Goodbye PET, hello ecological transition

Scientists at the National Renewable Energy Laboratory (NREL) discovered enzymes that could make it cheaper to recycle textile waste and polyester bottles instead of making them from petroleum.

By: María Ramírez

One of the main contributors to climate change is plastic waste, which chokes our waterways, pollutes our oceans, kills wildlife, and infiltrates our food chain. This climate crisis has prompted countries worldwide to look for ways to combat the pollution produced over the years.

A team of scientists at NREL discovered variants of "plastic-eating" enzymes adapted to destroy all varieties of PET, even the crystalline and durable ones. Gregg Beckham, the principal investigator at the National Renewable Energy Laboratory, commented, "The research community is developing promising alternatives, including enzymes designed to depolymerize PET."

Using advanced machine learning and synthetic biology methods, this group of scientists were able to discover new enzyme variants that can deconstruct all PET, even the most rigid PET, without the need to go through any further processing. In addition to the environmental contribution, a change would be seen economically because, thanks to this discovery, it could be cheaper to recycle PET than to

THEY ARE LOOKING TO FIND WAYS TO MAKE THE PROCESS CHEAPER, GREENER, AND MORE PROLIFIC FOR THE ENVIRONMENTAL COMMITMENTS OF THE PARIS AGREEMENT.

WE ARE REACHING A POINT WHERE COLLABORATIVE SCIENCE HAS ENORMOUS POTENTIAL TO ACCELERATE THE DEVELOPMENT AND DEPLOYMENT OF ENZYME-BASED SOLUTIONS AT SCALE

JOHN MCGEEHAN, A SCIENTIST WHO LED THE TEAM'S CONTRIBUTION FROM THE UNIVERSITY OF PORTSMOUTH (UOP).

manufacture it from scratch with petroleum.

Nature is so magnificent that it provides a way to return PET to its essential elements. This is where the concept of enzymatic recycling came to the fore. In 2016 Japanese scientists discovered a bacterium called "ideonella sakaiensis," breaking down old plastic bottles outside a recycling plant in Japan. John McGeehan, a scientist who led the team's contribution from the University of Portsmouth (UoP), said, "We are reaching a point where collaborative science has enormous potential to accelerate the development and deployment of enzyme-based solutions at scale."

However, rapid technological advances hit a crucial hurdle at the industrial level. Enzymes were only effective on a small percentage of PET products, but there were deconstruction difficulties for crystalline varieties. They could only accomplish the process if they were softened with extra heat and energy. And thanks to advances in bioinformatics and machine learning, a new search for enzyme sequences for crystalline PET began.

Japheth Gado, a computer scientist at NREL, built a statistical model to learn the biological rules of known plastic-deconstructing enzymes. With 3D renderings provided by DeepMind, researchers provided valuable clues about how the plastic-deconstructing enzymes in PET act. "This will allow us to improve the protein-engineered enzymes and find other enzymes in nature that are similar in terms of performance," Gado added.

This research is being funded by the U.S. Department of Energy's Offices of Advanced Manufacturing Technologies and Bioenergy. And they are looking to find ways to make the process cheaper, greener, and more prolific for the environmental commitments of the Paris Agreement.