Inhibition of growth, iron, and sulfur oxidation in <i>Thiobacillus ferrooxidans</i> by simple organic compounds

Abstract

Iron and sulfur oxidation by Thiobacillus ferrooxidans as well as growth on ferrous iron were inhibited by a variety of low molecular weight organic compounds. The influences of chemical structure of the organic inhibitors, pH, temperature, physical treatment of cells, and added inhibitory or stimulatory inorganic ions and iron oxidation suggest that a major factor contributing to the inhibitory effects on iron oxidation is the relative electronegativity of the organic molecule. The data also suggest that inhibitory organic compounds may (i) directly affect the iron-oxidizing enzyme system, (ii) react abiologically with ferrous iron outside the cell, (iii) interfere with the roles of phosphate and sulfate in iron oxidation, and (iv) nonselectively disrupt the cell envelope or membrane.