Our P4SB Partner ULEI has recently published the new article "Fast turbidimetric assay for analyzing the enzymatic hydrolysis of polyethylene terephthalate model substrates". It was written by Matheus Regis Belisário‐Ferrari, Ren Wei, Tobias Schneider, Annett Honak, and Wolfgang Zimmermann and first published on 15th of November 2018 in the Biotechnology Journal. Congtratulations to all involved!
Synthetic plastics such as polyethylene terephthalate (PET) can be cooperatively degraded by microbial polyester hydrolases and carboxylesterases, with the latter hydrolyzing the low‐molecular‐weight degradation intermediates. For the identification of PET‐degrading enzymes, efficient and rapid screening assays are required. Here we report a novel turbidimetric method in a microplate format for the fast screening of enzyme activities against the PET model substrates with two ester bonds bis‐(2‐Hydroxyethyl) terephthalate (BHET) and ethylene glycol bis‐(p‐methylbenzoate) (2PET). The carboxylesterase TfCa from Thermobifida fusca KW3 was used for validating the method. High correlation and regression coefficients between the experimental and fitted data confirmed the accuracy and reproducibility of the method and its feasibility for analyzing the kinetics of the enzymatic hydrolysis of the PET model substrates. A comparison of the hydrolysis of BHET and 2PET by TfCa using a kinetic model for heterogeneous catalysis indicated that the enzyme preferentially hydrolyzed the less bulky molecule BHET. The high‐throughput assay will facilitate the detection of novel enzymes for the biocatalytic modification or degradation of PET.
"Biodegradable Plastic Blends Create New Possibilities for End-of-Life Management of Plastics but They Are Not a Panacea for Plastic Pollution" was written by Tanja Narancic, Steven Verstichel, Srinivasa Reddy Chaganti, Laura Morales-Gamez, Shane T. Kenny, Bruno De Wilde, Ramesh Babu Padamati, and Kevin E. O’Connor. It was first published in Environmental Science & Technology 2018 52 (18) on 29th of August 2018. Congratulations to all involved!
Plastic waste pollution is a global environmental problem which could be addressed by biodegradable plastics. The latter are blended together to achieve commercially functional properties, but the environmental fate of these blends is unknown. We have tested neat polymers, polylactic acid (PLA), polyhydroxybutyrate, polyhydroxyoctanoate, poly(butylene succinate), thermoplastic starch, polycaprolactone (PCL), and blends thereof for biodegradation across seven managed and unmanaged environments. PLA is one of the world’s best-selling biodegradable plastics, but it is not home compostable. We show here that PLA when blended with PCL becomes home compostable. We also demonstrate that the majority of the tested bioplastics and their blends degrade by thermophilic anaerobic digestion with high biogas output, but degradation times are 3–6 times longer than the retention times in commercial plants. While some polymers and their blends showed good biodegradation in soil and water, the majority of polymers and their blends tested in this study failed to achieve ISO and ASTM biodegradation standards, and some failed to show any biodegradation. Thus, biodegradable plastic blends need careful postconsumer management, and further design to allow more rapid biodegradation in multiple environments is needed as their release into the environment can cause plastic Pollution.