Plastic-eating Enzyme May Solve Waste Problem
An incidental find by a joint UK and US research team could have the potential to revolutionize plastics recycling and possibly ease the increasing burden of waste in the environment.
While tweaking the structure of PETase, a recently discovered enzyme, John McGeehan, a professor at Portsmouth University in England, and Gregg Beckham of the US Department of Energy’s National Renewable Energy Laboratory (NREL), accidentally created a mutant enzyme that they say is better at breaking down the ubiquitous bottle polymer than PETase.
While in its original state the new enzyme needs a few days to start degrading the the researchers believe this can be speeded up and eventually become a viable large-scale process. With about 1 million plastic bottles sold each minute across the globe, and only 14% currently recycled, plastic particles in the ocean are becoming a pressing problem.
McGeehan says the new enzyme indicates a way to recycle clear plastic bottles back into clear plastic bottles, which could slash the need to produce new plastic.
As virgin PET is cheap, he said, “It is so easy for manufacturers to generate more of that stuff, rather than even try to recycle. But I believe there is a public driver here: perception is changing so much that companies are starting to look at how they can properly recycle these.”
In the research published in the journal Proceedings of the National Academy of Sciences, the team used the Diamond Light Source, near Oxford, UK, an intense beam of X-rays that is claimed to be 10 billion times brighter than the sun and can reveal individual atoms.
To the team, the structure of the enzyme looked very similar to one evolved by many bacteria to break down cutin, a natural polymer used as a protective coating by plants. But it was in manipulating the enzyme to explore this connection that they accidentally improved its ability to digest PET, McGeehan said.
“It is a modest improvement – 20% better – but that is not the point,” he said. “It’s incredible because it tells us that the enzyme is not yet optimized. It gives us scope to use all the technology used in other enzyme development for years and years and make a super-fast enzyme.”
