In Gram negative bacteria cadmium is targeted on DsbA gene in the periplasm. DsbA gene is responsible for the formation of disulfide. Cadmium resistance in some gram-positive bacteria was also found to be mediated by CadA-like proteins (Liu et al., 1997). In S. cerevisiae, cadmium is bound by glutathione, and the resulting cadmium-bis-glutathione to complex is transported by an ABC transporter the YCF1p transporter, into the vacuole (Li et al., 1996; Li et al., 1997). This may be a general principle in all eukaryotes. The multidrug-resistance-associated protein from man may complement YCF1 mutation with respect to cadmium resistance (Tommasini et al., 1996). In cyanobacteria transport may also be necessary for cadmium resistance because it contains various types of RNA- and P-type transport systems. Ncc, a nickel exporter (Schmidt and Schlegel 1994) and RND-driven systems like Czc a zinc exporter [53-54 Nies, 1995; Nies 1989b) present in gram-negative bacteria, and involved in detoxification of …show more content…
Siderophore enhances the mobility of metals and various types of metals such as Cd, Cu, Ni, Pb, Zn, and the actinides Th (IV), U (IV) and Pu (IV) are solubilized by siderophore (Schalk et al., 2011). These characteristics of siderophore are arises due to its ligand functionalities and with the help of this property siderophores may have a strong binding affinity or selectivity to metal other than Fe (Hernlem et al., 1999). Pseudomonas aeruginosa secrete the pyochelin siderophore and could chelate various types of metals, e.g. Ag+, Al3+, Cd2+, Co2+, Cr2+, Cu2+, Eu3+, Ga3+, Hg2+, Mn2+, Ni2+, Pb2+, Sn2+, Tb3+, Tl+ and Zn2+ (Braud et al., 2009a). Both types of siderophore (Phyto and microbial) are used in bioremediation technique, but many studies prove that phytosiderophore are more potent than microbial siderophore (Rajkumar et al., 2009; Rajkumar et al., 2010) because phytosiderophore have strong affinity for complex formation with metals especially with Fe, Cu, Zn, Ni and Cd (Awad and Romheld, 2000; Singh et al., 2008; Ahemad and Holmstrom,