Polyethylene conversion to mevalonate via catalyst-free autoxidation and bioconversion

Le résumé fourni par la source

Hybrid chemical and biological processes are promising strategies to valorize recalcitrant plastic waste streams by generating soluble oxygenates that can be biologically converted into a single product. Here, we show that acetic acid-mediated autoxidation in the absence of metal catalysts can deconstruct high-density polyethylene (HDPE) to soluble oxygenates at 80 C-mol% carbon yield. These yields are a major improvement over metal-catalyzed autoxidation, and the chemistry readily translates to post-consumer substrates. Multiple analytical approaches enabled identification of major product classes, including dicarboxylic acids (DCAs), 2-oxocarboxylic acids (ketoacids), and -lactone acids. An industrially relevant bacterium, Pseudomonas putida, was engineered to efficiently utilize ketoacids via a unique β-oxidation pathway discovered via barcoded transposon insertion libraries and transcriptomics. P. putida was then engineered to convert HDPE-derived DCAs and ketoacids into mevalonate, an exemplary high-value chemical. Overall, this study demonstrates a carbon-efficient, catalyst-free process for solubilizing HDPE to mixed oxygenates and highlights the need to improve the bioavailability of polyolefin-derived intermediates from oxidation.

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