Biosorption of copper, manganese, cadmium, and zinc by Pseudomonas putida isolated from contaminated sediments

Biosorption of Cu2+, Mn2+, Cd2+ , and Zn2+ by Pseudomonas putida growing on phenol as a sole carbon and energy source in a batch-stirred system was studied. The solution pH strongly affected the metal biosorption, and the optimum pH values for Cu2+, Mn2+, Cd2+, and Zn2+ were 5.0, 5.0, 6.0, and 6.0, respectively. The biosorption kinetics was found to be fast with equilibrium being attained within 120 min. According to the Langmuir isotherm model, the maximum biosorption capacities of Cu2+, Mn2+, Cd2+, and Zn2+ were 64.8, 25.6, 48.5, and 32.6 mg/g in single-solute system. In multi-metal systems, a clear decrease in biosorption capacity was observed due to strong competition between four metal ions in terms of occupancy binding sites. P. putida was able to survive metal concentrations as high as 300 mg/L for Cu2+, 150 mg/L for Mn2+, 100 mg/L for Cd2+, and 300 mg/L for Zn2+ and the intermixture consisting of Cu, Mn, Cd, and Zn at 50 mg/L each accompanied with the biodegradation of phenol. This study showed a potential simultaneous bioremediation of phenol and heavy metal pollutants in the environment.