Plastic bottles have been converted into vanilla flavouring using genetically engineered bacteria,
the first time a valuable chemical has been brewed from waste plastic.
Researchers have already developed mutant enzymes to break down the polyethene terephthalate polymer used for drinks bottles into its basic units, terephthalic acid (TA). Scientists have now used bugs to convert TA into vanillin.
Vanillin is used widely in the food and cosmetics industries and is an important bulk chemical used to make pharmaceuticals, cleaning products and herbicides. Global demand is growing and in 2018 was 37,000 tonnes, far exceeding the supply from natural vanilla beans. About 85% of vanillin is currently synthesised from chemicals derived from fossil fuels.
Joanna Sadler, of the University of Edinburgh, who conducted the new work, said: “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.”
Stephen Wallace, also of the University of Edinburgh, said: “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.”
The research, published in the journal Green Chemistry, used engineered E-coli bacteria to transform TA into vanillin. The scientists warmed a microbial broth to 37oC for a day, the same conditions as for brewing beer, Wallace said. This converted 79% of the TA into vanillin.
Next, scientists will further tweak the bacteria to increase the conversion rate further and work on scaling up the process to convert more significant amounts of plastic. Other valuable molecules could also be brewed from TA, such as some used in perfumes.
So the next time you eat your custard……
- Tim Hoskins, Sustainable Hertford Heath