Rapid depolymerization of poly(ethylene terephthalate) thin films by a dual-enzyme system and its impact on material properties.

Enzymatic hydrolysis holds great promise for plastic waste recycling and upcycling. The interfacial catalysis mode, and the variability of polymer specimen properties under different degradation conditions, add to the complexity and difficulty of understanding polymer cleavage and engineering better biocatalysts. We present a systemic approach to studying the enzyme-catalyzed surface erosion of poly(ethylene terephthalate) (PET) while monitoring/controlling operating conditions in real time with simultaneous detection of mass loss and changes in viscoelastic behavior.

Structural Insights into (Tere)phthalate-Ester Hydrolysis by a Carboxylesterase and Its Role in Promoting PET Depolymerization.

TfCa, a promiscuous carboxylesterase from , was found to hydrolyze polyethylene terephthalate (PET) degradation intermediates such as bis(2-hydroxyethyl) terephthalate (BHET) and mono-(2-hydroxyethyl)-terephthalate (MHET). In this study, we elucidated the structures of TfCa in its apo form, as well as in complex with a PET monomer analogue and with BHET. The structure-function relationship of TfCa was investigated by comparing its hydrolytic activity on various ortho- and para-phthalate esters of different lengths.

High-Throughput Screening for Thermostable Polyester Hydrolases.

Due to the promise of more sustainable recycling of plastics through biocatalytic degradation, the search for and engineering of polyester hydrolases have become a thriving field of research. Furthermore, among other methods, halo formation assays have become popular for the detection of polyester-hydrolase activity. However, established halo-formation assays are limited in their ability to screen for thermostable enzymes, which are particularly important for efficient plastic degradation.

Multiple Substrate Binding Mode-Guided Engineering of a Thermophilic PET Hydrolase.

Thermophilic polyester hydrolases (PES-H) have recently enabled biocatalytic recycling of the mass-produced synthetic polyester polyethylene terephthalate (PET), which has found widespread use in the packaging and textile industries. The growing demand for efficient PET hydrolases prompted us to solve high-resolution crystal structures of two metagenome-derived enzymes (PES-H1 and PES-H2) and notably also in complex with various PET substrate analogues. Structural analyses and computational modeling using molecular dynamics simulations provided an understanding of how product inhibition and multiple substrate binding modes influence key mechanistic steps of enzymatic PET hydrolysis.

Molecular and Biochemical Differences of the Tandem and Cold-Adapted PET Hydrolases Ple628 and Ple629, Isolated From a Marine Microbial Consortium.

Polybutylene adipate terephthalate (PBAT) is a biodegradable alternative to polyethylene and can be broadly used in various applications. These polymers can be degraded by hydrolases of terrestrial and aquatic origin. In a previous study, we identified tandem PETase-like hydrolases (Ples) from the marine microbial consortium I1 that were highly expressed when a PBAT blend was supplied as the only carbon source.

Biosensor and chemo-enzymatic one-pot cascade applications to detect and transform PET-derived terephthalic acid in living cells.

Plastic waste imposes a serious problem to the environment and society. Hence, strategies for a circular plastic economy are demanded. One strategy is the engineering of polyester hydrolases toward higher activity for the biotechnological recycling of polyethylene terephthalate (PET).

Engineering and evaluation of thermostable PETase variants for PET degradation.

Polyethylene terephthalate (PET) is a mass-produced petroleum-based synthetic polymer. Enzymatic PET degradation using, for example, PETase (PETase) can be a more environmentally friendly and energy-saving alternative to the chemical recycling of PET. However, PETase is a mesophilic enzyme with an optimal reaction temperature lower than the glass transition temperature ( ) of PET, where the amorphous polymers can be readily accessed for enzymatic breakdown.

Mechanism-Based Design of Efficient PET Hydrolases.

Polyethylene terephthalate (PET) is the most widespread synthetic polyester, having been utilized in textile fibers and packaging materials for beverages and food, contributing considerably to the global solid waste stream and environmental plastic pollution. While enzymatic PET recycling and upcycling have recently emerged as viable disposal methods for a circular plastic economy, only a handful of benchmark enzymes have been thoroughly described and subjected to protein engineering for improved properties over the last 16 years. By analyzing the specific material properties of PET and the reaction mechanisms in the context of interfacial biocatalysis, this Perspective identifies several limitations in current enzymatic PET degradation approaches.

Enzymatic degradation of polyethylene terephthalate nanoplastics analyzed in real time by isothermal titration calorimetry.

Plastics are globally used for a variety of benefits. As a consequence of poor recycling or reuse, improperly disposed plastic waste accumulates in terrestrial and aquatic ecosystems to a considerable extent. Large plastic waste items become fragmented to small particles through mechanical and (photo)chemical processes.

Fluorimetric high-throughput screening method for polyester hydrolase activity using polyethylene terephthalate nanoparticles.

Biocatalysis has recently emerged as a powerful and eco-friendly technology in waste plastic recycling, especially for the widely used polyethylene terephthalate (PET). So far, however, a high-throughput screening assay specifically toward PET-hydrolyzing activity has rarely been applied. This hinders the identification of new polyester hydrolases and their variants with adequate activities fulfilling the requirements for industrial applications.