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 E(1) 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 Mg(2+) influx was up-regulated all the while, znuB responsible for Zn(2+) 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 Mg(2+) and Zn(2+) in cytoplasm would prevent Cd(2+)-binding enzymes to decrease the harm to cell.