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Applied Microbiology and Biotechnology

, Volume 58, Issue 5, pp 651–657 | Cite as

Pitting corrosion inhibition of aluminum 2024 by Bacillus biofilms secreting polyaspartate or γ-polyglutamate

  •  D. Örnek
  •  A. Jayaraman
  •  B. Syrett
  •  C.-H. Hsu
  •  F. Mansfeld
  •  T. Wood
Original Paper

Abstract.

Pitting corrosion of aluminum 2024 in Luria Bertani medium was reduced by the secretion of anionic peptides by engineered and natural Bacillus biofilms and was studied in continuous reactors using electrochemical impedance spectroscopy. Compared to sterile controls, pitting was reduced dramatically by the presence of the biofilms. The secretion of a 20 amino acid polyaspartate peptide by an engineered Bacillus subtilis WB600/pBE92-Asp biofilm slightly reduced the corrosion rate of the passive aluminum alloy at pH 6.5; however, the secretion of γ-polyglutamate by a Bacillus licheniformis biofilm reduced the corrosion rate by 90% (compared to the B. subtilis WB600/pBE92 biofilm which did not secrete polyaspartate or γ-polyglutamate). The corrosion potential (E corr) of aluminum 2024 was increased by about 0.15–0.44 V due to the formation of B. subtilis and B. licheniformis biofilms as compared to sterile controls. The increase of E corr and the observed prevention of pitting indicate that the pitting potential (E pit) had increased. This result and the further decrease of corrosion rates for the passive aluminum alloy suggest that the rate of the anodic metal dissolution reaction was reduced by an inhibitor produced by the biofilms. Purified γ-polyglutamate also decreased the corrosion rates of aluminum 2024.

Keywords

Bacillus Aluminum Alloy Corrosion Rate Bacillus Subtilis Electrochemical Impedance Spectroscopy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  •  D. Örnek
    • 1
  •  A. Jayaraman
    • 1
  •  B. Syrett
    • 2
  •  C.-H. Hsu
    • 3
  •  F. Mansfeld
    • 3
  •  T. Wood
    • 1
  1. 1.Departments of Chemical Engineering & Molecular and Cellular Biology, University of Connecticut, Storrs, CT 06269–3222, USA
  2. 2.Electric Power Research Institute, Palo Alto, CA 94304–1395, USA
  3. 3.Materials Science & Engineering, University of Southern California, Los Angeles, CA 90089, USA

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