BACTERIAL PYRITE OXIDATION

II. THE EFFECT OF VARIOUS ORGANIC SUBSTANCES ON RELEASE OF IRON FROM PYRITE BY THIOBACILLUS FERROOXIDANS

Abstract

The role of Thiobacillus thiooxidans was investigated in the enhancement of pyrite oxidation by the mixtures of Thiobacillus ferrooxidans and T. thiooxidans. The oxidation of pyrite by T. ferrooxidans was remarkably enhanced by the addition of dead cell suspensions and cell-free extracts of both chemolithotrophic thiobacilli and heterotrophic bacteria. The same promoting effect on the bacterial pyrite oxidation was recognized with various substances such as protein, nucleic acid, yeast extract, peptone, and also surface-active agent. These results indicate that the enhancement of bacterial pyrite oxidation by the intact cells of T. thiooxidans is attributed at least partly to the organic substances excreted from T. thiooxidans cells into the pyrite medium, and that cellular organic substances have a physico-chemical effect on a direct interaction between iron-oxidizing bacteria and solid particles.