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."

Right now, microplastic degradation in wastewater treatment plants is a safer application to target- Aaron Yip, University of Waterloo PhD candidate

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.

What are microplastics?

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."

Still 'more work to be done'

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

"There's more work to be done to make this a lot more effective, but eventually the breakdown product will be essentially just like a sugar for the organism to eat," he said.

While the researchers will start with wastewater facilities, they also hope to find ways to clean up the plastic waste accumulating in oceans.

"We will assess the risks of using engineered, plastic-eating bacteria in the natural environment" said Aaron Yip, a PhD candidate in the University of Waterloo's department of chemical engineering. 

"Right now, microplastic degradation in wastewater treatment plants is a safer application to target. Many of these facilities are already designed to neutralize bacteria in wastewater, which would kill any engineered bacteria prior to discharging water back into the environment."

'No quick fix' for microplastics

Karen Wirsig, the plastics program manager for Environmental Defence, an advocacy organization, said it's too early to be overly excited about the research.

"My first reaction is it's a bit of a pipe dream... Scientific research is so important, but when we pretend that breakthroughs in a lab are going to solve a plastic pollution crisis at the scale that we know it to be at, it's wishful thinking," she told CBC News.

"There's probably all kinds of interesting things that the scientists can discover about how microbes can dissolve or eliminate microplastics from certain environments, [but], I'll be definitely watching this."

Wirsig said the news from the researchers is "interesting," in terms of a treatment method for wastewater and sewage, which she said is full of microplastics.

"Overall, the concern is when we see solutions or things like this that might be presented as solutions, it's really too late once microplastics are in the environment," Wirsig said.

"It's really a shame, and to try to treat them or manage them in the environment is never going to be easy and there is going to be no quick fix for that."

Wirsig said the priority needs to be on how to reduce the amount of plastic being made, adding the issue of microplastics is a major environmental and health concern. 

"Scientists and medical professionals are finding microplastics wherever they look for them — in the highest mountain peaks and the deepest ocean trenches, in Arctic ice, in all parts of the body."

Wirsig said the biggest threat posed by microplastics to the environment is likely to small organisms that mistake microplastics for food.

"These microplastics can build up in our food webs because as smaller organisms get eaten by larger organisms, we're basically concentrating these pollutants further and further into our food webs," Wirsig said.

"That's one of the ways they're likely getting into the human body — through the things we're eating, because they're also in the soil, they've been found in plants and vegetables that people eat, in fruits. 

"But one of the bigger concerns is fish, and so people who rely on fish in their diet are rightfully concerned about the amount of microplastics that are in these species."