• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.518-521
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• 2002

Poly(3-hydroxyalkanoate) copolyesters containing both carbon-carbon double and carbon-carbon triple bonds were produced by Pseudomonas oleovorans grown in mixtures of 10-undecynoic acid (10-UND($\equiv$)) and 10-undecenoic acid (10-UND(=)). The PHA content in the dry cells was usually 40 wt%. The bioconversion yield of ($10-UND({\equiv})$) to PHA by P. oleovorans was remarkably enhanced from 1% to over 24% as the fraction of 10-UND(=) in the carbon substrate mixtures increased from 0 to 50%. These values were higher than those obtained when P. oleovorans was grown in the same molar mixtures of ($10-UND({\equiv})$) and nonanoic acid (NA), indicating that 10-UND(=) was more efficient than NA as a cosubstrate in inducing cometabolic PHA production.

• Korean Journal of Microbiology
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• v.41 no.3
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• pp.225-231
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• 2005

The characteristics of cell growth and medium-chain-length polyhydroxyalkanoate (MCL-PHA) biosynthesis of Pseudomonas chlororaphis HS21 were investigated using plant oils as the carbon substrate. The organism was efficiently capable of utilizing plant oils, such as palm oil, corn oil, and sunflower oil, as the sole carbon source for growth and MCL-PHA production. When palm oil (5 g/L) was used as the carbon source, the cell growth and MCL-PHA accumulation of this organism occurred simultaneously, and a high dry cell weight (2.4 g/L) and MCL-PHA ($40.2\;mol{\%}$ of dry cell weight) was achieved after 30 hr of batch-fermentation. The repeating unit in the MCL-PHA produced from palm oil composed of 3-hydroxyhexanoate ($7.0\;mol{\%}$), 3-hydroxyoctanoate ($45.3\;mol{\%}$), 3-hydroxydecanoate ($39.0\;mol{\%}$), 3-hydroxydodecanoate ($6.8\;mol{\%}$), and 3-hydroxytetradecanoate ($1.9\;mol{\%}$), as determined by GC/MS. Even though glucose was a carbon substrate that support cell growth but not PHA production, the conversion rate of palm oil to PHA was significantly increased when glucose was fed as a cosubstrate, suggesting that bioconversion of some functionalized carbon substrates to related polymers in P chlororaphis HS21 could be enhanced by the co-feed of good carbon substrates for cell growth. In addition, the change of compositions of repeating units in MCL-PHAs synthesized from the plant oils was markedly affected by the supplementation of acrylic acid, an inhibitor of fatty acid ${\beta}-oxidation$. The addition of acrylic acid resulted in the increase of longer chain-length repeating units, such as 3-hydroxydodecanoate and 3-hydroxytetradecanoate, in the MCL-PHAs produced. Particularly, MCI-PHAs containing high amounts of unsaturated repeating units could be produced when sunflower oil and corn oil were used as the carbon substrate. These results suggested that the alteration of PHA synthesis pathway by acrylic acid addition can offer the opportunity to design new functional MCL-PHAs and other unusual polyesters that have unique physico-chemical properties.