Scientists accidentally created an enzyme that ‘eats’ PET plastic bottles

Another potential weapon in the fight against plastic pollution

Another potential weapon in the fight against plastic pollution

The bacterium Ideonella sakaiensis 201-F6 was discovered in 2016 in a waste recycling center in Japan. It uses PETase, an enzyme that works with water, to degrade polyethylene terephthalate (PET) as a food source. While examining PETase’s 3D atomic structure and understanding how it works, British and US researchers ended up accidentally engineering a faster and more efficient enzyme and they are now working on further improving it in order for it to be used industrially to break down plastics in a fraction of the time. It is important to note that the enzyme can also degrade polyethylene furandicarboxylate, or PEF, a bio-based substitute for PET plastics that is being hailed as a replacement for glass beer bottles. The research, led by teams at the University of Portsmouth and the US Department of Energy’s National Renewable Energy Laboratory (NREL), is published in Proceedings of the National Academy of Sciences (PNAS).

"We hoped to determine its structure to aid in protein engineering, but we ended up going a step further and accidentally engineered an enzyme with improved performance at breaking down these plastics," said NREL's lead researcher Gregg Beckham. Professor McGeehan, Director of the Institute of Biological and Biomedical Sciences in the School of Biological Sciences at Portsmouth, claimed that: “Serendipity often plays a significant role in fundamental scientific research and our discovery here is no exception. 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 University of Portsmouth and NREL collaborated with scientists from the UK’s Diamond Light Source, a synchrotron that uses intense beams of X-rays 10 billion times brighter than the sun to act as a microscope powerful enough to see individual atoms. “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”, said Professor McGeehan. “Being able to see the inner workings of this biological catalyst provided us with the blueprints to engineer a faster and more efficient enzyme.” Chief Executive of the Diamond Light Source, Professor Andrew Harrison, said: “The impact of such an innovative solution to plastic waste would be global. It is fantastic that UK scientists and facilities are helping to lead the way.”

The research was funded by the University of Portsmouth, NREL and the Biotechnology and Biological Sciences Research Council (BBSRC) Dr Colin Miles, Head of Strategy for Industrial Biotechnology at BBSRC, said: “This is a highly novel piece of science based on a detailed molecular-level understanding of an enzyme able to depolymerise a common type of plastic, whose persistence in the environment has become a global issue. It will be interesting to see whether, based on this study, the performance of the enzyme can be improved and made suitable for industrial-scale application in the recycling and the future circular economy of plastic.”

Scientists Bryon Donohoe and Nic Rorrer taking samples from a PET bottle as part of their investigation into plastic-eating enzymes Dennis Schroeder/NREL

Close-up: Electron microscope image of enzyme degrading PET plastic CREDIT: Dennis Schroeder / NREL

Source: University of Portsmouth News