Bioaccumulation of nickel from aqueous solutions by genetically engineered Escherichia coli

This study constructed a genetically engineered Escherichia coli JM109 which simultaneously expressed nickel transport system and metallothionein to remove and recover Ni2+ from aqueous solution. Bioaccumulation process was rapid and followed linearized Langmuir isotherm. A more than six-fold increase of Ni2+ binding capacity was obtained by genetically engineered E. coli cells compared with original host E. coli cells. A pH assay showed genetically engineered E. coli cells accumulated Ni2+ effectively over a broad range of pH (4–10). The presence of 1000 mg/L Na+ and Ca2+, or 50 mg/L Cd2+ or Pb2+ did not have a significant effect on Ni2+ bioaccumulation, while Mg2+, Hg2+ and Cu2+ posed a severe adverse influence on Ni2+ uptake by genetically engineered E. coli. Furthermore, genetically engineered E. coli cells did not require extra nutrients for Ni2+ bioaccumulation.