ENHANCED METALLOADSORPTION OF BACTERIAL-CELLS DISPLAYING POLY-HIS PEPTIDES

The properties of Escherichia coli cells, acquired by cell surface pre sentation of one or two hexahistidine (His) clusters carried by the ou ter membrane LamB protein, have been examined. Strains producing LamB hybrids with the His chains accumulated greater than 11-fold more Cd2 than E. coli cells expressing the protein without the His insert. Fur thermore, the hexa-His chains on the cell surface caused cells to adhe re reversibly to a Ni2+-containing solid matrix in a metal-dependent f ashion. Thus, expression of poly-His peptides enables bacteria to act as a metalloaffinity adsorbent. These results open up the possibility for biosorption of heavy ions using engineered microorganisms.