Recent advances in biocatalysts engineering for polyethylene terephthalate plastic waste green recycling

Samak, Nadia A.; Jia, Yantao; Sharshar, Moustafa Mohamed; Mu, Tingzhen; Yang, Maohua; Peh, Sumit; Xing, Jianmin

doi:10.1016/j.envint.2020.106144

Cited by 131 publications

(84 citation statements)

References 156 publications

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“…The presence of 2,5-pyridinedicarboxylate (2) and 2,6-naphthalenedicarboxylate (22) have less pronounced, but still signi cant, stabilising interactions with TphC, displaying ΔT m s of 1.4 ± 1.1°C and 1.4 ± 0.7°C, respectively. The other para-substituted dicarboxylate analogues (3,(5)(6)(8)(9)(10)(11) regioisomers (12)(13), hetero-aromatics (14)(15)(16)(17)(18)(19), bicyclic aromatics (20,23), the mono-carboxylate and carboxylate isosteres , unsaturated phenylpropanoates (45)(46)(47)(48)(49)(50), phenols (51)(52), aromatic esters (53)(54)(55)(56) and aliphatic dicarboxylates (57-61) had either negligible effect on ΔT m s or their interactions with TphC were found to be slightly destabilising under the assay conditions. This indicates that for optimal interaction a six-membered para-substituted aromatic dicarboxylate is required, that limited additional substitution with hydroxyl groups around the ring and minor heteroaromatic modi cations are tolerated, and that extended aromatic systems are partially tolerated.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, there is great interest in nding better strategies for PET bioconversion and recycling through engineering robust enzymes and microbial strains for its degradation, uptake and assimilation. Terephthalic acid (TPA) and ethylene glycol (EG), which together form a polymer chain, are the basic building blocks of PET and can be released by enzymatic hydrolysis via the action of different types of bacterial and fungal origin hydrolases, such as esterases, lipases, cutinases and carboxylesterases [17][18][19][20][21][22][23][24] . A bacterial strain, Ideonella sakaiensis was discovered that secreted two enzymes PETase, and MHETase which enable the microbe to grow on PET as a sole carbon source 25 .…”

Section: Introductionmentioning

confidence: 99%

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Structural basis of terephthalate recognition by solute binding protein TphC

Gautom

Dheeman

Levy

et al. 2021

Preprint

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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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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural basis of terephthalate recognition by solute binding protein TphC

Gautom

Dheeman

Levy

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…To increase the catalytic efficiency, stability, specificity, and selectivity of enzymes, immobilization of the enzyme system in suitable matrices is usually carried out (Samak et al, 2020). This enhancement in enzymatic properties is due to favorable structural changes in enzyme as a result of immobilization (Samak et al, 2020). PET hydrolases/cutinases have been immobilized on different matrixes for increasing thermostability.…”

Section: Immobilizationmentioning

confidence: 99%

Enzymatic Remediation of Polyethylene Terephthalate (PET)–Based Polymers for Effective Management of Plastic Wastes: An Overview

Maurya

Bhattacharya

Khare

2020

Front. Bioeng. Biotechnol.

102

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Globally, plastic-based pollution is now recognized as one of the serious threats to the environment. Among different plastics, polyethylene terephthalate (PET) occupies a pivotal place, its excess presence as a waste is a major environmental concern. Mechanical, thermal, and chemical-based treatments are generally used to manage PET pollution. However, these methods are usually expensive or generate secondary pollutants. Hence, there is a need for a cost-effective and environment-friendly method for efficient management of PET-based plastic wastes. Considering this, enzymatic treatment or recycling is one of the important methods to curb PET pollution. In this regard, PET hydrolases have been explored for the treatment of PET wastes. These enzymes act on PET and end its breakdown into monomeric units and subsequently results in loss of weight. However, various factors, specifically PET crystallinity, temperature, and pH, are known to affect this enzymatic process. For effective hydrolysis of PET, high temperature is required, which facilitates easy accessibility of substrate (PET) to enzymes. However, to function at this high temperature, there is a requirement of thermostable enzymes. The thermostability could be enhanced using glycosylation, immobilization, and enzyme engineering. Furthermore, the use of surfactants, additives such as Ca 2+ , Mg 2+ , and hydrophobins (cysteine-rich proteins), has also been reported to enhance the enzymatic PET hydrolysis through facilitating easy accessibility of PET polymers. The present review encompasses a brief overview of the use of enzymes toward the management of PET wastes. Various methods affecting the treatment process and different constraints arising thereof are also systematically highlighted in the review.

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“…Notably, for the commercial production of PET-hydrolyzing enzymes, the strains that allow secretory high-level expression should be used to avoid additional costly purification steps (Su et al, 2013). Since enzyme expression and purification add extra cost to the process, researchers developed the whole-cell microbial catalysts to degrade the PET by heterologous expression of PET-hydrolyzing enzymes (Samak et al, 2020). A promising strategy to overcome the problem of PET waste in marine environments where an engineered photosynthetic marine microalgae Phaeodactylum tricornutum with the ability to produce and secrete an improved PETase into the culture medium has been developed (Moog et al, 2019).…”

Section: Selective Degradation Of Pet By Microbial Enzymesmentioning

confidence: 99%

Engineering Microbes to Bio-Upcycle Polyethylene Terephthalate

Dissanayake

Jayakody

2021

Front. Bioeng. Biotechnol.

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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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Recent advances in biocatalysts engineering for polyethylene terephthalate plastic waste green recycling

Cited by 131 publications

References 156 publications

Structural basis of terephthalate recognition by solute binding protein TphC

Structural basis of terephthalate recognition by solute binding protein TphC

Enzymatic Remediation of Polyethylene Terephthalate (PET)–Based Polymers for Effective Management of Plastic Wastes: An Overview

Engineering Microbes to Bio-Upcycle Polyethylene Terephthalate

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