Scientists recently revealed that they have inadvertently engineered an enzyme that could help address the global plastic crisis.
Researchers from the U.S. Department of Energy's National Renewable Energy Laboratory and the University of Portsmouth in the United Kingdom created an enzyme that can digest polyethylene terephthalate (PET), the most commonly used thermoplastic polymer, and often used in the manufacturing of plastic bottles.
While studying a microbe that had been discovered in 2016 to naturally digest PET plastic, scientists decided to "tweak" the enzyme's structure to better understand this process. Instead of simply adjusting the structure, they “accidentally” made the enzyme even more efficient at breaking down the plastic.
"Serendipity often plays a significant role in fundamental scientific research and our discovery here is no exception," Professor John McGeehan, director of the Institute of Biological and Biomedical Sciences at the University of Portsmouth, said in a press release.
Not only is the "mutant" enzyme better at degrading PET, it can also degrade polyethylene furandicarboxylateor (PEF), a bio-based substitute being touted as a replacement for glass bottles. Nonetheless, after publishing their results this month in the journal Proceedings of the National Academy of Sciences, the scientists say the next step is to make the enzyme even better.
"Although the improvement is modest, this unanticipated discovery suggests that there is room to further improve these enzymes, moving us closer to a recycling solution for the ever-growing mountain of discarded plastics," McGeehan said.
People around the world use numerous plastic items every day without even taking notice. It's used in our clothes, our vehicles, our bathroom products and the packaging for our food and drinks. Each year, enough plastic is produced to circle our world four times, according to EcoWatch. The average American alone throws away approximately 185 pounds of plastic every year.
Unable to break down naturally, these plastics simply remain in landfills and waterways for hundreds of years and end up polluting the environment. But new discoveries, such as this mutant enzyme, may help address the problem.
"It's well within the possibility that in the coming years we will see an industrially viable process to turn PET and potentially other substrates like PEF, PLA, and PBS, back into their original building blocks so that they can be sustainably recycled," McGeehan said.
Still, some scientists caution that it's still too early to say how and if it will be used to address the plastic problem.
"The discovery is very cool. [It's] too early to say how useful the enzyme might prove to be, particularly on a 'global' scale, but it is a very cool first step," Emory University chemistry professor David Lynn told the AJC.
Ichiro Matsumura, a biochemistry professor at Emory, shared similar sentiments, and said that laboratory discoveries "aren't always translated into real-world solutions."
"Other mutant enzymes, such as those in laundry detergents or those widely used to make cheese, have significant though underappreciated impact upon our daily lives. Plastic pollution is a significant environmental problem and any solution will require more investment, technological development and political will," Ichiro said.
Although Ichiro described the Earth's plastic problem as "serious," he pointed out that the repercussions are not yet clear.
"The recent discovery shows that we are still discovering ways in which synthetic chemical compounds interact with biological macromolecules. It is possible that this kind of plastic, or a chemical offshoot of it, is reacting with molecules in species we have yet to discover," he said.
Ichiro also pointed out that there are six other types of plastic besides PET, including some that will be "more challenging" to break down.
"This discovery may not end the plastic problem on its own, but it can inspire people to learn more about the problem and discover their own ways to contribute to a solution," he said.
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