Bacterium-Based Heavy Metal Biosorbents: Enhanced Uptake of Cadmium by E. coli Expressing a Metallothionein Fused to β-Galactosidase

Abstract

We investigated the potential utility of a recombinant E. coli that expresses the human metallothionein II gene as a fusion protein with β-galactosidase as a heavy metal biosorbent. E. coli cells expressing the metallothionein fusion demonstrated enhanced binding of Cd2+ compared to cells that lack the metallothionein. It was shown that the metallothionein fusion was capable of efficiently removing Cd2+ from solutions. Approximately 40% of the Cd2+ accumulated by the recombinant cells free in suspension was associated with the outer cell membrane, and 60% of that was present in the cytoplasm.