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Qi X, Ma Y, Chang H, Li B, Ding M, Yuan Y. Evaluation of PET Degradation Using Artificial Microbial Consortia. Front Microbiol 2021; 12:778828. [PMID: 35003008 PMCID: PMC8733400 DOI: 10.3389/fmicb.2021.778828] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/06/2021] [Indexed: 01/30/2023] Open
Abstract
Polyethylene terephthalate (PET) biodegradation is regarded as an environmentally friendly degradation method. In this study, an artificial microbial consortium composed of Rhodococcus jostii, Pseudomonas putida and two metabolically engineered Bacillus subtilis was constructed to degrade PET. First, a two-species microbial consortium was constructed with two engineered B. subtilis that could secrete PET hydrolase (PETase) and monohydroxyethyl terephthalate hydrolase (MHETase), respectively; it could degrade 13.6% (weight loss) of the PET film within 7 days. A three-species microbial consortium was further obtained by adding R. jostii to reduce the inhibition caused by terephthalic acid (TPA), a breakdown product of PET. The weight of PET film was reduced by 31.2% within 3 days, achieving about 17.6% improvement compared with the two-species microbial consortium. Finally, P. putida was introduced to reduce the inhibition caused by ethylene glycol (EG), another breakdown product of PET, obtaining a four-species microbial consortium. With the four-species consortium, the weight loss of PET film reached 23.2% under ambient temperature. This study constructed and evaluated the artificial microbial consortia in PET degradation, which demonstrated the great potential of artificial microbial consortia in the utilization of complex substrates, providing new insights for biodegradation of complex polymers.
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Affiliation(s)
- Xinhua Qi
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Yuan Ma
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Hanchen Chang
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Bingzhi Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Mingzhu Ding
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Yingjin Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education), Frontier Science Center for Synthetic Biology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
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52
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Abstract
Abstract
The serious issue of textile waste accumulation has raised attention on biodegradability as a possible route to support sustainable consumption of textile fibers. However, synthetic textile fibers that dominate the market, especially poly(ethylene terephthalate) (PET), resist biological degradation, creating environmental and waste management challenges. Because pure natural fibers, like cotton, both perform well for consumer textiles and generally meet certain standardized biodegradability criteria, inspiration from the mechanisms involved in natural biodegradability are leading to new discoveries and developments in biologically accelerated textile waste remediation for both natural and synthetic fibers. The objective of this review is to present a multidisciplinary perspective on the essential bio-chemo-physical requirements for textile materials to undergo biodegradation, taking into consideration the impact of environmental or waste management process conditions on biodegradability outcomes. Strategies and recent progress in enhancing synthetic textile fiber biodegradability are reviewed, with emphasis on performance and biodegradability behavior of poly(lactic acid) (PLA) as an alternative biobased, biodegradable apparel textile fiber, and on biological strategies for addressing PET waste, including industrial enzymatic hydrolysis to generate recyclable monomers. Notably, while pure PET fibers do not biodegrade within the timeline of any standardized conditions, recent developments with process intensification and engineered enzymes show that higher enzymatic recycling efficiency for PET polymer has been achieved compared to cellulosic materials. Furthermore, combined with alternative waste management practices, such as composting, anaerobic digestion and biocatalyzed industrial reprocessing, the development of synthetic/natural fiber blends and other strategies are creating opportunities for new biodegradable and recyclable textile fibers.
Article Highlights
Poly(lactic acid) (PLA) leads other synthetic textile fibers in meeting both performance and biodegradation criteria.
Recent research with poly(ethylene terephthalate) (PET) polymer shows potential for efficient enzyme catalyzed industrial recycling.
Synthetic/natural fiber blends and other strategies could open opportunities for new biodegradable and recyclable textile fibers.
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53
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Gautom T, Dheeman D, Levy C, Butterfield T, Alvarez Gonzalez G, Le Roy P, Caiger L, Fisher K, Johannissen L, Dixon N. Structural basis of terephthalate recognition by solute binding protein TphC. Nat Commun 2021; 12:6244. [PMID: 34716322 PMCID: PMC8556258 DOI: 10.1038/s41467-021-26508-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 10/06/2021] [Indexed: 11/08/2022] Open
Abstract
Biological degradation of Polyethylene terephthalate (PET) plastic and assimilation of the corresponding monomers ethylene glycol and terephthalate (TPA) into central metabolism offers an attractive route for bio-based molecular recycling and bioremediation applications. A key step is the cellular uptake of the non-permeable TPA into bacterial cells which has been shown to be dependent upon the presence of the key tphC gene. However, little is known from a biochemical and structural perspective about the encoded solute binding protein, TphC. Here, we report the biochemical and structural characterisation of TphC in both open and TPA-bound closed conformations. This analysis demonstrates the narrow ligand specificity of TphC towards aromatic para-substituted dicarboxylates, such as TPA and closely related analogues. Further phylogenetic and genomic context analysis of the tph genes reveals homologous operons as a genetic resource for future biotechnological and metabolic engineering efforts towards circular plastic bio-economy solutions.
