Facing our plastic waste crisis: biorecycling as a promising solution
Yi Peng A , Apoorva Prabhu A and Chris Rinke A *A Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Qld, Australia.
Yi Peng is a Master of Molecular Biology and recent graduate from the Rinke Lab at the Australian Centre for Ecogenomics (ACE), The University of Queensland. Her major interests include marine microbial plastic degradation, enzyme discovery, protein expression and purification. |
Apoorva Prabhu is a PhD candidate in the Rinke Lab at ACE, The University of Queensland. Her major focus is on environmental microbiology, microbial genomics and machine learning. |
Dr Chris Rinke is an ARC Future Fellow and Senior Lecturer at ACE, The University of Queensland. His research focuses on phylogeny and metabolic capabilities of uncultured microbes, archaeal taxonomy, bacterial plastic degradation and viral communities. More details are available at the Rinke Lab website: http://rinkelab.org/. |
Microbiology Australia 44(1) 52-56 https://doi.org/10.1071/MA23013
Submitted: 25 January 2023 Accepted: 21 February 2023 Published: 8 March 2023
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the ASM. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
We are in a global plastic waste crisis. Plastic production has steadily increased over the last half century, while recycling rates remain as low as 9% in some nations, including Australia. Most plastic waste ends up in landfill or the environment as a lost resource, triggering the production of more virgin plastic to satisfy demands. Shifting away from this wasteful, linear economy towards a circular economy, where waste products are treated as a valuable resource and are recycled, will require considerable innovative advancements to our current plastic recycling methods. Biological recycling (biorecycling) has emerged as a promising solution, with several advantages over mechanical and chemical recycling. Using enzymatic reactions, long plastic polymers are cut into monomers without the need for high temperatures or chemical catalysts, and without affecting product quality. Biorecycling allows sustainable, commercially viable and near-infinite recycling of synthetic polymers. In this paper, we discuss reasons for our current plastic waste crisis, compare plastic recycling methods with a focus on biorecycling and explore commercial ventures of enzyme-based recycling technologies. We present recent developments in enzyme discovery, enzyme characterisations and protein engineering. Finally, we propose a strategy to move towards a circular plastic economy, by embracing biorecycling.
Keywords: biorecycling, enzyme discovery, plastic recycling, protein engineering, sustainable development.
References
[1] The Organisation for Economic Co-operation and Development (2022) The current plastics lifecycle is far from circular. OECD. https://www.oecd.org/environment/plastics/plastics-lifecycle-is-far-from-circular.htm[2] Geyer R (2020) Chapter 2 - Production, use, and fate of synthetic polymers. In Plastic Waste and Recycling (Letcher TM, ed.). pp. 13–32. Academic Press.
| Crossref |
[3] Andrady, AL and Neal, MA (2009) Applications and societal benefits of plastics. Philos Trans R Soc B Biol Sci 364, 1977–1984.
| Applications and societal benefits of plastics.Crossref | GoogleScholarGoogle Scholar |
[4] Geyer, R et al. (2017) Production, use, and fate of all plastics ever made. Sci Adv 3, e1700782.
| Production, use, and fate of all plastics ever made.Crossref | GoogleScholarGoogle Scholar |
[5] Chamas, A et al. (2020) Degradation rates of plastics in the environment. ACS Sustain Chem Eng 8, 3494–3511.
| Degradation rates of plastics in the environment.Crossref | GoogleScholarGoogle Scholar |
[6] United Nations Environment Programme (2014) Valuing plastic: the business case for measuring, managing and disclosing plastic use in the consumer goods industry. Division of Environmental Policy Implementation, UNEP. https://wedocs.unep.org/handle/20.500.11822/9238
[7] Australian Bureau of Statistics (2020) Waste Account, Australia, Experimental Estimates. ABS. https://www.abs.gov.au/statistics/environment/environmental-management/waste-account-australia-experimental-estimates/2018-19
[8] US Environmental Protection Agency (2022) Plastics: material–specific data. https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/plastics-material-specific-data
[9] Al-Salem, SM et al. (2009) Recycling and recovery routes of plastic solid waste (PSW): a review. Waste Manag 29, 2625–2643.
