Pollution breakthrough as new enzyme helps ‘eat’ plastic used in drinks bottles

·Contributor
·2 min read
Spilled garbage on the beach of the big city. Empty used dirty plastic bottles. Empty used dirty plastic bottles. Dirty sea sandy shore of the Black Sea. Environmental pollution. Ecological problem
Could the new enzyme help in the battle against plastic pollution? (Getty)

A new breakthrough could offer hope in the battle against plastic pollution - an enzyme which ‘eats’ plastic and could help to break down single-use drinks bottles.

More than 400 million tons of plastic waste are produced each year, the overwhelming majority of which ends up in landfills, the University of Portsmouth researchers say.

Scientists hope that ‘plastic-eating’ enzymes can help tackle the challenge of plastic pollution and develop biological systems that can convert waste plastic into valuable products.

The new enzyme helps break down terephthalate (TPA), one of the chemical building blocks of polyethylene terephthalate (PET) plastic, which is used to make single-use drinks bottles, clothing and carpets.

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Professor McGeehan, Director of the University's Centre for Enzyme Innovation, said: "The last few years have seen incredible advances in the engineering of enzymes to break down PET plastic into its building blocks.

“This work goes a stage further and looks at the first enzyme in a cascade that can deconstruct those building blocks into simpler molecules. These can then be utilised by bacteria to generate sustainable chemicals and materials, essential making valuable products out of plastic waste.

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Professor McGeehan said, "Using powerful X-ray at the Diamond Light Source, we were able to generate a detailed 3D structure of the TPADO enzyme, revealing how it performs this crucial reaction. This provides researchers with a blueprint for engineering faster and more efficient versions of this complex enzyme."

The research is published in The Proceedings of the National Academy of Sciences (PNAS), and builds on research from 2018 which engineered a natural enzyme that could break down PET plastic.

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The enzymes (PETase and MHETase) break the PET polymer into the chemical building blocks ethylene glycol (EG) and TPA.

This new research describes the next steps, specifically for managing TPA.

Professor Jen DuBois, Montana State University, said: "While ethylene glycol is a chemical with many uses - it's part of the antifreeze you put into your car, for example - TPA does not have many uses outside of PET, nor is it something that most bacteria can even digest.

“However, the Portsmouth team revealed that an enzyme from PET-consuming bacteria recognises TPA like a hand in a glove. Our group at MSU then demonstrated that this enzyme, called TPADO, breaks down TPA and pretty much only TPA, with amazing efficiency."

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