scholarly journals Enzymatic depolymerization of highly crystalline polyethylene terephthalate enabled in moist-solid reaction mixtures

2021 ◽  
Vol 118 (29) ◽  
pp. e2026452118
Author(s):  
Sandra Kaabel ◽  
J. P. Daniel Therien ◽  
Catherine E. Deschênes ◽  
Dustin Duncan ◽  
Tomislav Friščić ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Plastic Pollution ◽  
Solid Reaction ◽  
Humicola Insolens ◽  
Pollution Problem ◽  
Dilute Aqueous Solutions ◽  
Space Time Yield ◽  
Crystalline Forms ◽  
Enzymatic Depolymerization ◽  
Crystalline Polyethylene

Less than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, they lack activity toward the more crystalline forms of PET commonly found in consumer plastics, requiring the energy-expensive melt-amorphization step of PET before enzymatic depolymerization. We report here that, when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions or slurries, the cutinase from Humicola insolens can directly depolymerize amorphous and crystalline regions of PET equally, without any pretreatment, with a 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than reported in prior studies with high-crystallinity material. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products.

scholarly journals Clean Enzymatic depolymerization of highly crystalline polyethylene terephthalate in moist-solid reaction mixtures

2020 ◽  
Author(s):  
Sandra Kaabel ◽  
J. P. Daniel Therien ◽  
Catherine E. Deschênes ◽  
Dustin Duncan ◽  
Tomislav Friščić ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Metal Organic Framework ◽  
Direct Synthesis ◽  
Plastic Pollution ◽  
Solid Reaction ◽  
Pollution Problem ◽  
Metal Organic ◽  
Dilute Aqueous Solutions ◽  
Space Time Yield ◽  
Crystalline Forms

AbstractLess than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, the current consensus is that they lack activity towards the more crystalline forms of PET. We report here that when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions, enzymes can directly depolymerize high crystallinity PET in 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than prior reports. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products, which allows the direct synthesis of UiO-66 metal-organic framework.

Structural insights into dihydroxylation of terephthalate, a product of polyethylene terephthalate degradation

2022 ◽  
Author(s):  
Jai Krishna Mahto ◽  
Neetu Neetu ◽  
Monica Sharma ◽  
Monika Dubey ◽  
Bhanu Prakash Vellanki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Substrate Specificity ◽  
Polyethylene Terephthalate ◽  
Active Site ◽  
Catalytic Domain ◽  
Structural Features ◽  
Comamonas Testosteroni ◽  
Plastic Pollution ◽  
Microbial Utilization ◽  
Steady State Kinetics

Biodegradation of terephthalate (TPA) is a highly desired catabolic process for the bacterial utilization of this Polyethylene terephthalate (PET) depolymerization product, but to date, the structure of terephthalate dioxygenase (TPDO), a Rieske oxygenase (RO) that catalyzes the dihydroxylation of TPA to a cis -diol is unavailable. In this study, we characterized the steady-state kinetics and first crystal structure of TPDO from Comamonas testosteroni KF1 (TPDO KF1 ). The TPDO KF1 exhibited the substrate specificity for TPA ( k cat / K m = 57 ± 9 mM −1 s −1 ). The TPDO KF1 structure harbors characteristics RO features as well as a unique catalytic domain that rationalizes the enzyme’s function. The docking and mutagenesis studies reveal that its substrate specificity to TPA is mediated by Arg309 and Arg390 residues, two residues positioned on opposite faces of the active site. Additionally, residue Gln300 is also proven to be crucial for the activity, its substitution to alanine decreases the activity ( k cat ) by 80%. Together, this study delineates the structural features that dictate the substrate recognition and specificity of TPDO. Importance The global plastic pollution has become the most pressing environmental issue. Recent studies on enzymes depolymerizing polyethylene terephthalate plastic into terephthalate (TPA) show some potential in tackling this. Microbial utilization of this released product, TPA is an emerging and promising strategy for waste-to-value creation. Research from the last decade has discovered terephthalate dioxygenase (TPDO), as being responsible for initiating the enzymatic degradation of TPA in a few Gram-negative and Gram-positive bacteria. Here, we have determined the crystal structure of TPDO from Comamonas testosteroni KF1 and revealed that it possesses a unique catalytic domain featuring two basic residues in the active site to recognize TPA. Biochemical and mutagenesis studies demonstrated the crucial residues responsible for the substrate specificity of this enzyme.

