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Méndez-Zamora A, Diaz-Vidal T, Robles-Machuca M, Pereira-Santana A, Casas-Godoy L. Unveiling potential PET degrading eukaryotes through in silico bioprospecting of PETases. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 948:174978. [PMID: 39047840 DOI: 10.1016/j.scitotenv.2024.174978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/05/2024] [Accepted: 07/21/2024] [Indexed: 07/27/2024]
Abstract
This study addresses the environmental problem of PET plastic through in silico bioprospecting for the identification and experimental validation of novel PET degrading eukaryotes through the in silico bioprospectingI of PETases, employing a methodology that combines Hidden Markov Models (HMMs), clustering techniques, molecular docking, and dynamic simulations. A total of 424 putative PETase sequences were identified from 219 eukaryotic organisms, highlighting six sequences with low affinity energies. The Aspergillus luchuensis sequence showed the lowest Gibbs free energy and exhibited stability at different temperatures in molecular dynamics assays. Experimental validation, through a plate clearance assay and HPLC, confirmed PETase activity in three wild-type fungal strains, with A. luchuensis showing the highest efficiency. The results obtained demonstrate the effectiveness of combining computational and experimental approaches as proof of concept to discover and validate eukaryotes with PET-degrading capabilities opening new perspectives for the sustainable management of this type of waste and contributing to its environmental mitigation.
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Affiliation(s)
- Andrés Méndez-Zamora
- Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ), Avenida Normalistas 800, Col. Colinas de la Normal, C.P. 44270 Guadalajara, Jalisco, Mexico
| | - Tania Diaz-Vidal
- Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ), Avenida Normalistas 800, Col. Colinas de la Normal, C.P. 44270 Guadalajara, Jalisco, Mexico
| | - Marcela Robles-Machuca
- Tecnologia de alimentos, Secretaría de Investigación y Posgrado, Universidad Autónoma de Nayarit, Ciudad de la Cultura s/n, C.P. 63000 Tepic, Nayarit, Mexico
| | - Alejandro Pereira-Santana
- CONAHCYT-Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Parque Científico Tecnológico de Yucatán, 97302 Mérida, Yucatán, Mexico.
| | - Leticia Casas-Godoy
- CONAHCYT-Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Camino Arenero 1227, El Bajío, 45019 Zapopan, Jalisco, Mexico.
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2
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Amanna R, Rakshit SK. Review of nomenclature and methods of analysis of polyethylene terephthalic acid hydrolyzing enzymes activity. Biodegradation 2024; 35:341-360. [PMID: 37688750 DOI: 10.1007/s10532-023-10048-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 08/15/2023] [Indexed: 09/11/2023]
Abstract
Enzymatic degradation of polyethylene terephthalic acid (PET) has been gaining increasing importance. This has resulted in a significant increase in the search for newer enzymes and the development of more efficient enzyme-based systems. Due to the lack of a standard screening process, screening new enzymes has relied on other assays to determine the presence of esterase activity. This, in turn, has led to various nomenclatures and methods used to describe them and measure their activity. Since all PET-hydrolyzing enzymes are α/β hydrolases, they catalyze a serine nucleophilic attack and cleave an ester bond. They are lipases, esterases, cutinases and hydrolases. This has been used interchangeably, leading to difficulties while comparing results and evaluating progress. This review discusses the varied enzyme nomenclature being adapted, the different assays and analysis methods reported, and the strategies used to increase PET-hydrolyzing enzyme efficiency. A section on the various ways to quantify PET hydrolysis is also covered.
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Affiliation(s)
- Ruth Amanna
- Department of Biotechnology, Lakehead University, Thunder Bay, ON, Canada
- Biorefining Research Institute (BRI), Lakehead University, Thunder Bay, ON, Canada
| | - Sudip K Rakshit
- Department of Biotechnology, Lakehead University, Thunder Bay, ON, Canada.
- Biorefining Research Institute (BRI), Lakehead University, Thunder Bay, ON, Canada.
- Department of Chemical Engineering, Lakehead University, Thunder Bay, ON, Canada.
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3
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Martín-González D, de la Fuente Tagarro C, De Lucas A, Bordel S, Santos-Beneit F. Genetic Modifications in Bacteria for the Degradation of Synthetic Polymers: A Review. Int J Mol Sci 2024; 25:5536. [PMID: 38791573 PMCID: PMC11121894 DOI: 10.3390/ijms25105536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/17/2024] [Indexed: 05/26/2024] Open
Abstract
Synthetic polymers, commonly known as plastics, are currently present in all aspects of our lives. Although they are useful, they present the problem of what to do with them after their lifespan. There are currently mechanical and chemical methods to treat plastics, but these are methods that, among other disadvantages, can be expensive in terms of energy or produce polluting gases. A more environmentally friendly alternative is recycling, although this practice is not widespread. Based on the practice of the so-called circular economy, many studies are focused on the biodegradation of these polymers by enzymes. Using enzymes is a harmless method that can also generate substances with high added value. Novel and enhanced plastic-degrading enzymes have been obtained by modifying the amino acid sequence of existing ones, especially on their active site, using a wide variety of genetic approaches. Currently, many studies focus on the common aim of achieving strains with greater hydrolytic activity toward a different range of plastic polymers. Although in most cases the depolymerization rate is improved, more research is required to develop effective biodegradation strategies for plastic recycling or upcycling. This review focuses on a compilation and discussion of the most important research outcomes carried out on microbial biotechnology to degrade and recycle plastics.
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Affiliation(s)
- Diego Martín-González
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; (D.M.-G.); (A.D.L.); (S.B.)
| | - Carlos de la Fuente Tagarro
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; (D.M.-G.); (A.D.L.); (S.B.)
| | - Andrea De Lucas
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; (D.M.-G.); (A.D.L.); (S.B.)
| | - Sergio Bordel
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; (D.M.-G.); (A.D.L.); (S.B.)
- Institute of Sustainable Processes, Dr. Mergelina s/n, 47011 Valladolid, Spain
| | - Fernando Santos-Beneit
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, 47011 Valladolid, Spain; (D.M.-G.); (A.D.L.); (S.B.)
- Institute of Sustainable Processes, Dr. Mergelina s/n, 47011 Valladolid, Spain
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4
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Torres de Oliveira C, Alexandrino de Assis M, Lourenço Franco Cairo JP, Damasio A, Guimarães Pereira GA, Mazutti MA, de Oliveira D. Functional characterization and structural insights of three cutinases from the ascomycete Fusarium verticillioides. Protein Expr Purif 2024; 216:106415. [PMID: 38104791 DOI: 10.1016/j.pep.2023.106415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
Cutinases are serine esterases that belong to the α/β hydrolases superfamily. The natural substrates for these enzymes are cutin and suberin, components of the plant cuticle, the first barrier in the defense system against pathogen invasion. It is well-reported that plant pathogens produce cutinases to facilitate infection. Fusarium verticillioides, one important corn pathogens, is an ascomycete upon which its cutinases are poorly explored. Consequently, the objective of this study was to perform the biochemical characterization of three precursor cutinases (FvCut1, FvCut2, and FvCut3) from F. verticillioides and to obtain structural insights about them. The cutinases were produced in Escherichia coli and purified. FvCut1, FvCut2, and FvCut3 presented optimal temperatures of 20, 40, and 35 °C, and optimal pH of 9, 7, and 8, respectively. Some chemicals stimulated the enzymatic activity. The kinetic parameters revealed that FvCut1 has higher catalytic efficiency (Kcat/Km) in the p-nitrophenyl-butyrate (p-NPB) substrate. Nevertheless, the enzymes were not able to hydrolyze polyethylene terephthalate (PET). Furthermore, the three-dimensional models of these enzymes showed structural differences among them, mainly FvCut1, which presented a narrower opening cleft to access the catalytic site. Therefore, our study contributes to exploring the diversity of fungal cutinases and their potential biotechnological applications.
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Affiliation(s)
- Caroline Torres de Oliveira
- Department of Chemical and Food Engineering, Technology Center, Federal University of Santa Catarina, UFSC, Florianópolis, Brazil
| | - Michelle Alexandrino de Assis
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, Brazil
| | | | - André Damasio
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, Brazil
| | | | - Marcio Antonio Mazutti
- Department of Chemical Engineering, Technology Center, Federal University of Santa Maria, UFSM, Santa Maria, Brazil
| | - Débora de Oliveira
- Department of Chemical and Food Engineering, Technology Center, Federal University of Santa Catarina, UFSC, Florianópolis, Brazil.
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5
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Choi J, Kim H, Ahn YR, Kim M, Yu S, Kim N, Lim SY, Park JA, Ha SJ, Lim KS, Kim HO. Recent advances in microbial and enzymatic engineering for the biodegradation of micro- and nanoplastics. RSC Adv 2024; 14:9943-9966. [PMID: 38528920 PMCID: PMC10961967 DOI: 10.1039/d4ra00844h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024] Open
Abstract
This review examines the escalating issue of plastic pollution, specifically highlighting the detrimental effects on the environment and human health caused by microplastics and nanoplastics. The extensive use of synthetic polymers such as polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) has raised significant environmental concerns because of their long-lasting and non-degradable characteristics. This review delves into the role of enzymatic and microbial strategies in breaking down these polymers, showcasing recent advancements in the field. The intricacies of enzymatic degradation are thoroughly examined, including the effectiveness of enzymes such as PETase and MHETase, as well as the contribution of microbial pathways in breaking down resilient polymers into more benign substances. The paper also discusses the impact of chemical composition on plastic degradation kinetics and emphasizes the need for an approach to managing the environmental impact of synthetic polymers. The review highlights the significance of comprehending the physical characteristics and long-term impacts of micro- and nanoplastics in different ecosystems. Furthermore, it points out the environmental and health consequences of these contaminants, such as their ability to cause cancer and interfere with the endocrine system. The paper emphasizes the need for advanced analytical methods and effective strategies for enzymatic degradation, as well as continued research and development in this area. This review highlights the crucial role of enzymatic and microbial strategies in addressing plastic pollution and proposes methods to create effective and environmentally friendly solutions.
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Affiliation(s)
- Jaewon Choi
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Hongbin Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Yu-Rim Ahn
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Minse Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Seona Yu
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Nanhyeon Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Su Yeon Lim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Jeong-Ann Park
- Department of Environmental Engineering, Kangwon National University Chuncheon 24341 Republic of Korea
| | - Suk-Jin Ha
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Kwang Suk Lim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Hyun-Ouk Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
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6
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Bell EL, Rosetto G, Ingraham MA, Ramirez KJ, Lincoln C, Clarke RW, Gado JE, Lilly JL, Kucharzyk KH, Erickson E, Beckham GT. Natural diversity screening, assay development, and characterization of nylon-6 enzymatic depolymerization. Nat Commun 2024; 15:1217. [PMID: 38336849 PMCID: PMC10858056 DOI: 10.1038/s41467-024-45523-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
Successes in biocatalytic polyester recycling have raised the possibility of deconstructing alternative polymers enzymatically, with polyamide (PA) being a logical target due to the array of amide-cleaving enzymes present in nature. Here, we screen 40 potential natural and engineered nylon-hydrolyzing enzymes (nylonases), using mass spectrometry to quantify eight compounds resulting from enzymatic nylon-6 (PA6) hydrolysis. Comparative time-course reactions incubated at 40-70 °C showcase enzyme-dependent variations in product distributions and extent of PA6 film depolymerization, with significant nylon deconstruction activity appearing rare. The most active nylonase, a NylCK variant we rationally thermostabilized (an N-terminal nucleophile (Ntn) hydrolase, NylCK-TS, Tm = 87.4 °C, 16.4 °C higher than the wild-type), hydrolyzes 0.67 wt% of a PA6 film. Reactions fail to restart after fresh enzyme addition, indicating that substrate-based limitations, such as restricted enzyme access to hydrolysable bonds, prohibit more extensive deconstruction. Overall, this study expands our understanding of nylonase activity distribution, indicates that Ntn hydrolases may have the greatest potential for further development, and identifies key targets for progressing PA6 enzymatic depolymerization, including improving enzyme activity, product selectivity, and enhancing polymer accessibility.
