Scientists Made a Super-Enzyme That Absolutely Ravages Plastic Bottles
A two-enzyme cocktail can break down the most common plastic six times faster than before.
Scientists in many disciplines study ways to close the loop on plastic waste by recycling and reuse.
These enzymes evolved in bacteria and are synthesized and improved in the laboratory.
A newly discovered “super-enzyme” could finally mean effective recycling of plastic bottles and other materials, scientists say. The plastic-eating bacteria can digest plastic six times faster than current methods of chemically breaking it down.
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Scientists first discovered one enzyme several years ago, and the new “cocktail” replaces a previous version that had less plastic-eating complexity and robustness. In a new paper, a large team that spans the Atlantic delivers its findings as well as its recommendations for how to introduce the enzyme into the plastics supply chain. By combining two enzymes on purpose, laboratory scientists break polyethylene terephthalate (PET) into “intermediate” parts, and then into elementary parts.
The bacterial product PETase enzyme turns PET into its “constituent monomers,” or building blocks. Now that scientists know about the two-step enzyme system, they wonder if bacteria that have evolved some plastic-digesting mechanisms already will continue that way and grow mechanisms that will further digest plastic—in line with the two-step system scientists understand.
For now, they’ve mixed enzymes from two different kinds of bacteria into one system that breaks plastic down in phases that are much faster. “Our first experiments showed that they did indeed work better together, so we decided to try to physically link them, like two Pac-men joined by a piece of string,” University of Portsmouth professor and study leader John McGeehan said in a statement.
The enzymes work together to “chop” the most common consumer plastic into chemical building blocks, which means they can be reapplied as the ingredients for the next generation of plastics instead of distilling these ingredients from newly extracted petrochemicals. McGeehan is also director of the University of Portsmouth’s Centre for Enzyme Innovation, where scientists identify naturally occurring enzymes, study their chemical makeup, and find ways to synthesize them in the laboratory.
In this case, McGeehan and his colleagues used a sun-bright synchrotron light to illuminate and zoom in on the natural enzyme until they could see all the molecules and their fully assembled structure. That step, which is already hard work, was just the first of many:
“The new research combined structural, computational, biochemical and bioinformatics approaches to reveal molecular insights into its structure and how it functions. The study was a huge team effort involving scientists at all levels of their careers.”
There’s a striking causality contained in this research. “The leakage of plastics into the environment on a planetary scale has led to the subsequent discovery of multiple biological systems able to convert man-made polymers for use as a carbon and energy source,” the team writes. “These plastic-degrading systems offer a starting point for biotechnology applications toward a circular materials economy.”
That means bacteria began to evolve this enzymatic capacity because of the way humans carelessly disposed of plastics beginning after their popularization. But now, they’ve role-modeled a “circular materials economy” where what we put in is reused in earnest—by recycling or even by designing advanced materials that close their own loops based on application.
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