Scientists have engineered yeast to transform polyethylene terephthalate (PET) plastic — the material used in soda and water bottles — and agricultural waste into ingredients for protein-rich, 3D-printed cookies called µBites. This technology, developed as part of NASA’s Deep Space Food Challenge, aims to address both plastic pollution and food insecurity by converting waste materials into nutritious food. The system can produce proteins, fats, vitamins, and even vanilla flavoring from discarded materials, offering a potential solution for food production in extreme environments like deep-space missions. The project originated from a NASA initiative focused on creating sustainable food sources for deep space exploration, where astronauts cannot rely on regular food shipments from Earth. PET plastic, which is abundant and difficult to recycle, contains carbon-rich molecules that can be broken down and repurposed into useful compounds. While traditional methods use chemical reactions and solvents, researchers at Southern Illinois University Carbondale (SIU Carbondale) chose to use microbes instead, which can naturally perform complex biochemical processes. Before microbes can use the waste materials, they must be broken down into simpler compounds. The researchers use a process called oxidative hydrothermal dissolution, developed by SIU Carbondale’s Ken Anderson, which uses high heat and pressure with water and oxygen to break down resistant materials like PET plastic and agricultural waste. These broken-down molecules are then fed to specially engineered yeast, which convert them into proteins, fats, and flavoring compounds. Once the yeast-derived ingredients are produced, they are combined with fiber, starch, and sweetener, then printed into µBites using a 3D printer. While the cookies have shown safety in preliminary testing, formal taste tests are pending institutional approval. Participants have evaluated the cookies based on aroma, with most expressing willingness to try them in situations where food is scarce. Researchers are also working to expand the yeast’s capabilities, such as producing vanilla flavoring from plant biomass and beta carotene from PET-derived compounds. The team’s ultimate goal is to have microbes produce all the necessary ingredients for µBites, including starch and fiber, reducing the need for additional inputs. If successful, the cookies could be available for public use within a few years. Beyond Earth, this technology could support food production in remote or extreme environments, such as submarines, disaster zones, and future lunar or Martian colonies. The research has been supported by NASA and the National Science Foundation.