Enzymatic transformation of bacterial polyhydroxyalkanoates into repolymerizable oligomers directed towards chemical recycling

Sachiko Kaihara, Yasushi Osanai, Kimihito Nishikawa, Kazunobu Toshima, Yoshiharu Doi, Shuichi Matsumura

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20 Citations (Scopus)

Abstract

The enzymatic transformation into an oligomer was carried out with the objective of developing the chemical recycling of bacterial polyesters. Poly(R-3-hydroxyalkanoate)s (PHAs), such as poly[(R-3-hydroxybutyrate)-co-12%(R- 3-hydroxyhexanoate)] and poly[(R-3-hydroxybutyrate)-co-12%(R-3-hydroxyvalerate)] , were degraded by granulated Candida antarctica lipase B immobilized on hydrophilic silica (lipase GCA) in a diluted organic solvent at 70 °C. The degradation products were cyclic oligomers having a molecular weight of a few hundreds. The obtained cyclic oligomer was readily repolymerized by the same lipase (lipase GCA) to produce the corresponding polyester in a concentrated solution. The cyclic oligomer was copolymerized with ε-caprolactone using lipase to produce the corresponding terpolymers having an M̄w of 21 000. This is the first example of the enzymatic chemical recycling of bacterial PHAs using lipase. Poly(R-3-hydroxybutyrate) [P(3HB)] was also degraded into the linear-type R-3HB monomer to trimer by P(3HB)-depolymerase (PHBDP) in phosphate buffer at 37 °C. The degradation using PHBDP required a longer reaction time compared with the lipase-catalyzed degradation in organic solvent. The monomer composition of the oligomer depended on the origin of the PHBDP. The R-3HB monomer was predominately produced by PHBDP from Pseudomonas stutzeri, while the R-3HB dimer was produced by PHBDP from Alcaligenes faecalis T1. Repolymerization of these oligomers by lipase in concentrated organic solvent produced a relatively low-molecular-weight P(3HB)(e.g., M̄w = 2000).

Original languageEnglish
Pages (from-to)644-652
Number of pages9
JournalMacromolecular Bioscience
Volume5
Issue number7
DOIs
Publication statusPublished - 2005 Jul 14

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Keywords

  • Cyclic oligomers
  • Degradation
  • Enzymes
  • Poly(3-hydroxyalkanoate)s
  • Recycling

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

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