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Spotted: Some plastics are more difficult to recycle than others. One of these is polypropylene, a commonly used plastic that accounts for a significant portion the world’s plastic waste but has a recycling rate that is close to zero. Now, researchers at the University of Sydney have developed a way to break down polypropylene relatively quickly using fungi.

The team found that pre-treating the plastic with either UV light or heat allowed two types of fungi commonly found in soil and plants – Aspergillus terreus and Engyodontium album – to reduce the plastic by 21 per cent over 30 days, and by 25-27 per cent over 90 days. In the study, polypropylene in different forms was first treated with either ultraviolet light, heat, and Fenton’s reagent (an acidic solution of hydrogen peroxide and ferrous iron).

The fungi were added as single cultures to the treated polypropylene. Confirmation of the breakdown of the plastic was confirmed visually, using microscopy. The researchers hypothesise that, although the fungi have evolved to break down woody materials, the powerful enzymes they produce are able to break down a large variety of substances – including the polypropylene.

Professor Dee Carter, co-author of the study, explained: “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.”

The ubiquity of plastic and difficulties faced in its recycling have prompted innovators to search for sustainable ways to recycle the material or replace its use in various products. Springwise has spotted a compostable clay cup to replace single-use plastic cups and food packaging that can be peeled like an orange and eaten, composted, or dissolved in water.

Written By: Lisa Magloff