Scientists have been working on possible ways to reuse waste materials and make a positive contribution to the environment. One of the most invested and investigated materials is polyethylene terephthalate (PET) plastics due to their abundance and usefulness in several industries such as the production of bottles. Although there have already been ways discovered to convert PET plastics into newly produced PET, those ways do not significantly help with the overall repurposing of the material and usually are only used as opaque fibers for clothing or carpets. However, this new discovery of plastic conversion to produce vanilla flavoring, which is a compound ubiquitous in the food and cosmetic industries, is on another level in terms of its implications for the environment and the economy. The chemical aspect of the discovery is pretty interesting, however, in this article, we will not focus on those. If you want to further learn about the experiment and the chemical process, you can read the original research paper published in the journal Green Chemistry from here.
The discovery was made by Dr. Joanna Sadler, a Biotechnology and Biological Sciences Research Council Fellow, and Dr. Stephen Wallace, a senior lecturer in biotechnology, from the University of Edinburgh. Their starting point was to develop qualified technologies to valorize post-consumer PET plastic waste to balance the widespread applications of plastics with recycling. They used engineered Escherichia coli (E. coli) bacteria to directly upcycle the PET-derived monomer terephthalic acid (TA) into the small molecule vanillin.
The duo was worried about the possible byproducts that might change the fate of the overall discovery. However, through various experiments, they have found that the conversion process of PET into vanillin does not generate any hazardous waste, but instead just produces a mild reaction. Throughout their work, scientists mixed the engineered E. coli with the enzymatically broken down monomer pieces of the plastics. The mixture was then shaken continuously at 37 ℃ for a day and the resulting material was found to be 79% vanillin. Since the TA and vanillin have similar chemical compositions, the bacteria only needed to make minor changes to the number of hydrogens and oxygens that are bonded to the same carbon backbone. That makes the experiment a non-spontaneous enzymatic reaction that could easily be further improved and hence become a common way to eradicate plastic pollution and prevent the millions and billions of dollars being wasted on vanillin manufacturing. In fact, the scientist and a few colleagues have already started working on ways to scale up the process to convert larger amounts of plastics into vanillin. According to Wallace, working with E.coli makes their job easier as it can easily be modified. Furthermore, their access to a roboticised DNA assembly facility gives hope for other valuable molecules to be brewed from TA.
“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.”– Dr. Ellis Crawford, Royal Society of Chemistry Publishing Editor
Vanillin is an important bulk chemical that is used not only in the food and cosmetics industry, but also in the formulation of herbicides, antifoaming agents, and cleaning products. It usually is derived from the extract of vanilla beans and is an expensive substance with an extensive market size. In recent years, the growing vanillin demand lead industrial technologies to produce vanillin synthetically grow and grow and consequently, increase the expenses in this area. This high budget of synthetic vanillin production along with the extensive use and production of PET plastics was a huge burden on the world’s back and this new discovery will definitely save the world from such tremendous economic load.
Plastics normally lose nearly 95% of their original value after a single use which in fact leads to an estimated around $110 billion loss to the global economy per year. And the current system for recycling plastic isn’t doing what it claims and only recycles only 8.7% of the total produced plastics as EcoWatch points out. Considering that the global plastic waste crisis, both in terms of environment and economy, is now recognized as one of the most pressing environmental issues facing our planet, these new technologies are essential to enable a circular plastics economy in which no materials are wasted and gradually help significantly decrease plastic pollution. So, let’s get ready to eat ice cream flavored by the plastic-derived vanillin after further tests are made in order to ensure its edibility! And who knows, maybe all these pollution-causing plastic wastes can be converted into many other useful chemicals in the future and we will have a solution for the excessive dirtiness of our environment.
“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.”– Stephen Wallace
Sadler, Joanna C., and Stephen Wallace. “Microbial Synthesis of Vanillin from Waste Poly(Ethylene Terephthalate).” Green Chemistry, The Royal Society of Chemistry, 10 June 2021, pubs.rsc.org/en/content/articlelanding/2021/GC/D1GC00931A#!divAbstract.
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