Thermophilic whole‐cell degradation of polyethylene terephthalate using engineered <i>Clostridium thermocellum</i>

Yan, Fei; Wei, Ren; Cui, Qiu; Bornscheuer, Uwe T.; Liu, Yajun

doi:10.1111/1751-7915.13580

Cited by 140 publications

(59 citation statements)

References 57 publications

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“…The most progressed example is the use of enzymatic degradation of PET waste for recycling (4), but bioprocessing could also become important for remediation of microplastic pollution. This latter field has recently experienced important progress with the successful transformation of genes encoding plastic degrading enzymes into different microorganisms, which in turn becomes potential plastic scavengers (39–41). One common requirement for these applications is the design of better enzymes.…”

Section: Discussionmentioning

confidence: 99%

Comparative biochemistry of four polyester (PET) hydrolases

Baath

Borch

Jensen

et al. 2020

Preprint

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The potential of bioprocessing in a circular plastic economy has strongly stimulated research in enzymatic degradation of different synthetic resins. Particular interest has been devoted to the commonly used polyester, poly(ethylene terephthalate) (PET), and a number of PET hydrolases have been described. However, a kinetic framework for comparisons of PET hydrolases (or other plastic degrading enzymes) acting on the insoluble substrate, has not been established. Here, we propose such a framework and test it against kinetic measurements on four PET hydrolases. The analysis provided values of kcat and KM, as well as an apparent specificity constant in the conventional units of M−1s−1. These parameters, together with experimental values for the number of enzyme attack sites on the PET surface, enabled comparative analyses. We found that the PET hydrolase from Ideonella sakaiensis was the most efficient enzyme at ambient conditions, and that this relied on a high kcat rather than a low KM. Moreover, both soluble and insoluble PET fragments were consistently hydrolyzed much faster than intact PET. This suggests that interactions between polymer strands slow down PET degradation, while the chemical steps of catalysis and the low accessibility associated with solid substrate were less important for the overall rate. Finally, the investigated enzymes showed a remarkable substrate affinity, and reached half the saturation rate on PET, when the concentration of attack sites in the suspension was only about 50 nM. We propose that this is linked to nonspecific adsorption, which promotes the nearness of enzyme and attack sites.

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Section: Discussionmentioning

confidence: 99%

Comparative biochemistry of four polyester (PET) hydrolases

Baath

Borch

Jensen

et al. 2020

Preprint

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“…It is far from an economical option to directly use free enzymes in large-scale reactions due to the relatively short enzyme lifetimes and difficulty in enzyme recovery and reuse [105]. Engineering whole-cell biocatalysts constantly producing functional plastic-degrading enzymes could be a strategy to overcome the problem of short enzyme lifetimes [106,107]. Identifying and engineering microorganisms that naturally degrade plastics could be another potential solution for this issue.…”

