Studies on the accumulation of cadmium by a strain ofProteus mirabilis

A bacterium isolated from a wastewater plant sludge, identified as Proteus mirabilis, was tested for cadmium tolerance and accumulation capacity. The organism was able to grow in the presence of Cd2+ up to 300 mg l−1. Accumulation of cadmium is reported for growing and non-growing cells of the organism. In non-growing cultures a 70% removal of cadmium was observed when the initial concentration of Cd2+ was 1 mg l−1 whereas at the same concentration the removal by growing cells was only 22%. The metal was shown to be associated with the cell envelope (80%) and accumulated in the cytoplasm (20%).