Electrochemical study of heavy metals and metallothionein in yeast Yarrowia lipolytica
The bioaccumulation of heavy metals (cadmium, nickel, cobalt and zinc) and the effect of these metals on the production of metallothionein and metallothionein-like proteins (MT) in Yarrowia lipolytica was studied by electrochemical methods. The concentrations of heavy metals were determined by differential pulse voltammetry (DPV). A combination of the constant current chronopotentiometric stripping analysis (CPSA) and adsorptive transfer stripping technique (AdTS) was used to determine the content of NIT in cells. Both the bioaccumulation of heavy metals and the production of MT in different cell compartments of Y lipolytica exposed to heavy metals were monitored. The LD50 of each metal was determined from the number of viable cells in yeast cultures: LD50Cd (37.5 muM), LD50Ni (570 muM), LD50CO (700 muM), and LD50Zn (1800 muM). The highest concentrations of heavy metals were found in the cell wall and membrane debris while the lowest concentrations were detected in the cytoplasm. Cadmium and nickel showed the most significant effect on the production of MT. This study provides new insights into the ecophysiology of microorganisms and demonstrates the potential use of these electrochemical methods in biotechnology. (C) 2003 Elsevier Science B.V. All rights reserved.