Fungi found to digest polypropylene to cut plastic waste

SYDNEY, 17 April 2023:

Researchers at the University of Sydney have found two common strains of fungi were able to successfully biodegrade polypropylene in a laboratory experiment.

Typically found in soil and plants, Aspergillus terreus and Engyodontium album were able to break down polypropylene after it had been pre-treated with either UV light or heat – reducing the plastic by 21% over 30 days of incubation, and by 25-27% over 90 days.

The researchers hope their method could one day reduce the vast amount of plastic polluting the environment and lead to a greater understanding of how plastic pollution might biodegrade naturally under certain conditions.

School of Chemical and Biomolecular Engineering PhD student Amira Farzana Samat, the study’s lead author, noted in a statement: “Polypropylene is a common plastic used to make a huge variety of everyday products like food containers, coat hangers and cling film, but it only has a recycling rate of only 1%, meaning it is overrepresented in plastic waste and pollution globally.”

She said polypropylene is so infrequently recycled because of its short life as a packaging material and because it often becomes contaminated by other materials and plastics, necessitating new recycling methods that have minimal environmental impact.

“Plastic pollution is by far one of the biggest waste issues of our time. The vast majority of it isn’t adequately recycled, which means it often ends up in our oceans, rivers and in landfill.

“It’s been estimated that 109 million tonnes of plastic pollution have accumulated in the world’s rivers and 30 million tonnes now sit in the world’s oceans – with sources estimating this will soon surpass the total mass of fish.”

Professor Dee Carter, an expert in mycology – the study of fungi – in the School of Life and Environmental Sciences and co-author of the study, said: “Fungi are incredibly versatile and are known to be able to break down pretty much all substrates. This superpower is due to their production of powerful enzymes, which are excreted and used to break down substrates into simpler molecules that the fungal cells can then absorb.

“Often, these fungi have evolved to break down woody materials, but this ability can be repurposed to attack other substrates – this is why we find fungi growing on all sorts of man-made materials like carpets, painted furniture, grout around tiles, shower curtains, upholstery and even car headlights.

“Recent studies suggest some fungi may even degrade some of the ‘forever chemicals’ like PFAS, but the process is slow and not yet well understood. There is also evidence that the amount of plastic accumulated in the ocean is less than what might be expected based on production and disposal levels, and there is speculation that some of this ‘missing’ plastic may have been degraded by marine fungi.”