Biosynthesis and thermal properties of PHBV produced from levulinic acid by Ralstonia eutropha

PLoS One. 2013 Apr 4;8(4):e60318. doi: 10.1371/journal.pone.0060318. Print 2013.

Abstract

Levulinic acid (LA) can be cost-effectively produced from a vast array of renewable carbohydrate-containing biomaterials. LA could facilitate the commercialization of the polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and PHBV-based products as carbon substrates. Therefore, this paper focused on the production of PHBV by Ralstonia eutropha with LA for hydroxyvalerate (HV) production, which plays an important role in enhancing the thermal properties of PHBV. Accordingly, the HV content of PHBV varied from 0-40.9% at different concentrations of LA. Stimulation of cell growth and PHBV accumulation were observed when 2-6 g L(-1) LA was supplied to the culture. The optimal nitrogen sources were determined to be 0.5 g L(-1) ammonium chloride and 2 g L(-1) casein peptone. It was determined that the optimal pH for cell growth and PHBV accumulation was 7.0. When the cultivation was performed in large scale (2 L fermenter) with a low DO concentration of 30% and a pH of 7.0, a high maximum dry cell weight of 15.53 g L(-1) with a PHBV concentration of 12.61 g L(-1) (53.9% HV), up to 81.2% of the dry cell weight, was obtained. The melting point of PHBV found to be decreased as the fraction of HV present in the polymer increased, which resulted in an improvement in the ductility and flexibility of the polymer. The results of this study will improve the understanding of the PHBV accumulation and production by R. eutropha and will be valuable for the industrial production of biosynthesized polymers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bioreactors
  • Carbon / metabolism
  • Cupriavidus necator / growth & development
  • Cupriavidus necator / metabolism*
  • Fermentation
  • Glucose / metabolism
  • Levulinic Acids / metabolism*
  • Nitrogen / metabolism
  • Polyesters / chemistry*
  • Polyesters / metabolism*
  • Thermodynamics

Substances

  • Levulinic Acids
  • Polyesters
  • poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate)
  • Carbon
  • Glucose
  • Nitrogen
  • levulinic acid

Grants and funding

This work was supported by the National Basic Research Program of China (2013CB733505), National Natural Science Foundation of China (41071302), Xiamen Science and Technology committee (3502Z20121021, 3502Z20126005), Fujian Development and Reform Commission ([2011]1598) and Natural Science Foundation of Fujian Province of China (2010J05121). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.