New enzyme developed to recycle plastic

Plastic waste is a perennial problem that technology continues to try and overcome. A possible solution that is being explored is the use of enzymes that can break down plastics. Enzymes could potentially be used to break down specific plastic components and could possibly be more cost and energy efficient than other ways of breaking down or recycling plastics.  

Unfortunately, using enzymes comes with a host of problems, as they are often not stable or very effective under conditions that would make them useful at an industrial scale.

In an effort to overcome these challenges and design an enzyme useful for recycling plastics at an industrial level, scientists with the Manchester Institute of Biotechnology (MIB) have developed a new engineering platform. The platform can assess the ability to break down plastics of about 1,000 enzymes a day. The process uses directed evolution, where mutations are introduced and selected for, to create useful enzymes. 

To demonstrate the ability of this platform, scientists have used it to create an enzyme that degrades poly(ethylene) terephthalate (PET), the most common plastic used to make bottles. 

“The accumulation of plastic in the environment is a major global challenge. For this reason, we were keen to use our enzyme evolution capabilities to enhance the properties of plastic degrading enzymes to help alleviate some of these problems,” explained Dr. Elizabeth Bell, who led the experimental work at the MIB.

“We are hopeful that in the future our scalable platform will allow us to quickly develop new and specific enzymes are suitable for use in large-scale plastic recycling processes.”  

The new enzyme – called HotPETase – was developed by direct evolution starting with IsPETase, which is naturally created by the bacterium Ideonella sakaiensis to degrade PET. Unfortunately, the enzyme is unstable at hotter temperatures required for industrial recycling, so the researchers developed HotPETase, which works at 70°C (~158°F), making it more optimal. 

This engineering feat is a promising step forward. However, to continue the process, much collaborative and interdisciplinary work will be needed.  

The research was published in the journal Nature Catalysis. 

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By Erin Moody , Earth.com Staff Writer