Desert-dwelling bacteria that feed on sunlight, absorb carbon dioxide and release oxygen could be incorporated into a dye that replenishes the air in a Martian habitat.
Is called Chroococcidiopsis cubana, and scientists have developed a biocover that releases measurable amounts of oxygen on a daily basis while reducing the amount of carbon dioxide in the air around it. This has implications not only for space travel but also here on Earth, according to a team led by microbiologist Simon Krings of the University of Surrey in the UK.
“With the increase in greenhouse gases, especially CO2in the atmosphere and concerns about water scarcity due to rising global temperatures, we need innovative, environmentally friendly and sustainable materials,” says bacteriologist Susie Hingley-Wilson from the University of Surrey.
“Mechanically robust, ready-to-use biocoatings or ‘living paints’ could help address these challenges by reducing water consumption in typically water-intensive bioreactor-based processes.”
Chroococcidiopsis is a strange little breed of beasts. If there’s a place on Earth that you think life can’t buy, you’ll probably find a species of this bacteria there. It uses a strange type of photosynthesis that can make the most of extremely low light conditions, with a backup survival mechanism for even darker places. It is found in the darkness of ultra-deep caves and in the lower crust beneath the ocean floor.
Chroococcidiopsis cubana sometimes lives in deserts, in conditions not dissimilar to those of Mars. And like other cyanobacteria, its metabolism has some desirable properties. The bacterium takes up CO2which it fixes to be transformed through photosynthesis into organic compounds, releasing oxygen as part of the process.
Krings and her team wanted to develop a biocoating that used these properties. These are coatings, like paint, in which live bacteria are embedded in layers. They must be durable without containing ingredients that can harm the bacteria in them.
This is more challenging than it might seem: the biocoating matrix must be porous to allow hydration and cell transport, but mechanically strong and rigid. The team developed a method of mixing latex with nanoclay particles that achieves these properties by safely encapsulating their bacteria.
The next step was to make sure the paint worked as intended and that the little microbes in it continued to live happy little lives. The team monitored their coating for 30 days, taking measurements of oxygen and CO emissions2 entrance.
They found that the dye constantly released oxygen at a rate of up to 0.4 grams of oxygen per gram of biomass per day, and that this remained stable throughout the month. That’s up to 400 grams (14 ounces) of oxygen for every kilogram (35 ounces) of paint. In addition, the paint absorbs CO2. The researchers have named their invention Green Living Paint.
This production would probably not be sufficient on its own for a Martian habitation; a team of astronauts living on Mars for a year would need about 500 metric tons of oxygen; but every tiny bit of oxygen that can be used locally on the red planet will reduce the amount of oxygen that space missions will need to deliver there by spacecraft.
“The photosynthetic Chroococcidiopsis they have an extraordinary ability to survive in extreme environments, such as droughts and after high levels of exposure to ultraviolet radiation,” says Krings. “This makes them potential candidates for the colonization of Mars.”
The study was published in Microbiological spectrum.