Story by Sharon O. Isaalah
Scientists at the University of Texas at Austin have created a modified enzyme that can break down plastics that would otherwise take centuries to degrade in a matter of days.
The researchers, who published their findings in the peer-reviewed journal Nature, used machine learning to land on mutations to create a fast-acting protein that can break down building blocks of polyethene terephthalate (PET), a synthetic resin used in fibres for clothing and plastic that, per the study, accounts for 12 per cent of global waste.
It does so through a process called depolymerization, in which a catalyst separates the building blocks that makeup PET into their original monomers, which can then be repolymerized—built back into virgin plastic—and converted into other products. Most impressively, the enzymes broke down the plastic in one week.
“One thing we can do is we can break this down into its initial monomers,” Hal Alper, professor in Chemical Engineering and author on the paper, told Motherboard over the phone. “And that’s what the enzyme does. And then once you have your original monomer, it’s as if you’re making fresh plastic from scratch, with the benefit that you don’t need to use additional petroleum resources.”
“This has advantages over traditional belt recycling,” Alper added. “If you were to melt the plastic and then remold it, you’d start to lose the integrity of the plastic each round that you go through with recycling. Versus here, if you’re able to depolymerize and then chemically repolymerize, you can be making virgin PET plastic each and every time.”
Their work adds to an existing line of query on plastic-eating enzymes, which were first recorded in 2005 and have since been followed by the discovery of 19 distinct enzymes, the paper notes. These are derived from naturally occurring bacteria that have been located living on plastic in the environment.
But many of these naturally-occurring enzymes are made up of permutations of proteins that function well in their specific environments, but can’t be used in a wide range of settings.
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