Engineered yeasts help turn PET plastic and crop waste into protein-rich cookies

Plastic might be the last ingredient you would ever add to a cookie recipe. But a team of researchers is looking to change that. They’ve programmed yeasts to turn plastic and agricultural waste into edible proteins and flavoring molecules, creating a treat from trash. The technology not only offers a new upcycling method but could also sustain life in disaster zones or even deep-space missions with humans aboard.

The researchers presented their results at ACS Fall 2026, held Aug. 23–27, during the “Undergraduate and Graduate Research in Biochemistry and Chemical Biology” symposium at McCormick Place.

Turning waste carbon into food

As the world struggles with growing plastic pollution and increasing concerns about food security, researchers are looking for ways to turn one problem into a means of solving the other. A team from Southern Illinois University (SIU) Carbondale has put microbes to the test to transform plastic waste into edible food for humans. The work was conducted as part of a NASA-led project aimed at creating food for the resource-limited environment of deep-space exploration.

“We were trying to develop technologies for plastic upcycling to make more valuable products. We thought, why not focus on making food? Because plastic is carbon and food is carbon,” explains Associate Professor Lahiru Jayakody.

One of the most common forms of plastic is polyethylene terephthalate (PET), a material often used to make soda and water bottles. PET contains molecules with lots of carbon that could be rebuilt into something like a protein. And while that rebuilding could be done using chemical reactions and solvents in a lab, a simpler and more environmentally friendly solution is to outsource the work to microbes. Jayakody adds, “Microbes are very clever. So, we are using their traits to solve the problems we created.”

Scientists have long used microbes, including yeast, as miniature factories to make a variety of molecules. For example, insulin is no longer extracted from animal pancreases—now, yeast can be programmed to make it.

From PET to µBites

Similarly, Jayakody and graduate student Sandhya Jayasekara programmed a variety of yeasts, including baker’s yeast, to convert molecules present in plastic and agricultural waste into proteins, vitamins and flavorings.

The researchers took PET plastic, discarded corn plant stalks and leaves, and other biomass and put it through a proprietary process called oxidative hydrothermal dissolution. Created by SIU Carbondale Geology Professor Ken Anderson, this method uses water and oxygen at high temperatures and pressures to break down tough material into microbe-accessible pieces.

Then, those pieces are fed to the programmed yeasts, which transform them into a variety of new food ingredients, including proteins, fats and acids. Finally, the researchers add fiber, starch and sweetener to the mix and extrude it through a 3D printer, forming protein-rich cookies dubbed µBites (pronounced “microbites”).

Though the data show that µBites are safe to eat, the team is awaiting institutional approval to conduct taste tests. For now, the cookies have received high marks for aroma, with most participants agreeing that they would be willing to eat them in resource-limited situations.

Making the cookies more appealing

To make µBites into something consumers might opt for in less dire circumstances, Jayasekara created yeasts that can produce more food additives. Now, baker’s yeast can produce vanilla flavoring from plant biomass, while a different strain can turn ethylene glycol from PET into beta-carotene, which the body can convert into vitamin A. “We’re using microbes to develop the cookie into a more attractive, consumer-friendly product,” says Jayasekara.

In the future, Jayakody and his team hope to produce the main ingredients in µBites using microbes, including the added starch, fiber and sweetener. He also hopes µBites will be ready for public consumption within a few years and could be used both on Earth and in more extreme environments, like submarines or even colonies on the moon or Mars.

“Global food demand is expected to rise 35–56% by the year 2050, and about 30% of the world’s population will be at risk of hunger in the future. The way to address that, I believe, is by using microbes,” he concludes.

Who’s behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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