Abstract

A recombinant Bacillus subtilis clone displaying hexahistidine oligopeptide (6x-His) was generated to enhance the adsorption of Ni2+ and Cu2+ ions for environmental treatment application with initial concentrations of 2ppm to 200ppm. The equilibrium amount of metal ions adsorbed onto the bacteria increased with increasing of pH from 4.0 to 6.0. The engineered clone was shown to have a Ni2+ and Cu2+ relative adsorption of 1.33 and 1.8 as compared to the control strain, as expected. Among the models tested, namely the Langmuir, Freundlich isotherms, the biosorption equilibrium for both Ni2+ and Cu2+ was best described by the Langmuir model. For the ligand binding with heavy metal ions, namely the one and two site saturation, one and two site saturation with nonspecific, one and two site competition on cell for both engineered and control strain was best revealed by one site saturation.