Bacterial sex helps take on microplastics pollution

PET (polyethylene terephthalate) takes hundreds of years to degrade in the environment, breaking down over time into microplastic pieces less than 5mm long. Prolific across the food chain, the chemicals in these plastics are associated with insulin resistance, cancer and decreased reproductive health.

The Waterloo team added DNA to several species of bacteria found in wastewater. They used a natural process referred to as ‘bacterial sex’, where bacteria share genetic material with each other when multiplying. This enables the introduction of a new trait - FAST-PETase - into the target bacteria, giving them the ability to break down microplastics. The work is described in Microbial Technology.

“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 at Waterloo’s Department of Chemical Engineering.

“Microplastics in water also enhance the spread of antibiotic resistance, so this breakthrough could also address that concern.”

Testing found that the programmed bacteria could degrade about 40 per cent of a 0.25mm thick commercial PET film within four days at 50°C. According to Dr Brian Ingalls, a Professor in the Department of Applied Mathematics at Waterloo, the next phase of the research will model how the bacteria will perform under different circumstances.  

““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 Ingalls.

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

While the researchers will start with wastewater facilities, they also hope to address 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 student at 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 neutralise bacteria in wastewater, which would kill any engineered bacteria prior to discharging water back into the environment.”