Chemical characterization and ligand behaviour of Pseudomonas veronii 2E siderophores

Siderophores are low-molecular weight ligands secreted by bacteria as a survival strategy in Fe(III)-lacking environments. They bind not only Fe(III), but Co(II), Zn(II), Mn(II), Ni(II), Ga(III) as a detoxification alternative. The synthesis, purification and characterization of siderophores produced by Pseudomonas veronii 2E were evaluated to be applied in future environmental technologies. Optimal production was obtained in Fe(III)-free M9-succinate at 25 °C, 40 h and pH 6.9. Siderophores were chemically characterized as hydroxamate and catechol mixed-type. Spectroscopic analysis indicated their belonging to the pyoverdine family, behaving as ligand to Cd(II), Zn(II), Cu(II), Ni(II) and Cr(III), which promoted siderophoregenesis during growth. Siderophore-Cd(II) complexation was studied by electrochemical monitored titration revealing one family of moderate-strength binding sites. Mass spectral analysis evidenced the secretion of a variety of molecules (molecular mass ca.1200 u). Non pathogenic Pseudomonas veronii 2E siderophores represent a safe alternative for the concrete application of environmental technologies and clinical procedures.