The Mechanism of Copper Leaching by Intact Cells of Thiobacillus ferrooxidans

Abstract

Under aerobic conditions, washed intact cells of Thiobacillus ferrooxidans AP19-3 solubilized copper enzymatically from a copper concentrate containing Cu(20.48%), Fe(31.61%), 8(38.22%), Pb(3.84%), and Zn(4.22%). The optimum pH of copper solubilization from copper concentrate was at pH 3.0. In contrast, under anaerobic conditions or under aerobic conditions in the presence of sodium cyanide, inhibitor of iron oxidase, the amount of copper solubilized enzymatically from the ore markedly decreased, indicating that iron oxidase is involved in the copper solubilization. Under the conditions under which iron oxidase of the cells cannot operate, Fe2+ and Cu+ ions were produced enzymatically, suggesting that a hydrogen sulfide: ferric ion oxidoreductase (SFORase) was involved in this copper solubilization from the ore. A short treatment of the strain with 0.5% phenol completely destroyed the SFORase. However, this treatment did not affect the iron oxidase of the cells. A concomitant loss of the activity of copper solubilization from the ore was observed in 0.5% phenol-treated cells. The results strongly suggest that both iron oxidase and SFORase are crucial in copper ore leaching by T. ferrooxidans AP19-3. © 1990, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.

Source or Periodical Title

Agricultural and Biological Chemistry

ISSN

21369

Page

2293-2298

Document Type

Article

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