Toxicity Decrease of Cadmium by the Pigment Produced by Azomonas agilis PY101 in the Culture of Bacterial Cells and Vero Cells

The morphological patterns and the cytopathogenicity time of the Vero cells induced by free $Cd^{2+}$ and pigment-bound $Cd^{2+}$ were observed by inverted microscope in order to investigate the difference of cadmium toxicity. The Vero cells induced by Hee $Cd^{2+}$ of 0.1 mM were shown to have a fatal toxic effect and the cytopathogenicity could be seen early after 6$\pm$2 hours of incubation. Partially affected cells induced by pigment-bound $Cd^{2+}$ of 0.1 mM were shown and the cytopathogenicity could be seen after 20 hours of incubation. The Vero cells grown with free 0.001 mM $Cd^{2+}$ were also affected and the cytopathogenicity could be seen after 17 hours of incubation, whereas the Vero cells grown with 0.001 mM pigment- bound $Cd^{2+}$ were unaffected. The sensitivity of Escherichia coli DH5$\alpha$ bacterial cells was also examined after a short treatment with free $Cd^{2+}$ or pigment-bound $Cd^{2+}$. About 5% of cells survived after 0.01 mM of free $Cd^{2+}$ treatment, while about 68% of cells survived after 0.01 mM of pigment- bound $Cd^{2+}$.