Response of P. aeruginosa E 1 Gene Expression to Cadmium Stress

Heavy metal resistance microorganism plays an important role on polluted soil bioremediation. To obtain further knowledge of the resistant mechanism employed by cadmium-resistant bacteria, some gene expression profiles at transcription level were investigated in P. aeruginosa E1 subjected to cadmium stress using real-time PCR. Exposure to cadmium for 1 h, the expression of czcA, czcB, and czcC all reached the peak of up-regulation 8.82-, 4.83-, and 7.43-fold, respectively. The response of czcD was earlier and stronger than czcABC. CysM contributed to cysteine synthesis kept up-regulation within the beginning 2 h. The expression of mgtAE genes related to Mg2+ influx was up-regulated all the while, znuB responsible for Zn2+ transportation kept up-regulation from 30 min to 4 h. The result support the two cadmium-resistance mechanisms including effluxing and inactive the heavy metal ions. The mechanism was brought that increase of Mg2+ and Zn2+ in cytoplasm would prevent Cd2+-binding enzymes to decrease the harm to cell.