S Molaei - Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
S Yaghmaei - Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Z Ghobadi - Biochemical and Bioenvironmental Research Center, Sharif University of Technology, Tehran, Iran

Acidophilic microorganisms such as thiobacillus ferrooxidans have the capability to carry out process of biorecovery of heavy metals. Its principle is the microbial production of the sulphuric acid and simultaneous recovery of metals. Thiobacillus ferrooxidans derives the energy for their metabolism from ferrous iron oxidation process which can be affected by the presence of heavy metals in the medium. In this study the ability of thiobacillus ferrooxidans, on the biorecovery of heavy metals in shake flasks has been investigated. The adaptation of the thiobacillus ferrooxidans to a kind of heavy metal such as Ni+2 in the medium was developed through serial subculturing. Adaptation is easily carried out by continually growing the bacteria in an environment containing increasing concentrations of the toxic metal such that a culture tolerant to the toxic metal proliferates. Ni+2 adapted strains exhibited better biorecovery results compared to the wild strains in the biorecovery of nickel. Effects of several process variables such as optimum pH and temperature, redox potential, bacterial concentration in solution and ferrous iron concentration for the specific bacterial growth rate, were also investigated.

Adaptation, Biorecovery, Heavy Metals, Thiobacillus Ferrooxidans