Optimization of Ralstonia solanacearum cell growth using a central composite rotational design for the P(3HB) production: Effect of agitation and aeration

PLoS One. 2019 Jan 29;14(1):e0211211. doi: 10.1371/journal.pone.0211211. eCollection 2019.

Abstract

The intracellular accumulation of polyhydroxyalkanoates (PHAs) normally occurs after cell growth, during the second fermentation stage and under nutrient-limited conditions in the presence of a carbon excess. However, some microorganisms are able to accumulate PHAs as poly(3-hydroxybutyrate) [P(3HB)] during the first fermentation stage, the cell growth phase, without nutrient limitation, once they have been reported to utilize type II metabolism during the polymer accumulation phase. This study evaluated the effect of aeration and agitation on cell growth and P(3HB) accumulation in Ralstonia solanacearum RS, performed in a bioreactor for 24h at 32°C. A 22 central composite rotational design (CCRD) was used, with agitation (150 to 250 rpm) and aeration (0.3 to 1 vvm) as independent variables and optical density (OD600nm), dry cell weight (DCW), and P(3HB) yield as dependent variables. A significant polymer accumulation, until 70% of P(3HB), was observed, proving that R. solanacearum RS exhibited metabolism type II, regardless of the aeration process. The best results were obtained for 1 vvm and 250 rpm (+1, +1), with values of OD600nm (18.04) and DCW (4.82 g.L-1).

MeSH terms

  • Batch Cell Culture Techniques / methods*
  • Bioreactors / microbiology
  • Culture Media / metabolism
  • Fermentation
  • Hydroxybutyrates / metabolism*
  • Industrial Microbiology
  • Polyesters / metabolism*
  • Ralstonia solanacearum / growth & development*
  • Ralstonia solanacearum / metabolism
  • Rotation

Substances

  • Culture Media
  • Hydroxybutyrates
  • Polyesters
  • poly-beta-hydroxybutyrate

Grants and funding

The authors received no specific funding for this work. Sônia Maria Kesserlingh is employed by Company PHB Industrial. Company PHB Industrial provided support in the form of salary for author SMK, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section.