Using yeast as a catalyst for generating new parts during deep space missions. Source: Clemson University One of the key goals of space travel is re-usability. Once you are up in the harshness of space, resources will be extremely thin and stretched to the limits.

A team of researchers is working on new ways to make long space trips feasible. Astronauts are not be able to take many spare parts into space as they add to the cost of fuel to escape Earth’s gravity and decrease the amount of area available in the spacecraft.

"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," said Mark A. Blenner, a researcher from Clemson University. "Atom economy will become really important."

The space-saving solution resides in the astronauts themselves who will constantly generate waste from breathing, eating and using materials. Scientists are studying how to repurpose molecules from this waste and convert them into products the astronauts will need such as plastics, polyesters and nutrients.

"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," Blenner said.

The system uses a variety of strains of the yeast Yarrowia Lipolytica, which require both nitrogen and carbon to grow. Researchers found that the yeast can obtain nitrogen from urea in untreated urine and carbon from CO2, from exhaled breath or from the Martian atmosphere. Because the yeast requires a component to fix the carbon into a form it can ingest, the yeast relies on photosynthetic cyanobacteria or algae provided by the researchers.

One of the strains of yeast produces omega-3 fatty acids, which contribute to heart, eye and brain health. Another strain has been engineered to churn out monomers and link them to make polyester polymers, which could be used in a 3D printer to generate new plastic parts. Work continues to engineer other strains of yeast that could be used to produce a variety of monomers that can be polymerized into different types of polyesters with a range of properties, researchers say.

Currently, engineered yeast can only produce small amounts of polyesters or nutrients but researchers are seeking to boost output as well as looking into how this method could be used on Earth in fields such as fish farming or human nutrition.

The full research can be found in the Journal of the Royal Society.