University of Waterloo researchers engineer bacteria to eat microplastics. But is it a pipe dream?

Researchers at the University of Waterloo say they've made a breakthrough in introducing a new trait into bacteria found in wastewater, giving them the ability to break down microplastics.

Project lead researcher Marc Aucoin, a professor in the Ontario school's department of chemical engineering, said bacteria already exist in water systems to clean up microplastics, adding they are "biorobots that can be programmed to get the job done." 

"What we want to do is use a natural tool, [proteins], to be able to degrade the plastics," Aucoin said on CBC K-W's The Morning Edition.

The study, "Degradation of polyethylene terephthalate (PET) plastics by wastewater bacteria engineered via conjugation," was published in the U.S.-based journal Microbial Biotechnology.

The researchers use a natural process referred to as "bacterial sex," whereby bacteria share genetic material with each other when multiplying.

"[We're] engineering an organism to carry a transferable piece of DNA so that [the bacteria in wastewater] can all produce that tool to degrade the plastic."

The engineered bacteria are able to biodegrade polyethylene terephthalate (PET), a common plastic found in carpet, clothing and containers for food and beverages, the researchers say.

"In our lab, we've shown that that protein itself can help degrade a sample of plastic by 50 per cent in about four days," Aucoin said.

Most plastics aren't recycled and last for decades. When something made of plastic does break down, it fragments into small bits known as microplastics that can pollute and build up in the environment and leach chemicals. Scientists categorize degraded plastic waste products by size. Microplastics are tiny particles less than than five millimetres in diameter, or about the size of a sesame seed.

Sources of microplastics range from the microbeads used in cosmetic and personal care products to lentil-sized plastic pellets also known as nurdles.

In a study published in the March 2024 New England Journal of Medicine, researchers using special microscopy techniques found microplastic and nanoplastic chemicals in the plaque lining human arteries.

In the observational study of more than 250 patients who were having tests for carotid artery disease, finding polyethylene in their plaque was associated with heart problems compared to those without having any plastics detected. This type of study can't show whether the tiny plastics caused the heart problems, but indicated associations.

According to Aucoin, microplastics in water also enhance the spread of antibiotic resistance, "so this breakthrough could also address that concern."

The researchers are not yet at the stage to release the engineered bacteria into the wider environment, Aucoin said.