It's no secret that astronauts eat some weird food while in space. (I'm looking at you, thermostabilized pouches of breakfast sausage product.) But this new strain of yeast that turns astronaut urine into food is proof that there's really no limit to how weird science is willing to get when it comes to feeding astronauts in space.
The scientist behind this innovation is Mark A. Blemmer, a bioengineer and assistant professor at Clemson University, who received a grant from NASA in 2015 to study "Synthetic Biology for Recycling Human Waste into Nutraceuticals and Materials." In other words, how to turn pee into food—or, at least, food supplements—as well as material to use in 3D printing.
Blemmer and his team engineered two strains of yeast (from the family Yarrowia lipolytica, if you're nasty). One strain of this yeast creates the building blocks of polymer, which can be used to make plastics, while the other strain makes omega-3 fatty acids, a nutrient that can be consumed by humans and added to regular space food to make it more nutritious. The pee comes in because both of these engineered strains need carbon and nitrogen to grow, and these nutrients can be found in astronauts' waste.
Before you get totally squicked out by the idea of astronauts eating or using strains of yeast that are basically watered with their own urine, there are two very important things to know. The first is that urine is theoretically sterile, meaning there shouldn't be any bacteria that could get you sick floating around in there (unless, of course, you have a UTI or other infection). The second is that astronauts on the International Space Station have been turning their bodily fluids—specifically urine and sweat—into drinking water since 2009. They've also been using filtered urine to care for space plants.
If you're the kind of person who dreams of eating breakfast on Mars at some point in your lifetime, you should probably get used to the idea of eating food made from your urine, too. As Blemmer explained in a press release published by the American Chemical Society, "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." And for better or worse, that includes recycling pee.