Scientists at Clemson University have found a way to use biological systems in order to recycle human waste into both nutrients and plastics. Their findings were presented at the National Meeting of the American Chemical Society (ACS).
In order to achieve long-distance space flight, there are a number of critical obstacles must be surmounted. One of these obstacles is how astronauts will transport enough food to sustain themselves over several months or years. Due to size and weight constraints, it is not possible to simply send the astronauts with a large stockpile of nutrients to ration. Anyway, even if it were possible to deploy them with enough food to survive the mission, many essential nutrients have a limited shelf-life and would degrade before the end of the mission.
“If astronauts are going to make journeys that span several years, we’ll need to find a way to reuse and recycle everything they bring with them,”
“If astronauts are going to make journeys that span several years, we’ll need to find a way to reuse and recycle everything they bring with them,” says Dr Mark Blenner. “Having a biological system that astronauts can awaken from a dormant state to start producing what they need, when they need it, is the motivation for our project.”
In order to achieve this, Blenner and his colleagues have managed to genetically engineer several strains of the yeast Yarrowia lipolytica to produce a staggering range of useful compounds. Whilst one of the strains generates omega-3 fatty acids, essential to the human diet, another produces polyester polymers for use in 3D printing.
Blenner’s team realised that the yeast could survive almost exclusively on human waste.
However, generating nutrients and polymers aren’t the only bonuses to the engineered yeast – their choice of food also benefits the crew of the spacecraft. As the organisms require both nitrogen and carbon dioxide, Blenner’s team realised that the yeast could survive almost exclusively on human waste. While the urea in untreated urine acts as the nitrogen source, the carbon can be obtained from exhaled carbon dioxide. However, in order for the yeast to us the carbon, it must first be ‘fixed’ by a photosynthetic cyanobacteria or algae provided by the scientists (or astronauts).
Currently, the genetically engineered yeast strains can only produce a relatively small amount of product, but the team are working on increasing the output. They are also investigating the organisms’ potential on Earth.
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