| Recycling and recovery routes of plastic solid waste (PSW): a review.Crossref | GoogleScholarGoogle Scholar |
[10] Shamsuyeva, M and Endres, H-J (2021) Plastics in the context of the circular economy and sustainable plastics recycling: comprehensive review on research development, standardization and market. Compos Part C Open Access 6, 100168.
| Plastics in the context of the circular economy and sustainable plastics recycling: comprehensive review on research development, standardization and market.Crossref | GoogleScholarGoogle Scholar |
[11] Zhu, B et al. (2022) Enzyme discovery and engineering for sustainable plastic recycling. Trends Biotechnol 40, 22–37.
| Enzyme discovery and engineering for sustainable plastic recycling.Crossref | GoogleScholarGoogle Scholar |
[12] Ragaert, K et al. (2017) Mechanical and chemical recycling of solid plastic waste. Waste Manag 69, 24–58.
| Mechanical and chemical recycling of solid plastic waste.Crossref | GoogleScholarGoogle Scholar |
[13] Rahimi, A and García, JM (2017) Chemical recycling of waste plastics for new materials production. Nat Rev Chem 1, 0046.
| Chemical recycling of waste plastics for new materials production.Crossref | GoogleScholarGoogle Scholar |
[14] Lee, A and Liew, MS (2021) Tertiary recycling of plastics waste: an analysis of feedstock, chemical and biological degradation methods. J Mater Cycles Waste Manag 23, 32–43.
| Tertiary recycling of plastics waste: an analysis of feedstock, chemical and biological degradation methods.Crossref | GoogleScholarGoogle Scholar |
[15] Moharir, RV and Kumar, S (2019) Challenges associated with plastic waste disposal and allied microbial routes for its effective degradation: a comprehensive review. J Clean Prod 208, 65–76.
| Challenges associated with plastic waste disposal and allied microbial routes for its effective degradation: a comprehensive review.Crossref | GoogleScholarGoogle Scholar |
[16] Lu, H et al. (2022) Machine learning-aided engineering of hydrolases for PET depolymerization. Nature 604, 662–667.
| Machine learning-aided engineering of hydrolases for PET depolymerization.Crossref | GoogleScholarGoogle Scholar |
[17] Tournier, V et al. (2020) An engineered PET depolymerase to break down and recycle plastic bottles. Nature 580, 216–219.
| An engineered PET depolymerase to break down and recycle plastic bottles.Crossref | GoogleScholarGoogle Scholar |
[18] Yoshida, S et al. (2016) A bacterium that degrades and assimilates poly(ethylene terephthalate). Science 351, 1196–1199.
| A bacterium that degrades and assimilates poly(ethylene terephthalate).Crossref | GoogleScholarGoogle Scholar |
[19] Sanluis-Verdes, A et al. (2022) Wax worm saliva and the enzymes therein are the key to polyethylene degradation by Galleria mellonella. Nat Commun 13, 5568.
| Wax worm saliva and the enzymes therein are the key to polyethylene degradation by Galleria mellonella.Crossref | GoogleScholarGoogle Scholar |
[20] Kawai, F et al. (2019) Current knowledge on enzymatic PET degradation and its possible application to waste stream management and other fields. Appl Microbiol Biotechnol 103, 4253–4268.
| Current knowledge on enzymatic PET degradation and its possible application to waste stream management and other fields.Crossref | GoogleScholarGoogle Scholar |
[21] Zhang, Y et al. (2022) Biodegradation of polyethylene and polystyrene: from microbial deterioration to enzyme discovery. Biotechnol Adv 60, 107991.
| Biodegradation of polyethylene and polystyrene: from microbial deterioration to enzyme discovery.Crossref | GoogleScholarGoogle Scholar |
[22] Jeon, J-M et al. (2021) Biodegradation of polyethylene and polypropylene by Lysinibacillus species JJY0216 isolated from soil grove. Polym Degrad Stab 191, 109662.
