Scientists have discovered a new way of tackling the mounting issue of plastic pollution - by using bacteria to transform plastic waste into vanilla flavouring.

Researchers at the University of Edinburgh have used the common bacteria E. coli to convert post-consumer plastic into vanillin. 

The substance is the primary component of extracted vanilla beans and is responsible for the characteristic taste and smell of vanilla.

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Researchers say the vanillin produced may be fit for human consumption but further experimental tests are required.

The transformation could boost the circular economy, which aims to eliminate waste, keep products and materials in use and have positive impacts for synthetic biology, experts say.

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Joanna Sadler, lead author of the study, said: “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.”

Researchers have been developing new methods to tackle the global plastic crisis and recycle polyethylene terephthalate (PET).

PET is a strong, lightweight plastic derived from non-renewable materials such as oil and gas, and it is widely used for packaging foods and convenience-sized juices and water.

Approximately 50 million tonnes of PET waste is produced annually, causing serious economic and environmental impacts.

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While PET recycling is possible, existing processes create products that continue to contribute to plastic pollution worldwide. 

To tackle this problem, scientists from the University of Edinburgh used lab engineered E. coli to transform terephthalic acid – a molecule derived from PET – into the high value compound vanillin, via a series of chemical reactions.

The team also demonstrated how the technique works by converting a used plastic bottle into vanillin by adding the E. coli to the degraded plastic waste.

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Vanillin is widely used in the food and cosmetics industries, as well as the formulation of herbicides, antifoaming agents and cleaning products and its global demand exceeeded 37,000 tonnes in 2018. 

Dr Ellis Crawford, publishing editor at the Royal Society of Chemistry, said: “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.”