South coast university accidentally develops plastic-eating enzyme

Posted April 17, 2018

The discovery by researchers in the United Kingdom and USA could result in a recycling solution for millions of tonnes of plastic bottles and food containers made of polyethylene terephthalate, known as PET.

One man's trash is this enzyme's lunch.

Scientists investigating a naturally occuring bacterium have accidentally created a new enzyme that can digest plastic bottles.

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

The mutant enzyme has the ability to break down polyethylene terephthalate (PET), used in 70% of soft drinks, juice and water bottles.

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An global team of scientists has created a mutant enzyme that breaks down plastic drink bottles, according to the journal Proceedings of the National Academy of Sciences (the link is down at time of writing).

Prof McGeehan, director of the Institute of Biological and Biomedical Sciences in the School of Biological Sciences at Portsmouth, said: "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".

To begin experiments, the research team wanted to find out exactly how effective PETase was at digesting PET. NREL Senior Scientist Bryon Donohoe and postdoctoral researcher Nic Rorrer tested PETase by taking samples of PET from the soda bottles in Beckham's office and ran an experiment with PETase.

"These enzymes are not abundantly present in nature, so you would need to produce the enzyme first, then add it to the PET plastic to degrade it", Wim Soetaert, head of the Industrial Biotechnology Centre at the University of Ghent, pointed out.

So they mutated the PETase active site to make it more like cutinase, and unexpectedly found that this mutant enzyme was even better than the natural PETase at breaking down PET.

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A Japanese waste dump is an unlikely location for what may be a huge breakthrough in the plastics pollution crisis.

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

Independent scientists not directly involved with the research said it was exciting, but they cautioned that the enzyme's development as a potential solution for pollution was still at an early stage. "It is so easy for manufacturers to generate more of that stuff, rather than even try to recycle".

"They protect plant leaves", explained the University of Portsmouth researcher.

But, more significantly, it can also degrade polyethylene furandicarboxylate (PEF) - a bio-based substitute for PET plastics being hailed as a replacement for glass bottles.

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The team is now working to see if it can be improved to work faster and, in the long term, become a tool used to recycle PET plastic on an industrial scale by reducing it back to its building blocks so it can be reused.