Published March 25, 2025 | Version v1

Upcycling depolymerized PET waste into polyhydroxyalkanoates and triacylglycerols by a newly isolated Rhodococcus sp. strain.

  • 1. i4HB ‑ Institute for Health and Bioeconomy, NOVA School of Science and Technology
  • 2. UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology
  • 3. Avecom NV
  • 4. LIFE Research Institute, Technological University of the Shannon Midlands Midwest
  • 5. LIFE Research Institute, Technological University of the Shannon Midlands Midwest,
  • 6. i4HB ‑ Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA
  • 7. UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology,
  • 8. i4HB ‑ Institute for Health and Bioeconomy, NOVA School of Science and Technology,
  • 9. UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA

Description

The use of post-consumer polyethylene terephthalate (PET) wastes, which often contain various additives and contaminants such as metals and pigments that make mechanical recycling and reusability difficult, as feedstocks for microbial synthesis of value-added bio-based products is an emerging sustainable strategy for managing such wastes. This study evaluated the ability of a strain isolated from a plastic-contaminated site, Rhodococcus sp. isolate Ave7, to use terephthalic acid (TPA) obtained by chemically depolymerizing PET waste, as sole feedstock for cell growth and production of polyhydroxyalkanoates (PHAs) and triacylglycerols (TAGs) as intracellular storage compounds. The fed-batch bioreactor cultivation resulted in a cell dry weight production of 3.85 g/L, with PHA and TAG contents of 15.0 wt.% and 15.4 wt.%, respectively. Overall, the culture consumed 16.5 g/L TPA over a period of 73 h. The produced PHA was mainly composed of 3-hydroxyvalerate (3HV) monomers (> 90 wt.%). The accumulated TAGs presented a fatty acids profile rich in octadecenoic acid (C18:1; 52 wt.%), hexadecanoic acid (C16:0; 32 wt.%) and octadecanoic acid (C18:0; 12 wt.%). Overall, the strain Rhodococcus sp. Ave7 demonstrated a high capacity for TPA removal, converting it into cell biomass, PHA and TAGs, thus rendering this bioprocess a promising solution to reduce the plastic waste burden, in a circular and sustainable approach.

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Additional details

Related works

Is supplemented by
Dataset: 10.5281/zenodo.17195859 (DOI)

Funding

European Commission
EcoPlastiC - Eco conversion of lower grade PET and mixed recalcitrant PET plastic waste into high performing biopolymers 101046758