A plastic-eating enzyme could remove billions of tons of waste from landfills

An enzyme created by engineers at the University of Texas at Austin can break down plastics that normally take centuries to break down in hours or days.

This discovery could help solve one of the world’s most pressing environmental problems: what to do with the billions of tons of plastic waste piling up in landfills and polluting our lands and natural waters.

The enzyme has the potential to fuel large-scale recyclingthat would allow large industries to reduce their environmental impact by recovering and reusing plastics at the molecular level.

The possibilities of taking advantage of this state-of-the-art recycling process are endless. 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 economy for plastics.

Hal Alper, professor in the Department of Chemical Engineering at the University of Texas at Austin.

The project focuses on polyethylene terephthalate (PET)an important polymer found in most consumer packaging, including cookie wrappers, soft drink bottles, fruit and salad wrappers, and some fibers and textiles. It constitutes 12% of all waste in the world.

The enzyme was able to complete a “circular process” of breaking down the plastic into smaller parts (depolymerization) and then chemically bonding it (repolymerization). In some cases, these plastics can completely break down into monomers in as little as 24 hours.

Researchers from the Cockrell School of Engineering and the School of Natural Sciences have used a machine learning model to generate new mutations of a naturally occurring enzyme called PETase that allows bacteria to degrade PET plastics. 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 all PET water bottles, the researchers demonstrated the effectiveness of the enzyme. , which they call FAST-PETase (functional, active, stable and tolerant PETase).

This work truly demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence.

Andrew Ellington, professor at the Center for Synthetic Biology.

Recycling is the most obvious way to reduce plastic waste. But globally, less than 10% of all plastic is recycled. The most common method of disposing of plastic, other than throwing it in a landfill, is to burn it, which is expensive, requires a lot of energy, and releases harmful gases into the air. Other alternative industrial processes are the glycolysis, pyrolysis and/or methanolysis processes, which consume a lot of energy.

Biological solutions require much less energy. Research on enzymes for recycling plastics has progressed over the past 15 years. Until now, however, no one had been able to figure out how to make enzymes that could work efficiently at low temperatures so that they would be portable and affordable on a large industrial scale. FAST-PETase can perform the process below 50ºC.

Next, the team plans to work on scaling up enzyme production to prepare for industrial and environmental application. The researchers have filed a patent application for the technology and are considering several different uses. The most obvious are cleaning up landfills and greening industries that produce a lot of waste. But another key potential use is environmental rehabilitation. The team is investigating various ways to bring the enzymes into the field to clean up contaminated sites.

When considering environmental cleaning applications, an enzyme that can operate in the room temperature environment is needed. This requirement is where our technology has a huge advantage going forward.

Hal Alper

More information: www.nature.com (text in English).

Going through utexas.edu

Leave a Comment