University of Sydney researchers find solution to stubborn plastic

University of Sydney fungi

Polypropylene, a hard to recycle plastic, has successfully been biodegraded by two strains of fungi in a new experiment led by researchers at the University of Sydney.

Polypropylene is a common plastic used for a variety of products from packaging and toys to furnishing and fashion. It accounts for about 28 per cent of the world’s plastic waste, but only one per cent of it is recycled.

Researchers found two types of fungi in soil and plants, Aspergillus terreus and Engyodontium album, that were able to break down polypropylene after it had been pre-treated with either UV light or heat. Reducing the plastic by 21 per cent over 30 days of incubation, and by 25-27 per cent over 90 days.

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

Amira Farzana Samat, PhD student and the study’s lead author, said plastic pollution is one of the biggest waste issues at present.

“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,” Samat said.

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.

Professor Dee Carter, an expert in mycology (the study of fungi) and co-author of the study, said that fungi are versatile and known to be able to break down many substrates, offering a solution to the plastic problem.

“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,” Carter said.

“Often, these fungi have evolved to break down woody materials, but this ability can be repurposed to attack other substrates.

“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.”

The researchers are now set to explore, and develop a small-scale prototype for commercialisation.

Since completing the study, the team has isolated other microorganisms from the marine environment and used a similar process to degrade marine plastic waste, with results showing even higher degradation.

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