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 it’s an important step towards human survival systems based on cyanobacteria. “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 Cyprian Versailles from the University of Bremen in Germany, from by its ability to thrive in water that contains only dust, it can still be used to feed other microbes.

This could help make long-range missions to Mars sustainable. Here on Earth, cyanobacteria are not always the most compatible with other forms of life. They can be found in almost any habitat on the planet, and sometimes they produce powerful toxins that can kill others. Scientists believe that the mutation of cyanobacteria 2.4 billion years ago was largely responsible for our breathable atmosphere. And when cyanobacteria exploded in the landscape, they pumped oxygen into the atmosphere, causing a major change across the planet. All types of cyanobacteria are Oxygen is a byproduct of photosynthesis, and it is an invaluable source even today.

Scientists have been thinking about whether and how to harness the ability of cyanobacteria to produce oxygen to live on Mars (and in space). The Martian atmosphere is mainly composed of carbon dioxide (95%) and nitrogen (3%), both of which are fixed by cyanobacteria. This turns 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 cyanobacteria cannot s’ 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 different conditions. Some of the chambers used a culture medium to grow cyanobacteria, while others used Martian dust simulations. Some were subjected to Earth’s atmospheric pressure, while others were reduced to low pressure. Scientists found that Anabaena was growing “hardy,” and it is clear that it grew better on growing media than on Martian dust.

But the fact that they did develop was colossal success – indicating that the growth of cyanobacteria on Mars would not have to depend on ingredients imported from Earth. Then, to assess whether cyanobacteria growing in Martian conditions could continue to benefit, the researchers dried them. They used it as a substrate for growing Escherichia coli. This showed that sugars, amino acids, and other nutrients could be obtained from cyanobacteria to feed other ingredients, which could then be used for purposes such as drug production.

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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