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Affiliation(s)
- Elizabeth L Bell
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Gloria Rosetto
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Morgan A Ingraham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Kelsey J Ramirez
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Clarissa Lincoln
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Ryan W Clarke
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Japheth E Gado
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Jacob L Lilly
- Battelle Memorial Institute, Columbus, OH, 43201, USA
| | | | - Erika Erickson
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
- BOTTLE Consortium, Golden, CO, 80401, USA
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
- BOTTLE Consortium, Golden, CO, 80401, USA.
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Shi L, Zhu L. Recent Advances and Challenges in Enzymatic Depolymerization and Recycling of PET Wastes. Chembiochem 2024; 25:e202300578. [PMID: 37960968 DOI: 10.1002/cbic.202300578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/12/2023] [Accepted: 11/13/2023] [Indexed: 11/15/2023]
Abstract
Poly (ethylene terephthalate) (PET) is one of the most commonly used plastics in daily life and various industries. Enzymatic depolymerization and recycling of post-consumer PET (pc-PET) provides a promising strategy for the sustainable circular economy of polymers. Great protein engineering efforts have been devoted to improving the depolymerization performance of PET hydrolytic enzymes (PHEs). In this review, we first discuss the mechanisms and challenges of enzymatic PET depolymerization. Subsequently, we summarize the state-of-the-art engineering of PHEs including rational design, machine learning, and directed evolution for improved depolymerization performance, and highlight the advances in screening methods of PHEs. We further discuss several factors that affect the enzymatic depolymerization efficiency. We conclude with our perspective on the opportunities and challenges in bio-recycling and bio-upcycling of PET wastes.
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Affiliation(s)
- Lixia Shi
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Leilei Zhu
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, China
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8
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Qiu J, Chen Y, Zhang L, Wu J, Zeng X, Shi X, Liu L, Chen J. A comprehensive review on enzymatic biodegradation of polyethylene terephthalate. ENVIRONMENTAL RESEARCH 2024; 240:117427. [PMID: 37865324 DOI: 10.1016/j.envres.2023.117427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/11/2023] [Accepted: 10/15/2023] [Indexed: 10/23/2023]
Abstract
Polyethylene terephthalate (PET) is a polymer synthesized via the dehydration and condensation reaction between ethylene glycol and terephthalic acid. PET has emerged as one of the most extensively employed plastic materials due to its exceptional plasticity and durability. Nevertheless, PET has a complex structure and is extremely difficult to degrade in nature, causing severe pollution to the global ecological environment and posing a threat to human health. Currently, the methods for PET processing mainly include physical, chemical, and biological methods. Biological enzyme degradation is considered the most promising PET degradation method. In recent years, an increasing number of enzymes that can degrade PET have been identified, and they primarily target the ester bond of PET. This review comprehensively introduced the latest research progress in PET enzymatic degradation from the aspects of PET-degrading enzymes, PET biodegradation pathways, the catalytic mechanism of PET-degrading enzymes, and biotechnological strategies for enhancing PET-degrading enzymes. On this basis, the current challenges within the enzymatic PET degradation process were summarized, and the directions that need to be worked on in the future were pointed out. This review provides a reference and basis for the subsequent effective research on PET biodegradation.
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Affiliation(s)
- Jiarong Qiu
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China; Development Center of Science and Education Park of Fuzhou University, Jinjiang, 362251, China
| | - Yuxin Chen
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China
| | - Liangqing Zhang
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China; Development Center of Science and Education Park of Fuzhou University, Jinjiang, 362251, China.
| | - Jinzhi Wu
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China
| | - Xianhai Zeng
- College of Energy, Xiamen University, Xiamen 361102, China
| | - Xinguo Shi
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China
| | - Lemian Liu
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China
| | - Jianfeng Chen
- School of Advanced Manufacturing, Fuzhou University, Jinjiang 362251, China
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9
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Sui B, Wang T, Fang J, Hou Z, Shu T, Lu Z, Liu F, Zhu Y. Recent advances in the biodegradation of polyethylene terephthalate with cutinase-like enzymes. Front Microbiol 2023; 14:1265139. [PMID: 37849919 PMCID: PMC10577388 DOI: 10.3389/fmicb.2023.1265139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/15/2023] [Indexed: 10/19/2023] Open
Abstract
Polyethylene terephthalate (PET) is a synthetic polymer in the polyester family. It is widely found in objects used daily, including packaging materials (such as bottles and containers), textiles (such as fibers), and even in the automotive and electronics industries. PET is known for its excellent mechanical properties, chemical resistance, and transparency. However, these features (e.g., high hydrophobicity and high molecular weight) also make PET highly resistant to degradation by wild-type microorganisms or physicochemical methods in nature, contributing to the accumulation of plastic waste in the environment. Therefore, accelerated PET recycling is becoming increasingly urgent to address the global environmental problem caused by plastic wastes and prevent plastic pollution. In addition to traditional physical cycling (e.g., pyrolysis, gasification) and chemical cycling (e.g., chemical depolymerization), biodegradation can be used, which involves breaking down organic materials into simpler compounds by microorganisms or PET-degrading enzymes. Lipases and cutinases are the two classes of enzymes that have been studied extensively for this purpose. Biodegradation of PET is an attractive approach for managing PET waste, as it can help reduce environmental pollution and promote a circular economy. During the past few years, great advances have been accomplished in PET biodegradation. In this review, current knowledge on cutinase-like PET hydrolases (such as TfCut2, Cut190, HiC, and LCC) was described in detail, including the structures, ligand-protein interactions, and rational protein engineering for improved PET-degrading performance. In particular, applications of the engineered catalysts were highlighted, such as improving the PET hydrolytic activity by constructing fusion proteins. The review is expected to provide novel insights for the biodegradation of complex polymers.
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Affiliation(s)
- Beibei Sui
- School of Biological Science, Jining Medical University, Jining, Shandong, China
| | - Tao Wang
- School of Biological Science, Jining Medical University, Jining, Shandong, China
| | - Jingxiang Fang
- Rizhao Administration for Market Regulation, Rizhao, Shandong, China
| | - Zuoxuan Hou
- School of Biological Science, Jining Medical University, Jining, Shandong, China
| | - Ting Shu
- School of Biological Science, Jining Medical University, Jining, Shandong, China
| | - Zhenhua Lu
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang, China
| | - Fei Liu
- School of Biological Science, Jining Medical University, Jining, Shandong, China
| | - Youshuang Zhu
- School of Biological Science, Jining Medical University, Jining, Shandong, China
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10
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Li A, Cui H, Sheng Y, Qiao J, Li X, Huang H. Global plastic upcycling during and after the COVID-19 pandemic: The status and perspective. JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2023; 11:110092. [PMID: 37200549 PMCID: PMC10167783 DOI: 10.1016/j.jece.2023.110092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/10/2023] [Accepted: 05/08/2023] [Indexed: 05/20/2023]
Abstract
Plastic pollution has become one of the most pressing environmental issues worldwide since the vast majority of post-consumer plastics are hard to degrade in the environment. The coronavirus disease (COVID-19) pandemic had disrupted the previous effort of plastic pollution mitigation to a great extent due to the overflow of plastic-based medical waste. In the post-pandemic era, the remaining challenge is how to motivate global action towards a plastic circular economy. The need for one package of sustainable and systematic plastic upcycling approaches has never been greater to address such a challenge. In this review, we summarized the threat of plastic pollution during COVID-19 to public health and ecosystem. In order to solve the aforementioned challenges, we present a shifting concept, regeneration value from plastic waste, that provides four promising pathways to achieve a sustainable circular economy: 1) Increasing reusability and biodegradability of plastics; 2) Transforming plastic waste into high-value products by chemical approaches; 3) The closed-loop recycling can be promoted by biodegradation; 4) Involving renewable energy into plastic upcycling. Additionally, the joint efforts from different social perspectives are also encouraged to create the necessary economic and environmental impetus for a circular economy.
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Affiliation(s)
- Anni Li
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Haiyang Cui
- RWTH Aachen University, Templergraben 55, 52062 Aachen, Germany
| | - Yijie Sheng
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Jie Qiao
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - Xiujuan Li
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
| | - He Huang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210009, People's Republic of China
- School of Pharmaceutical Sciences, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
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11
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Sevilla ME, Garcia MD, Perez-Castillo Y, Armijos-Jaramillo V, Casado S, Vizuete K, Debut A, Cerda-Mejía L. Degradation of PET Bottles by an Engineered Ideonella sakaiensis PETase. Polymers (Basel) 2023; 15:polym15071779. [PMID: 37050393 PMCID: PMC10098701 DOI: 10.3390/polym15071779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/14/2023] Open
Abstract
Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. In recent years, enzymatic degradation of PET by Ideonella sakaiensis PETase (IsPETase), a cutinase-like enzyme, has emerged as a promising strategy to completely depolymerize this polymer into its building blocks. Here, inspired by the architecture of cutinases and lipases homologous to IsPETase and using 3D structure information of the enzyme, we rationally designed three mutations in IsPETase active site for enhancing its PET-degrading activity. In particular, the S238Y mutant, located nearby the catalytic triad, showed a degradation activity increased by 3.3-fold in comparison to the wild-type enzyme. Importantly, this structural modification favoured the function of the enzyme in breaking down highly crystallized (~31%) PET, which is found in commercial soft drink bottles. In addition, microscopical analysis of enzyme-treated PET samples showed that IsPETase acts better when the smooth surface of highly crystalline PET is altered by mechanical stress. These results represent important progress in the accomplishment of a sustainable and complete degradation of PET pollution.
