Engineers Create an Enzyme That Breaks Down Plastic Waste in Hours, Not Decades
A new study outlines the use of a specially created enzyme variant that vastly reduces the time it takes to break down the components of plastics.
We could even use the enzyme variant to clean up sites contaminated by plastic pollution, say the team that developed it.
In tests, products made from the polymer polyethylene terephthalate (PET) were broken down in a week and, in some cases, 24 hours – these are products that can take centuries to degrade properly in natural conditions.
"The possibilities are endless across industries to leverage this leading-edge recycling process," says chemical engineer Hal Alper from the University of Texas at Austin.
"Beyond the obvious waste management industry, this also provides corporations from every sector the opportunity to take a lead in recycling their products."
The team has called the enzyme FAST-PETase (functional, active, stable, and tolerant PETase). They developed the enzyme from a natural PETase that allows bacteria to degrade PET plastic and modified it using machine learning to pinpoint five mutations that would enable it to degrade the plastic faster under different environmental conditions.
Once the enzyme variant did its job of cutting the plastic down into its basic molecular units (depolymerization), the researchers then demonstrated they could put the plastic back together again (repolymerization) using chemical processes to create new plastic products.
Finding FAST-PETase involved the study of 51 different post-consumer plastic containers, five different polyester fibers, and fabrics and water bottles made from PET.
In tests on all of these products, the enzyme variant proved its effectiveness and at temperatures less than 50 degrees Celsius (122 degrees Fahrenheit).
"When considering environmental cleanup applications, you need an enzyme that can work in the environment at ambient temperature," says Alper. "This requirement is where our tech has a huge advantage in the future."
PET is in many consumer packaging, from textiles to soda bottles. On its own, it's thought to make up around 12 percent of all global waste. If that figure wasn't frightening enough, try this one: Globally, less than 10 percent of all plastics have been recycled.
The introduction of FAST-PETase could go some way to helping. The researchers say that it's relatively cheap, portable, and not too difficult to scale up to the sort of industrial levels that would be required.
Right now, the most common methods for disposing of plastic are to throw it in a landfill where it rots at a very slow rate, or to burn it – which costs a lot, uses up plenty of energy, and fills the atmosphere with noxious gas. It's clear that alternative strategies are desperately needed, and this could be one of them.
"This work really demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence," says biochemist Andrew Ellington from the University of Texas at Austin.
Full article published in Nature