Selective Adhesion of Thiobacillus ferrooxidans to Pyrite

Abstract

Bacterial adhesion to mineral surfaces plays an important role not only in bacterial survival in natural ecosystems, but also in mining industry applications. Selective adhesion was investigated with ThiobaciUus ferrooxidans by using four minerals, pyrite, quartz, chalcopyrite, and galena. Escherichia coli was used as a control bacterium. Contact angles were used as indicators of hydrophobicity, which was an important factor in the interaction between minerals and bacteria. The contact angle of E. coli in a 0.5% sodium chloride solution was 310, and the contact angle of T. ferrooxidans in a pH 2.0 sulfuric acid solution was 23°. E. coli tended to adhere to more hydrophobic minerals by hydrophobic interaction, while T. ferrooxidans selectively adhered to iron-containing minerals, such as pyrite and chalcopyrite. Ferrous ion inhibited the selective adhesion of T. ferrooxidans to pyrite competitively, while ferric ion scarcely inhibited such adhesion. When selective adhesion was quenched by ferrous ion completely, adhesion of T. ferrooxidans was controlled by hydrophilic interactions. Adhesion ofE. coli to pyrite exhibited a liner relationship on langmuir isotherm plots, but adhesion of T. ferrooxidans did not. T. ferrooxidans recognized the reduced iron in minerals and selectively adhered to pyrite and chalcopyrite by a strong interaction other than the physical interaction.

Silicate mineral dissolution during heap bioleaching

“…It was also observed that a greater proportion of the chalcopyrite was preferentially bioleached over the silicates. This is supported by the preferential attachment of acidophiles to sulfide minerals suggesting that these are their natural growth substrates (Edwards et al, 1999;Murr and Berry, 1976;Ohmura et al, 1993).…”

Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: a genetic analysis

“…The biofilm formation screen described above was performed using microtitre dishes composed of PVC. However, it is clear that bacteria form biofilms on a wide range of abiotic surfaces (Stanley, 1983;Fletcher, 1988;Lopez-Lopez et al, 1991;Ohmura et al, 1993;Reid et al, 1994;Makin and Beveridge, 1996). We tested the ability of the wild type and selected mutants to form biofilms on relatively hydrophobic surfaces (PVC, polycarbonate and polypropylene) and a relatively hydrophilic surface (borosilicate glass).…”

“…Biofilm bacteria are markedly different from their planktonic counterparts, as judged by gene expression, cellular physiology and the biofilm cells' increased resistance to antibiotics (Hoyle and Costerton, 1991;Costerton et al, 1995). Numerous reports have documented the ability of diverse bacterial species to form biofilms on a variety of abiotic surfaces of great importance in medicine and industry (Stanley, 1983;Fletcher, 1988;Lopez-Lopez et al, 1991;Ohmura et al, 1993;Reid et al, 1994;Makin and Beveridge, 1996). Previous studies exploring biofilm formation have generally focused on identifying the organisms that comprise biofilms, their physical and chemical properties and the architecture of the biofilm (Costerton et al, 1995).…”

The effects of metabolites from the indigenous Acidithiobacillus thiooxidans and temperature on the bioleaching of cadmium from soil

“…Similar to other Acidithiobacillus species, A. thiooxidans is thought to develop a mechanism that facilitates the attachment of cells to the surface of sulfur/sulfidic particles (Andrews, 1988;Konishi et al, 1995). Previous studies have shown that the attachment involves the effect of electric charges, surface irregularity, and cell membrane characteristics (Ohmura et al, 1993;Solari et al, 1992). In addition, it involves the excretion of extracellular polymeric substances (EPS), which are thought to mediate the contact between the cell and the surface (Bhavaraju et al, 1993;Kumar et al, 1991).…”