Synthesis of short-/medium-chain-length Poly(hydroxyalkanoate) Blends by Mixed Culture Fermentation of Glycerol

Biomacromolecules. Jul-Aug 2005;6(4):2106-12. doi: 10.1021/bm058005h.

Abstract

Glycerol was used as a substrate in the bio-production of poly(hydroxyalkanoates) (PHAs) in an effort to establish an alternative outlet for glycerol and produce value-added products. Pseudomonas oleovorans NRRL B-14682 and Pseudomonas corrugata 388 grew and synthesized poly(3-hydroxybutyrate) (P3HB) and medium-chain-length PHA (mcl-PHA) consisting primarily of 3-hydroxydecanoic acid (C(10:0); 44 +/- 2 mol %) and 3-hydroxydodecenoic acid (C(12:1); 31 +/- 2 mol %), respectively, from glycerol at concentrations up to 5% (v/v). Cellular productivity maximized at 40% for P. oleovorans in 5% (v/v) glycerol and 20% for P. corrugata in 2% (v/v) glycerol after 72 h. Increasing the glycerol media concentration from 1% to 5% (v/v) caused a 61% and 72% reduction in the molar mass (M(n)) of the P3HB and mcl-PHA polymers, respectively. Proton-NMR analysis of the glycerol-derived P3HB revealed that the M(n) decrease was the result of esterification of glycerol onto the polymer in a chain terminating position. However, no evidence of glycerol-based chain termination was present in the mcl-PHA. The growth patterns of P. oleovorans and P. corrugata on glycerol permitted their use as mixed cultures to produce natural blends of P3HB and mcl-PHA. By incorporating a staggered inoculation pattern and varying the duration of the fermentations, P3HB/mcl-PHA ratios were achieved that varied from 34:66 to 96:4.

MeSH terms

  • Alkanes / chemical synthesis*
  • Culture Media
  • Fermentation
  • Gas Chromatography-Mass Spectrometry
  • Glycerol / chemistry
  • Glycerol / metabolism*
  • Magnetic Resonance Spectroscopy
  • Polymers / chemical synthesis*
  • Pseudomonas / metabolism

Substances

  • Alkanes
  • Culture Media
  • Polymers
  • Glycerol