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Schubert SW, Thomsen TB, Clausen KS, Malmendal A, Hunt CJ, Borch K, Jensen K, Brask J, Meyer AS, Westh P. Relationships of crystallinity and reaction rates for enzymatic degradation of poly (ethylene terephthalate), PET. CHEMSUSCHEM 2024; 17:e202301752. [PMID: 38252197 DOI: 10.1002/cssc.202301752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024]
Abstract
Biocatalytic degradation of plastic waste is anticipated to play an important role in future recycling systems. However, enzymatic degradation of crystalline poly (ethylene terephthalate) (PET) remains consistently poor. Herein, we employed functional assays to elucidate the molecular underpinnings of this limitation. This included utilizing complementary activity assays to monitor the degradation of PET disks with varying crystallinity (XC), as well as determining enzymatic kinetic parameters for soluble PET fragments. The results indicate that an efficient PET-hydrolase, LCCICCG, operates through an endolytic mode of action, and that its activity is limited by conformational constraints in the PET polymer. Such constraints become more pronounced at high XC values, and this limits the density of productive sites on the PET surface. Endolytic chain-scissions are the dominant reaction type in the initial stage, and this means that little or no soluble organic product are released. However, endolytic cuts gradually and locally promote chain mobility and hence the density of attack sites on the surface. This leads to an upward concave progress curve; a behavior sometimes termed lag-phase kinetics.
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Affiliation(s)
- Sune W Schubert
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
| | - Thore B Thomsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
| | - Kristine S Clausen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
| | - Anders Malmendal
- Institute of Natural Science and Environmental Chemistry., Roskilde University, Universitetsvej 1, 28 C.1, DK-4000, Roskilde, Denmark
| | - Cameron J Hunt
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
| | - Kim Borch
- Novozymes A/S, Biologiens Vej 2, DK-2800, Kgs. Lyngby, Denmark
| | - Kenneth Jensen
- Novozymes A/S, Biologiens Vej 2, DK-2800, Kgs. Lyngby, Denmark
| | - Jesper Brask
- Novozymes A/S, Biologiens Vej 2, DK-2800, Kgs. Lyngby, Denmark
| | - Anne S Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, DK-2800, Kgs. Lyngby, Denmark
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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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Weigert S, Perez‐Garcia P, Gisdon FJ, Gagsteiger A, Schweinshaut K, Ullmann GM, Chow J, Streit WR, Höcker B. Investigation of the halophilic PET hydrolase PET6 from Vibrio gazogenes. Protein Sci 2022; 31:e4500. [PMID: 36336469 PMCID: PMC9679969 DOI: 10.1002/pro.4500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/21/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022]
Abstract
The handling of plastic waste and the associated ubiquitous occurrence of microplastic poses one of the biggest challenges of our time. Recent investigations of plastic degrading enzymes have opened new prospects for biological microplastic decomposition as well as recycling applications. For polyethylene terephthalate, in particular, several natural and engineered enzymes are known to have such promising properties. From a previous study that identified new PETase candidates by homology search, we chose the candidate PET6 from the globally distributed, halophilic organism Vibrio gazogenes for further investigation. By mapping the occurrence of Vibrios containing PET6 homologs we demonstrated their ubiquitous prevalence in the pangenome of several Vibrio strains. The biochemical characterization of PET6 showed that PET6 has a comparatively lower activity than other enzymes but also revealed a superior turnover at very high salt concentrations. The crystal structure of PET6 provides structural insights into this adaptation to saline environments. By grafting only a few beneficial mutations from other PET degrading enzymes onto PET6, we increased the activity up to three-fold, demonstrating the evolutionary potential of the enzyme. MD simulations of the variant helped rationalize the mutational effects of those mutants and elucidate the interaction of the enzyme with a PET substrate. With tremendous amounts of plastic waste in the Ocean and the prevalence of Vibrio gazogenes in marine biofilms and estuarine marshes, our findings suggest that Vibrio and the PET6 enzyme are worthy subjects to study the PET degradation in marine environments.
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Affiliation(s)
| | - Pablo Perez‐Garcia
- Department of Microbiology and BiotechnologyUniversity of HamburgHamburgGermany
| | | | | | | | | | - Jennifer Chow
- Department of Microbiology and BiotechnologyUniversity of HamburgHamburgGermany
| | - Wolfgang R. Streit
- Department of Microbiology and BiotechnologyUniversity of HamburgHamburgGermany
| | - Birte Höcker
- Department of BiochemistryUniversity of BayreuthBayreuthGermany
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Okeke ES, Ezeorba TPC, Chen Y, Mao G, Feng W, Wu X. Ecotoxicological and health implications of microplastic-associated biofilms: a recent review and prospect for turning the hazards into benefits. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:70611-70634. [PMID: 35994149 DOI: 10.1007/s11356-022-22612-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Microplastics (MPs), over the years, have been regarded as a severe environmental nuisance with adverse effects on our ecosystem as well as human health globally. In recent times, microplastics have been reported to support biofouling by genetically diverse organisms resulting in the formation of biofilms. Biofilms, however, could result in changes in the physicochemical properties of microplastics, such as their buoyancy and roughness. Many scholars perceived the microplastic-biofilm association as having more severe consequences, providing evidence of its effects on the environment, aquatic life, and nutrient cycles. Furthermore, other researchers have shown that microplastic-associated biofilms have severe consequences on human health as they serve as vectors of heavy metals, toxic chemicals, and antibiotic resistance genes. Despite what is already known about their adverse effects, other interesting avenues are yet to be fully explored or developed to turn the perceived negative microplastic-biofilm association to our advantage. The major inclusion criteria for relevant literature were that it must focus on microplastic association biofilms, while we excluded papers solely on biofilms or microplastics. A total of 242 scientific records were obtained. More than 90% focused on explaining the environmental and health impacts of microplastic-biofilm association, whereas only very few studies have reported the possibilities and opportunities in turning the microplastic biofilms association into benefits. In summary, this paper concisely reviews the current knowledge of microplastic-associated biofilms and their adverse consequences and further proposes some approaches that can be developed to turn the negative association into positive.
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Affiliation(s)
- Emmanuel Sunday Okeke
- Institute of Environmental Health and Ecological Security, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
- Department of Biochemistry, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, 41000, Nigeria
- Natural Science Unit, SGS, University of Nigeria, Nsukka, Enugu State, 41000, Nigeria
| | | | - Yao Chen
- Institute of Environmental Health and Ecological Security, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Guanghua Mao
- Institute of Environmental Health and Ecological Security, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Weiwei Feng
- Institute of Environmental Health and Ecological Security, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
| | - Xiangyang Wu
- Institute of Environmental Health and Ecological Security, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
- Institute of Environmental Health and Ecological Security, School of the Environment and Safety, Jiangsu University, 301 Xuefu Rd., 212013, Zhenjiang, Jiangsu, China.
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