The role of higher polythionates in the reduction of chromium(VI) by Acidithiobacillus and thiobacillus cultures

DONATI, EDGARDO R.; ALLEGRETTI PATRICIA,; FURLONG JORGE,

JOURNAL OF BIOTECHNOLOGY

Año: 2006 vol. 22 p. 55 - 61

0168-1656

In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of At. ferrooxidans cultures under acidic conditions was higher than that observed for At. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of At. thiooxidans cultures and much higher than that observed for At. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45 mm filter. In the fraction that comes from At. thiooxidans culture, polythionates (SxO62-) with 3-7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results.