Killing two birds with one stone: chemical and biological upcycling of polyethylene terephthalate plastics into food

Schaerer, Laura G.; Wu, Ruochen; Putman, Lindsay I.; Pearce, Joshua M.; Lü, Tao; Shonnard, David R.; Ong, Rebecca G.; Techtmann, Stephen M.

doi:10.1016/j.tibtech.2022.06.012

Cited by 25 publications

(28 citation statements)

References 108 publications

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“…In this manner, BHET was converted too β-ketoadipic acid, for example . In a related avenue, rPET was microbially degraded to generate biomass with potential use as a protein source . This aims at generating food from plastic waste, addressing two looming crises simultaneously.…”

Section: Upcycling Pet To Added Value Small Moleculesmentioning

confidence: 99%

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Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

2023

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We are facing a rapidly growing plastic pollution crisis, which is adversely affecting communities and ecosystems across the globe. Polymer scientists have an urgent obligation to develop and implement strategies for reutilizing plastic waste streams instead of continually relying on virgin feedstocks in plastic manufacturing. Postconsumer and postindustrial plastic items should be treated as valuable resources instead of discarding them. In order to do this, technological outlets must be developed to produce renewed materials using plastic waste as an input. Polyesters represent one of the largest plastic waste streams because they are commonly used in single-use beverage and food containers as well as textiles. Polyesters are also ideal candidates to exploit through chemical diversification, owing to the wide variety of functional derivatives that can be synthetically accessed via ester reactivity. This work highlights some recent developments related to diversifying polyester waste, with a focus on poly(ethylene terephthalate) (PET) as waste stream. The strategies encompass the production of both valuable small molecules prepared via degradation of PET and high-performance polymeric scaffolds derived from reactions with PET. Taking the recent ingenuity into consideration, based on these technological developments, an outlook is provided for the future of polyester waste streams. What are the next steps that are needed? Where are these trends headed? What gaps still exist, particularly with respect to assessment of sustainability and life cycle analysis? Collectively considering the examples highlighted here, there is great promise in the field of reutilizing waste streams as feedstocks for value-added materials.

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Section: Upcycling Pet To Added Value Small Moleculesmentioning

confidence: 99%

“…78 In a related avenue, rPET was microbially degraded to generate biomass with potential use as a protein source. 79 This aims at generating food from plastic waste, addressing two looming crises simultaneously. This of course requires further work to analyze safety and nutritional profiles of the protein sources.…”

Section: Moleculesmentioning

confidence: 99%

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

2023

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“…While techniques currently exist for chemical and biological recycling of PET, current chemical recycling techniques require the addition of catalysts and often use extreme processing conditions to depolymerize and reprocess PET into virgin material or other value-added products (Schaerer et al, 2022 ; Singh et al, 2021 ). Likewise, biological processing requires the addition of defined nutrient-rich media to support microbial growth.…”

Section: Introductionmentioning

confidence: 99%

“…By strategically using ammonium hydroxide to depolymerize PET, it may be possible to produce nitrogen-rich biodegradable plastic derivatives for microbial community degradation. Additionally, the alkaline product from chemical depolymerization could be neutralized with phosphoric acid, yielding a pH-neutral feedstock rich in nitrogen and phosphorus (Schaerer et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

“…Because the process for deconstructing PET demonstrated here results in a product rich in nitrogen and phosphorus, we expect the solution will be biodegraded without specialized medium or additional nutrients. We hope this streamlined process will form the basis of future industrial systems to upcycle PET waste into valuable products (such as food) before it pollutes the environment (Schaerer et al, 2022 ). Additionally, ammonium hydroxide treatment may also be used to deconstruct additional polymers, such as flexible polyurethane foam fragments, polycarbonate shards, polyester layers in multilayer plastics, and synthetic fabrics (pure nylon or polyester and nylon- and polyester-spandex blends).…”

Section: Introductionmentioning

confidence: 99%

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Versatile microbial communities rapidly assimilate ammonium hydroxide-treated plastic waste

Schaerer

Wood

Aloba

et al. 2023

Journal of Industrial Microbiology and Biotechnology

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Most plastic waste accumulates in landfills or the environment. Natural microbial metabolisms can degrade plastic polymers. Unfortunately, biodegradation of plastics is slow even under ideal conditions; depolymerization of plastic is the rate limiting step. Rapid chemical depolymerization yields biodegradable plastic monomers, improving biodegradation rates. Here we demonstrate that ammonium hydroxide depolymerizes PET into terephthalic acid and terephthalic acid monoamide which are rapidly metabolized by diverse consortia obtained from compost and sediment. By neutralizing the product with phosphoric acid prior to bioprocessing, the final product contains plastic-derived carbon and biologically accessible nitrogen and phosphorus from the process reactants, removing the need for culture medium. Three microbial consortia were able to degrade chemically deconstructed PET in ultrapure water and scavenged river water without the addition of nutrients, with no statistically significant difference in growth rate compared to communities grown on deconstructed PET in Bushnell Haas minimal culture medium. The consortia were dominated by Rhodococcus spp., Hydrogenophaga spp., and many lower abundance genera. All taxa were related to species known to degrade aromatic compounds. Microbial consortia are known to confer flexibility in processing diverse substrates. To highlight the versatility of these consortia, we also demonstrate that two microbial consortia can grow on similarly deconstructed polyesters, polyamides, and polyurethanes in water instead of medium. Our findings suggest that using microbial communities enable flexible bioprocessing of mixed plastic wastes. We also demonstrate the flexibility of this approach for coupled chemical deconstruction and bioprocessing.

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From Waste to Food: Toward the Creation of a Sustainable Food Generator

Lu,

Techtmann

2023

Curious Future Insight

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Killing two birds with one stone: chemical and biological upcycling of polyethylene terephthalate plastics into food

Cited by 25 publications

References 108 publications

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

Trends in Polyester Upcycling for Diversifying a Problematic Waste Stream

Versatile microbial communities rapidly assimilate ammonium hydroxide-treated plastic waste

From Waste to Food: Toward the Creation of a Sustainable Food Generator

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