β-Ketoadipic acid production from poly(ethylene terephthalate) waste via chemobiological upcycling

Sang Mook You, Si Seon Lee, Mi Hee Ryu, Hye Min Song, Min Soo Kang, Ye Jean Jung, Eun Chae Song, Bong Hyun Sung, Si Jae Park, Jeong Chan Joo, Hee Taek Kim, Hyun Gil Cha

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The upcycling of poly(ethylene terephthalate) (PET) waste can simultaneously produce value-added chemicals and reduce the growing environmental impact of plastic waste. In this study, we designed a chemobiological system to convert terephthalic acid (TPA), an aromatic monomer of PET, to β-ketoadipic acid (βKA), a C6 keto-diacid that functions as a building block for nylon-6,6 analogs. Using microwave-assisted hydrolysis in a neutral aqueous system, PET was converted to TPA with Amberlyst-15, a conventional catalyst with high conversion efficiency and reusability. The bioconversion process of TPA into βKA used a recombinant Escherichia coli βKA expressing two conversion modules for TPA degradation (tphAabc and tphB) and βKA synthesis (aroY, catABC, and pcaD). To improve bioconversion, the formation of acetic acid, a deleterious factor for TPA conversion in flask cultivation, was efficiently regulated by deleting the poxB gene along with operating the bioreactor to supply oxygen. By applying two-stage fermentation consisting of the growth phase in pH 7 followed by the production phase in pH 5.5, a total of 13.61 mM βKA was successfully produced with 96% conversion efficiency. This efficient chemobiological PET upcycling system provides a promising approach for the circular economy to acquire various chemicals from PET waste.

Original languageEnglish
Pages (from-to)14102-14109
Number of pages8
JournalRSC Advances
Volume13
Issue number21
DOIs
StatePublished - 9 May 2023

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© 2023 The Royal Society of Chemistry.

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