Astronauts need to travel light. Every extra ounce of provisions can hinder a rocket, and certain crucial foods may not survive journeys as long as NASA's proposed mission to Mars. But scientists are devising creative ways to maximize storage efficiency—including recycling astronauts’ urine and breath.

“As missions become longer in duration, astronauts will be generating more waste. So the question is, What do we do with all that waste?” asks Mark Blenner, a chemical engineer and synthetic biologist at Clemson University. Rather than bringing it back to Earth, Blenner and his colleagues have shown that yeast can convert waste products into essential nutrients—and even plastics that could be used to make tools.

The researchers found that Yarrowia lipolytica, a relative of baker's yeast, could survive by feeding on a component of human urine. Separately, they grew algae that converted carbon dioxide from exhaled air into carbon-rich nutrients, which the yeast then used to produce fatty acids. By splicing a few genes from algae and phytoplankton into the yeast's genome, Blenner's team got the microbes to “upgrade” these fatty acids to omega-3s, which are vital for human heart, eye and brain health. In another strain of Y. lipolytica, Blenner and his group altered the fatty acid production pathway to produce plastic polyesters that could be used to 3-D print tools in space. The researchers presented their findings at the American Chemical Society's biannual meeting in August.

“Yeast is a great organism to use for this kind of innovative research,” says Jitendra Joshi, technology integration lead for Advanced Exploration Systems at NASA, who was not involved in the work.

The researchers still need to demonstrate that the microorganisms can thrive and produce the useful products at the same rates in the low-gravity, high-radiation environment of space. But Blenner is hopeful that future astronauts will be “using yeast as their own flexible manufacturing platforms.”