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Affiliation(s)
- Trishnamoni Gautom
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
- Department of Biotechnology, Gauhati University, Guwahati, Assam, India
- Royal School of Bio-Sciences, Royal Global University, Guwahati, Assam, India
| | - Dharmendra Dheeman
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Colin Levy
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Thomas Butterfield
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Guadalupe Alvarez Gonzalez
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Philip Le Roy
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Lewis Caiger
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Karl Fisher
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Linus Johannissen
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Neil Dixon
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK.
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54
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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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55
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Roy PS, Garnier G, Allais F, Saito K. Strategic Approach Towards Plastic Waste Valorization: Challenges and Promising Chemical Upcycling Possibilities. CHEMSUSCHEM 2021; 14:4007-4027. [PMID: 34132056 DOI: 10.1002/cssc.202100904] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/13/2021] [Indexed: 06/12/2023]
Abstract
Plastic waste, which is one of the major sources of pollution in the landfills and oceans, has raised global concern, primarily due to the huge production rate, high durability, and the lack of utilization of the available waste management techniques. Recycling methods are preferable to reduce the impact of plastic pollution to some extent. However, most of the recycling techniques are associated with different drawbacks, high cost and downgrading of product quality being among the notable ones. The sustainable option here is to upcycle the plastic waste to create high-value materials to compensate for the cost of production. Several upcycling techniques are constantly being investigated and explored, which is currently the only economical option to resolve the plastic waste issue. This Review provides a comprehensive insight on the promising chemical routes available for upcycling of the most widely used plastic and mixed plastic wastes. The challenges inherent to these processes, the recent advances, and the significant role of the science and research community in resolving these issues are further emphasized.
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Affiliation(s)
- Pallabi Sinha Roy
- School of Chemistry, Monash University, Clayton, 3800, VIC, Australia
- BioPRIA, Department of Chemical Engineering, Monash University, Clayton, 3800, VIC, Australia
| | - Gil Garnier
- BioPRIA, Department of Chemical Engineering, Monash University, Clayton, 3800, VIC, Australia
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, 51110, Pomacle, France
| | - Florent Allais
- BioPRIA, Department of Chemical Engineering, Monash University, Clayton, 3800, VIC, Australia
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, 51110, Pomacle, France
| | - Kei Saito
- School of Chemistry, Monash University, Clayton, 3800, VIC, Australia
- BioPRIA, Department of Chemical Engineering, Monash University, Clayton, 3800, VIC, Australia
- Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University, Higashi-Ichijo-Kan, Yoshida-nakaadachicho 1, Sakyo-ku, Kyoto, 606-8306, Japan
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56
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Ghodke VM, Punekar NS. Environmental role of aromatic carboxylesterases. Environ Microbiol 2021; 24:2657-2668. [PMID: 34528362 DOI: 10.1111/1462-2920.15774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 01/14/2023]
Abstract
The carboxylesterases (EC 3.1.1.x) are widely distributed and form an important yet diverse group of hydrolases catalysing the ester bond cleavage in a variety of substrates. Besides acting on plant cell wall components like cutin, tannin and feruloyl esters, they are often the first line of defence to metabolize drugs, xenobiotics, pesticides, insecticides and plastic. But for the promiscuity of some carboxylesterases and cutinases, very few enzymes act exclusively on aromatic carboxylic acid esters. Infrequent occurrence of aromatic carboxylesterases suggests that aromatic carboxylesters are inherently more difficult to hydrolyse than the regular carboxylesters because of both steric and polar effects. Naturally occurring aromatic carboxylesters were rare before the anthropogenic activity augmented their environmental presence and diversity. An appraisal of the literature shows that the hydrolysis of aromatic carboxylic esters is a uniquely difficult endeavour and hence deserves special attention. Enzymes to hydrolyse such esters are evolving rapidly in nature. Very few such enzymes are known and they often display much lower catalytic efficiencies. Obviously, the esters of aromatic carboxylic acids, including polyethylene terephthalate waste, pose an environmental challenge. In this review, we highlight the uniqueness of aromatic carboxylesters and then underscore the importance of relevant carboxylesterases.
