en Molecular Microbiology Molecular Microbiology مقاله کامل Full Length/Original Article <p><strong>Background:</strong> Amongst the methods that remove heavy metals from environment, biosorption approaches have received increased attention because of their environmentally friendly and cost-effective feature, as well as their superior performances.<strong> Methods: </strong>In the present study, we investigated the ability of a surface-engineered <em>Escherichia coli</em>, carrying the cyanobacterial metallothionein on the cell surface, in the removal of Ca (II) from solution under different experimental conditions. The biosorption process was optimized using central composite design. In parallel, the kinetics of metal biosorption was studied, and the rate constants of different kinetic models were calculated. <strong>Results: </strong>Cadmium biosorption is followed by the second-order kinetics. Freundlich and Langmuir equations were used to analyze sorption data; characteristic parameters were determined for each adsorption isotherm. The biosorption process was optimized using the central composite design. The optimal cadmium sorption capacity (284.69 nmol/mg biomass) was obtained at 40&deg;C (pH 8) and a biomass dosage of 10 mg. The influence of two elutants, EDTA and CaCl₂, was also assessed on metal recovery. Approximately, 68.58% and 56.54% of the adsorbed cadmium were removed by EDTA and CaCl₂during desorption, respectively. The Fourier transform infrared spectrophotometer (FTIR) analysis indicated that carboxyl, amino, phosphoryl, thiol, and hydroxyl are the main chemical groups involved in the cadmium bioadsorption process. <strong>Conclusion:</strong> Results from this study implied that chemical adsorption on the heterogeneous surface of <em>E. coli</em> E and optimization of adsorption parameters provides a highly efficient bioadsorbent.&nbsp;</p> Adsorption, Kinetics, Response surface methodology, Fourier Transform Infrared Spectrophotometer 380 391 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-664&slc_lang=en&sid=1 Vida Tafakori No Department of Cell and Molecular Sciences, School of Biological Science, Kharazmi University, Tehran, Iran Reza Zadmard No Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran; Fatemeh Tabandeh No Department of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran; Mohammad Ali Amoozegar No Extremophiles Laboratory, Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran Gholamreza Ahmadian Yes Department of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran;