Biochemical Upcycling of PET via Glycolysis and Engineered Microbial Consortia

Polyethylene terephthalate (PET) waste remains a major environmental challenge due to its recalcitrance and low economic value. Here, we present an integrated biochemical approach that couples glycolysis with a synthetic microbial consortium to upcycle post-consumer PET (pcPET) into polyhydroxyalkanoates (PHA). Glycolysis efficiently depolymerized pcPET into bis(2-hydroxyethyl) terephthalate (BHET) in 2 h, circumventing the limitations of in vivo PET degradation. We engineered a two-species microbial consortium composed of Comamonas testosteroni RW31, able to metabolise terephthalic acid, and Pseudomonas putida JM37, able to consume ethylene glycol, each modified for the extracellular secretion of PET- and MHET-hydrolases, employing different plasmid architectures. This division of labour enabled rapid BHET hydrolysis and the subsequent upcycling of the released monomers into PHAs. The combination of the different strains allowed to select C. testosteroni pSEVA354-MHETase and P. putida pSEVA234-PETase as the best consortium, based on growth and PHAs content. Overall, this work proposes a strategy for PET waste depolymerisation and valorisation, highlighting the potential of mixed chemical and biological approaches and the use of non-conventional microbial chassis within engineered consortia.