Acidithiobacillus ferrooxidans strain SRDSM2 was isolated from silica containing soil sample collected at a Rajpardi lignite mine. The strain responded to the addition of 0.5 g/L peptone and 1.0 g/L tryptone soya broth in the ferrous sulphate tryptone soya broth (ITSB) medium with 35.3% and 29.6% increase in iron oxidation rate (IOR), but decrease in the IOR at higher peptone or tryptone soya broth levels. The presence of 4 mM of zinc as zinc sulphate in the medium increased the IOR by 24.4%. Forty percent of the inoculated cells survived even after exposure at 80 degrees C for 120 min and showed 30% ferrous iron oxidation. The V-max and K-s for iron oxidation by the isolate were 344.82 mg/L/h and 32.25 g/L respectively. The isolate was able to oxidized ferrous iron even in presence of 4.06 M ionic strength of medium and leached >85% copper and zinc from the polymetallic concentrate. Thus, this isolate can be used for bioextraction of metals from polymetallic concentrate. (C) 2010 Elsevier Ltd. All rights reserved.