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<p>Plastics derived from fossil feedstocks pose major recycling challenges, particularly crosslinked thermosets used in electronics, construction and composites. Polydiketoenamines (PDKs) are recyclable alternatives; however, monomers such as dimedone are petrochemical-derived and offer limited tunability. We computationally screened 144 β-keto-δ-lactones (BKDLs), identifying solvation free energy as the primary determinant of depolymerization temperature across a 20–60 °C range. We engineered hybrid type I polyketide synthases (PKSs) in <i>Escherichia</i> <i>coli</i> and <i>Streptomyces</i> hosts to biosynthesize BKDLs with diverse substituents and defined stereochemistry, reaching titers of 1.84 g L<sup>−1</sup> in bioreactors. Polymerization of chemically synthesized BKDLs identical to PKS products confirmed tunable glass transition temperatures (53–98 °C) and temperature-gated depolymerization. Different BKDLs yielded PDKs with thermal, mechanical, solvent-resistance and optical properties governed by substituent and chirality. Technoeconomic and life-cycle analyses indicate that corn-stover-derived BKDLs can outperform petrochemical dimedone on cost and greenhouse gas emissions. This study demonstrates that engineered PKSs can produce monomers for recyclable plastics with programmable depolymerization behavior.</p>

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Engineered polyketide synthases enable a microbial chassis for recyclable plastics with tunable properties

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月27日

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  • Zilong Wang,
  • Seokjung Cheong,
  • Hai Wang,
  • Jeremy Demarteau,
  • Alexander R. Epstein,
  • Baishakhi Bose,
  • Weixi Hu,
  • Matthias Schmidt,
  • Leah Keiser,
  • Mei Zhao,
  • Beibei Ge,
  • Alberto A. Nava,
  • Ramu Kakumanu,
  • Edward E. K. Baidoo,
  • Yan Chen,
  • Christopher J. Petzold,
  • Yifan Guo,
  • Nawa Raj Baral,
  • Nemi Vora,
  • Sarah L. Nordahl,
  • Yuzhong Liu,
  • Rithwik Ghanta,
  • Pablo Cruz-Morales,
  • Kevin Yin,
  • Robert W. Haushalter,
  • Kristin A. Persson,
  • Corinne D. Scown,
  • Brett A. Helms,
  • Jay D. Keasling

摘要

Plastics derived from fossil feedstocks pose major recycling challenges, particularly crosslinked thermosets used in electronics, construction and composites. Polydiketoenamines (PDKs) are recyclable alternatives; however, monomers such as dimedone are petrochemical-derived and offer limited tunability. We computationally screened 144 β-keto-δ-lactones (BKDLs), identifying solvation free energy as the primary determinant of depolymerization temperature across a 20–60 °C range. We engineered hybrid type I polyketide synthases (PKSs) in Escherichia coli and Streptomyces hosts to biosynthesize BKDLs with diverse substituents and defined stereochemistry, reaching titers of 1.84 g L−1 in bioreactors. Polymerization of chemically synthesized BKDLs identical to PKS products confirmed tunable glass transition temperatures (53–98 °C) and temperature-gated depolymerization. Different BKDLs yielded PDKs with thermal, mechanical, solvent-resistance and optical properties governed by substituent and chirality. Technoeconomic and life-cycle analyses indicate that corn-stover-derived BKDLs can outperform petrochemical dimedone on cost and greenhouse gas emissions. This study demonstrates that engineered PKSs can produce monomers for recyclable plastics with programmable depolymerization behavior.