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Affiliation(s)
- Maria Eduarda Sevilla
- Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología, Universidad Técnica de Ambato, Ambato 180216, Ecuador
| | - Mario D Garcia
- Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología, Universidad Técnica de Ambato, Ambato 180216, Ecuador
| | - Yunierkis Perez-Castillo
- Área de Ciencias Aplicadas, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de Las Américas, Quito 170125, Ecuador
- Grupo de Bio-Quimioinformática, Universidad de Las Américas, Quito 170125, Ecuador
| | - Vinicio Armijos-Jaramillo
- Grupo de Bio-Quimioinformática, Universidad de Las Américas, Quito 170125, Ecuador
- Ingeniería en Biotecnología, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de Las Américas, Quito 170125, Ecuador
| | - Santiago Casado
- Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología, Universidad Técnica de Ambato, Ambato 180216, Ecuador
| | - Karla Vizuete
- Centro de Nanociencia y Nanotecnología, Universidad de Las Fuerzas Armadas ESPE, Sangolquí 171103, Ecuador
| | - Alexis Debut
- Centro de Nanociencia y Nanotecnología, Universidad de Las Fuerzas Armadas ESPE, Sangolquí 171103, Ecuador
- Departamento de Ciencias de la Vida y Agricultura, Universidad de Las Fuerzas Armadas ESPE, Sangolquí 171103, Ecuador
| | - Liliana Cerda-Mejía
- Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología, Universidad Técnica de Ambato, Ambato 180216, Ecuador
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12
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Hellesnes KN, Vijayaraj S, Fojan P, Petersen E, Courtade G. Biochemical Characterization and NMR Study of a PET-Hydrolyzing Cutinase from Fusarium solani pisi. Biochemistry 2023; 62:1369-1375. [PMID: 36967526 PMCID: PMC10116592 DOI: 10.1021/acs.biochem.2c00619] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
In recent years, the drawbacks of plastics have become evident, with plastic pollution becoming a major environmental issue. There is an urgent need to find solutions to efficiently manage plastic waste by using novel recycling methods. Biocatalytic recycling of plastics by using enzyme-catalyzed hydrolysis is one such solution that has gained interest, in particular for recycling poly(ethylene terephthalate) (PET). To provide insights into PET hydrolysis by cutinases, we have here characterized the kinetics of a PET-hydrolyzing cutinase from Fusarium solani pisi (FsC) at different pH values, mapped the interaction between FsC and the PET analogue BHET by using NMR spectroscopy, and monitored product release directly and in real time by using time-resolved NMR experiments. We found that primarily aliphatic side chains around the active site participate in the interaction with BHET and that pH conditions and a mutation around the active site (L182A) can be used to tune the relative amounts of degradation products. Moreover, we propose that the low catalytic performance of FsC on PET is caused by poor substrate binding combined with slow MHET hydrolysis. Overall, our results provide insights into obstacles that preclude efficient PET hydrolysis by FsC and suggest future approaches for overcoming these obstacles and generating efficient PET-hydrolyzing enzymes.
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13
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Determinants for an Efficient Enzymatic Catalysis in Poly(Ethylene Terephthalate) Degradation. Catalysts 2023. [DOI: 10.3390/catal13030591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
The enzymatic degradation of the recalcitrant poly(ethylene terephthalate) (PET) has been an important biotechnological goal. The present review focuses on the state of the art in enzymatic degradation of PET, and the challenges ahead. This review covers (i) enzymes acting on PET, (ii) protein improvements through selection or engineering, (iii) strategies to improve biocatalyst–polymer interaction and monomer yields. Finally, this review discusses critical points on PET degradation, and their related experimental aspects, that include the control of physicochemical parameters. The search for, and engineering of, PET hydrolases, have been widely studied to achieve this, and several examples are discussed here. Many enzymes, from various microbial sources, have been studied and engineered, but recently true PET hydrolases (PETases), active at moderate temperatures, were reported. For a circular economy process, terephtalic acid (TPA) production is critical. Some thermophilic cutinases and engineered PETases have been reported to release terephthalic acid in significant amounts. Some bottlenecks in enzyme performance are discussed, including enzyme activity, thermal stability, substrate accessibility, PET microstructures, high crystallinity, molecular mass, mass transfer, and efficient conversion into reusable fragments.
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14
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Tournier V, Duquesne S, Guillamot F, Cramail H, Taton D, Marty A, André I. Enzymes' Power for Plastics Degradation. Chem Rev 2023; 123:5612-5701. [PMID: 36916764 DOI: 10.1021/acs.chemrev.2c00644] [Citation(s) in RCA: 56] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Plastics are everywhere in our modern way of living, and their production keeps increasing every year, causing major environmental concerns. Nowadays, the end-of-life management involves accumulation in landfills, incineration, and recycling to a lower extent. This ecological threat to the environment is inspiring alternative bio-based solutions for plastic waste treatment and recycling toward a circular economy. Over the past decade, considerable efforts have been made to degrade commodity plastics using biocatalytic approaches. Here, we provide a comprehensive review on the recent advances in enzyme-based biocatalysis and in the design of related biocatalytic processes to recycle or upcycle commodity plastics, including polyesters, polyamides, polyurethanes, and polyolefins. We also discuss scope and limitations, challenges, and opportunities of this field of research. An important message from this review is that polymer-assimilating enzymes are very likely part of the solution to reaching a circular plastic economy.
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Affiliation(s)
- Vincent Tournier
- Carbios, Parc Cataroux-Bâtiment B80, 8 rue de la Grolière, 63100 Clermont-Ferrand, France
| | - Sophie Duquesne
- Toulouse Biotechnology Institute, TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France, 135, avenue de Rangueil, F-31077 Toulouse Cedex 04, France
| | - Frédérique Guillamot
- Carbios, Parc Cataroux-Bâtiment B80, 8 rue de la Grolière, 63100 Clermont-Ferrand, France
| | - Henri Cramail
- Université Bordeaux, CNRS, Bordeaux INP, LCPO, 16 Avenue Pey-Berland, 33600 Pessac, France
| | - Daniel Taton
- Université Bordeaux, CNRS, Bordeaux INP, LCPO, 16 Avenue Pey-Berland, 33600 Pessac, France
| | - Alain Marty
- Carbios, Parc Cataroux-Bâtiment B80, 8 rue de la Grolière, 63100 Clermont-Ferrand, France
| | - Isabelle André
- Toulouse Biotechnology Institute, TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France, 135, avenue de Rangueil, F-31077 Toulouse Cedex 04, France
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15
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Cannon JA, Reynolds TB. Synergistic Mutations Create Bacillus Subtilisin Variants with Enhanced Poly-l-Lactic Acid Depolymerization Activity. Biomacromolecules 2023; 24:1141-1154. [PMID: 36780360 DOI: 10.1021/acs.biomac.2c01198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Enzymatic recycling of poly-l-lactic acid (PLLA) plastic has recently become an area of interest; however, investigation of enzymatic mechanisms and engineering strategies to improve activity remains limited. In this study, we have identified a subtilisin from Bacillus pumilus that has the ability to depolymerize high-molecular-weight PLLA. We performed a comparative, mutational analysis of this enzyme with a less active homologue from Bacillus subtilis to determine residues favored for activity. Our results demonstrate that both enzymes contain residues favored for PLLA depolymerization, with the generation of several hyperactive variants. In silico modeling suggests that increases in activity are due to opening of the binding pockets and increased surface hydrophobicity. Combinations of hyperactive mutations have synergistic effects with the generation of subtilisin variants with 830- and 184-fold increases in activity for B. subtilis and B. pumilus subtilisins, respectively. One B. pumilus subtilisin variant can visibly dissolve high-molecular-weight PLLA films.
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Affiliation(s)
- Jordan A Cannon
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee 37996, United States
| | - Todd B Reynolds
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee 37996, United States
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16
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Kumar V, Sharma N, Duhan L, Pasrija R, Thomas J, Umesh M, Lakkaboyana SK, Andler R, Vangnai AS, Vithanage M, Awasthi MK, Chia WY, LokeShow P, Barceló D. Microbial engineering strategies for synthetic microplastics clean up: A review on recent approaches. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023; 98:104045. [PMID: 36572198 DOI: 10.1016/j.etap.2022.104045] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/25/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Microplastics are the small fragments of the plastic molecules which find their applications in various routine products such as beauty products. Later, it was realized that it has several toxic effects on marine and terrestrial organisms. This review is an approach in understanding the microplastics, their origin, dispersal in the aquatic system, their biodegradation and factors affecting biodegradation. In addition, the paper discusses the major engineering approaches applied in microbial biotechnology. Specifically, it reviews microbial genetic engineering, such as PET-ase engineering, MHET-ase engineering, and immobilization approaches. Moreover, the major challenges associated with the plastic removal are presented by evaluating the recent reports available.
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Affiliation(s)
- Vinay Kumar
- Department of Community Medicine, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences (SIMATS), Thandalam, Chennai 602105, India; Ecotoxicity and Bioconversion Laboratory, Department of Community Medicine, Saveetha Medical College and Hospital, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai, Thandalam 602105, India.
| | - Neha Sharma
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Lucky Duhan
- Department of Biochemistry, Maharshi Dayanand University, Rohtak, India
| | - Ritu Pasrija
- Department of Biochemistry, Maharshi Dayanand University, Rohtak, India
| | - Jithin Thomas
- Department of Biotechnology, Mar Athanasius College, Kerala, India
| | - Mridul Umesh
- Department of Life Sciences, CHRIST (Deemed to be University), Bengaluru 560029, Karnataka, India
| | - Sivarama Krishna Lakkaboyana
- Department of Chemistry, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi, Chennai 600062, India
| | - Rodrigo Andler
- Escuela de Ingeniería en Biotecnología, Centro de Biotecnología de los Recursos Naturales (Cenbio), Universidad Católica del Maule, Chile
| | - Alisa S Vangnai
- Center of Excellence in Biocatalyst and Sustainable Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Meththika Vithanage
- Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka
| | - Mukesh Kumar Awasthi
- College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
| | - Wen Yi Chia
- Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, 43500 Semenyih, Selangor Darul Ehsan, Malaysia
| | - Pau LokeShow
- Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, 43500 Semenyih, Selangor Darul Ehsan, Malaysia; Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China; Department of Sustainable Engineering, Saveetha School of Engineering, SIMATS, Chennai 602105, India
| | - Damià Barceló
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research, IDAEA-CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain; Catalan Institute for Water Research (ICRA-CERCA), Parc Científic i Tecnològic de la Universitat de Girona, c/Emili Grahit, 101, Edifici H2O, 17003 Girona, Spain; Sustainability Cluster, School of Engineering, UPES, Dehradun, India
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17
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N-Amidation of Nitrogen-Containing Heterocyclic Compounds: Can We Apply Enzymatic Tools? Bioengineering (Basel) 2023; 10:bioengineering10020222. [PMID: 36829716 PMCID: PMC9951958 DOI: 10.3390/bioengineering10020222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/20/2023] [Accepted: 01/31/2023] [Indexed: 02/10/2023] Open
Abstract
Amide bond is often seen in value-added nitrogen-containing heterocyclic compounds, which can present promising chemical, biological, and pharmaceutical significance. However, current synthesis methods in the preparation of amide-containing N-heterocyclic compounds have low specificity (large amount of by-products) and efficiency. In this study, we focused on reviewing the feasible enzymes (nitrogen acetyltransferase, carboxylic acid reductase, lipase, and cutinase) for the amidation of N-heterocyclic compounds; summarizing their advantages and weakness in the specific applications; and further predicting candidate enzymes through in silico structure-functional analysis. For future prospects, current enzymes demand further engineering and improving for practical industrial applications and more enzymatic tools need to be explored and developed for a broader range of N-heterocyclic substrates.
