UK researchers have genetically engineered E. coli to transform some forms of plastic into vanillin, according to a study published in Green Chemistry (1). There were a few challenges to overcome, but the researchers believe this work could be a game-changer for recycling plastic.
Polyethylene terephthalate – or PET for short – is a widely used type of plastic. PET plastic can be recycled, but it usually involves transforming it into second-generation plastic instead of eliminating this material.
Now, Stephen Wallace and Joana Sadler, from the University of Edinburgh, want to transform this plastic into alternative products instead. To achieve this, the duo managed to genetically engineer E. coli to start converting terephthalic acid into vanillin, the compound responsible for the taste and smell of vanilla. Usually, vanillin is extracted from the vanilla plant, but an alternative source would be greatly welcomed as global demand typically outweighs supply. It’s still too early to say whether this vanillin could be produced to the standards required for human consumption, but at least it could be used for cosmetics and other applications.
“This is the first example of using a biological system to upcycle plastic waste into a valuable industrial chemical, and this has very exciting implications for the circular economy. The results from our research have major implications for the field of plastic sustainability and demonstrate the power of synthetic biology to address real-world challenges”, said Sadler, first author in this study.
The development stages proved to be quite challenging. First, it took a series of optimisations to find the best conditions to grow the bacteria to ensure that all enzymes required in the process could play their role in transforming terephthalic acid to vanillin. Second, the researchers had to find a way to “convince” E. coli bacteria to open up and metabolise the plastic. To overcome this, they used small amounts of alcohol to create tiny holes in the cell membrane to increase its permeability. Finally, as excessive amounts of vanillin can be toxic for this bacteria, Wallace and Sadler had to develop a way to remove it by extracting into oleyl alcohol.
“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 obtained”, said Wallace. The team plans to continue this research to optimise and scale up the process as well as design new pathways to create other valuable compounds from plastic.
“This is a really interesting use of microbial science at the molecular level to improve sustainability and work towards a circular economy. Using microbes to turn waste plastics, which are harmful to the environment, into an important commodity and platform molecule with broad applications in cosmetics and food is a beautiful demonstration of green chemistry”, concluded Dr Ellis Crawford, Editor at the Royal Society of Chemistry.
(1) Sadler, J and Wallace S (2021) Microbial synthesis of vanillin from waste poly(ethylene terephthalate). Green Chem, 23, 4665-4672
You make an excellent point that it is important for us to choose a qualified animal hospital for our pets.
My wife and I would like to have our dogs checked. I will look into reliable hospital for our pets.