Poly (ethylene terephthalate) (PET) is an abundant and extremely useful material with widespread uses throughout society. However, there is an urgent need to develop technologies to upgrade PET waste to combat plastic pollution and achieve a circular economy. While PET degradation and recycling technologies have been reported, examples focus on reusing the resulting monomers to make more PET or other second generation materials. Here we report on a novel way in technically produced Escherichia coli for the direct upcycling of the PET-derived monomer terephthalic acid into the value-adding low-molecular vanillin, a flavor compound ubiquitous in the food and cosmetics industry and an important bulk chemical. After process optimization, a 79 percent conversion of TA to vanillin was achieved, a 157-fold improvement over our initial conditions. Parameters such as temperature, cell permeabilization and on site Product removal was key to maximizing vanillin titers. Finally, we will demonstrate the conversion of post-consumer PET from a plastic bottle to vanillin by coupling the metabolic pathway with enzyme-catalyzed PET hydrolysis. This work demonstrates the first biological upcycling of post-consumer plastic waste to vanillin using an engineered microorganism.

Graphic Summary: Microbial Synthesis of Vanillin from Waste Poly (ethylene terephthalate)

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