Impact of growth environment and physiological state on metal immobilization by Pseudomonas aeruginosa PAO1

Ryan C. Hunter, Vernon R. Phoenix, Anuradha Saxena, Terry J. Beveridge

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Environmental growth conditions and cell physiology have the potential to influence bacterial surface-metal interactions in both planktonic and biofilm systems. Here, Pseudomonas aeruginosa was studied to determine the influence of these factors (pH, redox potential, and active respiration) on surface electrostatics and metal immobilization. Acid-base titrations revealed a decrease in ionizable ligands at pKa 5 (putative carboxyls) in cells grown below pH 6.2 and in cells grown anaerobically relative to cells grown under oxic and circumneutral pH conditions. This observation correlates with Western immunoblotting assays that revealed a reduction in carboxylated B-band lipopolysaccharide in these cells. Furthermore, spectrophotometric analysis revealed a decrease in zinc, copper, and iron immobilization in these cells, suggesting that lipopolysaccharide modification in response to environmental stimuli influences metal binding. The effect of active versus inactive metabolism on metal adsorption was also examined using respiration inhibitors carbonyl cyanide m-chlorophenylhydrazone and sodium azide. Cells treated with these compounds bound more zinc, copper, and iron than untreated controls, suggesting proton extrusion through respiration competes with metal cations for reactive groups on the cell surface. Accumulation of gold did not show the same trend, and transmission electron microscopy studies confirmed it was not a surface-mediated process. These results suggest that variations in growth environment and cell physiology influence metal accumulation by bacterial cell surfaces and may help to explain discontinuous accumulation of metal observed throughout microbial communities.

LanguageEnglish
Pages527-538
Number of pages12
JournalCanadian Journal of Microbiology
Volume56
Issue number7
Early online date24 Jun 2010
DOIs
Publication statusPublished - 31 Jul 2010

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Immobilization
Pseudomonas aeruginosa
Metals
Growth
Cell Physiological Phenomena
Respiration
Zinc
Copper
Iron
Sodium Azide
Biofilms
Static Electricity
Transmission Electron Microscopy
Gold
Adsorption
Oxidation-Reduction
Lipopolysaccharides
Cations
Protons
Western Blotting

Keywords

  • biofilms
  • microenvironments
  • biomineralization
  • acid-base titrations

Cite this

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Impact of growth environment and physiological state on metal immobilization by Pseudomonas aeruginosa PAO1. / Hunter, Ryan C.; Phoenix, Vernon R.; Saxena, Anuradha; Beveridge, Terry J.

In: Canadian Journal of Microbiology, Vol. 56, No. 7, 31.07.2010, p. 527-538.

Research output: Contribution to journalArticle

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