| Biodegradation of polyethylene and polypropylene by Lysinibacillus species JJY0216 isolated from soil grove.Crossref | GoogleScholarGoogle Scholar |
[23] Zhang, Z et al. (2022) Polyvinyl chloride degradation by a bacterium isolated from the gut of insect larvae. Nat Commun 13, 5360.
| Polyvinyl chloride degradation by a bacterium isolated from the gut of insect larvae.Crossref | GoogleScholarGoogle Scholar |
[24] European Commission (2021) Towards a true circular economy of PET plastics and textiles thanks to enzymatic recycling of waste. LIFE 3.0 - LIFE Project Public Page. https://webgate.ec.europa.eu/life/publicWebsite/project/details/5731
[25] Plastics Today (2022) Samsara Eco scales up carbon-neutral enzymatic recycling. https://www.plasticstoday.com/advanced-recycling/samsara-eco-scales-carbon-neutral-enzymatic-recycling
[26] Gambarini, V et al. (2021) Phylogenetic distribution of plastic-degrading microorganisms. mSystems 6, e01112-20.
| Phylogenetic distribution of plastic-degrading microorganisms.Crossref | GoogleScholarGoogle Scholar |
[27] Zrimec, J et al. (2021) Plastic-degrading potential across the global microbiome correlates with recent pollution trends. mBio 12, e02155-21.
| Plastic-degrading potential across the global microbiome correlates with recent pollution trends.Crossref | GoogleScholarGoogle Scholar |
[28] Yang, X-G et al. (2023) Plastic biodegradation by in vitro environmental microorganisms and in vivo gut microorganisms of insects. Front Microbiol 13, 1001750.
| Plastic biodegradation by in vitro environmental microorganisms and in vivo gut microorganisms of insects.Crossref | GoogleScholarGoogle Scholar |
[29] Sun, J et al. (2022) Insights into plastic biodegradation: community composition and functional capabilities of the superworm (Zophobas morio) microbiome in styrofoam feeding trials. Microb Genom 8, 000842.
| Insights into plastic biodegradation: community composition and functional capabilities of the superworm (Zophobas morio) microbiome in styrofoam feeding trials.Crossref | GoogleScholarGoogle Scholar |
[30] Oelschlägel, M et al. (2018) A review: the styrene metabolizing cascade of side-chain oxygenation as biotechnological basis to gain various valuable compounds. Front Microbiol 9, 490.
| A review: the styrene metabolizing cascade of side-chain oxygenation as biotechnological basis to gain various valuable compounds.Crossref | GoogleScholarGoogle Scholar |
[31] Joo, S et al. (2018) Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation. Nat Commun 9, 382.
| Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation.Crossref | GoogleScholarGoogle Scholar |
[32] Zhang, R et al. (2021) Gene silencing through CRISPR interference in bacteria: current advances and future prospects. Front Microbiol 12, 635227.
| Gene silencing through CRISPR interference in bacteria: current advances and future prospects.Crossref | GoogleScholarGoogle Scholar |
[33] Clure E (2022) Australian government pledges to recycle all plastics by 2040. In ABC News, 15 November 2022. https://www.abc.net.au/news/2022-11-15/australian-government-pledges-to-recycle-all-plastics-by-2040/101655630
[34] Vedelago C (2022) The fire that sparked the end of Coles and Woolies plastic recycling program. In The Sydney Morning Herald, 9 November 2022. https://www.smh.com.au/national/fire-signalled-fatal-end-to-coles-and-woolies-plastic-recycling-program-20221109-p5bwqb.html
[35] Phelan A (2022) REDcycle’s collapse is more proof that plastic recycling is a broken system. In The Conversation, 17 November 2022. http://theconversation.com/redcycles-collapse-is-more-proof-that-plastic-recycling-is-a-broken-system-194528