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18
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An NMR look at an engineered PET depolymerase. Biophys J 2022; 121:2882-2894. [PMID: 35794828 PMCID: PMC9388554 DOI: 10.1016/j.bpj.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/15/2022] [Accepted: 06/30/2022] [Indexed: 12/30/2022] Open
Abstract
Plastic environmental pollution is a major issue that our generation must face to protect our planet. Plastic recycling has the potential not only to reduce the pollution but also to limit the need for fossil-fuel-based production of new plastics. Enzymes capable of breaking down plastic could thereby support such a circular economy. Polyethylene terephthalate (PET) degrading enzymes have recently attracted considerable interest and have been subjected to intensive enzyme engineering to improve their characteristics. A quadruple mutant of Leaf-branch Compost Cutinase (LCC) was identified as a most efficient and promising enzyme. Here, we use NMR to follow the initial LCC enzyme through its different mutations that lead to its improved performance. We experimentally define the two calcium-binding sites and show their importance on the all-or-nothing thermal unfolding process, which occurs at a temperature of 72°C close to the PET glass transition temperature. Using various NMR probes such as backbone amide, methyl group, and histidine side-chain resonances, we probe the interaction of the enzymes with mono-(2-hydroxyethyl)terephthalic acid. The latter experiments are interpreted in terms of accessibility of the active site to the polymer chain.
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19
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Fungal Enzymes Involved in Plastics Biodegradation. Microorganisms 2022; 10:microorganisms10061180. [PMID: 35744698 PMCID: PMC9230134 DOI: 10.3390/microorganisms10061180] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 12/04/2022] Open
Abstract
Plastic pollution is a growing environmental problem, in part due to the extremely stable and durable nature of this polymer. As recycling does not provide a complete solution, research has been focusing on alternative ways of degrading plastic. Fungi provide a wide array of enzymes specialized in the degradation of recalcitrant substances and are very promising candidates in the field of plastic degradation. This review examines the present literature for different fungal enzymes involved in plastic degradation, describing their characteristics, efficacy and biotechnological applications. Fungal laccases and peroxidases, generally used by fungi to degrade lignin, show good results in degrading polyethylene (PE) and polyvinyl chloride (PVC), while esterases such as cutinases and lipases were successfully used to degrade polyethylene terephthalate (PET) and polyurethane (PUR). Good results were also obtained on PUR by fungal proteases and ureases. All these enzymes were isolated from many different fungi, from both Basidiomycetes and Ascomycetes, and have shown remarkable efficiency in plastic biodegradation under laboratory conditions. Therefore, future research should focus on the interactions between the genes, proteins, metabolites and environmental conditions involved in the processes. Further steps such as the improvement in catalytic efficiency and genetic engineering could lead these enzymes to become biotechnological applications in the field of plastic degradation.
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20
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Zhang Y, Pedersen JN, Eser BE, Guo Z. Biodegradation of polyethylene and polystyrene: From microbial deterioration to enzyme discovery. Biotechnol Adv 2022; 60:107991. [PMID: 35654281 DOI: 10.1016/j.biotechadv.2022.107991] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/10/2022] [Accepted: 05/26/2022] [Indexed: 11/24/2022]
Abstract
The global production of plastics has continuously been soaring over the last decades due to their extensive use in our daily life and in industries. Although synthetic plastics offer great advantages from packaging to construction and electronics, their low biodegradability induce serious plastic pollution that damage the environment, human health and make irreversible changes in the ecological cycle. In particular, plastics containing only carbon-carbon (C-C) backbone are less susceptible to degradation due to the lack of hydrolysable groups. The representative polyethylene (PE) and polystyrene (PS) account for about 40% of the total plastic production. Various chemical and biological processes with great potential have been developed for plastic recycle and reuse, but biodegradation seems to be the most attractive and eco-friendly method to combat this growing environmental problem. In this review, we first summarize the current advances in PE and PS biodegradation, including isolation of microbes and potential degrading enzymes from different sources. Next, the state-of-the-art techniques used for evaluating and monitoring PE and PS degradation, the scientific toolboxes for enzyme discovery as well as the challenges and strategies for plastic biodegradation are intensively discussed. In return, it inspires a further technological exploration in expanding the diversity of species and enzymes, disclosing the essential pathways and developing new approaches to utilize plastic waste as feedstock for recycling and upcycling.
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Affiliation(s)
- Yan Zhang
- Department of Biological and Chemical Engineering, Aarhus University, 8000 Aarhus, Denmark
| | | | - Bekir Engin Eser
- Department of Biological and Chemical Engineering, Aarhus University, 8000 Aarhus, Denmark
| | - Zheng Guo
- Department of Biological and Chemical Engineering, Aarhus University, 8000 Aarhus, Denmark.
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21
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Delangiz N, Aliyar S, Pashapoor N, Nobaharan K, Asgari Lajayer B, Rodríguez-Couto S. Can polymer-degrading microorganisms solve the bottleneck of plastics' environmental challenges? CHEMOSPHERE 2022; 294:133709. [PMID: 35074325 DOI: 10.1016/j.chemosphere.2022.133709] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/27/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Increasing world population and industrial activities have enhanced anthropogenic pollution, plastic pollution being especially alarming. So, plastics should be recycled and/or make them biodegradable. Chemical and physical remediating methods are usually energy consuming and costly. In addition, they are not ecofriendly and usually produce toxic byproducts. Bioremediation is a proper option as it is cost-efficient and environmentally friendly. Plastic production and consumption are increasing daily, and, as a consequence, more microorganisms are exposed to these nonbiodegradable polymers. Therefore, investigating new efficient microorganisms and increasing the knowledge about their biology can pave the way for efficient and feasible plastic bioremediation processes. In this sense, omics, systems biology and bioinformatics are three important fields to analyze the biodegradation pathways in microorganisms. Based on the above-mentioned technologies, researchers can engineer microorganisms with specific desired properties to make bioremediation more efficient.
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Affiliation(s)
- Nasser Delangiz
- Department of Plant Biotechnology and Breeding, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
| | - Sajad Aliyar
- Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
| | - Neda Pashapoor
- Department of Soil Science, Faculty of Agriculture, Urmia University, Urmia, Iran
| | | | - Behnam Asgari Lajayer
- Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
| | - Susana Rodríguez-Couto
- Department of Separation Science, LUT School of Engineering Science, LUT University, Sammonkatu 12, FI-50130 Mikkeli, Finland
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22
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Wei R, von Haugwitz G, Pfaff L, Mican J, Badenhorst CP, Liu W, Weber G, Austin HP, Bednar D, Damborsky J, Bornscheuer UT. Mechanism-Based Design of Efficient PET Hydrolases. ACS Catal 2022; 12:3382-3396. [PMID: 35368328 PMCID: PMC8939324 DOI: 10.1021/acscatal.1c05856] [Citation(s) in RCA: 74] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/04/2022] [Indexed: 01/06/2023]
Abstract
Polyethylene terephthalate (PET) is the most widespread synthetic polyester, having been utilized in textile fibers and packaging materials for beverages and food, contributing considerably to the global solid waste stream and environmental plastic pollution. While enzymatic PET recycling and upcycling have recently emerged as viable disposal methods for a circular plastic economy, only a handful of benchmark enzymes have been thoroughly described and subjected to protein engineering for improved properties over the last 16 years. By analyzing the specific material properties of PET and the reaction mechanisms in the context of interfacial biocatalysis, this Perspective identifies several limitations in current enzymatic PET degradation approaches. Unbalanced enzyme-substrate interactions, limited thermostability, and low catalytic efficiency at elevated reaction temperatures, and inhibition caused by oligomeric degradation intermediates still hamper industrial applications that require high catalytic efficiency. To overcome these limitations, successful protein engineering studies using innovative experimental and computational approaches have been published extensively in recent years in this thriving research field and are summarized and discussed in detail here. The acquired knowledge and experience will be applied in the near future to address plastic waste contributed by other mass-produced polymer types (e.g., polyamides and polyurethanes) that should also be properly disposed by biotechnological approaches.
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Affiliation(s)
- Ren Wei
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany,
| | - Gerlis von Haugwitz
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - Lara Pfaff
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - Jan Mican
- Loschmidt
Laboratories, Department of Experimental Biology and RECETOX, Faculty
of Science, Masaryk University, 625 00 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s University Hospital and
Faculty of Medicine, Masaryk University, 656 91 Brno, Czech Republic
| | - Christoffel P.
S. Badenhorst
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - Weidong Liu
- Tianjin
Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport
Economic Area, Tianjin, 300308, China
| | - Gert Weber
- Macromolecular
Crystallography, Helmholtz-Zentrum Berlin
für Materialien und Energie, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Harry P. Austin
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - David Bednar
- Loschmidt
Laboratories, Department of Experimental Biology and RECETOX, Faculty
of Science, Masaryk University, 625 00 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s University Hospital and
Faculty of Medicine, Masaryk University, 656 91 Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt
Laboratories, Department of Experimental Biology and RECETOX, Faculty
of Science, Masaryk University, 625 00 Brno, Czech Republic,International
Clinical Research Center, St. Anne’s University Hospital and
Faculty of Medicine, Masaryk University, 656 91 Brno, Czech Republic
| | - Uwe T. Bornscheuer
- Institute
of Biochemistry, Department of Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany,
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23
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Qi X, Yan W, Cao Z, Ding M, Yuan Y. Current Advances in the Biodegradation and Bioconversion of Polyethylene Terephthalate. Microorganisms 2021; 10:39. [PMID: 35056486 PMCID: PMC8779501 DOI: 10.3390/microorganisms10010039] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 01/04/2023] Open
Abstract
Polyethylene terephthalate (PET) is a widely used plastic that is polymerized by terephthalic acid (TPA) and ethylene glycol (EG). In recent years, PET biodegradation and bioconversion have become important in solving environmental plastic pollution. More and more PET hydrolases have been discovered and modified, which mainly act on and degrade the ester bond of PET. The monomers, TPA and EG, can be further utilized by microorganisms, entering the tricarboxylic acid cycle (TCA cycle) or being converted into high value chemicals, and finally realizing the biodegradation and bioconversion of PET. Based on synthetic biology and metabolic engineering strategies, this review summarizes the current advances in the modified PET hydrolases, engineered microbial chassis in degrading PET, bioconversion pathways of PET monomers, and artificial microbial consortia in PET biodegradation and bioconversion. Artificial microbial consortium provides novel ideas for the biodegradation and bioconversion of PET or other complex polymers. It is helpful to realize the one-step bioconversion of PET into high value chemicals.
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Affiliation(s)
- Xinhua Qi
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; (X.Q.); (W.Y.); (Z.C.); (Y.Y.)
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Wenlong Yan
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; (X.Q.); (W.Y.); (Z.C.); (Y.Y.)
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Zhibei Cao
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; (X.Q.); (W.Y.); (Z.C.); (Y.Y.)
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Mingzhu Ding
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; (X.Q.); (W.Y.); (Z.C.); (Y.Y.)
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Yingjin Yuan
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; (X.Q.); (W.Y.); (Z.C.); (Y.Y.)
