Journal Article

Bio-upcycling of even and uneven medium-chain-length diols and dicarboxylates to polyhydroxyalkanoates using engineered Pseudomonas putida

Mezzina, Mariela P., Polen, Tino, Nikel, Pablo I., Wierckx, Nick, de Witt, Jan, Schroth, Christoph, Wynands, Benedikt, Ackermann, Yannic S.

2024

Overview

Bio-upcycling of plastics is an emerging alternative process that focuses on extracting value from a wide range of plastic waste streams. Such streams are typically too contaminated to be effectively processed using traditional recycling technologies. Medium-chain-length (mcl) diols and dicarboxylates (DCA) are major products of chemically or enzymatically depolymerized plastics, such as polyesters or polyethers. In this study, we enabled the efficient metabolism of mcl-diols and -DCA in engineered Pseudomonas putida as a prerequisite for subsequent bio-upcycling. We identified the transcriptional regulator GcdR as target for enabling metabolism of uneven mcl-DCA such as pimelate, and uncovered amino acid substitutions that lead to an increased coupling between the heterologous β-oxidation of mcl-DCA and the native degradation of short-chain-length DCA. Adaptive laboratory evolution and subsequent reverse engineering unravelled two distinct pathways for mcl-diol metabolism in P. putida , namely via the hydroxy acid and subsequent native β-oxidation or via full oxidation to the dicarboxylic acid that is further metabolized by heterologous β-oxidation. Furthermore, we demonstrated the production of polyhydroxyalkanoates from mcl-diols and -DCA by a single strain combining all required metabolic features. Overall, this study provides a powerful platform strain for the bio-upcycling of complex plastic hydrolysates to polyhydroxyalkanoates and leads the path for future yield optimizations. Graphical Abstract

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Amino acids / Applied Microbiology / Bio-upcycling / Biotechnology / Carbon / Chemistry / Chemistry and Materials Science / Cloning / Composition / Control / Depolymerization / Dicarboxylates / Dicarboxylic acids / Diols / Enzymes / Enzymology / Genetic Engineering / Glycols / Greening the Plastics Industry: Advances and Challenges in Bioplastics Research / Hydrolysates / Hydroxy acids / Identification and classification / Metabolic engineering / Metabolism / Methods / Microbial Genetics and Genomics / Microbiology / Oxidation / Plasmids / Plastic debris / Polyester resins / Polyesters / Polyethers / Polyethylene / Polyhydroxyalkanoates / Polyolefins / Pseudomonas putida / Reverse engineering / Upcycling / Waste management / Waste streams