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Growth
of Thiobacillus ferrooxidans: Applied
and Environmental Microbiology, The concentrations of ferrous and ferric ions change dramatically during the course of the batch experiments usually performed to study the kinetics of the bacterial oxidation of ferrous ions and sulfide minerals. This change in concentration of the iron species during the course of the experiment often makes it difficult to interpret the results of these experiments, as is evidenced by the lack of consensus concerning the mechanism of bacterial leaching. If the concentrations of ferrous and ferric ions were constant throughout the course of the batch experiment, then the role of the bacteria could be easily established, because the rate of the chemical leaching should be the same at a given redox potential in the presence and in the absence of bacteria. In
this paper we report an experiment designed to obtain kinetic data
under these conditions. The redox potential is used as a measure
of the concentrations of ferrous and ferric ions, and the redox
potential of the leaching solution is controlled throughout the
experiment by electrolysis. The effects of ferrous, ferric, and
arsenite ions on the rate of growth of Thiobacillus ferrooxidans
on ferrous ions in this redox-controlled reactor are presented.
In addition, the growth of this bacterium on ferrous ions in batch
culture was also determined, and it is shown that the parameters
obtained from the batch culture and redox-controlled batch culture
are the same. An analysis of the results from the batch culture
indicates that the initial number of bacteria that are adapted to
the solution depends on the concentrations of ferrous and arsenite
ions.
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