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
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Urbanek AK, Kosiorowska KE, Mirończuk AM. Current Knowledge on Polyethylene Terephthalate Degradation by Genetically Modified Microorganisms. Front Bioeng Biotechnol 2021; 9:771133. [PMID: 34917598 PMCID: PMC8669999 DOI: 10.3389/fbioe.2021.771133] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
The global production of polyethylene terephthalate (PET) is estimated to reach 87.16 million metric tons by 2022. After a single use, a remarkable part of PET is accumulated in the natural environment as plastic waste. Due to high hydrophobicity and high molecular weight, PET is hardly biodegraded by wild-type microorganisms. To solve the global problem of uncontrolled pollution by PET, the degradation of plastic by genetically modified microorganisms has become a promising alternative for the plastic circular economy. In recent years many studies have been conducted to improve the microbial capacity for PET degradation. In this review, we summarize the current knowledge about metabolic engineering of microorganisms and protein engineering for increased biodegradation of PET. The focus is on mutations introduced to the enzymes of the hydrolase class-PETase, MHETase and cutinase-which in the last few years have attracted growing interest for the PET degradation processes. The modifications described in this work summarize the results obtained so far on the hydrolysis of polyethylene terephthalate based on the released degradation products of this polymer.
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Affiliation(s)
- Aneta K Urbanek
- Department of Biotechnology and Food Microbiology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Katarzyna E Kosiorowska
- Department of Biotechnology and Food Microbiology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Aleksandra M Mirończuk
- Department of Biotechnology and Food Microbiology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
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25
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Experimental and mathematical modeling approaches for biocatalytic post-consumer poly(ethylene terephthalate) hydrolysis. J Biotechnol 2021; 341:76-85. [PMID: 34534594 DOI: 10.1016/j.jbiotec.2021.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 08/12/2021] [Accepted: 09/12/2021] [Indexed: 11/22/2022]
Abstract
The environmental impact arising from poly(ethylene terephthalate) (PET) waste is notable worldwide. Enzymatic PET hydrolysis can provide chemicals that serve as intermediates for value-added product synthesis and savings in the resources. In the present work, some reaction parameters were evaluated on the hydrolysis of post-consumer PET (PC-PET) using a cutinase from Humicola insolens (HiC). The increase in PC-PET specific area leads to an 8.5-fold increase of the initial enzymatic hydrolysis rate (from 0.2 to 1.7 mmol L-1 h-1), showing that this parameter plays a crucial role in PET hydrolysis reaction. The effect of HiC concentration was investigated, and the enzymatic PC-PET hydrolysis kinetic parameters were estimated based on three different mathematical models describing heterogeneous biocatalysis. The model that best fits the experimental data (R2 = 0.981) indicated 1.68 mgprotein mL-1 as a maximum value of the enzyme concentration to optimize the reaction rate. The HiC thermal stability was evaluated, considering that it is a key parameter for its efficient use in PET degradation. The enzyme half-life was shown to be 110 h at 70 ºC and pH 7.0, which outperforms most of the known enzymes displaying PET hydrolysis activity. The results evidence that HiC is a very promising biocatalyst for efficient PET depolymerization.
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26
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Ahmaditabatabaei S, Kyazze G, Iqbal HMN, Keshavarz T. Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation. J Fungi (Basel) 2021; 7:931. [PMID: 34829219 PMCID: PMC8625934 DOI: 10.3390/jof7110931] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/26/2021] [Accepted: 10/30/2021] [Indexed: 02/05/2023] Open
Abstract
The ubiquitous persistence of plastic waste in diverse forms and different environmental matrices is one of the main challenges that modern societies are facing at present. The exponential utilization and recalcitrance of synthetic plastics, including polyethylene terephthalate (PET), results in their extensive accumulation, which is a significant threat to the ecosystem. The growing amount of plastic waste ending up in landfills and oceans is alarming due to its possible adverse effects on biota. Thus, there is an urgent need to mitigate plastic waste to tackle the environmental crisis of plastic pollution. With regards to PET, there is a plethora of literature on the transportation route, ingestion, environmental fate, amount, and the adverse ecological and human health effects. Several studies have described the deployment of various microbial enzymes with much focus on bacterial-enzyme mediated removal and remediation of PET. However, there is a lack of consolidated studies on the exploitation of fungal enzymes for PET degradation. Herein, an effort has been made to cover this literature gap by spotlighting the fungi and their unique enzymes, e.g., esterases, lipases, and cutinases. These fungal enzymes have emerged as candidates for the development of biocatalytic PET degradation processes. The first half of this review is focused on fungal biocatalysts involved in the degradation of PET. The latter half explains three main aspects: (1) catalytic mechanism of PET hydrolysis in the presence of cutinases as a model fungal enzyme, (2) limitations hindering enzymatic PET biodegradation, and (3) strategies for enhancement of enzymatic PET biodegradation.
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Affiliation(s)
- Seyedehazita Ahmaditabatabaei
- School of Life sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6UW, UK; (S.A.); (G.K.)
| | - Godfrey Kyazze
- School of Life sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6UW, UK; (S.A.); (G.K.)
| | - Hafiz M. N. Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Monterrey 64849, Mexico;
| | - Tajalli Keshavarz
- School of Life sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6UW, UK; (S.A.); (G.K.)
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Novy V, Carneiro LV, Shin JH, Larsbrink J, Olsson L. Phylogenetic analysis and in-depth characterization of functionally and structurally diverse CE5 cutinases. J Biol Chem 2021; 297:101302. [PMID: 34653507 PMCID: PMC8577158 DOI: 10.1016/j.jbc.2021.101302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/19/2021] [Accepted: 09/26/2021] [Indexed: 11/30/2022] Open
Abstract
Cutinases are esterases that release fatty acids from the apoplastic layer in plants. As they accept bulky and hydrophobic substrates, cutinases could be used in many applications, ranging from valorization of bark-rich side streams to plastic recycling. Advancement of these applications, however, requires deeper knowledge of cutinases' biodiversity and structure-function relationships. Here, we mined over 3000 members from carbohydrate esterase family 5 for putative cutinases and condensed it to 151 genes from known or putative lignocellulose-targeting organisms. The 151 genes were subjected to a phylogenetic analysis, which showed that cutinases with available crystal structures were phylogenetically closely related. We then selected nine phylogenic diverse cutinases for recombinant production and characterized their kinetic activity against para-nitrophenol substrates esterified with consecutively longer alkyl chains (pNP-C2 to C16). Each investigated cutinase had a unique activity fingerprint against the tested pNP substrates. The five enzymes with the highest activity on pNP-C12 and C16, indicative of activity on bulky hydrophobic compounds, were selected for in-depth kinetic and structure-function analysis. All five enzymes showed a decrease in kcat values with increasing substrate chain length, whereas KM values and binding energies (calculated from in silico docking analysis) improved. Two cutinases from Fusarium solani and Cryptococcus sp. exhibited outstandingly low KM values, resulting in high catalytic efficiencies toward pNP-C16. Docking analysis suggested that different clades of the phylogenetic tree may harbor enzymes with different modes of substrate interaction, involving a solvent-exposed catalytic triad, a lipase-like lid, or a clamshell-like active site possibly formed by flexible loops.
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Affiliation(s)
- Vera Novy
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden
| | - Leonor Vieira Carneiro
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Jae Ho Shin
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Johan Larsbrink
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden
| | - Lisbeth Olsson
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden.
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28
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Magalhães RP, Cunha JM, Sousa SF. Perspectives on the Role of Enzymatic Biocatalysis for the Degradation of Plastic PET. Int J Mol Sci 2021; 22:11257. [PMID: 34681915 PMCID: PMC8540959 DOI: 10.3390/ijms222011257] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/13/2021] [Accepted: 10/16/2021] [Indexed: 12/25/2022] Open
Abstract
Plastics are highly durable and widely used materials. Current methodologies of plastic degradation, elimination, and recycling are flawed. In recent years, biodegradation (the usage of microorganisms for material recycling) has grown as a valid alternative to previously used methods. The evolution of bioengineering techniques and the discovery of novel microorganisms and enzymes with degradation ability have been key. One of the most produced plastics is PET, a long chain polymer of terephthalic acid (TPA) and ethylene glycol (EG) repeating monomers. Many enzymes with PET degradation activity have been discovered, characterized, and engineered in the last few years. However, classification and integrated knowledge of these enzymes are not trivial. Therefore, in this work we present a summary of currently known PET degrading enzymes, focusing on their structural and activity characteristics, and summarizing engineering efforts to improve activity. Although several high potential enzymes have been discovered, further efforts to improve activity and thermal stability are necessary.
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Affiliation(s)
- Rita P. Magalhães
- UCIBIO—Applied Molecular Biosciences Unit, BioSIM—Departamento de Biomedicina, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal; (R.P.M.); (J.M.C.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
| | - Jorge M. Cunha
- UCIBIO—Applied Molecular Biosciences Unit, BioSIM—Departamento de Biomedicina, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal; (R.P.M.); (J.M.C.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
| | - Sérgio F. Sousa
- UCIBIO—Applied Molecular Biosciences Unit, BioSIM—Departamento de Biomedicina, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal; (R.P.M.); (J.M.C.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
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Abstract
Cutinases (EC 3.1.1.74) are serin esterases that belong to the α/β hydrolases superfamily and present in the Ser-His-Asp catalytic triad. They show characteristics between esterases and lipases. These enzymes hydrolyze esters and triacylglycerols and catalyze esterification and transesterification reactions. Cutinases are synthesize by plant pathogenic fungi, but some bacteria and plants have been found to produce cutinases as well. In nature they facilitate a pathogen’s invasion by hydrolyzing the cuticle that protects plants, but can be also used for saprophytic fungi as a way to nourish themselves. Cutinases can hydrolyze a wide range of substrates like esters, polyesters, triacylglycerols and waxes and that makes this enzyme very attractive for industrial purposes. This work discusses techniques of industrial interest such as immobilization and purification, as well as some of the most important uses of cutinases in industries.
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30
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Gao R, Pan H, Lian J. Recent advances in the discovery, characterization, and engineering of poly(ethylene terephthalate) (PET) hydrolases. Enzyme Microb Technol 2021; 150:109868. [PMID: 34489027 DOI: 10.1016/j.enzmictec.2021.109868] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 12/28/2022]
Abstract
Poly(ethylene terephthalate) (PET) is a class of polyester plastic composed of terephthalic acid (TPA) and ethylene glycol (EG). The accumulation of large amount of PET waste has resulted in severe environmental and health problems. Microbial polyester hydrolases with the ability to degrade PET provide an economy- and environment-friendly approach for the treatment of PET waste. In recent years, many PET hydrolases have been discovered and characterized from various microorganisms and engineered for better performance under practical application conditions. Here, recent progress in the discovery, characterization, and enzymatic mechanism elucidation of PET hydrolases is firstly reviewed. Then, structure-guided protein engineering of PET hydrolases with increased enzymatic activities, expanded substrate specificity, as well as improved protein stability is summarized. In addition, strategies for efficient expression of recombinant PET hydrolases, including secretory expression and cell-surface display, are briefly introduced. This review is concluded with future perspectives in biodegradation and subsequent biotransformation of PET wastes to produce value-added compounds.
