Mixed plastics waste valorization through tandem chemical oxidation and biological funneling

TLDR: This work shows that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion, and engineer a robust soil bacterium to funnel these oxygenated compounds into a single exemplary chemical product.

Abstract: Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of these materials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either β-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products. Description Funneling mixed waste with microbes Current plastic recycling methods require sorting by chemical composition, a method that is expensive and results in products that are of lower quality and value than the starting plastic. If plastic waste could instead be converted to valuable chemical intermediates, then economical use of mixed waste as a feedstock might be feasible. Sullivan et al. developed a two-stage oxidation and biological funneling approach that can break down and reform mixtures of common consumer plastics (see the Perspective by Yan). The end products can be adjusted by metabolic engineering of the microbes in the second step, which should enable tailored conversion into various platform or specialty chemicals. —MAF Autoxidation and biological funneling converts mixed plastics to a single product.