Affiliation:
1. Department of Microbiology, Umeå University, S-901 87 Umeå, Sweden
Abstract
ABSTRACT
We investigated the potential role of the three strains of
Thiobacillus caldus
(KU, BC13, and C-SH12) in arsenopyrite leaching in combination with a moderately thermophilic iron oxidizer,
Sulfobacillus thermosulfidooxidans
. Pure cultures of
T. caldus
and
S. thermosulfidooxidans
were used as well as defined mixed cultures. By measuring released iron, tetrathionate, and sulfur concentrations, we found that the presence of
T. caldus
KU and BC13 in the defined mixed culture lowered the concentration of sulfur, and levels of tetrathionate were comparable to or lower than those in the presence of
S. thermosulfidooxidans
. This suggests that
T. caldus
grows on the sulfur compounds that build up during leaching, increasing the arsenopyrite-leaching efficiency. This result was similar to leaching arsenopyrite with a pure culture of
S. thermosulfidooxidans
in the presence of yeast extract. Therefore, three possible roles of
T. caldus
in the leaching environment can be hypothesized: to remove the buildup of solid sulfur that can cause an inhibitory layer on the surface of the mineral, to aid heterotrophic and mixotrophic growth by the release of organic chemicals, and to solubilize solid sulfur by the production of surface-active agents. The results showed that
T. caldus
KU was the most efficient at leaching arsenopyrite under the conditions tested, followed by BC13, and finally C-SH12.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
165 articles.
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