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Affiliation(s)
- Rui Gao
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Haojie Pan
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Jiazhang Lian
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China; Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310027, China.
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31
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Pirillo V, Pollegioni L, Molla G. Analytical methods for the investigation of enzyme-catalyzed degradation of polyethylene terephthalate. FEBS J 2021; 288:4730-4745. [PMID: 33792200 PMCID: PMC8453989 DOI: 10.1111/febs.15850] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 03/03/2021] [Accepted: 03/29/2021] [Indexed: 01/11/2023]
Abstract
The polyester PET (poly(ethylene terephthalate)) plastic is chemically inert and remarkably persistent, posing relevant and global pollution concerns due to its accumulation in ecosystems across the globe. In past years, research focused on identifying bacteria active on PET and on the specific enzymes responsible for its degradation. Here, the enzymatic degradation of PET can be considered as an 'erosion process' that takes place on the surface of an insoluble material and results in an unusual, substrate-limited kinetic condition. In this review, we report on the most suitable models to evaluate the kinetics of PET-hydrolyzing enzymes, which takes into consideration the amount of enzyme adsorbed on the substrate, the enzyme-accessible ester bonds, and the product inhibition effects. Careful kinetic analysis is especially relevant to compare enzymes from different sources and evolved variants generated by protein engineering studies as well. Furthermore, the analytical methods most suitable to screen natural bacteria and recombinant variant libraries generated by protein engineering have been also reported. These methods rely on different detection systems and are performed both on model compounds and on different PET samples (e.g., nanoparticles, microparticles, and waste products). All this meaningful information represents an optimal starting point and boosts the process of identifying systems able to biologically recycle PET waste products.
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Affiliation(s)
- Valentina Pirillo
- The Protein Factory 2.0’Dipartimento di Biotecnologie e Scienze della VitaUniversità degli Studi dell'InsubriaVareseItaly
| | - Loredano Pollegioni
- The Protein Factory 2.0’Dipartimento di Biotecnologie e Scienze della VitaUniversità degli Studi dell'InsubriaVareseItaly
| | - Gianluca Molla
- The Protein Factory 2.0’Dipartimento di Biotecnologie e Scienze della VitaUniversità degli Studi dell'InsubriaVareseItaly
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32
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Ellis LD, Rorrer NA, Sullivan KP, Otto M, McGeehan JE, Román-Leshkov Y, Wierckx N, Beckham GT. Chemical and biological catalysis for plastics recycling and upcycling. Nat Catal 2021. [DOI: 10.1038/s41929-021-00648-4] [Citation(s) in RCA: 117] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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33
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Nikolaivits E, Pantelic B, Azeem M, Taxeidis G, Babu R, Topakas E, Brennan Fournet M, Nikodinovic-Runic J. Progressing Plastics Circularity: A Review of Mechano-Biocatalytic Approaches for Waste Plastic (Re)valorization. Front Bioeng Biotechnol 2021; 9:696040. [PMID: 34239864 PMCID: PMC8260098 DOI: 10.3389/fbioe.2021.696040] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 05/28/2021] [Indexed: 01/10/2023] Open
Abstract
Inspirational concepts, and the transfer of analogs from natural biology to science and engineering, has produced many excellent technologies to date, spanning vaccines to modern architectural feats. This review highlights that answers to the pressing global petroleum-based plastic waste challenges, can be found within the mechanics and mechanisms natural ecosystems. Here, a suite of technological and engineering approaches, which can be implemented to operate in tandem with nature's prescription for regenerative material circularity, is presented as a route to plastics sustainability. A number of mechanical/green chemical (pre)treatment methodologies, which simulate natural weathering and arthropodal dismantling activities are reviewed, including: mechanical milling, reactive extrusion, ultrasonic-, UV- and degradation using supercritical CO2. Akin to natural mechanical degradation, the purpose of the pretreatments is to render the plastic materials more amenable to microbial and biocatalytic activities, to yield effective depolymerization and (re)valorization. While biotechnological based degradation and depolymerization of both recalcitrant and bioplastics are at a relatively early stage of development, the potential for acceleration and expedition of valuable output monomers and oligomers yields is considerable. To date a limited number of independent mechano-green chemical approaches and a considerable and growing number of standalone enzymatic and microbial degradation studies have been reported. A convergent strategy, one which forges mechano-green chemical treatments together with the enzymatic and microbial actions, is largely lacking at this time. An overview of the reported microbial and enzymatic degradations of petroleum-based synthetic polymer plastics, specifically: low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), polyethylene terephthalate (PET), polyurethanes (PU) and polycaprolactone (PCL) and selected prevalent bio-based or bio-polymers [polylactic acid (PLA), polyhydroxyalkanoates (PHAs) and polybutylene succinate (PBS)], is detailed. The harvesting of depolymerization products to produce new materials and higher-value products is also a key endeavor in effectively completing the circle for plastics. Our challenge is now to effectively combine and conjugate the requisite cross disciplinary approaches and progress the essential science and engineering technologies to categorically complete the life-cycle for plastics.
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Affiliation(s)
- Efstratios Nikolaivits
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Brana Pantelic
- Eco-Biotechnology & Drug Development Group, Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | | | - George Taxeidis
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Ramesh Babu
- AMBER Centre, CRANN Institute, School of Chemistry, Trinity College Dublin, Dublin, Ireland
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | | | - Jasmina Nikodinovic-Runic
- Eco-Biotechnology & Drug Development Group, Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
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34
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Zhu B, Wang D, Wei N. Enzyme Discovery and Engineering for Sustainable Plastic Recycling. Trends Biotechnol 2021; 40:22-37. [PMID: 33676748 DOI: 10.1016/j.tibtech.2021.02.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 10/22/2022]
Abstract
The drastically increasing amount of plastic waste is causing an environmental crisis that requires innovative technologies for recycling post-consumer plastics to achieve waste valorization while meeting environmental quality goals. Biocatalytic depolymerization mediated by enzymes has emerged as an efficient and sustainable alternative for plastic treatment and recycling. A variety of plastic-degrading enzymes have been discovered from microbial sources. Meanwhile, protein engineering has been exploited to modify and optimize plastic-degrading enzymes. This review highlights the recent trends and up-to-date advances in mining novel plastic-degrading enzymes through state-of-the-art omics-based techniques and improving the enzyme catalytic efficiency and stability via various protein engineering strategies. Future research prospects and challenges are also discussed.
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Affiliation(s)
- Baotong Zhu
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, Indiana 46556, USA
| | - Dong Wang
- Department of Computer Science and Engineering, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, Indiana 46556, USA
| | - Na Wei
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, Indiana 46556, USA.
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35
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Bååth JA, Borch K, Jensen K, Brask J, Westh P. Comparative Biochemistry of Four Polyester (PET) Hydrolases*. Chembiochem 2021; 22:1627-1637. [PMID: 33351214 DOI: 10.1002/cbic.202000793] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/22/2020] [Indexed: 11/08/2022]
Abstract
The potential of bioprocessing in a circular plastic economy has strongly stimulated research into the enzymatic degradation of different synthetic polymers. Particular interest has been devoted to the commonly used polyester, poly(ethylene terephthalate) (PET), and a number of PET hydrolases have been described. However, a kinetic framework for comparisons of PET hydrolases (or other plastic-degrading enzymes) acting on the insoluble substrate has not been established. Herein, we propose such a framework, which we have tested against kinetic measurements for four PET hydrolases. The analysis provided values of kcat and KM , as well as an apparent specificity constant in the conventional units of M-1 s-1 . These parameters, together with experimental values for the number of enzyme attack sites on the PET surface, enabled comparative analyses. A variant of the PET hydrolase from Ideonella sakaiensis was the most efficient enzyme at ambient conditions; it relied on a high kcat rather than a low KM . Moreover, both soluble and insoluble PET fragments were consistently hydrolyzed much faster than intact PET. This suggests that interactions between polymer strands slow down PET degradation, whereas the chemical steps of catalysis and the low accessibility associated with solid substrate were less important for the overall rate. Finally, the investigated enzymes showed a remarkable substrate affinity, and reached half the saturation rate on PET when the concentration of attack sites in the suspension was only about 50 nM. We propose that this is linked to nonspecific adsorption, which promotes the nearness of enzyme and attack sites.
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Affiliation(s)
- Jenny Arnling Bååth
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800 Kgs., Lyngby, Denmark
| | - Kim Borch
- Novozymes A/S, Biologiens Vej 2, 2800 Kgs., Lyngby, Denmark
| | - Kenneth Jensen
- Novozymes A/S, Biologiens Vej 2, 2800 Kgs., Lyngby, Denmark
| | - Jesper Brask
- Novozymes A/S, Biologiens Vej 2, 2800 Kgs., Lyngby, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800 Kgs., Lyngby, Denmark
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36
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Tan Y, Henehan GT, Kinsella GK, Ryan BJ. An extracellular lipase from Amycolatopsis mediterannei is a cutinase with plastic degrading activity. Comput Struct Biotechnol J 2021; 19:869-879. [PMID: 33598102 PMCID: PMC7851449 DOI: 10.1016/j.csbj.2021.01.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/08/2021] [Accepted: 01/14/2021] [Indexed: 11/04/2022] Open
Abstract
Amycolatopsis mediterranei lipase (AML) exhibits cutinase-like structural features. AML shows 60–70% sequence similarity to a few plastic degrading cutinases. AML has the ability to degrade poly(caprolactone) and poly(butylene succinate).
An extracellular lipase from Amycolatopsis mediteranei (AML) with potential applications in process biotechnology was recently cloned and examined in this laboratory. In the present study, the 3D structure of AML was elucidated by comparative modelling. AML lacked the ‘lid’ structure observed in most true lipases and shared similarities with plastic degrading enzymes. Modelling and substrate specificity studies showed that AML was a cutinase with a relatively exposed active site and specificity for medium chain fatty acyl moieties. AML rapidly hydrolysed the aliphatic plastics poly(ε-caprolactone) and poly(1,4-butylene succinate) extended with 1,6-diisocyanatohexane under mild conditions. These plastics are known to be slow to degrade in landfill. Poly(L-lactic acid) was not hydrolysed by AML, nor was the aromatic plastic Polyethylene Terephthalate (PET). The specificity of AML is partly explained by active site topology and analysis reveals that minor changes in the active site region can have large effects on substrate preference. These findings show that extracellular Amycolatopsis enzymes are capable of degrading a wider range of plastics than is generally recognised. The potential for application of AML in the bioremediation of plastics is discussed.
