Desert-dwelling bacteria that feed on sunlight, absorb carbon dioxide and emit oxygen could be incorporated into paint that supplements the air in a habitat on Mars.
The bacteria is called Chroococcidiopsis cubana. Scientists have developed a biocoating that emits measurable amounts of oxygen on a daily basis. It also reduces the amount of carbon dioxide in the air around it. This has implications for both space exploration and applications on Earth. This information was provided by a team led by Simone Krings, a microbiologist at the University of Surrey in the U.K.
Suzie Hingley-Wilson is a bacteriologist at the University of Surrey. She said, “With the increase in greenhouse gasses, particularly CO2, in the atmosphere and concerns about water shortages due to rising global temperatures, we need innovative, environmentally friendly, and sustainable materials. Mechanically robust, ready-to-use biocoatings, or 'living paints,' could help meet these challenges by reducing water consumption in typically water-intensive bioreactor-based processes.”
If there is a place on Earth where it might seem that life could not possibly exist, it is likely that Chroococcidiopsis would be found there. It harnesses a rare kind of photosynthesis that can make the most of extremely low-light conditions. It also has a back-up survival mechanism for even darker places. It has been found in the utter darkness of ultra-deep caves and in the crust of the Earth below the ocean floor.
Chroococcidiopsis cubana lives in some deserts in conditions that are similar to the Martian surface. Like other cyanobacteria, its metabolism has some desirable properties. The bacterium takes in CO2 and transforms it via photosynthesis into organic compounds, releasing oxygen as part of the process.
Krings and her team wanted to develop a biocoating that harnesses these desirable properties. The biocoatings are like paint into which living bacteria are incorporated in layers. The layers have to durable without containing ingredients that could harm the bacteria therein.
This is very challenging. The biocoating matrix needs to be porous, to allow for hydration and cell transport, but mechanically robust and hard. The team developed a technique for mixing latex with nanoclay particles that provide these properties, safely encapsulating the bacteria.
The next step was to ensure that the paint was working as intended and the tiny microbes could thrive. The team observed their new biocoating for thirty days. They performed measurements of oxygen output and CO2 input.
The team found that the paint consistently released oxygen at a rate of up to four tenths of a gram of oxygen per gram of biomass per day. This remained steady for a whole month. That would amount to four hundred grams of oxygen for every kilogram of paint. The researchers named their invention Green Living Paint.
That oxygen output would probably not be sufficient on its own for a Martian habitat. A team of astronauts living on Mars for a year would need an estimated five hundred metric tons of oxygen. However, every little bit of oxygen that can be generated in situ on the red planet will reduce the amount of oxygen that space missions are going to need to ship there.
Kring said, “The photosynthetic Chroococcidiopsis have an extraordinary ability to survive in extreme environments, like droughts and after high levels of UV radiation exposure. This makes them potential candidates for Mars colonization."