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 Plastic-Degrading Potential across the Global Microbiome Correlates with Recent Pollution Trends

mBio ◽  
2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Jan Zrimec ◽  
Mariia Kokina ◽  
Sara Jonasson ◽  
Francisco Zorrilla ◽  
Aleksej Zelezniak
Keyword(s):  
Synthetic Biology ◽  
Polyethylene Terephthalate ◽  
Crucial Importance ◽  
Ambient Conditions ◽  
Degradation Processes ◽  
Plastic Degradation

Utilization of synthetic biology approaches to enhance current plastic degradation processes is of crucial importance, as natural plastic degradation processes are very slow. For instance, the predicted lifetime of a polyethylene terephthalate (PET) bottle under ambient conditions ranges from 16 to 48 years.

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 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.

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 Enzymes Involved in Plastic Degradation

2021 ◽  
pp. 95-110
Author(s):  
S.Z.Z. Cobongela
Keyword(s):  
Polyethylene Terephthalate ◽  
Synthetic Polymers ◽  
Chemical Degradation ◽  
Natural Resistance ◽  
Aquatic Life ◽  
Carbon Backbone ◽  
Catabolic Enzymes ◽  
Plastic Degradation ◽  
Global Increase ◽  
Physical And Chemical

The global increase in production of plastic and accumulation in the environment is becoming a major concern especially to the aquatic life. This is due to the natural resistance of plastic to both physical and chemical degradation. Lack of biodegradability of plastic polymers is linked to, amongst other factors, the mobility of the polymers in the crystalline part of the polyesters as they are responsible for enzyme interaction. There are significantly few catabolic enzymes that are active in breaking down polyesters which are the constituents of plastic. The synthetic polymers widely used in petroleum-based plastics include polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane (PUR), polystyrene (PS), polyamide (PA) and polyethylene terephthalate (PET) being the ones used mostly. Polymers with heteroatomic backbone such as PET and PUR are easier to degrade than the straight carbon-carbon backbone polymers such as PE, PP, PS and PVC.

Describing microbial degradation processes with the EVOLON model

1996 ◽  
Vol 16 (4) ◽  
pp. 237-244 ◽  
Author(s):  
Th. Bley ◽  
K.-F. Albrecht ◽  
D. Miethe ◽  
V. Riis ◽  
W. Babel
Keyword(s):  
Microbial Degradation ◽  
Degradation Processes

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 Biostimulation of in situ microbial degradation processes in organically-enriched sediments mitigates the impact of aquaculture

Chemosphere ◽  
2019 ◽  
Vol 226 ◽  
pp. 715-725 ◽  
Author(s):  
Francesca Ape ◽  
Elena Manini ◽  
Grazia Marina Quero ◽  
Gian Marco Luna ◽  
Gianluca Sarà ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Degradation Processes ◽  
The Impact
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