In this study different strategies were employed for adapting Acidithiobacillus ferrooxidans cells to both Zn(2+) ions and high grade sphalerite concentrate. The serial subculturing was found to be a very efficient strategy for adapting A ferrooxidans cells to higher Zn(2+) concentrations, as well as high grade sphalerite concentrate, provided that a suitable protocol was employed. Adaptation of A. ferrooxidans cells to 30 g/L Zn(2+) significantly enhanced the rate of bioleaching of Zn(2+) from high grade sphalerite concentrate. Preadaptation to Zn(2+) ion also shortened the time required to adapt the cells to the concentrate. A. ferrooxidans PTCC 1642, exhibited a higher rate of Zn(2+) bioleaching from high grade sphalerite concentrate compared to A. ferrooxidans DSMZ 583; however, due to the adaptation protocol employed the difference in performance of the two strains was not very great. Based on the results obtained in this study suggestions were given for the mechanisms during the adaptation of A. ferrooxidans cells to high grade sphalerite concentrate. (C) 2009 Elsevier Ltd. All rights reserved.