Scientists engineered plastic-eating ‘super-enzymes’ that can break down bottles in days

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Issue No. 42/2020 – Monday, 05 October 2020 (Business Insider)

More than 300 million tons of plastic are produced annually worldwide, and most plastics take centuries to break down.

 A new study describes a “super-enzyme” engineered using proteins derived from plastic- eating bacteria. It can recycle a common type of plastic in days.

 Such enzymes could help address the growing problem of plastic pollution.

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More than 300 million tons of plastic are produced annually worldwide. Most take hundreds of years to break down, and even then, they just splinter into tiny microplastic pieces that will likely never biodegrade. Microplastics make it into the food we eat and show up in our poop.

But new types of engineered enzymes, created from plastic-eating bacteria, appear able to break down plastics in a matter of days.

These “super-enzymes” were made by researchers at the Center for Enzyme Innovation in the UK and the National Renewable Energy Laboratory in Colorado. They break down a type of common plastic known as polyethylene terephthalate (PET) — used in single-use bottles as well as clothing and carpets — into its chemical building blocks.

Used at scale, they could reduce our reliance on fossil fuels (which are needed to produce new plastic), instead allowing manufacturers to reuse the same plastics over and over.

Researchers first discovered plastic-eating bacteria in 2016 at a bottle-recycling facility in Japan. The organisms produce two enzymes that help them break down PET within weeks. Scientists dubbed the enzymes PETase and MHETase.

In 2018, a group at the Center for Enzyme Innovation took PETase and tweaked it to increase the speed with which it deconstructed PET. This week, the team revealed in a new study that they improved on the process even further by stitching together DNA from PETase and MHETase into one “super-enzyme.”

“PETase attacks the surface of the plastics and MHETase chops things up further, so it seemed natural to see if we could use them together, mimicking what happens in nature,” biologist John McGeehan, the lead author of the study, said in a press release.

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