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Microcolony formation by the opportunistic pathogen Pseudomonas aeruginosa requires pyruvate and pyruvate

Olga E Petrova1, Jill R Schurr, Michael J Schurr

  • 1Department of Biological Sciences, Binghamton University, Binghamton, NY 13902, USA.

Molecular Microbiology
|August 31, 2012
PubMed

Insights

Microcolony formation in Pseudomonas aeruginosa biofilms is linked to pyruvate fermentation under stressful, oxygen-limited conditions. This process is regulated by MifR and involves specific pyruvate utilization genes.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Biofilm Formation

Background:

  • Biofilm architecture is characterized by microcolonies, but the mechanisms driving their formation are poorly understood.
  • The two-component regulator MifR is crucial for microcolony development in the pathogen Pseudomonas aeruginosa.

Purpose of the Study:

  • To elucidate the molecular mechanisms underlying microcolony formation in Pseudomonas aeruginosa biofilms.
  • To investigate the role of pyruvate metabolism in P. aeruginosa biofilm development and microcolony architecture.

Main Methods:

  • Global transcriptomic and proteomic analyses to identify molecular changes associated with microcolony formation.
  • Genetic manipulation of key metabolic genes (uspK, acnA, ldhA) and the regulator MifR.
  • Assessment of biofilm formation and microcolony development under varying pyruvate concentrations.

Main Results:

  • Microcolony formation correlates with stressful, oxygen-limiting conditions, activating stress responses and anaerobic fermentation, particularly pyruvate fermentation.
  • Inactivation of pyruvate utilization genes (uspK, acnA, ldhA) phenocopies mifR mutants, impairing microcolony formation.
  • Pyruvate availability directly influences biofilm and microcolony formation; its depletion inhibits, while addition enhances it.
  • While pyruvate addition partially rescues mifR mutants, expressing ldhA fully restores microcolony formation in mifR mutants, highlighting the role of lactate dehydrogenase.

Conclusions:

  • The fermentative utilization of pyruvate is a key adaptation specific to microcolony formation within the P. aeruginosa biofilm environment.
  • MifR regulates microcolony formation, likely by influencing pyruvate metabolism and the expression of genes involved in anaerobic respiration and fermentation.

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