Chemostat cultivation and transcriptional analyses of Clostridium acetobutylicum mutants with defects in the acid and acetone biosynthetic pathways

Daniel Hönicke, Tina Lütke-Eversloh, Ziyong Liu, Dörte Lehmann, Wolfgang Liebl, Armin Ehrenreich

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Clostridium acetobutylicum is a model organism for the biotechnologically important acetone–butanol–ethanol (ABE) fermentation. With the objective to rationally develop strains with improved butanol production, detailed insights into the physiological and genetic mechanisms of solvent production are required. Therefore, pH-controlled phosphate-limited chemostat cultivation and DNA microarray technology were employed for an in-depth analysis of knockout mutants with defects in the central fermentative metabolism. The set of studied mutants included strains with inactivated phosphotransacetylase (pta), phosphotransbutyrylase (ptb), and acetoacetate decarboxylase (adc) encoding genes, as well as an adc/pta double knockout mutant. A comprehensive physiological characterization of the mutants was performed by continuous cultivation, allowing for a well-defined separation of acidogenic and solventogenic growth, combined with the advantage of the high reproducibility of steady-state conditions. The ptb-negative strain C. acetobutylicum ptb::int(87) exhibited the most striking metabolite profile: Sizable amounts of butanol (29 ± 1.3 mM) were already produced during acidogenic growth. The product patterns of the mutants as well as accompanying transcriptomic data are presented and discussed.

Original languageEnglish
Pages (from-to)9777-9794
Number of pages18
JournalApplied Microbiology and Biotechnology
Volume98
Issue number23
DOIs
StatePublished - 15 Nov 2014

Keywords

  • Biobutanol
  • Biofuel
  • Chemostat cultivation
  • ClosTron
  • DNA microarray

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