Scientists engineer a plastic-eating enzyme

By accident, Scientists have created a mutant enzyme that breaks down plastic drinks bottles. The breakthrough could solve the global plastic pollution crisis by enabling for the first time the full recycling of bottles.

Professor John McGeehan from the University of Portsmouth said: “There’s a big misconception that plastics bottles get turned into other plastic bottle.”

The enzyme has been created following a ‘find’ in 2016 in Japan. A Japanese group found a bacteria in a recycling dump that was essentially living off the plastic. The University of Portsmouth believed that the bacteria had swapped eating natural polyesters for human-made ones, just by mutating one of the enzymes it was making.

The gene used for the enzyme was taken to the Diamond Light Source, a massive x-ray microscope, where they were able to create a 3D structure and see the original building blocks of the enzyme. Armed with this knowledge the team the university scientists were spurred on to recreate this enzyme. However, they actually created a better enzyme.

A better enzyme?

The international team tweaked the enzyme to see how it had evolved. Resulting tests showed they had inadvertently made the molecule even better at breaking down the PET (polyethylene terephthalate) plastic used for soft drink bottles.

The new mutant enzyme has a downside at present. It takes a few days to start breaking down the plastic. However, on a positive note, this is far faster than the centuries it takes in the oceans. The researchers are optimistic this process can be sped up even further.

How will it be used for recycling?

“Plastic bottles are rarely turned intoother plastic bottle. When plastic pellets are made during the recycling process, it loses some of its properties. This means it’s only suitable for lower-value use, such as material fibres for clothing or carpets. Eventually, it’s effectively worthless and ends up in landfill or being incinerated”

Professor McGeehan goes on to explain “Our idea would be that you have a large vat of plastic bottles, pour the enzyme solution in and digest the plastic to its original building blocks. That would allow us to remake the plastic from scratch. This would close the loop on the process and make it 100% recyclable.”