Scientists have discovered an enzyme that can "digest" plastic and revolutionalise recycling, but environmentalists warn the "miracle" breakthrough should not make designers complacent about the need to reduce use of the material.

Scientists at the University of Portsmouth and from the US Department of Energy "inadvertently engineered" the enzyme that rapidly breaks down polyethylene terephthalate (PET) – the rigid plastic commonly used to make drinks bottles.

The teams were investigating the structure of a naturally occurring bacteria that breaks down PET, when they accidentally engineered the new more efficient enzyme.

The enzyme could provide a "recycling solution for the ever-growing mountain of discarded plastics", according to John McGeehan, director of the Institute of Biological and Biomedical Sciences at Portsmouth.

The enzyme could offer solution for waste plastic

As the environmental impact of virgin plastics becomes increasingly clear recycled plastics are increasingly being experimented with and used in design.

While the breakthrough could allow plastics to be recycled more efficiently in the future, Cyrill Gutsch founder of plastic alternative campaigning organisation Parley for the Oceans, warned that designers should continue to work to reduce their use of plastic.

"We can not put our hopes on a miracle and we can not expect solutions for harmful substances to be without side affects. Who knows if these enzymes will start eating our brains, and who knows if there is a way to scale the affect up to a level where they can be really impactful," Gutsch told Dezeen.

Designers urged to continue reducing plastic use

Gutsch, who describes plastic as a design failure, urged designers and manufactures to continue working to reduce their use of the material.

"At this point in time what we really can count on is if we stop making plastic, if we start taking plastic back from nature, and if we are developing new materials that can replace plastic in the long run, that we can bet on this strategy," he continued.

Called PETase, the naturally occurring bacteria that degrades PET was discovered in a Japanese recycling centre in 2016.

The scientists mapped the bacteria and created an "ultra-high-resolution 3D model" using a microscope at the Diamond Light Source facility in Oxfordshire, England, which is powerful enough to see individual atoms.

PETase enzyme is a mutation of naturally existing bacteria

The scientists noted the bacteria had some unusual features and during testing they accidentally created a PETase mutant that they found could break down PTE much more efficiently than the natural bacteria.

"Serendipity often plays a significant role in fundamental scientific research and our discovery here is no exception," said McGeehan.

"Although the improvement is modest, this unanticipated discovery suggests that there is room to further improve these enzymes, moving us closer to a recycling solution for the ever-growing mountain of discarded plastics."

The accidental breakthrough could lead to PET and other plastic substitutes such as PEF, which is touted as a replacement for glass beer bottles, becoming easily recyclable.

"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," said McGeehan.

"We can all play a significant part in dealing with the plastic problem, but the scientific community who ultimately created these 'wonder-materials', must now use all the technology at their disposal to develop real solutions."

Earlier this year Ecobirdy created a range of colourful furniture from the recycled material, while last year Adidas collaborated with Parley for the Oceans to recreate a classic shoe from waste plastic.

Image is by David Jones, courtesy of University of Portsmouth.