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A new cocktail of enzymes that accelerates the degradation of plastic offers a step forward in finding a new way of recycling that is faster, more affordable and works on a larger scale than current methods, British and American researchers said this week.
The “superzyme” could be used to break down plastic bottles much more quickly than current recycling methods and create the raw material to make new ones, according to scientists. And it can make material reuse easier.
“This is a very exciting development for plastics recycling and environmental stewardship,” said Jim Pfaendtner, a professor of chemistry at the University of Washington.
An estimated 359 million tons of plastic is produced annually worldwide, with at least 150 million tons in landfills or in the environment.
Once prized for their durability, plastics can take up to 450 years to degrade in the ocean, if at all, according to the National Oceanic and Atmospheric Administration. Much of it breaks down into small fragments known as microplastics that have been found in marine life, ocean water, and in the guts of humans.
Researchers are increasingly looking for solutions, including biodegradable plastic.
As the world grapples with climate change and the need to burn far less fossil fuels, oil and gas companies looking for alternatives to oversupply are turning to making more plastics like PET, one of the most common plastics popular in the world. It is found in soda bottles, synthetic clothing, and packaging.
The study, published Monday in the journal PNAS by a team of scientists from the University of Portsmouth and the National Renewable Energy Laboratory and other US institutions, focuses on a combination of two enzymes derived from a bacterium discovered in Japan in 2016. Scientists discovered that this bacteria could degrade PET.
In 2018, the team managed to break down the plastic with one of the two enzymes. But when the second enzyme is added, the students discovered, the process works six times faster.
“The original building blocks are recovered,” explained Professor John McGeehan, director of the Enzyme Innovation Center and co-leader of the team. And those building blocks can be reused.
These scientists are not alone in the race to find a faster and cheaper way to break down plastic.
In a breakthrough earlier this year, researchers from the Institute of Sciences of Toulouse and Carbios, a French bioindustrial company, published in Nature the findings of another enzyme that degraded PET in 10 hours. Alain Marty, Carbios’s chief scientific officer, said his company’s process was more efficient for “infinite recycling of PET” and was already in a “pilot industrial stage.”
The process developed by McGeehan’s team is slower: Recycling a plastic bottle can still take days or weeks. Now they are exploring the pre-softening of the plastic and other alternatives to reduce the degradation time to hours. They also hope to expand their operations.
Since the study was published, GlaxoSmithKline, a British pharmaceutical company, has offered the team the use of fermenters at a nearby penicillin production plant.
Even with advances in recycling, a problem remains: how to get the plastic to recycling plants in the first place. Experts have said that much of the barrier to recycling PET and other plastic waste lies in recovering it from the ocean and managing the waste responsibly.
“We created this problem in the first place,” said Mr. McGeehan.
Still, he said, it’s good that nature provided a solution.
