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Emerging research continues to illuminate potential health implications of microplastic exposure. A March 2024 study published in the New England Journal of Medicine found that patients with polyethylene fragments detected in carotid artery plaque had a significantly higher risk of adverse cardiovascular events (hazard ratio, 4.53; 95% CI, 2.00 to 10.27; P<0.001), though further research is needed to establish causality.
Even as flawed factoids swirl about how much plastic we’re actually consuming—researchers worldwide are looking for ways to curb plastic pollution at the source. One such approach aims to harness nature’s own ingenuity to break down plastics more effectively, offering a potential line of defense before microplastics even reach our plates or drinking water.
University of Waterloo’s ‘plastic-eating bacteria’
Research Context
A team at the University of Waterloo has engineered a potential breakthrough against microplastic pollution, focusing on polyethylene terephthalate (PET)—a plastic found in clothing, carpets, and various food/beverage containers. By introducing new DNA into commonly found wastewater bacteria, they’ve enabled these microbes to produce an enzyme capable of degrading PET.
The 2022 video below, titled “Live-cell imaging of horizontal gene transfer between E. coli in a microfluidic device,” demonstrates the conjugation mechanism (“bacterial sex”) that forms the methodological foundation of the Waterloo researchers’ recent work on plastic degradation.
How it works
In their paper, Degradation of polyethylene terephthalate (PET) plastics by wastewater bacteria engineered via conjugation published in Microbial Biotechnology, researchers at the University of Waterloo showed that several native wastewater bacteria could be genetically modified to produce enzymes capable of breaking down PET plastics. The team successfully transferred PETase genes to multiple bacterial strains commonly found in wastewater treatment plants, demonstrating up to 30% degradation of PET microplastics under laboratory conditions.
The authors note that while this proof-of-concept offers a promising approach to tackle microplastic pollution, historical evidence suggests careful consideration is needed. They cite a field study in Estonia where engineered Pseudomonas putida was released to treat phenol contamination from an oil shale mine fire. The introduced genes were still detectable in native microbes six years after deployment. Given this pecedent, the authors emphasize that biocontainment strategies and genetic stability assurance are prerequisites for any large-scale deployment of engineered plastic-degrading bacteria.
The researchers used bacterial conjugation—sometimes dubbed “bacterial sex”—to transfer engineered plasmids from one microbe to another. Once the plasmid is transferred, the recipient bacteria express PETase, a specialized enzyme that acts like molecular scissors. “What we want to do is use a natural tool, [proteins], to be able to degrade the plastics,” explains lead researcher Ph.D. Marc Aucoin. The PETase enzyme chemically snips apart PET’s long polymer chains, effectively breaking them down into smaller molecules.
Progress so far
While the work remains a proof-of-concept, the results are noteworthy: Under lab conditions, the enzyme degraded about 40% of a 0.25 mm–thick commercial PET film in four days at 50°C. Scaling up this approach, however, poses significant challenges—especially regarding cost, efficiency, and biocontainment to ensure no genetically modified organisms escape into natural ecosystems.
Expert reactions
Reactions to the project have been mixed:
- Optimistic Perspective: Lead research and coauthor Aucoin highlights wastewater treatment plants as a logical starting point: “Right now, microplastic degradation in wastewater treatment plants is a safer application to target,” he said in a press release. In such a controlled setting, potential GMO risks might be better managed.
- Skeptical Perspective: Environmental advocates like Karen Wirsig (Environmental Defence) called the idea in a CBC article a “pipe dream,” warning against viewing any single lab breakthrough as a one-size-fits-all fix: “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.
One of the largest dietary sources of microplastics is bottled water. Here, lowest and highest number plastic particles found per liter bottled water location and brand” by PLASTIC ATLAS | Appenzeller/Hecher/Sack is licensed under CC BY 4.0. | Heinrich Böll Stiftung
