Researchers have engineered bacteria that is commonly found in the treatment plants to break down microplastic pollution before it has a chance to persist in the environment.

“Wastewater treatment plants are one of the major pathways for microplastics to enter the environment. In general, microplastics are contaminants of global concern that pose risks to ecosystems and human health,” the authors wrote in the study. “With a focus on wastewater, a major pathway for microplastics to enter the environment, this study demonstrates a proof of concept for engineering environmental microbiomes to rapidly degrade PET plastics.”

University of Waterloo researchers added DNA to several bacteria species found in wastewater. They then allowed them to biodegrade a common plastic — polyethylene terephthalate (PET) — found in clothing, carpet and food and beverage containers, a press release from the University of Waterloo said.

Conjugation of pFAST-PETase-cis into wastewater bacteria. Microbial Biotechnology (2024). DOI: 10.1111/1751-7915.70015

It takes hundreds of years for PET plastics to degrade in the natural environment. They break down over time into microplastics — plastic pieces less than five millimeters in length — which then enter the food chain. Chemicals in these plastics can lead to decreased reproductive health, insulin resistance and cancer, among other adverse health impacts.

“Think of these bacteria that already exist in water systems to clean up microplastics as biorobots that can be programmed to get the job done,” said Dr. Marc Aucoin, a chemical engineering professor at the University of Waterloo, in the press release. “Microplastics in water also enhance the spread of antibiotic resistance, so this breakthrough could also address that concern.”

The research team used “bacterial sex,” a natural process where genetic material is shared between bacteria when they multiply. This enables a new trait to be introduced into the target bacteria, making them able to break down microplastics.

“As next steps, we will use modelling to understand how well the bacteria transfer the new genetic information under different environmental conditions and thus how effectively they can break down the plastics,” said Dr. Brian Ingalls, a professor of applied mathematics at the University of Waterloo, in the press release.

“The long-term vision is to break down microplastics in wastewater treatment plants at scale.”

The team also hopes to discover ways to clean up plastic waste accumulating in the world’s oceans.

“We will assess the risks of using engineered, plastic-eating bacteria in the natural environment,” said Aaron Yip, Ph.D. candidate in the University of Waterloo’s Department of Chemical Engineering, in the press release. “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.”

The study, “Degradation of polyethylene terephthalate (PET) plastics by wastewater bacteria engineered via conjugation,” was published in the journal Microbial Biotechnology.