A some more ingredients are required, but it is a significant step-towards cyanobacteria-based life support systems for human habitats once we finally make our way over there.
“Here we show that cyanobacteria can-use gases available in the Martian atmosphere, at a low total pressure, as their source of carbon & nitrogen,” said astrobiologist Cyprien Verseux of University of Bremen in Germany.
“Under these conditions, cyanobacteria kept-their ability to grow in water containing only Mars-like dust and be used for feeding other microbes. This might help make future missions to Mars sustainable.”
Here on Earth, cyanobacteria are not always the most compatible with other life. It can be often found in almost every habitat on the planet earth and sometimes produces powerful toxins which can kill other organisms.
Yet we’d not be here without it. Scientists believe that a cyanobacteria boom 2.4-billion-year ago was largely responsible for our breathable atmosphere. When it exploded on-to the scene, cyanobacteria pumped the atmosphere with oxygen, dramatically altering the whole planet.
All species of cyanobacteria produce oxygen as a photosynthetic byproduct and they’re an invaluable source of-it, even today.
For some years, scientists considering, if & the how we might harness cyanobacteria’s ability to produce oxygen so as to live on Mars (& in space).
This carries additional benefits. Mars atmosphere is made from mostly carbon dioxide (95%) & nitrogen (3%), both of which are fixed by cyanobacteria, converting-them into organic compounds & nutrients respectively.
However, Mars atmospheric pressure is a significant setback. It’s just one percent of Earth’s atmospheric pressure, too low for the presence of liquid water & cyanobacteria cannot grow in it directly or extract enough nitrogen. But recreating the conditions of earth’s atmosphere on Mars is challenging, especially the pressure.
So Verseux & his team sought a middle-ground. They developed a bio-reactor called Atmos that has atmospheric pressure about 10 percent of that of Earth, but uses only what can be found on Mars, although in inverted proportions: 96% nitrogen & 4% carbon dioxide.
Also included in the bio-reactor was water, which can-be obtained on Mars from melted ice, which is actually abundant on the surface in certain places and a Martian regolith simulant, a mixture of minerals created here-on Earth using only what can be found on Mars.
The system, comprising 9 glass & steel vessels, was carefully temperature & pressure controlled & monitored at all times.
The team selected a species of nitrogen-fixing cyanobacteria that preliminary tests showed would be presumably to thrive under these conditions, Anabaena sp. PCC 7938 and tested it under different conditions.
Some chambers used a culture medium to-grow the cyanobacteria, while others used simulated Mars regolith. Some were exposed-to Earth atmospheric pressure, while others were reduced to low-pressure.
The scientists found that not-only did their Anabaena grow, it did so vigorously. Obviously, it grew better on the culture medium than on the Mars regolith, but the very fact was that it grew at all on the regolith constitutes a huge success, indicating the growth of cyanobacteria on Mars wouldn’t have to rely-on imported ingredients from Earth.
This showed that sugars, amino acids & other nutrients can be obtained from the cyanobacteria to feed other cultures, which may then be used for other purposes like producing medications.
There is, of course, much-more work to be done.
Atmos was designed to check whether cyanobacteria could-be grown under certain atmospheric conditions, to not maximize efficiency and the parameters of the bio-reactor will depend upon many factors in the Mars mission, including the mission payload & architecture. Anabaena might not even be the best cyanobacteria for the job.
Now, the concept has been proven, though, the team can get to-work optimizing a bio-reactor system that may, one day, keep-us alive on Mars.
“Our bio-reactor, Atmos, isn’t the cultivation system we could use on Mars: it’s meant to test, on Earth, the conditions we’d provide there,” Verseux said.
“But our results will help guide the design of a Martian cultivation system. We want to go from this proof of concept to a system which can be used on Mars efficiently.”
The research has been published-in Frontiers in Microbiology.