Worldwide team engineers plastic digesting enzyme

PET now lasts for hundreds of years in the environment and this accidental discovery could provide a viable recycling solution for millions of tonnes of bottles and packaging. During this study, they inadvertently engineered an enzyme that is better still at degrading the plastic than the one that evolved in nature.

Researchers in the United States and Britain have accidentally engineered an enzyme which eats plastic and may eventually help solve the growing problem of plastic pollution, a study said on Monday (Tuesday in Manila).

Another is the recently discovered enzyme that consumes PET plastics called PETase, which scientists at the University of Portsmouth and the US Department of Energy's National Renewable Energy Laboratory (NREL) used as a starting point for their groundbreaking research. This is the first time an organism has been able to break down plastic, which it does using two specialised enzymes. The Guardian reported an worldwide team of researchers, building on that finding, began studying the bacterium to understand how it functioned - and then accidentally engineered it to be even better.

The paper, "Characterization and engineering of a plastic-degrading aromatic polyesterase", will be published this week in the Proceedings of the National Academy of Sciences (PNAS).

Professor 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".

Researchers say they are now working on further improvements to the enzyme, with the hope of eventually scaling it up for industrial use in breaking down plastics. When the team tweaked the enzyme to study the link, they unexpectedly improved its ability to eat PET.

The world has a serious plastic crisis right now. It's possible that within the next few years there could be an industrially viable process for turning PET into other substances or back into its "original building blocks" so it can be sustainably recycled, he added.

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. The enzymes can get through plastic in just days compared to the centuries it takes for the resistant PET to breakdown in landfills or oceans.

PET is relatively easy to recycle, but over half of global PET waste is not collected for recycling, according to research from the Ellen MacArthur Foundation, and only 7 percent of bottles are recycled into new bottles (most go into lower-value products).

In addition to digesting PET, the new enzyme was also capable of degrading polyethylene furandicarboxylate (PEF), a bio-based form of plastic being hailed as a replacement for glass beer bottles.

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