Spoiler alert: it’s actually not the first man-made plastic-eating enzyme.
But it is six times faster than the last one.
Let’s back up…
We know plastic takes hundreds of years to biodegrade, and given our recklessly ubiquitous use of plastics in the world, that’s a big problem.
When most people consider the plastic crisis, they think of towering landfills, the Great Pacific Garbage Patch, and giving single-use water bottle-buyers dirty looks (even if we know logically that doesn’t make anyone a bad person.)
The reason plastic doesn’t break down for so long is polyethylene terephthalate (PET), which is the most common thermoplastic used in single-use bottles, garments, carpets, and more.
One report from the Pew Charitable Trusts even projected that new plastic polluting our oceans could triple by 2040, up to 29 million metric tons per year.
And the approach will need to be multifaceted – we won’t find one single solution that rids the world of its plastics.
We’ll need all hands on deck in the scientific community in order to extract our existing waste, come up with innovative and sustainable solutions for the future, and attempt to recycle the plastic in the environment to avoid burning more fossil fuels.
That’s why scientists labored throughout 2016 to come up with a viable, working enzyme called PETase, that uses principles found in organic bacteria to break PET down to its structural atoms.
The PETase Journey
When Japanese researchers found Ideonella sakaiensis strain 201-F6 bacteria in the sludge outside of a bottling factory, eating through the PET in the plastics, they knew they were onto something.
PETase, the eventual enzyme they developed, works by splitting chemical bonds, or esters, in PET. That breaks the actual PET compound down into molecules small enough to be eaten by bacteria.
The PETase created in the lab was more effective than the microbe found in the dirt, and everyone was pretty excited. The microbes were shown to be able to eat away at the PET, not at breakneck speeds, but much faster than the several centuries that would’ve been required without it.
PETase, however, starts to break down PET in about 96 hours.
It was pretty groundbreaking when it was discovered – but science moves pretty fast.
And recently, researchers have been able to combine PETase with another enzyme to turbocharge the speed at which PET returns to atom form.
The New and Improved PETase
In a report released on September 23rd, 2020, this new combination enzyme can eat plastic up to six times faster than PETase alone.
This has enormous implications for the future of recycling.
We won’t get into the weeds about the molecular science of it all, but here’s how it works: PETase meets another enzyme called MHETase.
When the two mix, they break PET down at twice the speed. But they don’t just mix. The researchers use an X-ray device called the Diamond Light Source, with rays 10 billion times brighter than the sun, to create a blueprint of MHETase.
Using that blueprint, they then determined how to suture the DNA of MHETase to PETase, harnessing not just the power of both enzymes individually, but the power of the beast the two create when they are turned into one enzyme.
This stitching is actually not at all uncommon in the sustainable research space.
It’s frequently used in the creation of biofuels, the likes of which international oil giant BP is now investing heavily in.
Although the new enzyme is pretty impressive, it’s not the end of the road for our plastic troubles. Researchers have received funding to continue experimenting on the recycling plastic of PET.
By recycling it, we won’t have to generate new plastic. We’ll also keep new PET from finding its way into our wilderness and water supplies.
But the issue of recycling – and how rigidly the rules are being followed, if at all – is an entirely separate conversation, worthy of its own article.
For now, it’s important to stay informed about developments happening now and on the horizon that may change the landscape of our pollution future, especially when one sustainable solution borrows from another.
We work our best when we combine skill sets and methods, and so does the microbial kingdom.
The answer to our unnatural plastic problem seems to be found within nature itself.