Section: Concluding Remarks and Future Perspectivesmentioning

confidence: 99%

Enzyme discovery and engineering for sustainable plastic recycling

Zhu

Wang

Wei

2022

Trends in Biotechnology

178

114

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The drastically increasing amount of plastic waste is causing an environmental crisis that requires innovative technologies for recycling post-consumer plastics to achieve waste valorization while meeting environmental quality goals. Biocatalytic depolymerization mediated by enzymes has emerged as an efficient and sustainable alternative for plastic treatment and recycling. A variety of plasticdegrading enzymes have been discovered from microbial sources. Meanwhile, protein engineering has been exploited to modify and optimize plastic-degrading enzymes. This review highlights the recent trends and up-to-date advances in mining novel plastic-degrading enzymes through state-of-the-art omics-based techniques and improving the enzyme catalytic efficiency and stability via various protein engineering strategies. Future research prospects and challenges are also discussed. Biocatalysis as an Emerging Solution for the Global Plastic Waste ChallengePlastic materials play a revolutionary role in the modern world, although the enormous manufacture and extensive use of plastic commodities inevitably generate an extraordinary amount of post-consumer plastic waste. Around 12 000 million metric tons of plastic waste are predicted to accumulate in landfills and the natural environment by 2050 [1]. Improper handling of plastic waste has caused a grand environmental challenge. The debris of plastic waste, especially microplastics (see Glossary), can impose hazardous effects on various organisms and eventually threaten human well-being [2-5]. In addition, the degradation resistance of plastics further escalates their adverse environmental impacts [6]. Therefore, it is urgent to develop innovative technologies for treatment and recycling of post-consumer plastics, to achieve both waste valorization and environmental protection.Enzymatic biocatalysis has gained increasing attention as an eco-friendly alternative to conventional plastic treatment and recycling methods (Box 1) [7]. To date, various microbial plastic-degrading enzymes have been discovered, representing promising biocatalyst candidates for plastic depolymerization. Considering the ubiquity of plastics in different ecosystems and the tremendous metabolic and genetic diversity of microorganisms, microbial communities in various habitats have likely evolved capabilities in plastic decomposition and utilization. The plastic-degrading enzymes identified so far might only account for a small portion of the enzymes relevant to plastic depolymerization in the environment. Therefore, it is of ever-growing interest to explore diverse environments to discover new plastic-degrading enzymes with desirable properties and functionalities. However, naturally occurring plasticdegrading enzymes are not well suited for synthetic plastic degradation in industrial applications due to poor thermostability and low catalytic activity. Particularly, synthetic plastic materials usually possess distinct physical and chemical properties (e.g., high crystallinity) that render them more resistant to...

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“…In recent years, considerable progress concerning plastic polymers with hydrolysable groups in their backbones, as PET, PA, or PUR were reported, obtained mainly by polyaddition or polycondensation. Several studies described the ability of microorganisms and enzymes to degrade these plastics [33][34][35][36][37][38][39][40][41][42][43][44][45][46]. Typical enzymes are cutinases, lipases, and carboxylesterases [47].…”

Section: Microbial and Enzymatic Plastics Biotransformationmentioning

confidence: 99%

MIXed Plastics Biodegradation and UPcycling Using Microbial Communities: The EU Horizon 2020 Project MIX-UP

Ballerstedt

Tiso

Wierckx

et al. 2021

Preprint

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This article introduces the EU Horizon 2020 research project MIX-UP, “Mixed plastics biodegradation and upcycling using microbial communities”. The project focuses on the ambitious vision to change the traditional linear value chain of plastics to a sustainable, biodegradable based one. In MIX-UP, plastic mixtures containing five of the top six fossil-based recalcitrant plastics (PE, PUR, PP, PET, and PS), along with upcoming biobased and biodegradable plastics (bioplastics) such as PHA and PLA, will be used as feedstock for microbial transformations. The generated new workflow increases recycling quotas and adds value to present poorly recycled plastic waste streams. Consecutive controlled enzymatic and microbial degradation of mechanically pre-treated plastics waste combined with subsequent microbial conversion to polymers and value-added chemicals by mixed cultures. Through optimization of known plastic-degrading enzymes by integrated protein engineering, high specific binding capacities, stability, and catalytic efficacy towards a broad spectrum of plastic polymers under high salt content and temperature conditions will be achieved. Another focus lies in the search and isolation of novel enzymes active on recalcitrant polymers. MIX-UP will also enhance the production of enzymes and formulate enzyme cocktails tailored to specific waste streams. In vivo and in vitro application of these cocktails enables stable, self-sustaining microbiomes to convert the released plastic monomers selectively into value-added products, key building blocks, and biomass. Any of the remaining material recalcitrant to the enzymatic activity will be recirculated into the process by physicochemical treatment. The Chinese-European MIX-UP is a multidisciplinary and industry-participating consortium to address the market need for novel sustainable routes to valorize plastic waste streams. MIX-UP realizes a circular (bio) plastic economy and will contribute where mechanical and chemical plastic recycling show limits.

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Thermophilic whole‐cell degradation of polyethylene terephthalate using engineered Clostridium thermocellum

Cited by 140 publications

References 57 publications

Comparative biochemistry of four polyester (PET) hydrolases

Comparative biochemistry of four polyester (PET) hydrolases

Enzyme discovery and engineering for sustainable plastic recycling

MIXed Plastics Biodegradation and UPcycling Using Microbial Communities: The EU Horizon 2020 Project MIX-UP

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