Metal-related genes (afe_0654, afe_0671, afe_0674, afe_1143, afe_1144, and afe_2126) were cloned to identify whether those genes existed in Acidithiobacillus ferrooxidans strain DC (A. ferrooxidans DC). The deduced amino acid sequences of those genes were analyzed by bioinformatics. The tolerance levels of A. ferrooxidans DC to Mn(2+), Zn(2+), and Cd(2+) were determined, which were 0.52, 0.42, and 0.16 mol/L for ferrous iron-grown cells and 0.38, 0.18, and 0.08 mol/L for sulfur-grown cells, respectively. Real-time quantitative PCR was employed to analyze the transcriptional levels of the metal-related genes when ferrous iron- and sulfur-grown cells of A. ferrooxidans DC, respectively, exposed to Mn(2+), Zn(2+), and Cd(2+). The metal-related genes were up-regulated when A. ferrooxidans DC exposed to Mn(2+). When A. ferrooxidans DC exposed to Zn(2+), the metal-related genes were up-regulated in sulfur-grown cells; afe_0654 and afe_0674 were down-regulated, and the others were up-regulated in ferrous iron-grown cells. Afe_2126 was down-regulated, and the others were up-regulated when A. ferrooxidans DC exposed to Cd(2+). According to experimental results and bioinformatics analysis, the proteins encoded by afe_0654 and afe_0674 may relate with Mn(2+) and Cd(2+) efflux. It needed further study whether they relate with Zn(2+) transport. Proteins encoded by afe_0671, afe_1143, and afe_1144 may relate with the efflux of Mn(2+), Zn(2+), and Cd(2+). The protein encoded by afe_2126 may relate with Mn(2+) and Zn(2+) efflux and Cd(2+) uptake.

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