| Sumario: | Acidithiobacillus ferrooxidans obtains its energy from the oxidation of ferrous iron, elemental sulfur, or partially oxidized sulfur compounds. The ability of this microorganism to solubilize metal sulfides is successfully applied in biomining operations. Genomic, metagenomic, and high-throughput proteomic studies of the global regulatory responses that biomining microorganisms use to adapt to their changing environment are just beginning to emerge. To further study some of the components involved in sulfur metabolism, differential expression proteomics of total periplasmic proteins was done by high-resolution LTQ FT ion trap mass spectrometry. Of 216 proteins found in the periplasm, several of them changed their levels of synthesis during growth of A. ferrooxidans ATCC 23270 in thiosulfate, elemental sulfur and ferrous iron. Thirty-four percent of them corresponded to unknown proteins. Forty-one proteins were exclusively present in sulfur-grown cells and 14 in thiosulfate-grown cells. The putative genes coding for these proteins were localized in the available genomic sequence of A. ferrooxidans ATCC 23270. The genomic context around several of these genes suggests their involvement in sulfur metabolism and possibly in sulfur oxidation and formation of FeS clusters. Many of the periplasmic proteins changing their expression during growth in sulfur compounds may have important roles yet to be described in the sulfur metabolism of this acidophilic microorganism. This knowledge will eventually help to improve mineral bioleaching processes.
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