Rapid method for detection and detoxification of heavy metal ions in waterenvironments using phytochelatin

Phytochelatins (PCs, (gamma Glu-Cys)(n)-Gly (n=2-11)) are produced by highe r plants, algae, and some fungi in response to heavy metal ion exposure. A rapid and convenient method for quantifying heavy metal ion concentrations in water environments was developed using a chemically synthesized PC as a mediator. The chelating ability of the PC and quantification of the thiol g roup were utilized to measure heavy metal ions at low concentrations. The m ethod requires only ten minutes for measurement and only 1 ml of a liquid s ample. A range of homogeneous PCs (n = 4-7) were chemically synthesized usi ng a peptide synthesizer. These, especially PC7, exhibited higher sensitivi ty and consistency of measurement than the native PC from Silene cucubalus, which produced a mixture of PC2, PC3, and PC4. Detoxification of heavy met al ions in vitro by PC was also investigated. Using the paper disc method, the cell growth inhibition zone caused by cadmium ion against Salmonella ty phimurium TA1538 was significantly decreased by addition of PC. Furthermore , at the minimum inhibitory concentration of cadmium ion (200 mu M) in a nu trient broth culture of S. typhimurium, cell growth was almost completely r ecovered by addition of PC to the medium.