Cadmium biosorption and toxicity to six cadmium‐resistant gram‐positive bacteria isolated from contaminated soil

Six Cd‐resistant bacterial strains were isolated from a soil receiving dredged sediments and containing Cd at concentration of 50 mg kg −1 . The isolates, identified as gram‐positive, were studied with regard to their ability to tolerate and accumulate Cd at concentrations varying from 0 to 100 mg L −1 . Results showed an increase in accumulated Cd in bacteria with increasing Cd concentrations in solution. Isolates were shown to tolerate higher Cd concentrations than a Bacillus subtilis strain used as a control. One of the isolates, identified as Bacillus brevis , was found to be the most resistant to Cd, with an ability to accumulate the toxic metal up to 70 mg −1 of cells (dry weight). Mn was found to reduce Cd toxicity and accumulation in B. brevis . This strain may have some potential interest in reclamation of metal‐contaminated soils.