Scientists have been exploring the potential of enzymes to help recycle plastics for nearly two decades. However, the last six to 12 years have shown quite significant progress in this regard.
In 2016, Japanese researchers discovered a bacterium that used enzymes to break down polyethylene terephthalate (commonly known as PET plastic) within weeks.
A technical version of these enzymes, called PETase, improved performance even further, and in 2020 we saw scientists develop an even more powerful version that broke PET plastics up to six times faster.
Now a new study, published in the journal natureuses machine learning to design a fast-acting enzyme that degrades certain forms of plastic in just 24 hours, with stability that makes it suitable for wide-scale adoption.
The research analyzed a number of products made from PET plastics
According to researchers at the University of Texas (UT), application of the technology has been limited by an inability to perform well at low temperatures and different pH ranges, in addition to lack of efficacy in direct control of untreated plastic waste and slow reaction rates.
To solve these problems, the team developed a machine learning model that might predict which mutations in a PETase enzyme would allow it to have these abilities.
This involved analyzing a range of PET plastic products, such as containers, water bottles and fabrics, then using the model to design a new and improved enzyme called FAST-PETase (Functional, Active, Stable and tolerant).
The newly created enzyme was found to be superior at breaking down PET plastics at temperatures between 30°C and 50°C and over a wide range of pH levels. It was able to almost completely degrade 51 different untreated PET products in one week. In some experiments, it did this in just 24 hours.
The study also demonstrated a process for recycling PET from loop closed, in which FAST-PETase was used to break down plastics and then the recovered monomers were used to chemically reconstruct the material.
“When considering environmental cleaning applications, you need an enzyme that can function in the room temperature environment,” said study author Hal Alper, Ph.D in Chemical Engineering. and professor at UT. “This requirement is where our technology has a huge advantage going forward. »
With the ability to rapidly break down post-consumer plastic waste at low temperatures, the researchers believe they have found a technique that is portable, affordable and has the potential for industrial scale adoption.
They have filed a patent application for the technology and hope to see it used in landfills and polluted areas. “The possibilities are endless across all industries to take advantage of this state-of-the-art recycling process,” Alper said. “In addition to the obvious waste management industry, this also offers companies in all sectors the opportunity to lead the way in recycling their products. With these more sustainable enzymatic approaches, we can begin to envision a true circular plastics economy.
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