Mars may not have many things at this time in terms of life, but the dusty red planet may not be as inhospitable as it seems.
New experiments have shown that cyanobacteria (blue-green algae) can grow successfully in Martian atmospheric conditions.
A few more ingredients are needed, of course, but it’s a significant step toward cyanobacterial-based life support systems for human habitats when we finally get there.
“Here we show that cyanobacteria can use the gases available in the Martian atmosphere at low total pressure as a source of carbon and nitrogen,” said astrobiologist Cyprien Verseux of the University of Bremen in Germany.
“Under these conditions, cyanobacteria have retained their ability to grow in water that contains only dust similar to that of Mars and could continue to be used to feed other microbes. This could contribute to the long-term sustainability of missions. Mars”
Here on Earth, cyanobacteria are not always the most compatible with other lives. It can be found in almost every habitat on the planet and sometimes produces powerful toxins that can kill other organisms.
However, we may not be here without her. Scientists believe that a boom of cyanobacteria 2.4 billion years ago was largely responsible for our breathable atmosphere. When it exploded on stage, cyanobacteria pumped the atmosphere with oxygen, dramatically altering the entire planet.
All species of cyanobacteria produce oxygen as a photosynthetic byproduct and are an invaluable source, even today.
For several years, scientists have been thinking about whether and how we could capitalize on the ability of cyanobacteria to produce oxygen to live on Mars (and in space).
This would have additional benefits. Mars’ atmosphere consists mainly of carbon dioxide (95%) and nitrogen (3%), both of which are fixed by cyanobacteria, turning them into organic compounds and nutrients, respectively.
However, the atmospheric pressure of Mars is a significant obstacle. It is only 1 percent of the Earth’s atmospheric pressure, too low for the presence of liquid water, and cyanobacteria cannot grow directly in it and cannot extract enough nitrogen. But recreating the conditions of the Earth’s atmosphere on Mars is also a challenge, especially pressure.
So Verseux and his team looked for a middle ground. They have developed a bioreactor called the Atmos, which has an atmospheric pressure around 10% of that of Earth, but uses only what can be found on Mars, although in reverse proportions: 96% nitrogen and 4% carbon dioxide.
Also included in the bioreactor was water – which can be obtained on Mars from molten ice, which is abundant on the surface in some places – and a regular Martian simulant, a mixture of minerals created here on Earth using only what can be found on Mars. .
The system, comprising nine glass and steel vessels, was carefully controlled by temperature and pressure and was constantly monitored.
Atmos. (C. Verseux / ZARM)
The team selected a species of nitrogen-fixing cyanobacteria, which preliminary tests showed would be most likely to thrive under these conditions, Anabaena sp. PCC 7938 and I tested it in different conditions.
Some chambers used a culture medium to grow cyanobacteria, while others used the simulated Mars regiment. Some were exposed to the Earth’s atmospheric pressure, while others were reduced to low pressure.
Scientists have discovered that they have not only done so Anabaena grows, made it “vigorous.” Obviously, it has grown better on the culture medium than on the Mars rule, but the fact that it has not grown at all on the rule is a massive success – indicating that the growth of cyanobacteria on Mars should not be based on ingredients imported from Earth.
Then, to assess whether cyanobacteria grown under Martian conditions could continue to be useful, the researchers dried it and used it as a substrate to grow Escherichia coli.
This showed that sugars, amino acids and other nutrients can be obtained from cyanobacteria to feed other crops, which can then be used for other purposes, such as the production of medicines.
There is, of course, much more work to be done.
Atmos was designed to test whether cyanobacteria can be grown under certain atmospheric conditions, not to maximize efficiency, and bioreactor parameters will depend on many factors in the Mars mission, including payload and mission architecture. Anabaena may not even be the best cyanobacterium for this job.
Now that the concept has been proven, however, the team can start working on optimizing a bioreactor system that can one day keep us alive on Mars.
“Our bioreactor, Atmos, is not the cultivation system we would use on Mars: it is meant to test, on Earth, the conditions we provide there,” Verseux said.
“But our results will help guide the design of a Martian cultivation system … We want to move from this proof of concept to a system that can be used effectively on Mars.”
The research was published in Frontiers in microbiology.