Accumulation of some metal ions on Bacillus licheniformis

Pure species of Bacillus licheniformis was used to remove ions from aqueous and simulated waste solutions. Metal ion accumulation on B. licheniformis was fast. Maximum uptake occurred at pH 4+/-0.5 and at 25+/-3 degreesC. One gram of dry B. licheniformis was found to accumulate 115 mg cerium, 34 mg copper and 11 mg cobalt from aqueous solutions. The presence of certain foreign ions such as calcium, sodium and potassium decreased the uptake of ions by B. licheniformis, while citrate and EDTA prevent the uptake. Electron microscopic investigations showed that cerium (III), copper (II) and cobalt (II) accumulated extracellulary around the surface wall of B. licheniformis cells. A bio-adsorption mechanism between the metal ions and B. licheniformis cell wall was proposed.