Contribution of cell elongation to the biofilm formation of Pseudomonas aeruginosa during anaerobic respiration

PLoS One. 2011 Jan 18;6(1):e16105. doi: 10.1371/journal.pone.0016105.

Abstract

Pseudomonas aeruginosa, a gram-negative bacterium of clinical importance, forms more robust biofilm during anaerobic respiration, a mode of growth presumed to occur in abnormally thickened mucus layer lining the cystic fibrosis (CF) patient airway. However, molecular basis behind this anaerobiosis-triggered robust biofilm formation is not clearly defined yet. Here, we identified a morphological change naturally accompanied by anaerobic respiration in P. aeruginosa and investigated its effect on the biofilm formation in vitro. A standard laboratory strain, PAO1 was highly elongated during anaerobic respiration compared with bacteria grown aerobically. Microscopic analysis demonstrated that cell elongation likely occurred as a consequence of defective cell division. Cell elongation was dependent on the presence of nitrite reductase (NIR) that reduces nitrite (NO(2) (-)) to nitric oxide (NO) and was repressed in PAO1 in the presence of carboxy-PTIO, a NO antagonist, demonstrating that cell elongation involves a process to respond to NO, a spontaneous byproduct of the anaerobic respiration. Importantly, the non-elongated NIR-deficient mutant failed to form biofilm, while a mutant of nitrate reductase (NAR) and wild type PAO1, both of which were highly elongated, formed robust biofilm. Taken together, our data reveal a role of previously undescribed cell biological event in P. aeruginosa biofilm formation and suggest NIR as a key player involved in such process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis
  • Biofilms*
  • Mutant Proteins
  • Nitric Oxide / metabolism
  • Nitric Oxide / pharmacology
  • Nitrite Reductases / genetics
  • Nitrite Reductases / metabolism
  • Pseudomonas aeruginosa / cytology*
  • Pseudomonas aeruginosa / physiology*

Substances

  • Mutant Proteins
  • Nitric Oxide
  • Nitrite Reductases