Mars may not have many things right now, depending on 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 required, of course, but it’s a significant step toward cyanobacterial-based life support systems for human habitats when we finally head there.
“Here we show that cyanobacteria can use the gases available in the Martian atmosphere, at a 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 maintained their ability to grow in waters that contained only Mars-like dust and could still be used to feed other microbes. This could help make missions to Mars sustainable in the long run.”
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.
Still, we may not be here without him. Scientists believe a cyanobacterial boom 2.4 billion years ago was primarily responsible for our breathable atmosphere. When it exploded on the scene, cyanobacteria bombarded the atmosphere with oxygen, dramatically altering the entire planet.
All species of cyanobacteria produce oxygen as a photosynthetic byproduct, and are an invaluable source of it, even today.
For some years now, scientists have been considering whether and how we could harness the ability of cyanobacteria to produce oxygen so we can live on Mars (and in space).
This would entail additional benefits. The atmosphere of Mars is composed mainly of carbon dioxide (95%) and nitrogen (3%), both fixed by cyanobacteria, converting them respectively into organic compounds and nutrients.
However, the atmospheric pressure on Mars 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 cannot grow directly there or extract enough nitrogen. But recreating the conditions of the Earth’s atmosphere on Mars is also a challenge, especially the pressure.
So Verseux and his team looked for a midpoint. They developed a bioreactor called Atmos that has an atmospheric pressure of about 10 percent of that of Earth, but uses only what can be found on Mars, albeit in inverted proportions: 96 percent nitrogen and 4 percent of carbon dioxide.
The bioreactor also included water, which can be obtained on Mars from molten ice, which is abundant on the surface in certain places, and a simulant of Martian regolith, a mixture of minerals created here on Earth using only what can be found on Mars.
The system, consisting of nine glass and steel containers, was carefully controlled with temperature and pressure and controlled at all times.
Atmos. (C. Verseux / ZARM)
The team selected a species of nitrogen-fixing cyanobacteria that preliminary tests showed would likely thrive in these conditions, Anabaena sp. PCC 7938 and tested it in various conditions.
Some cameras used a culture medium to grow cyanobacteria, while others used the simulated Mars regolith. Some were exposed to the Earth’s atmospheric pressure, while others were reduced to low pressure.
Scientists found that they didn’t just do it Anabaena grow, he did so “vigorously.” Obviously, it grew better in the culture medium than in the Mars rule, but the fact that it grew in the rule is a massive success, indicating that the growth of cyanobacteria on Mars should not depend on imported ingredients from Mars. the 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 drug production.
Of course, there is much more work to be done.
Atmos was designed to test whether cyanobacteria could 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 work.
Now that the concept has been demonstrated, 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 culture system we would use on Mars: it aims to test, on Earth, the conditions we would provide,” Verseux said.
“But our results will help guide the design of a Martian culture system … We want to move from this proof of concept to a system that can be used on Mars efficiently.”
The research has been published in Frontiers in microbiology.