A so-called super enzyme that eats plastics could go further in finding ways to tackle the pollution crisis, scientists say.
Elevated proteins contain enzymes produced by two types of bacteria that feed in plastic bottles, known as Iodonella saccinosis.
Professor John McGihan, director of the Enzyme Innovation Center at the University of Portsmouth, said that while natural degradation can take hundreds of years, super-enzymes can transform plastic into its core materials or building blocks in just a few days.
He told the PA News Agency: “Currently we have these building blocks from fossil resources like oil and gas, which is not really useless. But if we can add enzymes to waste plastics, we can start breaking it down in a matter of days.”
The process will allow plastics to “continuously create and reuse, reducing our reliance on fossil resources,” he added.
In 2018, Professor McGihan and his team accidentally discovered an engineered version of an enzyme, Pitases, that was able to break down plastic in a matter of days.
For their study, published in the Journal of the National Academy of Sciences Processing, the professor and his team mixed Pitase with a second enzyme, MHTAG, and found that “the digestion of plastic bottles was literally doubled.”
Professor McGihan, one of the authors of the study, said: “I was able to make a super-enzyme six times faster than the original Petes enzyme alone.
“It’s moving forward significantly because it’s going to take hundreds of years for the plastic that ends up in our oceans today to break down naturally. Eventually, with the light and waves of the sun, it will start to break into smaller pieces – and we’ll end up with microplastics.” – a serious problem for organisms living in the environment.
Experiments have shown that this super-enzyme is able to break down a type of plastic used in soft drink and fruit juice packaging, known as PET (polyethylene terephthalate).
Although it is said to be highly recyclable, discarded PET persists in the environment for hundreds of years before declining. In addition to PET, the super-enzyme PEF (polyethylene furavate) also works on a sugar-based bioplastic used to make beer bottles. Professor McGihan added, however, that super-enzymes have not been able to break down other types of plastics.
For the next part of their study, researchers will look at ways to further accelerate the breaking-down process so that the technology can be adapted for commercial purposes.
Professor McGihan said: “The faster we can make enzymes, the faster we can break down the plastic and it will be commercially viable.”