New chemical gives hope in battle against plastic pollution

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Two scientists have accidentally stumbled upon an organic enzyme that can eat some of our worst polluting plastics, providing a possible solution to what is arguably one of the world's biggest environmental problems.

The discovery came as a team of scientists from the University of Portsmouth in the United Kingdom and the National Renewable Energy Laboratory in the US examined an enzyme produced by the Japanese bacteria to find out more about its structure.

PET persists for hundreds of years in the environment before it degrades and the discovery may mean that significantly more plastic waste could be recycled.

"The Diamond Light Source recently created one of the most advanced X-ray beamlines in the world and having access to this facility allowed us to see the 3D atomic structure of PETase in incredible detail", says Professor John McGeehan from the University of Portsmouth.

PET is relatively easy to recycle, but over half of global PET waste is not collected for recycling, according to research from the Ellen MacArthur Foundation, and only 7 percent of bottles are recycled into new bottles (most go into lower-value products).

However, researchers from Britain's University of Portsmouth and the U.S. Department of Energy's National Renewable Energy Laboratory say they may have serendipitously discovered an enzyme that can eat PET plastic. "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".

For instance, the tweaked PETase is also able to break down a PET substitute called PEF (polyethylene furandicarboxylate), which the natural PETase can't process.

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Finding that this enzyme was helping a bacteria to break down, or digest, PET plastic, the researchers chose to "tweak" its structure by adding some amino acids, said John McGeehan, a professor at Portsmouth who co-led the work.

Once they understood its structure, the team noted that they could improve the performance of PETase by adjusting a few residues on its surface.

Some companies that rely on PET have committed to do more. And the problem with the recycled plastic is that it can only be turned into fiber that is used in other applications; think carpeting, fleece and tote bags.

"What actually happened was that we improved the enzyme, which was a bit of a shock", said John McGeehan.

Originally discovered in Japan, the enzyme is produced by a bacterium which "eats" PET. "But the scientific community who ultimately created these 'wonder-materials, ' must now use all the technology at their disposal to develop real solutions".

The team behind the research at Portsmouth University includes PhD students and even undergraduates, and when I visited their lab their excitement was infectious.

The researchers found that the PETase mutant was better than the natural PETase in degrading PET.