Microplastic Degradation by Engineered Bacteria

Microplastic pollution is a growing environmental issue, as even modern wastewater treatment plants cannot completely remove it. Researchers at the University of Waterloo have developed a solution: they genetically modified natural bacteria from wastewater facilities to break down microplastics.

Scientists introduced DNA sequences into several bacterial species found in wastewater plants, equipping them with the ability to degrade polyethylene terephthalate (PET) – a plastic widely used in textiles, packaging, and containers.

PET is known for its durability and takes centuries to degrade. During this process, it fragments into microplastic particles that enter the environment. "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," explains Dr. Marc Aucoin, Professor of Chemical Engineering.

The genetic modification occurs via a natural mechanism known as bacterial conjugation, where bacteria exchange genetic material, allowing the transfer of new traits such as plastic degradation.

A laboratory study demonstrated this technique using two bacterial strains labeled with red and green fluorescence. The exchange of genetic material enabled the green strain to fluoresce yellow. Researchers applied this same method to introduce plastic-degrading capabilities into wastewater bacteria.

"As next steps, we will use modeling 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." says Dr. Brian Ingalls from the Department of Applied Mathematics. The long-term goal is to integrate this technology into existing wastewater treatment plants to tackle microplastics at the source.

Researchers are also exploring potential applications in marine environments.

Key Benefits of This Approach:

• Targets microplastic pollution at its source
• Utilizes naturally occurring bacteria
• Reduces the environmental persistence of PET plastics
• Minimizes the spread of antibiotic resistance linked to microplastics

"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," explains Aaron Yip, a PhD candidate in Chemical Engineering. This ensures that genetically modified organisms do not unintentionally spread into the environment.

The study, "Degradation of polyethylene terephthalate (PET) plastics by wastewater bacteria engineered via conjugation," appears in Microbial Biotechnology.