Mutant enzyme that eats plastic bottles could help end global crisis

17 Apr 2018

Plastic waste. Image: Nokuro/Shutterstock

The accidental discovery of the power of a mutant enzyme found in a Japanese dump could revolutionise how we recycle plastic.

The past few months in particular have shone a bright spotlight on the issues of plastic waste, not only in our surroundings, but across the world’s oceans in the form of microplastics.

Furthermore, efforts to recycle the abundance of plastic bottles have been limited by the technology available, which can only reuse the plastic in a small range of products.

From centuries to days

Now, however, The Guardian is reporting that the discovery of an enzyme in a Japanese dump in 2016 has reaped enormous dividends thanks to an accidental breakthrough made by a team of scientists from the University of Portsmouth in the UK.

By revealing the detailed structure of the enzyme, the team believes that it could, for the first time, allow for the full recycling of all plastic bottles, drastically cutting the amount of plastic waste in the world.

The mutant enzyme is on another level when it comes to the speed needed to break down a plastic bottle as tests show it can eliminate one in a matter of days (compared with nature, which would take centuries).

The researchers also believe that, with further tinkering, the enzyme could be improved again to speed up the process, further allowing for its use on an industrial scale.

“What we are hoping to do is use this enzyme to turn this plastic back into its original components, so we can literally recycle it back to plastic,” said Prof John McGeehan.

“It means we won’t need to dig up any more oil and, fundamentally, it should reduce the amount of plastic in the environment.”

Recycled plastic for bottles

Currently, recycled plastic is limited as it is typically just reused for other products such as clothing, but this breakthrough could allow for clear plastic bottles to be broken down and made once again into bottles.

This, by its nature, would drastically reduce the cost of plastic bottle production.

“You are always up against the fact that oil is cheap, so virgin PET is cheap,” said McGeehan.

“It is so easy for manufacturers to generate more of that stuff, rather than even try to recycle. But, I believe there is a public driver here: perception is changing so much that companies are starting to look at how they can properly recycle these.”

The team revealed how the enzyme’s structure was remarkably similar to one used by bacteria to break down cutin, a natural polymer used as a protective coating by plants.

When the team began to alter it, it found an improvement in its ability to eat PET by 20pc.

“It’s great and a real finding,” McGeehan said.

Plastic waste. Image: Nokuro/Shutterstock

Colm Gorey was a senior journalist with Silicon Republic