Vanillin, with the molecular formula C8H8O3, is the primary component of vanilla bean extract. Global vanillin demand in 2018 reached about 37,000 metric tons—as good a sign as any of its importance in the pharmaceutical, cleaning, cosmetics, and food industries—and has far exceeded the supply given by natural vanilla beans. As a result, around 85% of vanillin produced worldwide is instead sourced by synthetic vanillin, produced by chemicals derived from fossil fuels. A new study published in Green Chemistry, however, might add a new, more sustainable source to the mix: waste poly(ethylene terephthalate), also known as PET plastic, identifiable by the “1” resin identification code (RIC) commonly embossed on most plastic bottles the world over that are made with it.
Researchers from the University of Edinburgh may have lit up a pathway to transform PET into vanillin by employing the services of Escherichia coli (E. coli) bacteria in a microbial broth together with terephthalic acid (TA), a building block of PET. While previous studies had already developed ways of reverting waste PET into its components such as TA—with some even using enzymes to do the job—the landmark research provides a method for further upcycling of PET into a functional compound that can be reintroduced to the global supply chain.
The study did so by combining both TA and E. coli into a microbial “broth,” then heating the solution to 37 °C for about a day. According to researcher Stephen Wallace, from the University of Edinburgh, this converted about 79% of the TA present in the mix into vanillin. The team wishes to push the vanillin conversion rate further by tweaking the E. coli’s DNA; said Wallace: “We think we can do that pretty quickly. We have an amazing roboticized DNA assembly facility here.”
In a statement made by Joanna Sadler, first author of the work and also from the University of Edinburgh, their work “challenges the perception of plastic being a problematic waste,” further saying that “it demonstrates [plastic’s] use as a new carbon resource from which high value products can be made.” The team also hopes to explore the possibility of upscaling the conversion process further, as well as the possibility of converting TA to other functional compounds other than vanillin, in future works.
Bibliography
- Carrington, D. (2021, June 15). Scientists convert used plastic bottles into vanilla flavouring. The Guardian. Retrieved August 30, 2021, from https://www.theguardian.com/environment/2021/jun/15/scientists-convert-used-plastic-bottles-into-vanilla-flavouring
- Sadler, J. C., & Wallace, S. (2021). Microbial synthesis of vanillin from waste poly (ethylene terephthalate). Green Chemistry.
