Scientists from the US National Renewable Energy Laboratory and the University of Portsmouth have published an article in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS) on the discovery of an enzyme system that can more quickly degrade waste plastics. Based on enzymes extracted from bacteria that have evolved over time to depolymerize plastics, the “two-enzyme system for polyethylene terephthalate (PET) deconstruction . . . employs one enzyme to convert the polymer into soluble intermediates and another enzyme to produce the constituent PET monomers.”
This enzyme system is different from the one developed in April 2020 by a group of French researchers (FPF reported). That earlier system was able to depolymerize 90% of PET plastics within 10 hours, but required being heated above 70 degrees Celsius. The system described in the latest PNAS article is able to operate at room temperature and complete the degradation at a faster rate. Prof John McGeehan from the University of Portsmouth told The Guardian that “when [they] linked the enzymes, rather unexpectedly, [they] got a dramatic increase in activity. This is a trajectory towards trying to make faster enzymes that are more industrially relevant. But it’s also one of those stories about learning from nature, and then bringing it into the lab.”
The engineered enzyme is much too large to be produced naturally by bacteria and needs to be created in the laboratory. While it has been estimated that the process could be scaled up industrially within the next couple of years, some stakeholders are concerned that such technologies do not address the root of the plastic pollution problem (FPF reported). Instead, they are calling for reducing the production and use of highly persistent materials such as plastics and shifting to more efficient consumption and use of materials that do not require advanced waste treatment processes.
Damian Carrington (September 28, 2020). “New super-enzyme eats plastic bottles six times faster.” The Guardian
Oliver Morrison (October 1, 2020). “New plastic-eating ‘super enzyme’ offers hope for full recycling.” Beverage Daily
Karen Laird (October 2, 2020). “Two is better than one: Teaming enzymes together speeds up PET breakdown process.” Sustainable Plastics
Knott, B. et al. (September 28, 2020). “Characterization and engineering of a two-enzyme system for plastics depolymerization.” Proceedings of the National Academy of Sciences