking down perchlorate to another bacterium, E. coli, which lives in intestines. We hope they’ll be effective there too.”

Why can’t we just send that Dechloromonas to Mars? For a start, it’s a relatively unknown bacterium, while E.coli is one of the most researched beings in the world, the most prominent workhorse in microbiology. Researchers know how to grow it, genetically adapt it, etc. It’s the established technology, and that makes working with it easier: if your skis don’t fit in your car, it’s easier to fit a rack onto your car roof than to turn your skis into a snow scooter that can also drive to Austria.

The Mars detoxifier will also need to undergo much more revision before it’s ready for the Red Planet. The surface of Mars is inhospitable, being bitterly cold. It also has radiation bombs that rip organic molecules to pieces, but even in greenhouses, Earth bacteria are probably not suited for a life on Mars. They might have to endure more UV and cosmic radiation than on Earth, and then there’s the question of the effects of Mars’ lower gravity – about forty per cent less than gravity on Earth.

That’s the question the Leiden iGEM team want to tackle first: Airbus’s division Defence & Space has already lent them a “Random Positioning Machine”. “It’s a sort of reverse centrifuge”, explains Broeken. “It rotates your cells to erase the effects of gravity because gravity works on all sides, as it were. We can adjust it so that the cells point downwards exactly forty per cent of the time, to simulate the gravity on Mars.”

“We expect certain genes to switch on or off more often due to the changes in gravity”, says Van Oosterhoud. “And if they do, the ‘promotor’, i.e. the piece of DNA that switches those genes on and off, will be the centre of our attention”, adds Broeken. “And then we could use it to switch the genes we’re interested in on and off on Mars.” Van Oosterhoud explains: “We at least want a promotor that we know will work in Martian gravity. It would be a pity if the gene switches on here in the lab but not on Mars.”

The students are aiming to produce “biobricks” rather than build a fully functional perchlorate-guzzler suitable for Mars. Biobricks are pieces of DNA such as genes or promotors that are easy to copy and paste using methods laid down by the international community. Just as different computers can communicate because they use a standard software protocol, the biobrick agreements are standard in biotechnology. Broeken continues: “If the system is then developed for E.colli, and there’s a proof of concept, you can transfer it to another bacterium.

There are already thousands of biobricks, including a number of genes belonging to the Deinococcus radiodurans bacterium, first found in tins of meat which had been treated with gamma rays to sterilise them. Those genes make bacteria extremely resilient to radiation, UV light and dehydration. Isn’t it possible to make a kind of super-detoxifier that can survive outside a greenhouse and that can turn perchlorate into oxygen to improve Mars’ atmosphere sufficiently for humans?

“It’s certainly not our intention to turn Mars into a second Earth!” exclaims Broeken. “If you turn such a bacterium loose, Mars would be covered in it. We don’t know for sure whether there is or isn’t any other life there, and what the consequences would be. Also, we’re only spending one summer holiday on this project as it is; we don’t need to solve every imaginable problem.”

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Gardening Life on Mars

There’s a definite problem for anyone hoping to grow anything on Mars: the soil is …