Experiment reveals what could help keep humans alive

New experiments have shown that cyanobacteria (also known as blue-green algae) can successfully grow under the conditions of the Martian atmosphere. A few more ingredients are needed, of course, but this is an important step towards human survival systems based on cyanobacteria. habitats, when We finally get there.

“Here we show that cyanobacteria can use gases available in the Martian atmosphere, at low total pressure, as a source of carbon and nitrogen,” said astrophysicist Cyprian Versailles of the University of Bremen in Germany. “Under these conditions, the cyanobacteria maintained their ability to thrive in water. Which only contains dust and can still be used to feed other microbes. This could help make the missions sustainable. long distance to Mars. ”Here on Earth, cyanobacteria are not always the most compatible with other life forms. They can be found in almost every habitat on the planet, and sometimes they produce powerful toxins that can kill d ‘other organizations.

Scientists believe that the mutation of cyanobacteria 2.4 billion years ago was largely responsible for our breathable atmosphere. And when cyanobacteria exploded into the landscape, they pumped oxygen into the atmosphere, radically altering the entire planet. All types of cyanobacteria produce oxygen as a byproduct of photosynthesis, an invaluable resource even today.

Scientists have been thinking about whether and how to harness the ability of cyanobacteria to produce oxygen in order to live on Mars (and in space). The Martian atmosphere is composed mainly of carbon dioxide (95%) and nitrogen (3%), both of which are fixed by cyanobacteria. It transforms them into organic compounds and nutrients, respectively. However, the atmospheric pressure of Mars represents a major setback, as it is only 1% of the atmospheric pressure of the Earth, and it is so low due to the presence of liquid water and the cyanobacteria cannot stand. develop directly there, nor extract enough nitrogen. But reconfiguring Earth’s atmospheric conditions on Mars is also a challenge, especially the pressure.

So Versailles and his team looked for a compromise, and they developed a bioreactor called Atmos which has an atmospheric pressure of about 10% of Earth’s pressure, which can be found on Mars, despite the inverted ratios: 96% d nitrogen and 4% carbon dioxide. . Water has been included. Also in the bioreactor – which can be obtained on Mars from melted ice, which is abundant on the surface in some places – and simulates Martian regolith, a mixture of minerals created here on Earth using only what can be find on the surface of Mars. The system, consisting of nine glass and steel vessels, has been carefully controlled for temperature and pressure, and monitored at all times.

The team selected a species of nitrogen-fixing cyanobacteria, which preliminary testing showed is most likely to thrive under these conditions: Anabaena sp. PCC 7938, and tested it under various conditions. Some have been subjected to Earth’s atmospheric pressure, while others have decreased to low pressure.

Scientists found that Anabaena grew “vigorously”, and it clearly grew better on culture medium than on Martian dust, but the fact that it did grow is a huge success – indicating that the growth of cyanobacteria on Mars will not have to depend on ingredients imported from Earth. Then, to assess whether cyanobacteria growing in Mars conditions could continue to benefit, the researchers dried them and used them as a substrate for growing Escherichia coli. This showed that sugars, amino acids and other nutrients could be obtained from cyanobacteria to nourish other ingredients, which could be They are then used for purposes like the production of drugs.

The Atmos system is designed to test whether cyanobacteria can be grown under certain weather conditions, and not to maximize efficiency, and the bioreactor parameters will depend on many factors of the mission to Mars, including payload and architecture. of the mission. Anabaena might not be the best cyanobacterium for the job, and now the team can work on improving a bioreactor system that could one day keep us alive on Mars.

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