A Plastic-Eating Enzyme Gives Hope to Recycling Efforts

A mutant bacterium that eats plastic may advance recycling efforts.One million plastic bottles are produced every minute, and only a fraction of them are recycled. A mutant bacterium that eats plastic may advance recycling efforts.

Researchers from the University of Portsmouth in Britain and the U.S. Department of Energy’s National Renewable Energy Laboratory have accidentally improved a plastic-eating bacterial enzyme, called PETase.

The bacterium was first discovered in 2016 at a PET-bottle recycling plant in Japan, where it had naturally evolved to break down polyethylene terephthalate (PET), the material used in many plastic bottles.

When the researchers were examining the proteins of this wonder bug, they inadvertently made it 20 percent more efficient, enabling the enzyme to break down plastic back to its original form within a few days.

Currently, only 14 percent of the bottles produced are recycled, and the salvaged material can only be turned into opaque fibers for clothing and carpets, not into bottles again. But, an enzyme that breaks down PET into more basic chemicals would make it easier for manufacturers to recycle the plastic back into a new high-grade PET, rather than producing new plastic from oil.

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Much work is left to be done, however, as even a liter of a solution with the improved enzyme can only break down a few milligrams of plastic per day, but the researchers are hoping to use their findings to make an enzyme that works much faster and can be used commercially.

Polyethylene terephthalate is also known as polyester in clothing or fabrics but is called PET in the production of bottles, jars, containers, and packaging. PET makes up 20 percent of all plastic production worldwide. The plastic takes centuries to break down naturally and is a major source of pollution in landfills and oceans.

Every year an estimated eight million tons of plastic end up in the ocean, and seabirds and marine animals confuse the colorful plastics for food and ingest it. Furthermore, scientists predict that by 2050, there could be as much plastic mass in the ocean as there is fish.

Related: Plastic Patch in Pacific Ocean is Much Larger Than We Believed

Advances in the enzyme, though, could make it possible for more plastic to be recycled and fewer virgin plastic bottles to be produced, which means less debris ends up in the environment.

John McGeehan, one of the scientists involved in the project, explained, “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.”

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