Scientists have created a ‘super-enzyme’ that degrades plastic six times faster than its predecessor to enable the full recycling of plastic bottles and potentially mixed-fabric clothes.
The super-enzyme was created by mixing two separate enzymes, which were found in a plastic-eating bug discovered at a Japanese waste site in 2016.
Two years after the initial discovery, researchers revealed an engineered version of the first enzyme that was able to break down plastic in a few days. They determined that the structure of the enzyme, called PETase, can attack the hard, crystalline surface of plastic bottles, and that one mutant version of it worked 20% faster.
The latest study, published in Proceedings of the National Academy of Sciences, analysed the second enzyme, which doubles the speed of the breakdown of the chemical groups liberated by the first enzyme.
When the two enzymes were combined, scientists saw a further tripling of the speed, meaning plastic can be broken down six times faster than with PETase alone.
Prof. John McGeehan, from the University of Portsmouth, UK, told The Guardian:
When we linked the enzymes, rather unexpectedly, we 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.
Exciting news! Our @portsmouthuni scientists @CEI_UoP who re-engineered the plastic-dissolving enzyme PETase have now created an enzyme ‘cocktail’ which can digest plastic up to six times faster! https://t.co/8XW3UvCXUC
— Revolution Plastics (@UoPPlastics) September 28, 2020
The creation of the super-enzyme could prove vital in the fight against plastic pollution, which is a global issue. Plastic is dumped in landfill sites and litters the landscape and the oceans, and humans are now known to consume and breathe microplastic particles.
It is currently very difficult to break down plastic bottles into their chemical constituents in order for them to be recycled, meaning more plastic is being produced year after year to meet demand.
McGeehan explained that by collaborating with other enzyme-producing companies, such as the French company Carbios, and by combining different approaches with the super-enzyme, it could be ready for commercial use ‘within the next year or two’.
The research team, made up of scientists at the University of Portsmouth and four US institutions, is now examining how the enzymes can be tweaked to make them work even faster.
There’s huge potential. We’ve got several hundred in the lab that we’re currently sticking together.
The scientists have been in talks with big fashion companies that produce mixed fabrics of polyester and cotton about the possibility of adapting the super-enzyme to recycle mixed-fabric clothes, which could be done by combining it with existing enzymes that work to break down natural fibres.
Those working on plastic recycling efforts have admitted that strong, lightweight materials like plastic are very useful, so true recycling is key in the solution to plastic pollution.
If you have a story you want to tell, send it to UNILAD via [email protected]