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Affiliation(s)
- Venkatesh M Ghodke
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Narayan S Punekar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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57
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Dissanayake L, Jayakody LN. Engineering Microbes to Bio-Upcycle Polyethylene Terephthalate. Front Bioeng Biotechnol 2021; 9:656465. [PMID: 34124018 PMCID: PMC8193722 DOI: 10.3389/fbioe.2021.656465] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/12/2021] [Indexed: 11/21/2022] Open
Abstract
Polyethylene terephthalate (PET) is globally the largest produced aromatic polyester with an annual production exceeding 50 million metric tons. PET can be mechanically and chemically recycled; however, the extra costs in chemical recycling are not justified when converting PET back to the original polymer, which leads to less than 30% of PET produced annually to be recycled. Hence, waste PET massively contributes to plastic pollution and damaging the terrestrial and aquatic ecosystems. The global energy and environmental concerns with PET highlight a clear need for technologies in PET "upcycling," the creation of higher-value products from reclaimed PET. Several microbes that degrade PET and corresponding PET hydrolase enzymes have been successfully identified. The characterization and engineering of these enzymes to selectively depolymerize PET into original monomers such as terephthalic acid and ethylene glycol have been successful. Synthetic microbiology and metabolic engineering approaches enable the development of efficient microbial cell factories to convert PET-derived monomers into value-added products. In this mini-review, we present the recent progress of engineering microbes to produce higher-value chemical building blocks from waste PET using a wholly biological and a hybrid chemocatalytic-biological strategy. We also highlight the potent metabolic pathways to bio-upcycle PET into high-value biotransformed molecules. The new synthetic microbes will help establish the circular materials economy, alleviate the adverse energy and environmental impacts of PET, and provide market incentives for PET reclamation.
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Affiliation(s)
- Lakshika Dissanayake
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Lahiru N. Jayakody
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
- Fermentation Science Institute, Southern Illinois University, Carbondale, IL, United States
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58
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Nikulin M, Švedas V. Prospects of Using Biocatalysis for the Synthesis and Modification of Polymers. Molecules 2021; 26:2750. [PMID: 34067052 PMCID: PMC8124709 DOI: 10.3390/molecules26092750] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/30/2021] [Accepted: 05/04/2021] [Indexed: 11/16/2022] Open
Abstract
Trends in the dynamically developing application of biocatalysis for the synthesis and modification of polymers over the past 5 years are considered, with an emphasis on the production of biodegradable, biocompatible and functional polymeric materials oriented to medical applications. The possibilities of using enzymes not only as catalysts for polymerization but also for the preparation of monomers for polymerization or oligomers for block copolymerization are considered. Special attention is paid to the prospects and existing limitations of biocatalytic production of new synthetic biopolymers based on natural compounds and monomers from biomass, which can lead to a huge variety of functional biomaterials. The existing experience and perspectives for the integration of bio- and chemocatalysis in this area are discussed.
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Affiliation(s)
- Maksim Nikulin
- Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, Lenin Hills 1, bldg. 40, 119991 Moscow, Russia;
| | - Vytas Švedas
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Lenin Hills 1, bldg. 73, 119991 Moscow, Russia
- Research Computing Center, Lomonosov Moscow State University, Lenin Hills 1, bldg. 4, 119991 Moscow, Russia
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59
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Heyde SAH, Arnling Bååth J, Westh P, Nørholm MHH, Jensen K. Surface display as a functional screening platform for detecting enzymes active on PET. Microb Cell Fact 2021; 20:93. [PMID: 33933097 PMCID: PMC8088578 DOI: 10.1186/s12934-021-01582-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/20/2021] [Indexed: 11/21/2022] Open
Abstract
Poly(ethylene terephthalate) (PET) is the world’s most abundant polyester plastic, and its ongoing accumulation in nature is causing a global environmental problem. Currently, the main recycling processes utilize thermomechanical or chemical means, resulting in the deterioration of the mechanical properties of PET. Consequently, polluting de novo synthesis remains preferred, creating the need for more efficient and bio-sustainable ways to hydrolyze the polymer. Recently, a PETase enzyme from the bacterium Ideonella sakaiensis was shown to facilitate PET biodegradation, albeit at slow rate. Engineering of more efficient PETases is required for industrial relevance, but progress is currently hampered by the dependency on intracellular expression in Escherichia coli. To create a more efficient screening platform in E. coli, we explore different surface display anchors for fast and easy assaying of PETase activity. We show that PETases can be functionally displayed on the bacterial cell surface, enabling screening of enzyme activity on PET microparticles – both while anchored to the cell and following solubilization of the enzymes.
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Affiliation(s)
- Sophia A H Heyde
- Novozymes A/S, Biologiens Vej 2, 2800, Kgs. Lyngby, Denmark.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet B220, 2800, Kgs. Lyngby, Denmark
| | - Jenny Arnling Bååth
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800, Kgs. Lyngby, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800, Kgs. Lyngby, Denmark
| | - Morten H H Nørholm
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet B220, 2800, Kgs. Lyngby, Denmark
| | - Kenneth Jensen
- Novozymes A/S, Biologiens Vej 2, 2800, Kgs. Lyngby, Denmark.
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60
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A simple and novel method for the production of polyethylene terephthalate containing agar plates for the growth and detection of bacteria able to hydrolyze this plastic. J Microbiol Methods 2021; 185:106222. [PMID: 33865904 DOI: 10.1016/j.mimet.2021.106222] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/22/2022]
Abstract
Polyethylene terephthalate is used in the manufacture of many products. Microbes able to hydrolyze the plastic are known, and offer promise for practical waste management. Screening for hydrolysis usually involves unwieldy culturing in the presence of film. A rapid screening method based on culturing on agar plates is here described.
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