At the moment, there may not be much going on in life, but the dusty red planet may not be as inhospitable as it seems.
New experiments have shown that cyanobacteria (also known as blue-green algae) can grow successfully in the atmosphere of Mars.
Of course, a few more ingredients are needed, but it’s an important step towards cyanobacteria – based life support systems for human habitats when we finally get there.
“Here we are showing that cyanobacteria can use gases available in the Martian atmosphere, at a low total pressure, as their carbon and nitrogen source,” said astrobiologist Cyprien Verseux of the University of Bremen in Germany.
“Under these conditions, cyanobacteria have retained their ability to grow in water containing only Mars-like matter and can still be used to feed other microbes. This could help make long-term shipments to Mars sustainable.”
Here on earth, cyanobacteria are not always the best with other lives. It occurs in almost every habitat on the planet, and sometimes produces powerful toxins that can kill other organisms.
Yet we may not be without it. Scientists believe that a surge of cyanobacteria 2.4 billion years ago was largely responsible for our breathing atmosphere. When it exploded at the scene, cyanobacteria pumped the atmosphere with oxygen and dramatically changed the entire planet.
All species of cyanobacteria produce oxygen as a photosynthetic by-product, and it is an invaluable source of it, even today.
Scientists have been considering for several years whether and how we can harness the ability of cyanobacteria to make oxygen to live on Mars (and in space).
This will have additional benefits. Mars’ atmosphere consists mostly of carbon dioxide (95 percent) and nitrogen (3 percent), both of which are fixed by cyanobacteria, and converted into organic compounds and nutrients, respectively.
However, Mars’ atmospheric pressure is a significant setback. It is only 1 percent of the earth’s atmospheric pressure, too low for the presence of liquid water, and cyanobacteria can not grow directly in it or extract enough nitrogen. But recreating the conditions of the Earth’s atmosphere on Mars is also challenging, especially the pressure.
So Verseux and his team were looking for a middle ground. They developed a bioreactor called Atmos, which has about 10 percent of the Earth’s atmospheric pressure, but can only be found on Mars, albeit in inverse proportions: 96 percent nitrogen and 4 percent carbon dioxide.
The bioreactor also includes water – which can be obtained on Mars from molten ice, which is abundant in certain places on the surface – and a Mars regolith simulant, a mixture of minerals created here on Earth, and used only be what can be found on Mars. .
The system, which consists of nine glass and steel barrels, is carefully controlled by temperature and pressure and monitored at all times.
Atmos. (C. Verseux / ZARM)
The team selected a species of nitrogen-fixing cyanobacteria that, according to preliminary tests, would probably thrive under these conditions, Anabaena sp. PCC 7938, and tested it under different conditions.
Some rooms used a culture medium to grow the cyanobacteria, while others used a simulated Mars regolith. Some were exposed to atmospheric pressure on Earth, while others were under low pressure.
The scientists found that it was not just their Anabaena growth, it did “powerfully”. Of course, it grew better on the culture medium than on the Mars regolith, but the fact that it grew in the regolith at all is a great success, suggesting that the growth of cyanobacteria on Mars is not on imported constituents of the earth. do not have to trust.
To determine if the cyanobacteria that can be grown in Martian conditions can still be useful, the researchers dried them and used them as a substrate to grow. Escherichia coli.
It has shown that sugars, amino acids and other nutrients can be obtained from the cyanobacteria to feed other cultures, which can then be used for other purposes, such as producing medicine.
Of course, there is a lot more work to do.
Atmos are designed to test whether cyanobacteria can be cultured under certain atmospheric conditions, not to maximize efficiency, and the parameters of the bioreactor will depend on many factors in the Mars mission, including the mission payload and architecture. Anabaena may not even be the best cyanobacteria for the job.
Now that the concept has been proven, however, the team can begin to optimize a bioreactor system that could one day bring us to life on Mars.
“Our bioreactor, Atmos, is not the breeding system we would use on Mars; it is meant to test the conditions on earth that we would offer there,” Verseux said.
“But our results will help guide the design of a Mars cultivation system … We want to move from this proof-of-concept to a system that can be used efficiently on Mars.”
The research was published in Boundaries in microbiology.