The discovery of a different type of PETase enzyme, published in Nature, could help solve one of the most pressing environmental problems: what to do with the millions of tons of plastic waste piling up in landfills and polluting land and oceans.
According to information published by the University of Texas, the enzyme has the potential to accelerate recycling on a large scale, which will allow major industries to reduce their environmental impact thanks to the recovery and reuse of plastic at the molecular level.
“The possibilities are endless in every industry to take advantage of this revolutionary recycling process,” says Hal Alper, a professor in the Makita Department of Chemical Engineering at the University of Texas. “Besides the waste management industry, of course, this also provides companies in all sectors the opportunity to take the lead in recycling their products. With these more sustainable enzymatic methods, we can begin to envision a true circular economy for plastics.”
The project focuses on polyethylene terephthalate (PET), a polymer found in most consumer goods packaging, including food packaging and soft drink bottles and in some fibers and textiles, which accounts for 12% of all waste worldwide.
The enzyme was able to complete a “circular process” of breaking the plastic into smaller pieces (depolymerization) and then linking them together chemically (repolymerizing). In some cases, these plastics were completely broken down into monomers in as little as 24 hours, the University of Texas confirms.
Researchers from the Cockrell School of Engineering and the College of Natural Sciences used a machine-learning model to generate new mutations in a natural enzyme called PETase, which allows bacteria to degrade PET plastic. The model predicts that mutations in these enzymes make it possible to achieve the goal of rapidly depolymerizing post-consumer plastic waste at lower temperatures.
Through this process, which involved studying 51 different post-consumer plastic packaging, five different polyester fibers, textiles and water bottles, all made from PET, the researchers demonstrated the effectiveness of the enzyme, which they called FAST-PETase, which is short for “functional, active, stable and tolerant PETase.” (which can be translated in Portuguese as functional, active, stable and tolerant PETase).
“This work really demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence,” says Andrew Ellington, a professor at the Center for Systems and Synthetic Biology, who led his team developing 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 University of Texas says the most common way to dispose of plastic, in addition to putting it in landfill, is to burn it, which is expensive, uses a lot of energy and releases harmful gases into the atmosphere. Other alternatives include industrial processes such as hydrolysis, pyrolysis and/or methanol decomposition, which require a lot of energy.
The foundation says biological solutions use much less energy. « Searching for enzymes for recycling
Plastics have advanced in the past fifteen years. However, until now, no one has been able to figure out how to make enzymes that can work efficiently at lower temperatures, to make them portable and affordable on a large industrial scale. FAST-PETase can perform the process at as little as 50°C,” the University of Texas highlights.
The next steps will be to scale up the production of enzymes for industrial and environmental application. Researchers have already submitted a patent application and are analyzing its use in various fields.
“When considering environmental cleaning applications, you need an enzyme that can operate at room temperature. This requirement is where our technology has a significant advantage in the future,” summarizes Hal Alper.