Imaging and modelling of poly(3-hydroxybutyrate) synthesis in Paracoccus denitrificans

Sergio Bordel, Rob J.M. van Spanning, Fernando Santos-Beneit*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Poly(3-hydroxybutyrate) (PHB) granule formation in Paracoccus denitrificans Pd1222 was investigated by laser scanning confocal microscopy (LSCM) and gas chromatography analysis. Cells that had been starved for 2 days were free of PHB granules but resynthesized them within 30 min of growth in fresh medium with succinate. In most cases, the granules were distributed randomly, although in some cases they appeared in a more organized pattern. The rates of growth and PHB accumulation were analyzed within the frame of a Genome-Scale Metabolic Model (GSMM) containing 781 metabolic genes, 1403 reactions and 1503 metabolites. The model was used to obtain quantitative predictions of biomass yields and PHB synthesis during aerobic growth on succinate as sole carbon and energy sources. The results revealed an initial fast stage of PHB accumulation, during which all of the acetyl-CoA originating from succinate was diverted to PHB production. The next stage was characterized by a tenfold lower PHB production rate and the simultaneous onset of exponential growth, during which acetyl-CoA was predominantly drained into the TCA cycle. Previous research has shown that PHB accumulation correlates with cytosolic acetyl-CoA concentration. It has also been shown that PHB accumulation is not transcriptionally regulated. Our results are consistent with the mentioned findings and suggest that, in absence of cell growth, most of the cellular acetyl-CoA is channeled to PHB synthesis, while during exponential growth, it is drained to the TCA cycle, causing a reduction of the cytosolic acetyl-CoA pool and a concomitant decrease of the synthesis of acetoacetyl-CoA (the precursor of PHB synthesis).

Original languageEnglish
Article number113
Pages (from-to)1-8
Number of pages8
JournalAMB Express
Volume11
Early online date9 Aug 2021
DOIs
Publication statusPublished - Dec 2021

Bibliographical note

Funding Information:
This work was supported by the Regional Government of Castilla y León and the EU-FEDER (CLU 2017-09 and UIC 071). Dr. Fernando Santos-Beneit was supported at the Vrije Universiteit Amsterdam by a European Erasmus grant.

Publisher Copyright:
© 2021, The Author(s).

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Funding

This work was supported by the Regional Government of Castilla y León and the EU-FEDER (CLU 2017-09 and UIC 071). Dr. Fernando Santos-Beneit was supported at the Vrije Universiteit Amsterdam by a European Erasmus grant.

Keywords

  • Acetyl-CoA
  • LSCM
  • Metabolic modelling
  • Nile Red
  • Poly-3-hydroxybutyrate (PHB)
  • Polyhydroxyalkanoates (PHA)
  • Storage inclusions

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