There is little to love about plastic. Most of the manufacturing processes still rely on fossil fuels, it often still takes generations to decompose, and their microscopic residue is contaminating the planet (as well as our bodies). But chemical engineers at Southern Illinois University (SIU) Carbondale are developing a NASA-backed process that turns toxic plastic into something surprisingly edible—and possibly even delicious.
According to work presented this week at the fall meeting of the American Chemical Society (ACS), reprogrammed yeasts can now turn plastic and even agricultural waste into flavoring molecules and digestible proteins.
“We were trying to develop technologies for plastic upcycling to make more valuable products,” explained SIU microbiologist Lahiru Jayakody. “We thought, why not focus on making food? Because plastic is carbon and food is carbon.”
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The team’s method focuses on polyethylene terephthalate (PET), a common variant usually seen in plastic bottles. PET is laden with carbon, and that means it hypothetically can be repurposed into protein-like molecules. This can be done in a laboratory with solvents and chemical additives, but another creative option may involve enlisting microbes like yeast in the cause. It’s far from the first time scientists have reprogrammed the tiny organisms to help humanity. For example, insulin manufacturing once relied on harvesting the hormone from animal pancreases, but the industry now predominantly harnesses altered yeasts. Jayakody wants to apply similar principles to the planet’s plastic problem.
“The way to address that, I believe, is by using microbes,” he said.
Researchers recently reprogrammed various yeasts, including those normally used in baking to crave the molecules inside both plastics and agricultural byproducts. They then ran PET plastics, corn stalks, and other biomass leftovers through a novel process called oxidative hydrothermal dissolution. As the name implies, water and oxygen are heated to an extremely high temperature, which breaks down the unwanted materials into microscopic debris. The reprogrammed yeasts are then introduced into the solution, where they get to work devouring the previously unappealing compounds. The yeast then produces multiple cornerstone food molecules like acids, fats, and proteins. These components are finally combined with sweetener, starch, and to make a paste that can be 3D-printed into high-protein cookies that chemists have dubbed µBites (aka “microbites”).
While the futuristic treats received high ratings on overall aroma and the underlying science implies that µBites are safe to eat, researchers still must wait for institutional approval before beginning actual taste tests. In the meantime, engineers are also programming yeasts to convert other plant biomass into vanilla flavoring, as well as turn PET’s ethylene glycol into beta-carotene that serves as a reliable source of vitamin A.
Jayakody’s team envisions future iterations of µBites and similar upcycled foods as a valuable menu item in resource-restricted environments like submarines and even in space—hence the funding from NASA’s Deep Space Food Challenge. However, the immediate benefits may be far more terrestrial. Jayakody cites recent reports that estimate global food demand rising as much as 56 percent by 2050, making around one-third of Earth’s population at risk for hunger.
“Microbes are very clever. So, we are using their traits to solve the problems we created,” he said.
