Poly(3-hydroxybutyrate) Synthesis From Glycerol by a Recombinant Escherichia Coli arcA Mutant in Fed-Batch Microaerobic Cultures

Appl Microbiol Biotechnol. 2008 Jan;77(6):1337-43. doi: 10.1007/s00253-007-1255-7. Epub 2007 Nov 22.

Abstract

Poly(3-hydroxybutyrate) (PHB) synthesis was analyzed under microaerobic conditions in a recombinant Escherichia coli arcA mutant using glycerol as the main carbon source. The effect of several additives was assessed in a semi-synthetic medium by the 'one-factor-at-a-time' technique. Casein amino acids (CAS) concentration was an important factor influencing both growth and PHB accumulation. Three factors exerting a statistically significant influence on PHB synthesis were selected by using a Plackett-Burman screening design [glycerol, CAS, and initial cell dry weight (CDW) concentrations] and then optimized through a Box-Wilson design. Under such optimized conditions (22.02 g l(-1) glycerol, 1.78 g l(-1) CAS, and 1.83 g l(-1) inoculum) microaerobic batch cultures gave rise to 8.37 g l(-1) CDW and 3.52 g l(-1) PHB in 48 h (PHB content of 42%) in a benchtop bioreactor. Further improvements in microaerobic PHB accumulation were obtained in fed-batch cultures, in which glycerol was added to maintain its concentration above 5 g l(-1). After 60 h, CDW and PHB concentration reached 21.17 and 10.81 g l(-1), respectively, which results in a PHB content of 51%. Microaerobic fed-batch cultures allowed a 2.57-fold increase in volumetric productivity when compared with batch cultures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Outer Membrane Proteins / metabolism
  • Biomass
  • Bioreactors / microbiology*
  • Culture Media / chemistry
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism
  • Glucose / metabolism
  • Glycerol / metabolism*
  • Hydroxybutyrates / metabolism*
  • Industrial Microbiology
  • Models, Theoretical
  • Mutation
  • Polyesters / metabolism*
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism
  • Time Factors

Substances

  • Bacterial Outer Membrane Proteins
  • Culture Media
  • Escherichia coli Proteins
  • Hydroxybutyrates
  • Polyesters
  • Repressor Proteins
  • arcA protein, E coli
  • poly-beta-hydroxybutyrate
  • Glucose
  • Glycerol