Mechanism of growth inhibition by tungsten in Acidithiobacillus ferrooxidans

Tsuyoshi Sugio, Hiroyuki Kuwano, Atsunori Negishi, Terunobu Maeda, Fumiaki Takeuchi, Kazuo Kamimura

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Cell growth of three hundred iron-oxidizing bacteria isolated from natural environments was inhibited strongly by 0.05 mM, and completely by 0.2 mM of sodium tungstate (Na2WO4), respectively. Since no great difference in the level of tungsten inhibition was observed among the 300 strains tested, the mechanism of inhibition by Na2WO4 was studied with Addithiobacillus ferrooxidans strain AP19-3. When resting cells of AP19-3 were incubated in 0.1 M β-alanine-SO2-4 buffer (pH 3.0) with 0.1 mM Na2WO4 for 1 h, the amount of tungsten bound to the cells was 12 μg/mg protein. The optimum pH for tungsten binding to the resting cells was 2∼3. Approximately 2 times more tungsten bound to the cells at pH 3.0 than at pH 6.0. The tungsten binding was specifically inhibited by sodium molybdenum. However, copper, nickel, cadmium, zinc, manganese, cobalt, and vanadate did not disturb tungsten binding to the resting cells. The iron-oxidizing activity of AP19-3 was inhibited 24, 62, and 77% by 1, 5, and 10 mM of Na2WO4, respectively. Among the components of iron oxidation enzyme system, iron:cytochrome c oxidoreductase activity was not inhibited by 10 mM of Na2WO4. In contrast, the activity of cytochrome c oxidase purified highly from the strain was inhibited 50 and 72%, respectively, by 0.05 and 0.1 mM of Na2WO4. The amounts of tungsten bound to plasma membrane, cytosol fraction, and a purified cytochrome c oxidase were 8, 0.5, and 191 μg/mg protein, respectively. From the results, the growth inhibition by Na2WO4 observed in A. ferrooxidans is explained as follows: tungsten binds to cytochrome c oxidase in plasma membranes and inhibits cytochrome c oxidase activity, and as a results, the generation of energy needed for cell growth from the oxidation of Fe2+ is stopped.

Original languageEnglish
Pages (from-to)555-562
Number of pages8
JournalBioscience, Biotechnology and Biochemistry
Volume65
Issue number3
DOIs
Publication statusPublished - Mar 1 2001

Keywords

  • Acidithiobacillus ferrooxidans
  • Cytochrome c oxidase
  • Inhibition site
  • Tungsten

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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