Study on Removal of Cadmium by Rhodopseudomonas palustris

Abstract:

The influences of oxygen supply and illumination, carbon sources, pH and temperature on the growth of Rhodopseudomonas palustris S stain and removal for cadmium were studied. The results showed that the removal rate in presence of 25mg/L of cadmium was the highest, reaching 85%, under oxygen supply and dark, carbon source with malic acid, pH=7.0 and temperature at 30℃. Under the optimal condition, the removal rate reached 85% in presence of 10mg/L～25mg/L of cadmium, while it was only 23% in presence of 150mg/L of cadmium. The distribution analysis of Cd²⁺ in different fractions of cell showed that 63.5% of Cd²⁺ was on cell wall and 33.5% of Cd²⁺ was in protoplast. Simultaneity, transmission electron microscopy photos of cell ultra thin section revealed that the removal of cadmium ions was mainly completed on cell wall.