Oxygen supply strongly influences metabolic fluxes, the production of poly(3-hydroxybutyrate) and alginate, and the degree of acetylation of alginate in Azotobacter vinelandii

Tania Castillo, Elmar Heinzle, Susanne Peifer, Konstantin Schneider, Carlos F. Peña M

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The aim of this study was to evaluate carbon flux in Azotobacter vinelandii using metabolic flux analysis (MFA) under high and low aeration conditions to achieve an improved understanding of how these changes could be related to alginate acetylation and PHB production. Changes in oxygen availability had a considerable impact on the metabolic fluxes and were reflected in the growth rate, the specific glucose consumption rate, and the alginate and PHB yields. The main differences at the metabolic flux level were observed in three important pathways. The first important difference was consistent with respiratory protection; an increase in the flux generated through the tricarboxylic acid (TCA) cycle for cultures grown under high aeration conditions (up to 2.61 times higher) was observed. In the second important difference, the fluxes generated through pyruvate dehydrogenase, phosphoenol pyruvate carboxykinase and pyruvate kinase, all of which are involved in acetyl-CoA metabolism, increased by 10,43.9 and 17.5%, respectively, in cultures grown under low aeration conditions compared with those grown under high aeration conditions. These changes were related to alginate acetylation, which was 2.6 times higher in the cultures with limited oxygen, and the changes were also related to a drastic increase in PHB production. Finally, the glyoxylate shunt was active under both of the conditions that were tested, and a 2.79-fold increase was observed in cultures that were grown under the low aeration condition. (C) 2013 Elsevier Ltd. All rights reserved.
Original languageEnglish
JournalProcess Biochemistry
Volume48
Issue number7
Pages (from-to)995-1003
Number of pages9
ISSN1359-5113
DOIs
Publication statusPublished - 2013
Externally publishedYes

Keywords

  • A. vinelandii
  • Metabolic flux
  • Alginate
  • Acetylation
  • PHB

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