Plastic Bottles Can Be Recycled into Vanilla Flavoring
Imagine a future where our plastic waste problem could literally be eaten away for dessert. No, chefs can't serve up "plastic bottle a la mode," but research published this month in the journal Green Chemistry has demonstrated how a used plastic bottle can be converted into vanilla flavoring.
Researchers at Scotland's University of Edinburgh have used genetically modified E. coli bacteria to turn a plastic bottle into vanillin -- the primary source for the taste and smell of vanilla. Researchers even believe that this plastic-derived vanillin is likely safe for human consumption, however, further experiments would be required, according to the university's news site. Though vanillin can be extracted naturally from vanilla beans, those beans are expensive, so synthetic vanillin is far more common: Reportedly, 85 percent of vanillin is produced this way.
"This is a really interesting use of microbial science at the molecular level to improve sustainability and work towards a circular economy," Ellis Crawford, publishing editor at the Royal Society of Chemistry, was quoted as saying. "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."
Importantly, these experiments didn't simply turn plastic bottles into bowls of vanilla ice cream. The scientists had to follow a number of intermediary steps. As The Guardian explains, first, the plastic -- polyethylene terephthalate (or PET) -- has to be broken down into terephthalic acid (TA) using engineered "super-enzymes." Then, the engineered E. coli is used to transform that TA into vanillin.
Even then, only 79 percent of the TA was converted, though the researchers believe they can improve that rate. "We think we can do that pretty quickly," Stephen Wallace, one of the paper's two co-authors, told the British paper. "We have an amazing roboticized DNA assembly facility here." They also plan to scale up production and search for other useful molecules besides vanillin that could be made with this method.
"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," Wallace stated.
Joanna Sadler, the paper's other author, added, "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."