PLASTIC-EATING ENZYME MAY SAVE PLANET
Researchers’ accidental creation could be answer to plastic pollution
RESEARCHERS in the United States and Britain have accidentally engineered an enzyme that eats plastic and may help solve the growing problem of plastic pollution, a study said on Monday.
More than eight million tonnes of plastic are dumped into oceans every year, and concern is mounting over this petroleum-derived product’s toxic legacy on human health and the environment.
Despite recycling efforts, most plastic can persist for hundreds of years in the environment, so researchers are searching for better ways to eliminate it.
Scientists at the University of Portsmouth and the US Energy Department’s National Renewable Energy Laboratory decided to focus on a naturally-occurring bacterium found in Japan a few years ago.
Japanese researchers believe the bacterium evolved fairly recently in a waste recycling centre, since plastics were not invented until the 1940s.
Known as Ideonella sakaiensis, it appears to feed exclusively on a type of plastic known as polyethylene terephthalate (PET), used widely in plastic bottles.
The researchers’ goal is to understand how one of its enzymes — called petase — worked, by figuring out its structure.
“But they ended up going a step further and accidentally engineered an enzyme that was even better at breaking down PET Proceedings of the National Academy of Sciences, US journal.
Using a powerful X-ray 10 billion times brighter than the sun, they were able to make an ultrahigh-resolution 3D model of the enzyme.
Scientists from the University of South Florida and the University of Campinas, Brazil, did computer modelling that showed petase looked similar to another enzyme, cutinase, found in fungus and bacteria.
One area was a bit different, though, and researchers hypothesised that this was the part that allowed it to degrade man-made plastic.
So, they mutated the petase active site to mak e it more like cutinase, and unexpectedly found that this mutant enzyme was even better than the natural PETase at breaking down PET.