To dissolve pyrite or sulphur, leaching bacteria like Acidithiobacillus ferrooxidans attach to these substrata by extracellular polymeric substances (specifically, lipopolysaccharides). The primary attachment to pyrite at pH 2 is mediated by exopolymer-complexed iron(III) ions in an electrostatic interaction with the negatively charged pyrite surface. Cells grown on sulphur exhibit a different composition of the extracellular lipopolysaccharides, namely with increased hydrophobic properties, and do not attach to pyrite. Thus, the cells adapt the chemical composition of their exopolymers to the substrate/substratum. It is concluded that the mechanism of bacterial pyrite oxidation is basically indirect. The actual corrosive agents are iron(III) ions. Preliminary data indicate that active strains complex more iron(III) ions in their EPS than less active ones. Obviously, the exopolymeric layer comprises a reaction space for the regeneration of these ions by the activity of the iron oxidising bacteria.
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Research Article|
March 01 2001
The EPS of Acidithiobacillus ferrooxidans - a model for structure-function relationships of attached bacteria and their physiology
T. Gehrke;
1Institute for General Botany, Department of Microbiology, University of Hamburg, Ohnhorststraße 18, D-22609 Hamburg, Germany
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R. Hallmann;
R. Hallmann
1Institute for General Botany, Department of Microbiology, University of Hamburg, Ohnhorststraße 18, D-22609 Hamburg, Germany
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K. Kinzler;
K. Kinzler
1Institute for General Botany, Department of Microbiology, University of Hamburg, Ohnhorststraße 18, D-22609 Hamburg, Germany
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W. Sand
W. Sand
1Institute for General Botany, Department of Microbiology, University of Hamburg, Ohnhorststraße 18, D-22609 Hamburg, Germany
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Water Sci Technol (2001) 43 (6): 159–167.
Citation
T. Gehrke, R. Hallmann, K. Kinzler, W. Sand; The EPS of Acidithiobacillus ferrooxidans - a model for structure-function relationships of attached bacteria and their physiology. Water Sci Technol 1 March 2001; 43 (6): 159–167. doi: https://doi.org/10.2166/wst.2001.0365
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