Engineered ‘Super Enzyme’ Breaks Down Plastic

The new enzyme could allow for infinite recycling of common PET plastic used in water bottles and clothing

A pile of empty plastic, unlabeled water bottles
Plastics can take hundreds of years to naturally degrade in the environment, something this new combination of enzymes can accomplish in a matter of days. Photo by Fachrul Reza/NurPhoto via Getty Images

Just ten percent of plastic waste in the United States gets recycled. One of the reasons for that dismal figure is that it’s actually not that easy to recycle plastic and turn it back into a useful product. Now, researchers have combined a pair of enzymes engineered to break down plastic faster than ever before, reports Damian Carrington for the Guardian.

These engineered enzymes, described in a paper published this week in the journal the Proceedings of the National Academy of Sciences, were derived from plastic-eating bacteria first discovered by Japanese scientists in 2016. The bacteria’s feat of reducing stubborn plastics to their constituent parts was impressive, but it was just too slow. Since its discovery, researchers have been working to improve the efficiency of its enzymes.

The new souped-up versions of the enzymes produced by the bacteria, called PETase and MHETase, can break down the nearly ubiquitous PET plastic (polyethylene terephthalate), which is found in everything from water bottles to carpets, into molecules that other bacteria are capable of dealing with, reports Dharna Noor for Gizmodo. In 2018, many of the same researchers authored a study on using PETase alone to break down plastics, but by adding MHETase the team was able to make the process six times faster, according to a statement.

Super enzyme breaks down plastic
This new "super enzyme" can break down the PET plastic commonly found in water bottles and clothing. This illustration shows how researchers were able to stitch the two enzymes (MHETase and PETase) together to create a new super enzyme that more efficiently breaks down plastic than either enzyme alone. Rosie Graham / University of Portsmouth

Plastics can take hundreds of years to naturally degrade in the environment, something this new combination of enzymes can accomplish in a matter of days. Making new plastic relies on fossil fuels, which are a limited resource that pollutes the environment and drives climate change, John McGeehan, a biochemist at Portsmouth University and senior author of the study, tells Sara Rigby of PA News. Using these newly unveiled enzymes could allow plastics to be “made and reused endlessly, reducing our reliance on fossil resources,” he adds.

According to the Guardian, the researchers say their “super enzyme” could be used to recycle plastic “within a year or two.” At the moment, McGeehan tells CNN’s Jack Guy that their newly developed process is “still way too slow” to be commercially viable.

The super-enzyme can also deal with polyethylene furanoate (PEF), a bioplastic used in some beer bottles, but cannot break down other types of plastic such as polyvinyl chloride (PVC).

McGeehan and his team are now hoping to speed the process up even further to make it more useful for commercial recycling, per PA News.

“The faster we can make the enzymes, the quicker we can break down the plastic, and the more commercially viable it will be,” McGeehan tells PA News. “Oil is very cheap so we need to compete with that by having a very cheap recycling process.”

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