Abstract
This paper analyzes the resistance mechanism of At. Ferrooxidans to heavy metal ions, and compares the tolerance of different strains to Cu2+ and the expression of At. Ferrooxidans strains under different concentrations of Mn2+, Zn2+ and Cd2+. The results show that: the three selected At. Ferrooxidans strains, DY1, DY2 and DY3, differ in terms of Cu2+ toleration and S and Fe2+ oxidizing abilities. The maximum tolerable Cu2+ concentrations of DY1, DY2 and DY3 are 0.41mol/L, 0.20mol/L and 0.04mol/L, respectively. DY1 has the strongest oxidizing ability to S element, but the weakest oxidizing ability to Fe2+ ions among the three strains; DY3 has the strongest oxidizing ability to Fe2+ ions. There are differences in the adaptability of different strains to the leaching system. The copper resistance gene of the strains are stimulated to a certain degree by the Cu2+ in the culture solutions. the Cu2+ resistance of the strains is proportional to the resistance gene of the strain itself. The stronger the resistance of the strain to Cu2+, the more unlikely for the relevant resistance gene to be expressed in large quantities at low Cu2+ concentration in the culture solution. The maximum tolerated concentrations of Mn2+, Zn2+ and Cd2+ are 0.38 mol/L, 0.18 mol/L and 0.08 mol/L for the selected At. Ferrooxidans strains. The three heavy metal elements on the strains are ranked as Mn2+
