Engineering the Escherichia coli outer membrane protein OmpC for metal bioadsorption

The outer membrane protein, OmpC, from Escherichia coli was used to display metal-binding poly-histidine peptides on the surface of this bacterium. SD S-PAGE analysis of outer membrane protein preparations confirmed the expres sion of the metal-binding epitopes inserted in position 162 of the mature O mpC protein. Display of these epitopes was confirmed by epifluorescence mic roscopy of cells bound to Ni2+-NTA-agarose beads and metal adsorption exper iments. The cells harboring one or two copies of the metal binding epitope were able to adsorb 3 to 6 times more Zn2+ (13.8 mu mol g(-1) cell), Fe3+ ( 35.3 mu mol g(-1) cell), and Ni2+ (9.9 mu mol g(-1) cell) metallic ions tha n control cells expressing the wild-type OmpC.