Shingwekar, D.; Laster, H.; Kemp, H.; Mellies, J.L. Two-Step Chemo-Microbial Degradation of Post-Consumer Polyethylene Terephthalate (PET) Plastic Enabled by a Biomass-Waste Catalyst. Bioengineering2023, 10, 1253.
Shingwekar, D.; Laster, H.; Kemp, H.; Mellies, J.L. Two-Step Chemo-Microbial Degradation of Post-Consumer Polyethylene Terephthalate (PET) Plastic Enabled by a Biomass-Waste Catalyst. Bioengineering 2023, 10, 1253.
Shingwekar, D.; Laster, H.; Kemp, H.; Mellies, J.L. Two-Step Chemo-Microbial Degradation of Post-Consumer Polyethylene Terephthalate (PET) Plastic Enabled by a Biomass-Waste Catalyst. Bioengineering2023, 10, 1253.
Shingwekar, D.; Laster, H.; Kemp, H.; Mellies, J.L. Two-Step Chemo-Microbial Degradation of Post-Consumer Polyethylene Terephthalate (PET) Plastic Enabled by a Biomass-Waste Catalyst. Bioengineering 2023, 10, 1253.
Abstract
Polyethylene terephthalate (PET) pollution poses significant environmental consequences, and thus new degradation methods must be explored to mitigate this problem. We previously demonstrated that a consortium of three Pseudomonas and two Bacillus species can synergistically degrade PET in culture. The consortium more readily consumes Bis(2-Hydroxyethyl) terephthalate (BHET), a byproduct made in PET depolymerization, compared to PET, and can fully convert BHET into metabolically usable monomers terephthalic acid (TPA) and ethylene glycol (EG). Because of its crystalline structure, the main limitation of the biodegradation of post-consumer PET is the initial transesterification from PET to BHET, depicting the need for the transesterification step in the degradation process. Additionally, there have been numerous studies done on the depolymerization reaction of PET to BHET, yet few have tested the biocompatibility of that product with a bacterial consortium. In this report, a two-step process was implemented for sustainable PET biodegradation, where PET is first depolymerized to form BHET using an Orange Peel Ash (OPA) catalyzed glycolysis reaction, followed by complete degradation of the BHET glycolysis product by the bacterial consortium. Results show that OPA-catalyzed glycolysis reactions can fully depolymerize PET, with an average BHET yield of 92% (w/w) and that the reaction product is biocompatible with the bacterial consortium. After inoculation with the consortium, 19% degradation of the glycolysis product was observed in 2 weeks, for a total degradation percentage of 17% when taking both steps into account. Furthermore, the 10-week total BHET degradation rate was 35%, demonstrating that the glycolysis products are biocompatible with the consortium for longer periods of time, for a total two-step degradation rate of 33% over 10 weeks. While we predict complete degradation is achievable using this method, further experimentation with the consortium can allow for a circular recycling process, where TPA can be recovered from culture media and reused to create new materials.
Keywords
Polyethylene terephthalate; PET plastic; depolymerization; biocatalys; biodegradation; glycolysis; recycling
Subject
Chemistry and Materials Science, Polymers and Plastics
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
