Biotechnological Products and Process Engineering

Applied Microbiology and Biotechnology

, Volume 87, Issue 6, pp 2037-2045

Optimization of growth media components for polyhydroxyalkanoate (PHA) production from organic acids by Ralstonia eutropha

  • Yung-Hun YangAffiliated withDepartment of Biology, Massachusetts Institute of TechnologyDepartment of Microbial Engineering, Konkuk University
  • , Christopher J. BrighamAffiliated withDepartment of Biology, Massachusetts Institute of Technology
  • , Charles F. BuddeAffiliated withDepartment of Chemical Engineering, Massachusetts Institute of Technology
  • , Paolo BoccazziAffiliated withDepartment of Biology, Massachusetts Institute of Technology
  • , Laura B. WillisAffiliated withDepartment of Biology, Massachusetts Institute of TechnologyBiomaterials Science and Engineering Laboratory, Massachusetts Institute of Technology
  • , Mohd Ali HassanAffiliated withDepartment of Biotechnology and Biomolecular Science, Universiti Putra Malaysia
  • , Zainal Abidin Mohd YusofAffiliated withResearch & Technology Division, SIRIM Berhad
  • , ChoKyun RhaAffiliated withBiomaterials Science and Engineering Laboratory, Massachusetts Institute of Technology
  • , Anthony J. SinskeyAffiliated withDepartment of Biology, Massachusetts Institute of TechnologyDivision of Health Sciences Technology, Massachusetts Institute of TechnologyEngineering Systems Division, Massachusetts Institute of Technology Email author 

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Abstract

We employed systematic mixture analysis to determine optimal levels of acetate, propionate, and butyrate for cell growth and polyhydroxyalkanoate (PHA) production by Ralstonia eutropha H16. Butyrate was the preferred acid for robust cell growth and high PHA production. The 3-hydroxyvalerate content in the resulting PHA depended on the proportion of propionate initially present in the growth medium. The proportion of acetate dramatically affected the final pH of the growth medium. A model was constructed using our data that predicts the effects of these acids, individually and in combination, on cell dry weight (CDW), PHA content (%CDW), PHA production, 3HV in the polymer, and final culture pH. Cell growth and PHA production improved approximately 1.5-fold over initial conditions when the proportion of butyrate was increased. Optimization of the phosphate buffer content in medium containing higher amounts of butyrate improved cell growth and PHA production more than 4-fold. The validated organic acid mixture analysis model can be used to optimize R. eutropha culture conditions, in order to meet targets for PHA production and/or polymer HV content. By modifying the growth medium made from treated industrial waste, such as palm oil mill effluent, more PHA can be produced.

Keywords

Polyhydroxyalkanoate Ralstonia eutropha Organic acid Mixture model