Scientists Turn Plastic Waste Into Vanilla Flavoring

Vanilla ice cream may soon be made from plastic bottles. Scientists have figured out a way to convert plastic waste into vanilla flavoring using genetically engineered bacteria, according to a new study.

Vanillin, which is the compound that carries most of the smell and taste of vanilla, can be extracted naturally from vanilla beans. But it can also be made synthetically. About 85% of vanillin is currently made from chemicals taken from fossil fuels.

Vanillin is found in a wide variety of food, cosmetic, pharmaceutical, cleaning and herbicide products. The demand is “growing rapidly,” the authors wrote in the study. In 2018, the global demand for vanillin was about 40,800 tons (37,000 metric tons). It’s expected to grow to 65,000 tons (59,000 metric tons) by 2025, according to the study, published June 10 in the journal Green Chemistry.

The demand for vanillin “far exceeds” the vanilla bean supply, so scientists have resorted to producing vanillin synthetically. In the most recent study, researchers used a new method to convert plastic waste into vanillin. This solution both supplies vanillin and reduces plastic pollution.

Previous studies showed how to break down plastic bottles made from polyethylene terephthalate into its basic subunit, known as terephthalic acid. In the new study, two researchers at The University of Edinburgh in Scotland genetically engineered E. coli bacteria to convert terephthalic acid into vanillin.  Terephthalic acid and vanillin have very similar chemical compositions and the engineered bacteria only needs to make minor changes to the number of hydrogens and oxygens that are bonded to the same carbon backbone. 

The researchers mixed their genetically engineered bacteria with terephthalic acid and kept them at 98.6 degrees Fahrenheit (37 degree Celsius) for a day. About 79% of the terephthalic acid converted into vanillin. 

“The global plastic waste crisis is now recognized as one of the most pressing environmental issues facing our planet,” the authors wrote in the study. About 1 million plastic bottles are sold every minute around the world, and only 14% are recycled. Those that are recycled can only be turned into fibers for things like clothing and carpets. 

“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,” co-author Stephen Wallace, a senior lecturer in biotechnology at The University of Edinburgh, told The Guardian.

Now, the study authors hope to further improve the bacteria to be able to convert even more terephthalic acid into vanillin.