Researchers from the University of Edinburgh in Scotland have developed a plastic-eating E. coli bacteria that can efficiently turn polyethylene terephthalate (PET) plastic bottles into adipic acid, one of the most important monomers in the polymer industry, used to make nylon materials, drugs, and fragrances.
The scientists used PET from post-industrial waste and a post-consumer PET bottle as samples. They began by assembling the eight genes required for adipic acid synthesis from terephthalate in E. coli. Based on those genes, they developed a new E. coli strain that produced enzymes that could transform terephthalic acid into compounds such as muconic acid and adipic acid. To transform the muconic acid into adipic acid, they used a second type of E. coli, which produced hydrogen gas, and a palladium catalyst.
Results show that the reaction takes place in aqueous media at room temperature and produces adipic acid in 79% conversion (115 mg/L) in 24 hours.
“We believe this is the first report of the bioproduction of adipic acid from a plastic waste source, substantiating the use of microbial biotechnology as a solution to the valorisation of this abundant “waste” feedstock while also diverting chemical manufacturing routes away from the sole use of raw petrochemicals,” the scientists wrote.
They shared their findings in “Microbial Upcycling of Waste PET to Adipic Acid,” recently published in ACS Central Science. Going forward, the team will look for pathways to biosynthesize additional higher-value products.