Sulfur species investigation in extra- and intracellular sulfur globules of acidithiobacillus ferrooxidansand acidithiobacillus caldus

摘要

The sulfur chemical speciation in extracellular and intracellular sulfur globules of Acidithiobacillus ferrooxidans and Acidithiobacil-lus caldus were investigated with an integrated approach including scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy and sulfur K-edge X-ray absorption near edge structure spectroscopy (XANES). The results indicated that both strains can accumulate extracellular sulfur globules when grown on thiosulfate, and the major sulfur chemical speci-ation of which were S_8 for A. ferrooxidans and mixture of ring sulfur and polythionate for A. caldus, respectively. In contrast, A. ferrooxidans can accumulate both linear sulfur and S_8 internally when grown with sulfur powder and thiosulfate, whereas A. cal-dus did not accumulate intracellular sulfur globules. In addition, the fitted results of sulfur K-edge XANES spectra indicated that the reduced glutathione (containing thiols groups) were involved in sulfur bio-oxidation of both strains and the tetrathionate were the intermediate products during thiosulfate metabolism by two strains.