Mixed Polyamide and Polyester Upcycling via Chemical Autoxidation and Engineered Pseudomonas putida

Journal Article · Fri Sep 19 00:00:00 EDT 2025 · Reaction Chemistry and Engineering

DOI:https://doi.org/10.1039/D5RE00351B· OSTI ID:3013265

Eaglesfield, Ross ^[1]; Frey, Brandon ^[1]; Lahive, Ciaran ^[1]; Cuthbertson, Amy ^[1]; Kuatsjah, Eugene ^[1]; Ramirez, Kelsey ^[1]; Avina, Young-Saeng ^[1]; Alt, Hannah ^[1]; Banakis, Natalie ^[2]; Knauer, Katrina ^[1]; Beckham, Gregg ^[1]; Werner, Allison ^[1]

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1. National Renewable Energy Lab., Golden, CO (United States)
2. Patagonia

Polyamides, such as nylons, are often used in multi-component materials, like textiles and packaging, and are accompanied with unique recycling challenges. Recently, autoxidation and bioconversion has emerged as a tandem approach for the conversion of mixed plastics waste to single products, however the fate of polyamides in these processes is unknown. Here, we optimized the autoxidation of nylon-6 and nylon-6,6 depolymerization, achieving >92 mol% nitrogen recovery from both substrates, predominantly as acetamide, and 20-27 mol% carbon recovery (not including acetamide). Experiments with 13C-labeled acetic acid demonstrated that the carbon in acetamide was solvent derived. Autoxidation of mixed nylon-6 and poly(ethylene terephthalate) (PET) post-consumer fibers resulted in similar carbon and nitrogen recoveries from nylon, while PET was depolymerized to terephthalic acid (TPA) at >65 C-mol% recovery. Next, we engineered Pseudomonas putida KT2440 to utilize acetamide as the sole carbon and nitrogen source for growth through the constitutive expression of genes encoding amidase enzymes, including a native amidase (PP_0613) shown to be active on C2-C4 amides. Heterologous chromosomal expression of amiE, encoding the amidase from P. aeruginosa, was found to be superior to PP_0613 constitutive expression in genome integrated strains. Prior engineering to enable TPA conversion to ..beta..-ketoadipate pathway intermediate protocatechuate was leveraged and combined with deletion of pcaD to produce muconolactone as a product. Finally, a stacked strain engineered for conversion of acetamide, TPA, and DCAs was evaluated on the reaction product from autoxidation of mixed post-consumer nylon and PET fibers without any supplemental nitrogen, achieving quantitative yields in the presence of supplemental carbon.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing and Materials Technologies Office (AMMTO); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Bioenergy Technologies Office
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 3013265
• Report Number(s): NREL/JA-2A00-94999
• Journal Information: Reaction Chemistry and Engineering, Journal Name: Reaction Chemistry and Engineering
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
acetamide
depolymerization
nylon
poly(ethylene terephthalate)
post-consumer fibers