The regulation of sulfur use by ferrous ion in Thiobacillus ferrooxidans.

Abstract

The use of elemental sulfur (S°) as an energy source by T. ferrooxidans API9-3 was completely inhibited by above 108mMof Fe2+ added to S°(l %)-salts medium, in which about 0.6mM Fe2+ remained after 30 days cultivation without being oxidized. In contrast, the use of Fe2 + by this strain was not inhibited by S°. It was found that specific activities of hydrogen sulfide: ferric ion oxidoreductase (SFORase) and sulfite : ferric ion oxidoreductase, which are crucial in sulfur and sulfite oxidations of this strain, were completely inhibited by 20 mmand 1 mMFe2 + , suggesting that this may be a main cause for the cells not using sulfur as an energy source. The SFORaseactivity of the cells incubated with S°-Fe2+-salts medium decreased to 39% of that in control cells without Fe2+, suggesting that Fe2 + added to the mediuminhibits a sulfite : ferric ion oxidoreductase, and as a results sulfite ions are accumulated in the cells and this damages the SFORase. Sodium sulfite completely inhibited cell growth on S°-salts medium at 0.1 mM, but not on iron-salts medium.

Leaching of Zinc Sulfide by Thiobacillus ferrooxidans : Experiments with a Controlled Redox Potential Indicate No Direct Bacterial Mechanism

“…Samples of the mineral particles were covered with a large amount of exopolymer, suggesting that large numbers of bacteria were present on the surfaces. In addition, the sulfur that was present previously was no longer present, suggesting that the bacteria oxidized the sulfur to sulfate (34,42,45). The SEM analysis indicated that the bacteria were attached to the surfaces for the duration of the experiment; however, after about 47 h large numbers of bacteria were present on the mineral particles.…”

A comparative study of substrate utilisation by Sulfobacillus species in mixed ferrous ion and tetrathionate growth medium

“…Sugio et al [17] interpreted their results as showing that >0.1M ferrous ion in iron(II)-elemental sulfur growth medium (0.108 M Fe 2+ and 1 % elemental sulfur)…”

Sensitivity of Iron-Oxidizing Bacteria, Thiobacillus ferrooxidans and Leptospirillum ferrooxidans , to Bisulfite Ion

“…To understand the basic physiology of L. ferrooxidans and to apply the bacterium to bacterial leaching, it is quite important to study the reason L. ferrooxidans strains failed to grow on sulfur-salt medium even though they had the enzymes involved in sulfur oxidation. We have shown that approximately 0.02 to 0.05 mM bisulfite ion, harmful to these ironoxidizing bacteria, is produced as an intermediate during sulfur oxidation by SFORase not only in T. ferrooxidans but also in L. ferrooxidans (1,8,14,16). Thus, to find a clue towards solving this complicated but interesting physiological problem in ironoxidizing bacteria, we first compared the sensitivities of ironoxidizing bacteria to the bisulfite ion.…”