Vanilla extract—by bacteria, from plastic

Scientists from the University of Edinburgh are working on a delicious new way to recycle plastic. In a paper published June 10 in Green Chemistry, the researchers said they bioengineered bacteria to turn plastic into vanillin, the chemical that creates vanilla’s flavor.

After discovering a plastic-eating bacteria in Japan in 2016, a British-led research team developed an enzyme that could break down plastics used in packaging into terephthalic acid. Researchers Joanna Sadler and Stephen Wallace say they’ve now deployed genetically engineered strains of E. coli that break down terephthalic acid into vanillin. The Edinburgh scientists hope the discovery could make plastic recycling more economically viable and help keep plastic bottles out of landfills.

“The global plastic waste crisis is now recognized as one of the most pressing environmental issues facing our planet,” Sadler and Wallace wrote in their report.

Despite the promise of ubiquitous blue recycling containers across the Western world, most plastic ends up in landfills, according to a 2020 report by NPR. That’s because cleaning and recycling used plastic bottles and containers costs more than producing new plastic. Sadler and Wallace focused on what they call upcycling: transforming used plastic into something more valuable through chemistry.

Vanilla beans are the fruit of certain orchid plants. Some years, the forests of Madagascar produce about 80 percent of the world’s vanilla beans. Dependence on the island nation’s production leaves the world vanilla market vulnerable to adverse weather. When a single cyclone in 2017 ripped through the island and damaged an estimated 30 percent of vanilla bean crops, prices soared above $600 per kilogram, competing with the value of silver by weight.

Real vanilla is a luxury item—food makers have long depended on synthetic flavor. According to The Guardian, 85 percent of the world’s vanillin is created from fossil fuels rather than vanilla beans. Sadler and Wallace hope their plastic-eating, vanillin-producing E. coli bacteria finds an economic niche.

This isn’t the first time scientists have genetically modified E. coli strains to create clever solutions. In 2013, a team of researchers at the University of Exeter announced they’d created a strain that could consume fat and produce diesel fuel. And in 2018, scientists at Japan’s RIKEN research institute reported they modified E. coli to create an important chemical useful for producing a variety of industrial goods from galvanized steel to nylon.

Next up, Sadler and Wallace, will focus on fine-tuning the bacteria and the process to increase productivity. “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,” Wallace told The Guardian.