Plastic waste dumped in landfills could be disposed of sooner than expected, after engineers developed an enzyme capable of breaking it down in just hours.
Millions of tonnes of plastic are left to waste each year, piling up in landfills and polluting land and waterways – usually taking centuries to degrade.
A team from the University of Texas at Austin has created a new enzyme variant capable of boosting large-scale recycling, thereby reducing the impact of plastic pollution.
The work focuses on PET (polyethylene terephthalate), which is a polymer found in most consumer plastics, including bottles, packaging and some textiles.
The enzyme was able to complete a “circular process” of breaking down the plastic into smaller parts and chemically putting it back together in as little as 24 hours.
They called it FAST-PETase (Functional, Active, Stable and Tolerant PETase), developed from a natural PETase that allows bacteria to degrade and modify plastic.
Plastic waste dumped in landfills could be disposed of sooner than expected, after engineers developed an enzyme capable of breaking it down in just hours. Image bank
It’s able to operate at ambient temperatures, rather than extreme heat or cold, making it a viable option for tackling plastic already in landfills, the team said.
The enzyme has the potential to boost large-scale recycling, allowing large industries to reduce their environmental impact by recovering and reusing plastics at the molecular level.
“The possibilities are endless across all industries to take advantage of this advanced recycling process,” said Hal Alper, professor in the McKetta Department of Chemical Engineering at UT Austin.
“Beyond the obvious waste management industry, it also offers companies in all sectors the opportunity to take the lead in recycling their products.
“With these more sustainable enzymatic approaches, we can begin to envision a true circular plastics economy.”
The project focuses on polyethylene terephthalate (PET), one of the most common plastic polymers used in consumer goods, which accounts for 12% of global waste.
Millions of tonnes of plastic are left to waste each year, piling up in landfills and polluting land and waterways – usually taking centuries to degrade. Image bank
The enzyme acted on the PET by breaking the plastic down into smaller parts, a process known as depolymerization, before chemically reassembling it in the reverse process called repolymerization.
In some cases, they were able to completely break down certain plastics into monomers, the small, mostly organic molecules that make up the plastic, in less than 24 hours.
Researchers from the Cockrell School of Engineering and the College of Natural Sciences used machine learning to generate mutations in natural PETase.
The model predicts which mutations of these enzymes would achieve the goal of rapidly depolymerizing post-consumer plastic waste at low temperatures.
Through this process, which included studying 51 different post-consumer plastic containers, five different polyester fibers and fabrics, and water bottles all made from PET, the researchers proved the effectiveness of the enzyme.
“This work really demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence,” said Andrew Ellington, who led the development of the machine learning model.
Recycling is the most obvious way to reduce plastic waste, but globally less than 10% of all plastic has been recycled, the rest ends up going to landfill and ultimately burned – which is energy intensive and very polluting.
Biological solutions, including the breakdown of plastic by bacteria, require much less energy, and enzyme research has advanced significantly over the past 15 years.
However, until now, no one had been able to figure out how to make enzymes that could work efficiently at low temperatures.
This is essential to operate at scale and to make them both portable and affordable on an industrial scale.
FAST-PETase can perform the process between 86 and 122 degrees Fahrenheit.
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A team from the University of Texas at Austin has created a new enzyme variant capable of boosting large-scale recycling, thereby reducing the impact of plastic pollution. Image bank
The team now plans to begin work on scaling up enzyme production, to prepare it for industrial and environmental application on real-world plastic waste.
The researchers have filed a patent application for the technology and envision several different uses, the most obvious being cleaning up landfills and greening waste-intensive industries.
But another key potential use is environmental remediation, with the hope that in future the enzymes could be sent into the field to clean up polluted sites.
“When considering environmental cleaning applications, you need an enzyme that can perform in the room temperature environment. This requirement is where our technology has a huge advantage going forward,” Alper said.
The results were published in the journal Nature.