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Affiliation(s)
- Yeqi Tan
- School of Food Sciences and Environmental Health, Technological University Dublin, Grangegorman, Dublin 7 D07 H6K8, Ireland
| | - Gary T Henehan
- School of Food Sciences and Environmental Health, Technological University Dublin, Grangegorman, Dublin 7 D07 H6K8, Ireland
| | - Gemma K Kinsella
- School of Food Sciences and Environmental Health, Technological University Dublin, Grangegorman, Dublin 7 D07 H6K8, Ireland
| | - Barry J Ryan
- School of Food Sciences and Environmental Health, Technological University Dublin, Grangegorman, Dublin 7 D07 H6K8, Ireland
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Sanders D, Grunden A, Dunn RR. A review of clothing microbiology: the history of clothing and the role of microbes in textiles. Biol Lett 2021; 17:20200700. [PMID: 33435848 PMCID: PMC7876606 DOI: 10.1098/rsbl.2020.0700] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/14/2020] [Indexed: 12/11/2022] Open
Abstract
Humans have worn clothing for thousands of years, and since its invention, clothing has evolved from its simple utilitarian function for survival to become an integral part of society. While much consideration has been given to the broad environmental impacts of the textile and laundering industries, little is known about the impact wearing clothing has had on the human microbiome, particularly that of the skin, despite our long history with clothing. This review discusses the history of clothing and the evolution of textiles, what is and is not known about microbial persistence on and degradation of various fibres, and what opportunities for the industrial and environmental application of clothing microbiology exist for the future.
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Affiliation(s)
- Deaja Sanders
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Amy Grunden
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Robert R. Dunn
- Department of Applied Ecology, North Carolina State University, Raleigh, NC 27695, USA
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Samak NA, Jia Y, Sharshar MM, Mu T, Yang M, Peh S, Xing J. Recent advances in biocatalysts engineering for polyethylene terephthalate plastic waste green recycling. ENVIRONMENT INTERNATIONAL 2020; 145:106144. [PMID: 32987219 DOI: 10.1016/j.envint.2020.106144] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/10/2020] [Accepted: 09/13/2020] [Indexed: 05/21/2023]
Abstract
The massive waste of poly(ethylene terephthalate) (PET) that ends up in the landfills and oceans and needs hundreds of years for degradation has attracted global concern. The poor stability and productivity of the available PET biocatalysts hinder their industrial applications. Active PET biocatalysts can provide a promising avenue for PET bioconversion and recycling. Therefore, there is an urgent need to develop new strategies that could enhance the stability, catalytic activity, solubility, productivity, and re-usability of these PET biocatalysts under harsh conditions such as high temperatures, pH, and salinity. This has raised great attention in using bioengineering strategies to improve PET biocatalysts' robustness and catalytic behavior. Herein, historical and forecasting data of plastic production and disposal were critically reviewed. Challenges facing the PET degradation process and available strategies that could be used to solve them were critically highlighted and summarized. In this review, we also discussed the recent progress in enzyme bioengineering approaches used for discovering new PET biocatalysts, elucidating the degradation mechanism, and improving the catalytic performance, solubility, and productivity, critically assess their strength and weakness and highlighting the gaps of the available data. Discovery of more potential PET hydrolases and studying their molecular mechanism extensively via solving their crystal structure will widen this research area to move forward the industrial application. A deeper knowledge of PET molecular and degradation mechanisms will give great insight into the future identification of related enzymes. The reported bioengineering strategies during this review could be used to reduce PET crystallinity and to increase the operational temperature of PET hydrolyzing enzymes.
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Affiliation(s)
- Nadia A Samak
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; College of Chemical Engineering, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China; Processes Design and Development Department, Egyptian Petroleum Research Institute, Nasr City, 11727 Cairo, Egypt
| | - Yunpu Jia
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; College of Chemical Engineering, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China
| | - Moustafa M Sharshar
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; College of Chemical Engineering, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China
| | - Tingzhen Mu
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
| | - Maohua Yang
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
| | - Sumit Peh
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; College of Chemical Engineering, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China
| | - Jianmin Xing
- CAS Key Laboratory of Green Process and Engineering & State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; College of Chemical Engineering, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China.
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A suspension-based assay and comparative detection methods for characterization of polyethylene terephthalate hydrolases. Anal Biochem 2020; 607:113873. [DOI: 10.1016/j.ab.2020.113873] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/22/2020] [Accepted: 07/13/2020] [Indexed: 12/27/2022]
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Characterization and engineering of a two-enzyme system for plastics depolymerization. Proc Natl Acad Sci U S A 2020; 117:25476-25485. [PMID: 32989159 PMCID: PMC7568301 DOI: 10.1073/pnas.2006753117] [Citation(s) in RCA: 190] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Deconstruction of recalcitrant polymers, such as cellulose or chitin, is accomplished in nature by synergistic enzyme cocktails that evolved over millions of years. In these systems, soluble dimeric or oligomeric intermediates are typically released via interfacial biocatalysis, and additional enzymes often process the soluble intermediates into monomers for microbial uptake. The recent discovery of a two-enzyme system for polyethylene terephthalate (PET) deconstruction, which employs one enzyme to convert the polymer into soluble intermediates and another enzyme to produce the constituent PET monomers (MHETase), suggests that nature may be evolving similar deconstruction strategies for synthetic plastics. This study on the characterization of the MHETase enzyme and synergy of the two-enzyme PET depolymerization system may inform enzyme cocktail-based strategies for plastics upcycling. Plastics pollution represents a global environmental crisis. In response, microbes are evolving the capacity to utilize synthetic polymers as carbon and energy sources. Recently, Ideonella sakaiensis was reported to secrete a two-enzyme system to deconstruct polyethylene terephthalate (PET) to its constituent monomers. Specifically, the I. sakaiensis PETase depolymerizes PET, liberating soluble products, including mono(2-hydroxyethyl) terephthalate (MHET), which is cleaved to terephthalic acid and ethylene glycol by MHETase. Here, we report a 1.6 Å resolution MHETase structure, illustrating that the MHETase core domain is similar to PETase, capped by a lid domain. Simulations of the catalytic itinerary predict that MHETase follows the canonical two-step serine hydrolase mechanism. Bioinformatics analysis suggests that MHETase evolved from ferulic acid esterases, and two homologous enzymes are shown to exhibit MHET turnover. Analysis of the two homologous enzymes and the MHETase S131G mutant demonstrates the importance of this residue for accommodation of MHET in the active site. We also demonstrate that the MHETase lid is crucial for hydrolysis of MHET and, furthermore, that MHETase does not turnover mono(2-hydroxyethyl)-furanoate or mono(2-hydroxyethyl)-isophthalate. A highly synergistic relationship between PETase and MHETase was observed for the conversion of amorphous PET film to monomers across all nonzero MHETase concentrations tested. Finally, we compare the performance of MHETase:PETase chimeric proteins of varying linker lengths, which all exhibit improved PET and MHET turnover relative to the free enzymes. Together, these results offer insights into the two-enzyme PET depolymerization system and will inform future efforts in the biological deconstruction and upcycling of mixed plastics.
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Dong Q, Yuan S, Wu L, Su L, Zhao Q, Wu J, Huang W, Zhou J. Structure-guided engineering of a Thermobifida fusca cutinase for enhanced hydrolysis on natural polyester substrate. BIORESOUR BIOPROCESS 2020. [DOI: 10.1186/s40643-020-00324-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractCutinases could degrade insoluble polyester, including natural cutin and synthetic plastic. However, their turnover efficiency for polyester remains too low for industrial application. Herein, we report the 1.54-Å resolution X-ray crystal structure of a cutinase from Thermobifida fusca and modeling structure in complex with a cutin mimic oligo-polyester C24H42O8. These efforts subsequently guided our design of cutinase variants with less bulky residues in the vicinity of the substrate binding site. The L90A and I213A variants exhibit increased hydrolysis activity (5- and 2.4-fold, respectively) toward cutin and also showed enhanced cotton scouring efficiency compared with the wild-type enzyme.
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Wiltschi B, Cernava T, Dennig A, Galindo Casas M, Geier M, Gruber S, Haberbauer M, Heidinger P, Herrero Acero E, Kratzer R, Luley-Goedl C, Müller CA, Pitzer J, Ribitsch D, Sauer M, Schmölzer K, Schnitzhofer W, Sensen CW, Soh J, Steiner K, Winkler CK, Winkler M, Wriessnegger T. Enzymes revolutionize the bioproduction of value-added compounds: From enzyme discovery to special applications. Biotechnol Adv 2020; 40:107520. [DOI: 10.1016/j.biotechadv.2020.107520] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 10/18/2019] [Accepted: 01/13/2020] [Indexed: 12/11/2022]
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Weinberger S, Beyer R, Schüller C, Strauss J, Pellis A, Ribitsch D, Guebitz GM. High Throughput Screening for New Fungal Polyester Hydrolyzing Enzymes. Front Microbiol 2020; 11:554. [PMID: 32390956 PMCID: PMC7193820 DOI: 10.3389/fmicb.2020.00554] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/16/2020] [Indexed: 11/30/2022] Open
Abstract
There is a strong need for novel and more efficient polyester hydrolyzing enzymes in order to enable the development of more environmentally friendly plastics recycling processes allowing the closure of the carbon cycle. In this work, a high throughput system on microplate scale was used to screen a high number of fungi for their ability to produce polyester-hydrolyzing enzymes. For induction of responsible enzymes, the fungi were cultivated in presence of aliphatic and aromatic polyesters [poly(1,4-butylene adipate co terephthalate) (PBAT), poly(lactic acid) (PLA) and poly(1,4-butylene succinate) (PBS)], and the esterase activity in the culture supernatants was compared to the culture supernatants of fungi grown without polymers. The results indicate that the esterase activity of the culture supernatants was induced in about 10% of the tested fungi when grown with polyesters in the medium, as indicated by increased activity (to >50 mU/mL) toward the small model substrate para-nitrophenylbutyrate (pNPB). Incubation of these 50 active culture supernatants with different polyesters (PBAT, PLA, PBS) led to hydrolysis of at least one of the polymers according to liquid chromatography-based quantification of the hydrolysis products terephthalic acid, lactic acid and succinic acid, respectively. Interestingly, the specificities for the investigated polyesters varied among the supernatants of the different fungi.
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Affiliation(s)
- Simone Weinberger
- Department of Agrobiotechnology, Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.,Austrian Center of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria
| | - Reinhard Beyer
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christoph Schüller
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Joseph Strauss
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Alessandro Pellis
- Department of Agrobiotechnology, Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Doris Ribitsch
- Department of Agrobiotechnology, Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.,Austrian Center of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria
| | - Georg M Guebitz
- Department of Agrobiotechnology, Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.,Austrian Center of Industrial Biotechnology (ACIB), Tulln an der Donau, Austria
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44
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Biundo A, Subagia R, Maurer M, Ribitsch D, Syrén PO, Guebitz GM. Switched reaction specificity in polyesterases towards amide bond hydrolysis by enzyme engineering. RSC Adv 2019; 9:36217-36226. [PMID: 35540575 PMCID: PMC9074940 DOI: 10.1039/c9ra07519d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/28/2019] [Indexed: 01/03/2023] Open
Abstract
The recalcitrance of plastics like nylon and other polyamides contributes to environmental problems (e.g. microplastics in oceans) and restricts possibilities for recycling. The fact that hitherto discovered amidases (EC 3.5.1. and 3.5.2.) only show no, or low, activity on polyamides currently obstructs biotechnological-assisted depolymerization of man-made materials. In this work, we capitalized on enzyme engineering to enhance the promiscuous amidase activity of polyesterases. Through enzyme design we created a reallocated water network adapted for hydrogen bond formation to synthetic amide backbones for enhanced transition state stabilization in the polyester-hydrolyzing biocatalysts Humicola insolens cutinase and Thermobifida cellulosilytica cutinase 1. This novel concept enabled increased catalytic efficiency towards amide-containing soluble substrates. The afforded enhanced hydrolysis of the amide bond-containing insoluble substrate 3PA 6,6 by designed variants was aligned with improved transition state stabilization identified by molecular dynamics (MD) simulations. Furthermore, the presence of a favorable water-molecule network that interacted with synthetic amides in the variants resulted in a reduced activity on polyethylene terephthalate (PET). Our data demonstrate the potential of using enzyme engineering to improve the amidase activity for polyesterases to act on synthetic amide-containing polymers.
