Browsing by Author "Richter, P. Konstantin"

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    Antarctic Polyester Hydrolases Degrade Aliphatic and Aromatic Polyesters at Moderate Temperatures
    (2022) Blazquez-Sanchez, Paula; Engelberger, Felipe; Cifuentes-Anticevic, Jeronimo; Sonnendecker, Christian; Grinen, Aransa; Reyes, Javiera; Diez, Beatriz; Guixe, Victoria; Richter, P. Konstantin; Zimmermann, Wolfgang; Ramirez-Sarmiento, Cesar A.
    Polyethylene terephthalate (PET) is one of the most widely used synthetic plastics in the packaging industry, and consequently has become one of the main components of plastic waste found in the environment. However, several microorganisms have been described to encode enzymes that catalyze the depolymerization of PET. While most known PET hydrolases are thermophilic and require reaction temperatures between 60 degrees C and 70 degrees C for an efficient hydrolysis of PET, a partial hydrolysis of amorphous PET at lower temperatures by the polyester hydrolase IsPETase from the mesophilic bacterium Ideonella sakaiensis has also been reported. We show that polyester hydrolases from the Antarctic bacteria Moraxella sp. strain TA144 (Mors1) and Oleispira antarctica RB-8 (OaCut) were able to hydrolyze the aliphatic polyester polycaprolactone as well as the aromatic polyester PET at a reaction temperature of 25 degrees C. Mors1 caused a weight loss of amorphous PET films and thus constitutes a PET-degrading psychrophilic enzyme. Comparative modeling of Mors1 showed that the amino acid composition of its active site resembled both thermophilic and mesophilic PET hydrolases. Lastly, bioinformatic analysis of Antarctic metagenomic samples demonstrated that members of the Moraxellaceae family carry candidate genes coding for further potential psychrophilic PET hydrolases.
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    Low Carbon Footprint Recycling of Post-Consumer PET Plastic with a Metagenomic Polyester Hydrolase
    (2022) Sonnendecker, Christian; Oeser, Juliane; Richter, P. Konstantin; Hille, Patrick; Zhao, Ziyue; Fischer, Cornelius; Lippold, Holger; Blazquez-Sanchez, Paula; Engelberger, Felipe; Ramirez-Sarmiento, Cesar A.; Oeser, Thorsten; Lihanova, Yuliia; Frank, Ronny; Jahnke, Heinz-Georg; Billig, Susan; Abel, Bernd; Straeter, Norbert; Matysik, Joerg; Zimmermann, Wolfgang
    Earth is flooded with plastics and the need for sustainable recycling strategies for polymers has become increasingly urgent. Enzyme-based hydrolysis of post-consumer plastic is an emerging strategy for closed-loop recycling of polyethylene terephthalate (PET). The polyester hydrolase PHL7, isolated from a compost metagenome, completely hydrolyzes amorphous PET films, releasing 91 mg of terephthalic acid per hour and mg of enzyme. Vertical scanning interferometry shows degradation rates of the PET film of 6.8 mu m h(-1). Structural analysis indicates the importance of leucine at position 210 for the extraordinarily high PET-hydrolyzing activity of PHL7. Within 24 h, 0.6 mg(enzyme) g(PET)(-1) completely degrades post-consumer thermoform PET packaging in an aqueous buffer at 70 degrees C without any energy-intensive pretreatments. Terephthalic acid recovered from the enzymatic hydrolysate is then used to synthesize virgin PET, demonstrating the potential of polyester hydrolases as catalysts in sustainable PET recycling processes with a low carbon footprint.