Scientists were inspired by Pac-Man and invented a plastic-eating "cocktail", which may help eliminate plastic waste.
It consists of two enzymes-PETase and MHETase-produced by a bacteria called Ideonella sakaiensis that feeds on plastic bottles.
Unlike natural degradation, which takes hundreds of years, this super enzyme can convert plastic into its original "components" within a few days.
These two enzymes work together, like "two Pac-Man connected by a string" chewing on a snack ball.
This new super enzyme digests plastic 6 times faster than the original PETase enzyme discovered in 2018.
Its target is polyethylene terephthalate (PET), the most common thermoplastic used to make disposable beverage bottles, clothing, and carpets, which usually take hundreds of years to decompose in the environment.
Professor John McGeehan of the University of Portsmouth told the PA news agency that at present, we obtain these basic resources from fossil resources such as oil and natural gas. This is indeed unsustainable.
"But if we can add enzymes to waste plastic, we can break it down in a few days."
In 2018, Professor McGeehan and his team stumbled upon a modified version of an enzyme called PETase that can break down plastic in just a few days.
In their new study, the research team mixed PETase with another enzyme called MHETase and found that "the digestibility of plastic bottles has almost doubled."
Then, the researchers used genetic engineering to link these two enzymes together in the laboratory, just like "connecting two Pac-Man with a rope."
"PETase will erode the surface of the plastic, and MHETase will further cut, so see if we can use them together to imitate the situation in nature, it seems natural." Professor McGeehan said.
"Our first experiment showed that they do work better together, so we decided to try to connect them."
"We are very pleased to see that our new chimeric enzyme is three times faster than the naturally evolved isolate enzyme, which opens up new avenues for further improvements."
Professor McGeehan also used the Diamond Light Source, a synchrotron located in Oxfordshire. It uses a powerful X-ray 10 billion times brighter than the sun as a microscope, which is strong enough to see individual atoms.
This allowed the research team to determine the three-dimensional structure of the MHETase enzyme and provide them with a molecular blueprint to begin designing a faster enzyme system.
In addition to PET, this super enzyme can also be used for PEF (polyethylene furanate), a sugar-based bioplastic used for beer bottles, although it cannot break down other types of plastics.
The team is currently looking for ways to further speed up the decomposition process so that the technology can be used for commercial purposes.
"The faster we make enzymes, the faster we decompose plastics, and the higher its commercial viability," said Professor McGeehan.
This research has been published in the Proceedings of the National Academy of Sciences.
