Applied Microbiology and Biotechnology

, Volume 77, Issue 5, pp 1119–1129

Metabolites produced by Pseudomonas sp. enable a Gram-positive bacterium to achieve extracellular electron transfer

  • The Hai Pham
  • Nico Boon
  • Peter Aelterman
  • Peter Clauwaert
  • Liesje De Schamphelaire
  • Lynn Vanhaecke
  • Katrien De Maeyer
  • Monica Höfte
  • Willy Verstraete
  • Korneel Rabaey
Applied Microbial and Cell Physiology

DOI: 10.1007/s00253-007-1248-6

Cite this article as:
Pham, T.H., Boon, N., Aelterman, P. et al. Appl Microbiol Biotechnol (2008) 77: 1119. doi:10.1007/s00253-007-1248-6

Abstract

Previous studies revealed the abundance of Pseudomonas sp. in the microbial community of a microbial fuel cell (MFC). These bacteria can transfer electrons to the electrode via self-produced phenazine-based mediators. A MFC fed with acetate where several Pseudomonas sp. were present was found to be rich in a Gram-positive bacterium, identified as Brevibacillus sp. PTH1. Remarkably, MFCs operated with only the Brevibacillus strain in their anodes had poor electricity generation. Upon replacement of the anodic aqueous part of Brevibacillus containing MFCs with the cell-free anodic supernatants of MFCs operated with Pseudomonas sp. CMR12a, a strain producing considerable amounts of phenazine-1-carboxamide (PCN) and biosurfactants, the electricity generation was improved significantly. Supernatants of Pseudomonas sp. CMR12a_Reg, a regulatory mutant lacking the ability to produce PCN, had no similar improvement effect. Purified PCN, together with rhamnolipids as biosurfactants (1 mg L−1), could clearly improve electricity generation by Brevibacillus sp. PTH1, as well as enable this bacterium to oxidize acetate with concomitant reduction of ferric iron, supplied as goethite (FeOOH). When added alone, PCN had no observable effects on Brevibacillus’ electron transfer. This work demonstrates that metabolites produced by Pseudomonas sp. enable Gram-positive bacteria to achieve extracellular electron transfer. Possibly, this bacterial interaction is a key process in the anodic electron transfer of a MFC, enabling Brevibacillus sp. PTH1 to achieve its dominance.

Keywords

Electrochemically active bacteriaMicrobial interactionElectron shuttlePhenazinesBiosurfactantSynergistic effect

Supplementary material

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • The Hai Pham
    • 1
  • Nico Boon
    • 1
  • Peter Aelterman
    • 1
  • Peter Clauwaert
    • 1
  • Liesje De Schamphelaire
    • 1
  • Lynn Vanhaecke
    • 1
  • Katrien De Maeyer
    • 2
  • Monica Höfte
    • 2
  • Willy Verstraete
    • 1
  • Korneel Rabaey
    • 1
    • 3
  1. 1.Laboratory of Microbial Ecology and Technology (LabMET)Ghent UniversityGhentBelgium
  2. 2.Laboratory of PhytopathologyGhent UniversityGhentBelgium
  3. 3.Advanced Wastewater Management CentreUniversity of QueenslandBrisbaneAustralia