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Affiliation(s)
- Antonino Biundo
- Austrian Centre of Industrial Biotechnology (ACIB) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
| | - Raditya Subagia
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences (BOKU) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
| | - Michael Maurer
- Department of Bioengineering, University of Applied Sciences Mauerbachstrasse 43 1140 Vienna Austria
| | - Doris Ribitsch
- Austrian Centre of Industrial Biotechnology (ACIB) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences (BOKU) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
| | - Per-Olof Syrén
- Science for Life Laboratory, Department of Fibre and Polymer Technology and Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology Tomtebodavägen 23, Box 1031 17165 Solna Sweden
| | - Georg M Guebitz
- Austrian Centre of Industrial Biotechnology (ACIB) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
- Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences (BOKU) Konrad Lorenz Strasse 20 3430 Tulln an der Donau Austria
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45
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Noro J, Castro TG, Gonçalves F, Ribeiro A, Cavaco‐Paulo A, Silva C. Catalytic Activation of Esterases by PEGylation for Polyester Synthesis. ChemCatChem 2019. [DOI: 10.1002/cctc.201900451] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jennifer Noro
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
| | - Tarsila G. Castro
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
| | - Filipa Gonçalves
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
| | - Artur Ribeiro
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
| | - Artur Cavaco‐Paulo
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
| | - Carla Silva
- Center of Biological Engineering University of Minho Campus de Gualtar 4710-057 Braga Portugal
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46
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Palm GJ, Reisky L, Böttcher D, Müller H, Michels EAP, Walczak MC, Berndt L, Weiss MS, Bornscheuer UT, Weber G. Structure of the plastic-degrading Ideonella sakaiensis MHETase bound to a substrate. Nat Commun 2019; 10:1717. [PMID: 30979881 PMCID: PMC6461665 DOI: 10.1038/s41467-019-09326-3] [Citation(s) in RCA: 183] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 03/05/2019] [Indexed: 11/09/2022] Open
Abstract
The extreme durability of polyethylene terephthalate (PET) debris has rendered it a long-term environmental burden. At the same time, current recycling efforts still lack sustainability. Two recently discovered bacterial enzymes that specifically degrade PET represent a promising solution. First, Ideonella sakaiensis PETase, a structurally well-characterized consensus α/β-hydrolase fold enzyme, converts PET to mono-(2-hydroxyethyl) terephthalate (MHET). MHETase, the second key enzyme, hydrolyzes MHET to the PET educts terephthalate and ethylene glycol. Here, we report the crystal structures of active ligand-free MHETase and MHETase bound to a nonhydrolyzable MHET analog. MHETase, which is reminiscent of feruloyl esterases, possesses a classic α/β-hydrolase domain and a lid domain conferring substrate specificity. In the light of structure-based mapping of the active site, activity assays, mutagenesis studies and a first structure-guided alteration of substrate specificity towards bis-(2-hydroxyethyl) terephthalate (BHET) reported here, we anticipate MHETase to be a valuable resource to further advance enzymatic plastic degradation.
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Affiliation(s)
- Gottfried J Palm
- Molecular Structural Biology, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Lukas Reisky
- Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Dominique Böttcher
- Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Henrik Müller
- Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Emil A P Michels
- Molecular Structural Biology, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Miriam C Walczak
- Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Leona Berndt
- Molecular Structural Biology, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Manfred S Weiss
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße15, 12489, Berlin, Germany
| | - Uwe T Bornscheuer
- Biotechnology & Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany.
| | - Gert Weber
- Molecular Structural Biology, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany. .,Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany.
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Fecker T, Galaz-Davison P, Engelberger F, Narui Y, Sotomayor M, Parra LP, Ramírez-Sarmiento CA. Active Site Flexibility as a Hallmark for Efficient PET Degradation by I. sakaiensis PETase. Biophys J 2019; 114:1302-1312. [PMID: 29590588 DOI: 10.1016/j.bpj.2018.02.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 02/06/2018] [Accepted: 02/08/2018] [Indexed: 12/21/2022] Open
Abstract
Polyethylene terephthalate (PET) is one of the most-consumed synthetic polymers, with an annual production of 50 million tons. Unfortunately, PET accumulates as waste and is highly resistant to biodegradation. Recently, fungal and bacterial thermophilic hydrolases were found to catalyze PET hydrolysis with optimal activities at high temperatures. Strikingly, an enzyme from Ideonella sakaiensis, termed PETase, was described to efficiently degrade PET at room temperature, but the molecular basis of its activity is not currently understood. Here, a crystal structure of PETase was determined at 2.02 Å resolution and employed in molecular dynamics simulations showing that the active site of PETase has higher flexibility at room temperature than its thermophilic counterparts. This flexibility is controlled by a novel disulfide bond in its active site, with its removal leading to destabilization of the catalytic triad and reduction of the hydrolase activity. Molecular docking of a model substrate predicts that PET binds to PETase in a unique and energetically favorable conformation facilitated by several residue substitutions within its active site when compared to other enzymes. These computational predictions are in excellent agreement with recent mutagenesis and PET film degradation analyses. Finally, we rationalize the increased catalytic activity of PETase at room temperature through molecular dynamics simulations of enzyme-ligand complexes for PETase and other thermophilic PET-degrading enzymes at 298, 323, and 353 K. Our results reveal that both the binding pose and residue substitutions within PETase favor proximity between the catalytic residues and the labile carbonyl of the substrate at room temperature, suggesting a more favorable hydrolytic reaction. These results are valuable for enabling detailed evolutionary analysis of PET-degrading enzymes and for rational design endeavors aiming at increasing the efficiency of PETase and similar enzymes toward plastic degradation.
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Affiliation(s)
- Tobias Fecker
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine, and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo Galaz-Davison
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine, and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Felipe Engelberger
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine, and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Yoshie Narui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio.
| | - Loreto P Parra
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine, and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Chemical and Bioprocesses Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - César A Ramírez-Sarmiento
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine, and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
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48
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De Hoe GX, Zumstein MT, Getzinger GJ, Rüegsegger I, Kohler HPE, Maurer-Jones MA, Sander M, Hillmyer MA, McNeill K. Photochemical Transformation of Poly(butylene adipate- co-terephthalate) and Its Effects on Enzymatic Hydrolyzability. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2472-2481. [PMID: 30726677 DOI: 10.1021/acs.est.8b06458] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Biodegradable polyesters are being increasingly used to replace conventional, nondegradable polymers in agricultural applications such as plastic film for mulching. For many of these applications, poly(butylene adipate- co-terephthalate) (PBAT) is a promising biodegradable material. However, PBAT is also susceptible to photochemical transformations. To better understand how photochemistry affects the biodegradability of PBAT, we irradiated blown, nonstabilized, transparent PBAT films and studied their enzymatic hydrolysis, which is considered the rate-limiting step in polyester biodegradation. In parallel, we characterized the irradiated PBAT films by dynamic mechanical thermal analysis. The rate of enzymatic PBAT hydrolysis decreased when the density of light-induced cross-links within PBAT exceeded a certain threshold. Mass-spectrometric analysis of the enzymatic hydrolysis products of irradiated PBAT films provided evidence for radical-based cross-linking of two terephthalate units that resulted in the formation of benzophenone-like molecules. In a proof-of-principle experiment, we demonstrated that the addition of photostabilizers to PBAT films mitigated the negative effect of UV irradiation on the enzymatic hydrolyzability of PBAT. This work advances the understanding of light-induced changes on the enzyme-mediated hydrolysis of aliphatic-aromatic polyesters and will therefore have important implications for the development of biodegradable plastics.
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Affiliation(s)
- Guilhem X De Hoe
- Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455-0431 , United States
| | - Michael T Zumstein
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Gordon J Getzinger
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Isabelle Rüegsegger
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Hans-Peter E Kohler
- Environmental Microbiology , Swiss Federal Institute of Aquatic Science and Technology (Eawag) , 8600 Dübendorf , Switzerland
| | - Melissa A Maurer-Jones
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Michael Sander
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
| | - Marc A Hillmyer
- Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455-0431 , United States
| | - Kristopher McNeill
- Institute of Biogeochemistry and Pollutant Dynamics , ETH Zurich , 8092 Zurich , Switzerland
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Debuissy T, Pollet E, Avérous L. Biotic and Abiotic Synthesis of Renewable Aliphatic Polyesters from Short Building Blocks Obtained from Biotechnology. CHEMSUSCHEM 2018; 11:3836-3870. [PMID: 30203918 DOI: 10.1002/cssc.201801700] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Indexed: 06/08/2023]
Abstract
Biobased polymers have seen their attractiveness increase in recent decades thanks to the significant development of biorefineries to allow access to a wide variety of biobased building blocks. Polyesters are one of the best examples of the development of biobased polymers because most of them now have their monomers produced from renewable resources and are biodegradable. Currently, these polyesters are mainly produced by using traditional chemical catalysts and harsh conditions, but recently greener pathways with nontoxic enzymes as biocatalysts and mild conditions have shown great potential. Bacterial polyesters, such as poly(hydroxyalkanoate)s (PHA), are the best example of the biotic production of high molar mass polymers. PHAs display a wide variety of macromolecular architectures, which allow a large range of applications. The present contribution aims to provide an overview of recent progress in studies on biobased polyesters, especially those made from short building blocks, synthesized through step-growth polymerization. In addition, some important technical aspects of their syntheses through biotic or abiotic pathways have been detailed.
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Affiliation(s)
- Thibaud Debuissy
- BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087, Strasbourg Cedex 2, France
| | - Eric Pollet
- BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087, Strasbourg Cedex 2, France
| | - Luc Avérous
- BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087, Strasbourg Cedex 2, France
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Abstract
Synthetic polymers are ubiquitous in the modern world but pose a global environmental problem. While plastics such as poly(ethylene terephthalate) (PET) are highly versatile, their resistance to natural degradation presents a serious, growing risk to fauna and flora, particularly in marine environments. Here, we have characterized the 3D structure of a newly discovered enzyme that can digest highly crystalline PET, the primary material used in the manufacture of single-use plastic beverage bottles, in some clothing, and in carpets. We engineer this enzyme for improved PET degradation capacity and further demonstrate that it can also degrade an important PET replacement, polyethylene-2,5-furandicarboxylate, providing new opportunities for biobased plastics recycling. Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.
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