Fortuitously Produced Enzyme Eats Plastic Helping Combat Plastic Pollution

Andrew Cummings
April 17, 2018

The mutated version digests some of the most commonly polluting plastics, including those made of polyethylene terephthalate, or PET, faster than the original enzyme.

Scientists have created a mutant enzyme that breaks down plastic drinks bottles - by accident.

PET, patented as a plastic in the 1940s, has not existed in nature for very long, so the team set out to determine how the enzyme evolved and if it might be possible to improve it.

The new research sprang from the discovery of bacteria in a Japanese waste recycling centre that had evolved the ability to feed on plastic.

The global team, led by Professor John McGeehan of the University of Portsmouth, UK, tested the evolutionary process of the enzyme, inadvertently discovering that they had improved the capabilities of the enzyme in breaking down PET bottles. Researchers from the National Renewable Energy Laboratory of US Energy Department and the University of Portsmouth have shown a concern to explore the naturally producing bacterium that first discovered a few years back in Japan.

"The engineering process is much the same as for enzymes now being used in bio-washing detergents and in the manufacture of biofuels", said McGeehan.

Using a super-powerful X-ray, 10 billion times brighter than the Sun, they were able to make an ultra-high-resolution three-dimensional model of the enzyme.

Researchers say they are now working on further improvements to the enzyme, with the hope of eventually scaling it up for industrial use in breaking down plastics.

The Ministry of Environment, Forest and Climate Change has recently notified the amendments in Plastic Waste Management Rules 2018. Although it is said to be recyclable, discarded PET can last for centuries before it degrades.

Professor McGeehan said: "The engineering process is much the same as for enzymes now being used in bio-washing detergents and in the manufacture of biofuels - the technology exists and it's well within the possibility that in the coming years we will see an industrially viable process to turn PET and potentially other substrates like PEF, PLA, and PBS, back into their original building blocks so that they can be sustainably recycled".

"I think [the new research] is very exciting work, showing there is strong potential to use enzyme technology to help with society's growing waste problem", said Oliver Jones, a chemist at RMIT University in Melbourne, Australia, and not part of the research team.

The alliance will work with NGOs and business to share expertise, including the World Economic Forum, Fauna and Flora International, Coca-Cola and Sky, which has been campaigning around the plastics issue through its Sky Ocean Rescue project.

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