Researchers from the University of Waterloo (UWaterloo) added DNA to several species of bacteria found in wastewater, allowing them to biodegrade polyethylene terephthalate (PET), a persistent microplastic found in carpet, clothing and food containers that has been linked to health problems.
The researchers use a natural process they refer to as “bacterial sex”, where bacteria share genetic material with each other when multiplying. It enables the introduction of a new trait into the target bacteria, giving them the ability to break down microplastics.
“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 professor in UWaterloo’s Department of Chemical Engineering. “Microplastics in water also enhance the spread of antibiotic resistance, so this breakthrough could also address that concern.”
PET plastics take hundreds of years to degrade in the environment. Over time, they break down into microplastics, pieces of plastic less than 5 mm long, which enter the food chain. Chemicals in these plastics are associated with insulin resistance, cancer and decreased reproductive health, according to the researchers.
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Dr. Brian Ingalls, a professor in UWaterloo’s Department of Applied Mathematics, said that the team intends to use modelling to understand how well the bacteria transfer the new genetic information under different environmental conditions.
“The long-term vision is to break down microplastics in wastewater treatment plants at scale,” he said, noting that plants are a major pathway for microplastics to enter the environment.
Aaron Yip, a PhD candidate in UWaterloo’s Department of Chemical Engineering, said that microplastic degradation in wastewater treatment plants is a safer application to target, but the researchers also hope to find ways to clean up plastic waste accumulating in bodies of water.
“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,” noted Yip.
Yip added that the team will later assess the risks of using engineered, plastic-eating bacteria in the natural environment.
The study, Degradation of polyethylene terephthalate (PET) plastics by wastewater bacteria engineered via conjugation, appears in the journal Microbial Biotechnology.
