Bio-upcycling of polyethylene terephthalate

Over 359 million tons of plastics were produced worldwide in 2018, with significant growth expected in the near future, resulting in the global challenge of end-of-life management. The recent identification of enzymes that degrade plastics previously considered non-biodegradable opens up opportunities to steer the plastic recycling industry into the realm of biotechnology. Here, we present the sequential conversion of polyethylene terephthalate (PET) into two types of bioplastics: a medium chain-length polyhydroxyalkanoate (PHA) and a novel bio-based poly(amide urethane) (bio-PU). PET films were hydrolyzed by a thermostable polyester hydrolase yielding 100% terephthalate and ethylene glycol. A terephthalate-degrading Pseudomonas was evolved to also metabolize ethylene glycol and subsequently produced PHA. The strain was further modified to secrete hydroxyalkanoyloxy-alkanoates (HAAs), which were used as monomers for the chemo-catalytic synthesis of bio-PU. In short, we present a novel value-chain for PET upcycling, adding technological flexibility to the global challenge of end-of-life management of plastics. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/993592v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1433e0dorg.highwire.dtl.DTLVardef@19efc71org.highwire.dtl.DTLVardef@cf97f7org.highwire.dtl.DTLVardef@101f123_HPS_FORMAT_FIGEXP M_FIG C_FIG