Why Global Citizens Should Care
Plastic pollution threatens the integrity of ecosystems around the world. The United Nations calls on countries to curb plastic waste, improve recycling standards, and ultimately develop circular models of production — a sustainable method encouraged by the scientists behind this new research. You can join us in taking action related issues here.

Science has come up with all sorts of wacky solutions to the plastic pollution crisis.

So far the human race has stumbled upon caterpillars that tuck into plastic like a snack; accidentally discovered a mutant bacterium that breaks plastic down to its original, recyclable material; and then invented a “super enzyme” that degrades plastic six times faster than normal.

I mean, we could, you know, use less plastic. Or modify our supply chains, tax producers, or actually recycle the plastic we do use properly, instead of sending it to landfills abroad. But in lieu of all that funky stuff, science has come back for another bite at the cherry: using genetically engineered bacteria to convert plastic bottles into a tasty vanilla flavouring.

One of the big issues with plastic is a thing called polyethylene terephthalate (PET) — basically the light, strong material that makes up a lot of plastic packaging, especially bottles. It can take around 450 years to break down, meaning it can cause chaos in our natural environment.

There has already been research conducted into how you can break it down much faster using some of those mutant plastic eating enzymes we mentioned earlier. Essentially, you Benjamin Button it: turning it back into terephthalic acid, the compound used to make PET in the first place.

But new research from the University of Edinburgh, published in the journal Green Chemistry, has gone one step further: working out how to turn that original acid into vanillin, a hugely valuable chemical for the food and cosmetics sector that, among other things, can be used to make products like vanilla flavouring, herbicides, and cleaning products.

According to Joanna Sadler and Stephen Wallace, the co-authors of the study, research of this kind usually focuses on how PET can be better recycled to create more PET. But their project was more about “biological upcycling” into something more useful and sustainable.

“This is the first example of using a biological system to upcycle plastic waste into a valuable industrial chemical and it has very exciting implications for the circular economy,” Sadler said.

Wallace added: “Our work challenges the perception of plastic being a problematic waste and instead demonstrates its use as a new carbon resource from which high value products can be made.”

They did it by genetically modifying bacteria called Escherichia coli (you might know it as E coli, some strains of which can cause infections). The Guardian reports that they then used this in a broth, warmed for a day to 37 degrees Celsius — the same temperature used to brew beer.

This then magically transformed most of the terephthalic acid (79%) into the vanillin. The next step for the scientists is to work out how to do this at scale, converting more plastic at once.

“This is a really interesting use of microbial science to improve sustainability,” said Ellis Crawford, of the Royal Society of Chemistry. “Using microbes to turn waste plastics, which are harmful to the environment, into an important commodity, is a beautiful demonstration of green chemistry.”

Reporting from the Guardian in 2017 found that a million plastic bottles were bought every single minute around the world — 20,000 bottles a second — a number that was expected to rise 20% by this year. More recently, the most comprehensive research on the subject to date suggested that plastic bottles were the second most common item found in ocean litter. 


Defend the Planet

Scottish Scientists Just Worked Out How to Convert Plastic Bottles Into Vanilla Flavouring

By James Hitchings-Hales