scholarly journals Current Advances in the Biodegradation and Bioconversion of Polyethylene Terephthalate

2021 ◽  
Vol 10 (1) ◽  
pp. 39
Author(s):  
Xinhua Qi ◽  
Wenlong Yan ◽  
Zhibei Cao ◽  
Mingzhu Ding ◽  
Yingjin Yuan
Keyword(s):  
Polyethylene Terephthalate ◽  
Microbial Consortium ◽  
Tricarboxylic Acid Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Microbial Consortia ◽  
Plastic Pollution ◽  
One Step ◽  
Complex Polymers ◽  
The One

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.

scholarly journals Preliminary Study on Abundance of Microplastic in Sediments and Water Samples Along the Coast of Pakistan (Sindh and Balochistan)-Northern Arabian Sea

2021 ◽  
Vol 22 (Special Issue) ◽  
Author(s):  
Quratulan Ahmed ◽  
Qadeer Mohammad Ali ◽  
Levent Bat ◽  
Aysah Oztekin ◽  
Sehrish Memon ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Sea Water ◽  
Plastic Material ◽  
Plastic Pollution ◽  
Sediment Samples ◽  
Water And Sediment ◽  
Northern Arabian Sea ◽  
Pollution Problem ◽  
High Pollution ◽  
Preliminary Study

Plastic material dominates our life and accordingly, it dominates the environment as a pollutant. Pakistan coasts are facing with plastic pollution problem like the rest of the world. The number and types of microplastics found in sea water and sediment samples from 25 locations along the Arabian Sea coast of Pakistan were explored in this study. The results of the present study show that the region is under a high pollution from microplastics. Microplastic abundance in seawater was found as mean 582.12±246.14 particle. L-1 and in sediment samples was mean 987.40±617.06 particle.kg-1 dry sediment. Microplastic concentration was maximum in Manora both seawater and sediment samples. Fibers were major contribution to total microplastics, up to 99% of all samples both seawater and sediment samples.

scholarly journals Microbial Degradation of Plastics and Approaches to Make it More Efficient

Microbiology ◽  
2021 ◽  
Vol 90 (6) ◽  
pp. 671-701
Author(s):  
I. B. Kotova ◽  
Yu. V. Taktarova ◽  
E. A. Tsavkelova ◽  
M. A. Egorova ◽  
I. A. Bubnov ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Microbial Degradation ◽  
Microscopic Fungi ◽  
Slow Process ◽  
Plastic Pollution ◽  
Degradation Processes ◽  
Worldwide Production ◽  
Plastic Degradation

Abstract— The growing worldwide production of synthetic plastics leads to increased amounts of plastic pollution. Even though microbial degradation of plastics is known to be a very slow process, this capacity has been found in many bacteria, including invertebrate symbionts, and microscopic fungi. Research in this field has been mostly focused on microbial degradation of polyethylene, polystyrene, and polyethylene terephthalate (PET). Quite an arsenal of different methods is available today for detecting processes of plastic degradation and measuring their rates. Given the lack of generally accepted protocols, it is difficult to compare results presented by different authors. PET degradation by recombinant hydrolases from thermophilic actinobacteria happens to be the most efficient among the currently known plastic degradation processes. Various approaches to accelerating microbial plastic degradation are also discussed.

scholarly journals Engineering Microbes to Bio-Upcycle Polyethylene Terephthalate

2021 ◽  
Vol 9 ◽  
Author(s):  
Lakshika Dissanayake ◽  
Lahiru N. Jayakody
Keyword(s):  
Polyethylene Terephthalate ◽  
Metabolic Pathways ◽  
Aquatic Ecosystems ◽  
Value Added ◽  
Building Blocks ◽  
Chemical Recycling ◽  
Plastic Pollution ◽  
Microbial Cell Factories ◽  
Cell Factories ◽  
Value Added Products

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.

scholarly journals Knowledge and Opportunities from the Plastisphere: A Prelude for the Search of Plastic Degrading Bacteria on Coastal Environments

