plastic waste dump

Plastic-eating enzyme developed with machine learning could solve waste crisis

Image credit: DT

An enzyme that can break down environment-throttling plastics, that typically take centuries to degrade, in as little as a matter of hours has been developed by scientists at The University of Texas at Austin (UT Austin).

The discovery could help to solve the world’s escalating plastic waste crisis, which is filling up landfills and polluting oceans. The researchers said the new enzyme has the potential to “supercharge” recycling on a large scale that would allow major industries to reduce their environmental impact by recovering and reusing plastics at the molecular level.

“The possibilities are endless across industries to leverage this leading-edge recycling process,” said Professor Hal Alper, a researcher at UT Austin. “Beyond the obvious waste management industry, this also provides corporations from every sector the opportunity to take a lead in recycling their products. Through these more sustainable enzyme approaches, we can begin to envision a true circular plastics economy.”

The project focuses on PET plastic, a significant polymer found in most consumer packaging, including containers, bottles, fruit and salad packaging, and certain fibres and textiles that makes up 12 per cent of all global waste.

The enzyme was able to complete a “circular process” of breaking down the plastic into smaller parts (depolymerisation) and then chemically putting it back together (repolymerisation). In some cases, these plastics can be fully broken down to monomers in as little as 24 hours.

The researchers used a machine-learning model to generate novel mutations to a natural enzyme called PETase that allows bacteria to degrade PET plastics. The model predicts which mutations in these enzymes would accomplish the goal of quickly depolymerising post-consumer waste plastic at low temperatures.

Through this process, which included studying 51 different post-consumer plastic containers, five different polyester fibres and fabrics and water bottles all made from PET, the researchers proved the effectiveness of the enzyme, which they are calling FAST-PETase.

“This work really demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence,” said Professor Andrew Ellington, whose team led the development of the machine-learning model.

Research on enzymes for plastic recycling has advanced during the past 15 years. However, until now, no one had been able to figure out how to make enzymes that could operate efficiently at low temperatures to make them both portable and affordable at large industrial scale. FAST-PETase can perform the process at less than 50°C.

Up next, the team plans to work on scaling up enzyme production to prepare for industrial and environmental application. Cleaning up landfills and greening high waste-producing industries are the most obvious. But another key potential use is environmental remediation. The team is looking at a number of ways to get the enzymes out into the field to clean up polluted sites.

“When considering environmental clean-up applications, you need an enzyme that can work in the environment at ambient temperature. This requirement is where our tech has a huge advantage in the future,” Alper said.

Yesterday, E&T revealed that none of the flexible plastic waste that Sainsbury’s collects from its customers as part of a controversial nationwide initiative is currently recycled in the UK.

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