Scientists improve “superzyme” that degrades plastic 0:59
(CNN) –– Scientists created a new ‘superzyme’ that can break down plastic up to six times faster than the previous enzyme they had worked on.
A team of researchers who had previously redesigned a plastic-eating enzyme called PETase have now combined it with a second enzyme to speed up the process, according to a news release from the University of Portsmouth.
The supeenzyme could have important implications for the recycling of polyethylene terephthalate (PET). This is the most common thermoplastic used in single-use beverage bottles, carpets, and clothing.
PET takes hundreds of years to degrade in the environment. The PETase enzyme can break it down to its basic elements in a few days.
John McGeehan, co-lead author and director of the Center for Enzyme Innovation at the University of Portsmouth, told CNN that this latest development represents a major step toward using enzymes to recycle plastic and reduce plastic pollution.
“We were actually quite surprised that it worked so well,” McGeehan said. In any case, he stressed that the process “is still too slow” to be commercially viable.
McGeehan told CNN that the researchers have received funding to conduct more experiments. He further explained that successful developments in the area could mean that existing PET could be recycled instead of using fossil fuels to create new plastic.
“We’re seeing (potential) huge energy savings,” said McGeehan.
How does it work?
The superenzyme combines PETase and MHETase. A mixture of the two breaks down PET twice as fast as PETase alone, while connecting the two enzymes increases the speed three times as fast.
McGeehan used the Diamond Light Source, a device that uses X-rays 10 billion times brighter than the Sun to see individual atoms, to map MHETase’s molecular structure.
The researchers were then able to engineer the new superzyme by connecting MHETase and PETase. What they did was effectively join the DNA from the enzymes to create a long chain, McGeehan told CNN.
The technique is commonly used in the biofuel industry, which uses enzymes to break down cellulases. However, McGeehan said this is the first time he’s been aware of enzymes combining to break down plastic.
The full study was published Monday in the journal Proceedings of the National Academy of Sciences.
How else can plastic break down?
Microplastics found in an Antarctic aquatic animal 1:12
Plastic pollution is one of the most pressing environmental problems. A recent report by The Pew Charitable Trusts projected that the volume of plastic entering the ocean could nearly triple to 29 million metric tons per year by 2040. This is equivalent to 50 kg for every meter of coastline on the planet.
He also said that there was “no one-size-fits-all” but that “an ambitious recycling strategy” could reduce plastic pollution by between 31% and 45%.
In April, French firm Carbios announced the publication of a study on its own PET-eating enzyme. This will be tested at a demonstration plant near the city of Lyon in 2021, according to a company press release.
Other possible solutions include the tiny wax worm, which can chew through plastic, even polyethylene – a common, non-biodegradable plastic that currently clogs landfills and seas – thanks to its gut bacteria.
Mealworms, the larval stage of the mealworm beetle, could also contribute. Around 3,000 to 4,000 mealworms can break down a Styrofoam cup of coffee in about a week thanks to the bacteria that live in your intestines.