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Luis Felipe Avilés-Ramírez ◽  
Joanna M. Ortiz-Alcantara ◽  
Ma. Leticia Arena-Ortiz
Keyword(s):  
Human Populations ◽  
Coastal Environments ◽  
Plastic Pollution ◽  
General Process ◽  
Pollution Problem ◽  
Degrading Bacteria ◽  
Scientific Papers ◽  
Microbial Strains ◽  
Microbial Agents ◽  
Broad Understanding

Plastic pollution has become an urgent issue, since its invasion to every ecosystem has led to multiple impacts on the environment and human populations. Certain microbial strains and genera had shown the ability to biodegrade plastic sources under laboratory conditions. In this minireview, we collect and analyze scientific papers and reports of this microbial activity as we contextualize this information on the global plastic pollution problem, to provide an updated state of the art of plastic biodegradation with microbial agents. Along with a broad understanding of the general process of plastic biodegradation hosted by microorganisms. The contributions of this minireview come from the identification of research gaps, as well as proposals for new approaches. One of the main proposals focuses on coastal environments and in particular coastal wetlands as a great microbiome source with potential for plastic biodegradation, whether reported or undiscovered. Our final proposal consists of the application of this knowledge into technologic tools and strategies that have a remarkable impact on the battle against the plastic pollution problem.

scholarly journals Fusion of Chitin-Binding Domain From Chitinolyticbacter meiyuanensis SYBC-H1 to the Leaf-Branch Compost Cutinase for Enhanced PET Hydrolysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Rui Xue ◽  
Yinping Chen ◽  
Huan Rong ◽  
Ren Wei ◽  
Zhongli Cui ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Enzymatic Hydrolysis ◽  
Polyethylene Terephthalate ◽  
Binding Domain ◽  
Plastic Pollution ◽  
Pet Waste ◽  
Chitin Binding Domain ◽  
C Terminus ◽  
Measurable Activity ◽  
Hydrolysis Of

Polyethylene terephthalate (PET) is a mass-produced petroleum-based non-biodegradable plastic that contributes to the global plastic pollution. Recently, biocatalytic degradation has emerged as a viable recycling approach for PET waste, especially with thermophilic polyester hydrolases such as a cutinase (LCC) isolated from a leaf-branch compost metagenome and its variants. To improve the enzymatic PET hydrolysis performance, we fused a chitin-binding domain (ChBD) from Chitinolyticbacter meiyuanensis SYBC-H1 to the C-terminus of the previously reported LCCICCG variant, demonstrating higher adsorption to PET substrates and, as a result, improved degradation performance by up to 19.6% compared to with its precursor enzyme without the binding module. For compare hydrolysis with different binding module, the catalytic activity of LCCICCG-ChBD, LCCICCG-CBM, LCCICCG-PBM and LCCICCG-HFB4 were further investigated with PET substrates of various crystallinity and it showed measurable activity on high crystalline PET with 40% crystallinity. These results indicated that fusing a polymer-binding module to LCCICCG is a promising method stimulating the enzymatic hydrolysis of PET.

scholarly journals Kas atsakingas už švarius vandenynus?

2020 ◽  
pp. 202-228
Author(s):  
Gretė Bagdonaitė ◽  
Leila Abi Chaker
Keyword(s):  
Negative Impact ◽  
Plastic Waste ◽  
Plastic Pollution ◽  
International Regulation ◽  
Ocean Pollution ◽  
Pollution Problem ◽  
Production And Consumption ◽  
Ocean Ecosystem ◽  
Key Aspects ◽  
National Economies

More and more oceans are polluted by plastic waste emmitted by humans. Unrestricted production and consumption of plastic products have a major negative impact not only on the world’s lungs – the oceans but also on human health. Ocean plastic pollution is caused by human activities, particularly land-based activities. Therefore, this article addresses two key aspects that should be tackled with this pollution problem. First, the article presents the existing international regulation directed against ocean pollution by land-based sources, highlighting its inefficiencies and shortcomings, while suggesting what decisions should be taken on the international scene. Secondly, Secondly, it discusses ways in which the amount of plastic waste generated can be reduced, with positive consequences not only for the ocean ecosystem but also for national economies.

Sign in / Sign up

Export Citation Format

Share Document