Researchers Engineer Yeast to Turn Plastic Waste Into an Edible Snack

A team of researchers led by Lahiru Jayakody, an applied microbiologist at Southern Illinois University Carbondale, has genetically engineered several yeast species to convert a mixture of degraded plastic and agricultural waste into an edible, protein-rich food. The NASA-funded project was presented at the Fall Meeting of the American Chemical Society.

The researchers modified a strain of the yeast Saccharomyces cerevisiae to produce the flavouring compound vanillin from ferulic acid, a substance found in plant waste. They also engineered a strain of the yeast Rhodosporidium toruloides to break down ethylene glycol, a component of degraded polyethylene terephthalate, or PET, plastic, and produce beta-carotene, a precursor to vitamin A. PET is a common plastic used in bottles and packaging.

By breaking down a mix of degraded PET plastic and discarded corn stalks into a form the engineered yeasts could digest, the team produced a mash of proteins and fats they say is theoretically edible. Adding starch, fibre and a touch of sweetener, they pressed the mixture into bite-sized snacks they call "µBites," shaped using a 3D printer. Jayakody said the goal was to use microbes to help address rising global food demand, which the team projects will grow 35-56% by 2050, alongside the ongoing problem of plastic waste.

The researchers have not yet received approval to eat the snacks themselves and say more work is needed to find economically viable ways to collect and process plastic waste at scale. Jayakody said the same library of engineered microbes could eventually help NASA address the challenge of feeding astronauts on long space missions or future off-world colonies.