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Enzyme which devours our plastic waste created by accident

Researchers have created an enzyme which may help solve our worldwide plastic pollution problem.

Researchers have accidentally engineered an enzyme capable of digesting common plastics.

The enzyme may have been a fluke but could prove to be a solution to our worst pollution problems which are causing extreme damage to our environment, oceans, and wildlife.

Scientists at the University of Portsmouth revealed the chance finding this week.

Together with the US Department of Energy's National Renewable Energy Laboratory (NREL), the team was conducting a study into PETase, a recently-discovered enzyme which digests polyethylene terephthalate (PET), the plastic used to create plastic bottles and which takes hundreds of years to degrade.

An interesting facet of this enzyme, which allows bacteria to consume plastic as a food source, is that it is thought to have evolved naturally in a Japanese recycling center several years ago.

Professor John McGeehan, Director of the Institute of Biological and Biomedical Sciences at the University of Portsmouth and Dr. Gregg Beckham at NREL set to work examining the enzyme in order to map its crystal structure.

The engineers turned to UK-based Diamond Light Source to create a 3D replica of the enzyme using intense X-Ray beams.

After creating the 3D replica, the pair accidentally engineered a new kind of enzyme which is "even better at degrading the plastic than the one that evolved in nature."

Rather than requiring hundreds of years to degrade, the enzyme allows bacteria to consume plastics in a matter of days.

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

This "mutant" was developed after the 3D map revealed the enzyme looked similar to a cutinase enzyme, prompting the engineers to tweak the PETase in an attempt to see whether or not it would demonstrate the same chemical reactions as a cutinase and to try and ascertain how the PETase evolved.

Thus, an accidental success was born. In addition to being more effective at degrading PET than its naturally-occurring cousin, the enzyme is also able to eat polyethylene furandicarboxylate (PEF), which is being considered as a replacement for glass beer bottles.

The enzyme is an exciting prospect. While in no way ready to be let loose to devour our waste, the engineers have already set to work to improve the enzyme further for use industrially to break down plastics.

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"Few could have predicted that since plastics became popular in the 1960s huge plastic waste patches would be found floating in oceans, or washed up on once pristine beaches all over the world," McGeehan says. "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."

The research was funded by the University of Portsmouth, NREL and the Biotechnology and Biological Sciences Research Council (BBSRC).

The findings have been published in the journal Proceedings of the National Academy of Sciences (PNAS) (login required).

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