Solubilization of Minerals by Bacteria: Electrophoretic Mobility of Thiobacillus ferrooxidans in the Presence of Iron, Pyrite, and Sulfur

Abstract

ThiobaciUus ferrooxidans is an obligate acidophile that respires aerobically on pyrite, elemental sulfur, or soluble ferrous ions. The electrophoretic mobility of the bacterium was determined by laser Doppler velocimetry under physiological conditions. When grown on pyrite or ferrous ions, washed cells were negatively charged at pH 2.0. The density of the negative charge depended on whether the conjugate base was sulfate, perchlorate, chloride, or nitrate. The addition of ferric ions shifted the net charge on the surface asymptotically to a positive value. When grown on elemental sulfur, washed cells were close to their isoelectric point at pH 2.0. Both pyrite and colloidal sulfur were negatively charged under the same conditions. The electrical double layer

Effect of Various Ions, pH, and Osmotic Pressure on Oxidation of Elemental Sulfur by Thiobacillus thiooxidans

“…The results reported in this paper for the effect of salts and pH on sulfur oxidation by T. thiooxidans are best explained by a combination of the following five events: (i) activation of sulfur oxidation in T. thiooxidans by increasing concentrations of salts at low concentrations (below 0.1 M) according to the Derjaguin-Landau-Verwey-Overbeek theory of charge neutralization on the surface of colloid particles (2,9,14,28); (ii) based on the expected response of acidophilic bacteria (1,7,13), inhibition by some permeant anions at low-pH conditions due to destruction of ⌬ (positive inside), allowing the H ϩ to leak in from outside (order of increasing inhibition: HSO 4…”

A Novel Mineral Flotation Process Using Thiobacillus ferrooxidans

“…Therefore, the zeta potentials of the minerals used in this study were estimated ( Table 5). All of the minerals had negatively charged surfaces, and the surfaces of T. ferrooxidans cells are also negatively charged (4). Thus, electrostatic interaction would not produce the essential force necessary for T. ferrooxidans adhesion; in fact, the negative charges would repel one another (6).…”

Importance of Extracellular Polymeric Substances fromThiobacillus ferrooxidansfor Bioleaching

“…In Table 3 the data indicate that attachment was dependent on the growth substrate. Whereas sulfur-grown cells attached only to hydrophobic surfaces (sulfur, adsorbent resin), iron(II) sulfate-grown cells adhered exclusively to negatively charged substrata (pyrite [6,15], cationexchange resin). Pyrite-grown cells accepted both substrata.…”