Journal of Microbiology and Biotechnology

The Korean Society for Microbiology and Biotechnology (한국미생물·생명공학회)
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Effect of C/N Ratio on the Production of Poly(3-hydroxyalkanoates) by the Methylotroph Paracoccus denitrificans

  • Kim, Byung-Ki (Biomacromolecules Research Laboratory, Department of Microbiology, Gyeongsang National University) ;
  • Yoon, Sung-Chul (Biomacromolecules Research Laboratory, Department of Microbiology, Gyeongsang National University, Department of Polymer Science and Engineering, University of Massachusetts) ;
  • Nam, Jae-Do (Department of Polymer Science and Engineering, Sungkyunkwan University) ;
  • Lenz, Robert-W. (Department of Polymer Science and Engineering, University of Massachusetts)
  • Published : 1997.12.01
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Abstract

Two series of carbon sources, linear primary $C_1$~$C_9$ alcohols and linear $C_2$~$C_{10}$ monocarboxylic acids were tested for PHA synthesis in Paracoccus denitrificans. The results showed that the growth-associated synthesis of PHA could be referred only to the carbon sources with odd number of carbon except methanol. For all carbon sources with even number of carbon, nitrogen limitation was required to induce PHA synthesis in P. denitrificans. Poly(3-hydroxyvalerate)[P(3HV)] homopolymer was synthesized from $C_5$, $C_7$, and $C_9$ while growing in the presence of nitrogen, but the nitrogen depletion in the later growth period incorporated 3-hydroxybutyrate(3HB) unit into the polymer chain. The optimum C/N ratio for P(3HV) homopolymer production was found to be 10 when the strain was grown on 10 ml/l of valeric acid for 96 h. P. denitrificans synthesized P(3HB-co-3HV) copolymers from n-hexanoic and n-octanoic acid. The microstructural characterics of the P(3HB-co-3HV) copolymer from n-propanol was investigated using $^13C$-nuclear magnetic resonance spectroscopy, showing a structural heterogeneity.

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