Bioaccumulation characterization of zinc and cadmium by Streptomyces zinciresistens, a novel actinomycete

The bioaccumulation characteristics of Zn(2+) and Cd(2+) by a novel species, Streptomyces zinciresistens CCNWNQ0016(T), were investigated. S. zinciresistens accumulated Zn(2+) and Cd(2+) mainly on the cell wall followed by intracellular accumulation. The mycelium was deformed, aggregated and formed precipitate of zinc and cadmium on the cell surface. Electron dense granules were detected on the cell wall as well as within the cytoplasm. The amino, carboxyl, hydroxyl and carbonyl groups were responsible for the biosorption of Zn(2+) and Cd(2+). The Langmuir isotherm model fitted the experimental data of metals adsorption processes better than Freundlich isotherm model. Cu(2+) and Cr(3+) competed for adsorption sites on the cell surface with Zn(2+) and Cd(2+). 87.33% and 98.11% recovery of Zn(2+) and Cd(2+), respectively, could be obtained at pH≤2 from metal-loaded biomass of S. zinciresistens desorption.