Tandem chemical deconstruction and biological upcycling of poly(ethylene terephthalate) to β-ketoadipic acid by Pseudomonas putida KT2440

Metab Eng. 2021 Sep:67:250-261. doi: 10.1016/j.ymben.2021.07.005. Epub 2021 Jul 12.


Poly(ethylene terephthalate) (PET) is the most abundantly consumed synthetic polyester and accordingly a major source of plastic waste. The development of chemocatalytic approaches for PET depolymerization to monomers offers new options for open-loop upcycling of PET, which can leverage biological transformations to higher-value products. To that end, here we perform four sequential metabolic engineering efforts in Pseudomonas putida KT2440 to enable the conversion of PET glycolysis products via: (i) ethylene glycol utilization by constitutive expression of native genes, (ii) terephthalate (TPA) catabolism by expression of tphA2IIA3IIBIIA1II from Comamonas and tpaK from Rhodococcus jostii, (iii) bis(2-hydroxyethyl) terephthalate (BHET) hydrolysis to TPA by expression of PETase and MHETase from Ideonella sakaiensis, and (iv) BHET conversion to a performance-advantaged bioproduct, β-ketoadipic acid (βKA) by deletion of pcaIJ. Using this strain, we demonstrate production of 15.1 g/L βKA from BHET at 76% molar yield in bioreactors and conversion of catalytically depolymerized PET to βKA. Overall, this work highlights the potential of tandem catalytic deconstruction and biological conversion as a means to upcycle waste PET.

Keywords: Bio-upcycling; MHETase; Metabolic engineering; PETase; Plastics upcycling; Terephthalic acid.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adipates
  • Burkholderiales
  • Ethylenes
  • Hydrolases
  • Phthalic Acids
  • Polyethylene Terephthalates*
  • Pseudomonas putida* / genetics
  • Rhodococcus


  • Adipates
  • Ethylenes
  • Phthalic Acids
  • Polyethylene Terephthalates
  • 3-oxoadipic acid
  • terephthalic acid
  • Hydrolases

Supplementary concepts

  • Ideonella sakaiensis
  • Rhodococcus jostii