The highly effective cadmium-resistant mechanism of Pseudomonas aeruginosa and the function of pyoverdine induced by cadmium.

Pyoverdine (PVD) plays an important role in reducing cadmium (Cd) accumulation in plants. Some Pseudomonas aeruginosa (P. aeruginosa) species can produce PVD under Cd(Π) stress. However, the function of Cd(Π)-induced PVD remains unclear. In this study, we isolated a highly effective Cd(Π)-resistant P. aeruginosa which can secrete PVD under Cd(Π) stress and found that PVD secretion has a dose-dependent relationship with Cd(Π) concentration. PVD can form a PVD-Cd complex with Cd(Π), though the PVD-Cd complex is unable to be adsorbed by the cell or enter the cell, so the complexation of PVD and Cd(Π) impedes Cd(Π) adsorption on the cell surface and alleviates the oxidative stress, lipid peroxidation, and morphological destruction of the cell caused by Cd(Π) and effectively improves the resistance of P. aeruginosa to Cd(Π). In summary, our research results indicate that the Cd(Π) resistance mechanism of P. aeruginosa screened is the complexation of PVD for Cd(Π) and the adsorption of bacteria for Cd(Π); furthermore, PVD plays an important role in improving the Cd(Π)-resistant ability of bacteria. This study provides a deeper understanding of the highly effective Cd(Π) resistance mechanism of P. aeruginosa and the function of Cd(Π)-induced PVD in bacteria.