Uptake and Bioaccumulation of Cr(III) in Yeast Saccharomyces cerevisiae

Uptake and Bioaccumulation of Cr(III) in Yeast Saccharomyces cerevisiae

Martin Batič^1,2, Peter Raspor²¹Biotechnology Department, Mlinotest d.d., Tovarniška 14, 5270 Ajdovščina, Slovenia
²Food Science and Technology Department, Biotechnical Faculty, Chair of Biotechnology,University of Ljubljana, Jamnikarjeva 101, 1000 Liubljana, Slovenia

Article history:
Received October 21, 1997
Accepted November 11, 1998

Key words:
yeasts, nutrient, chromium, toxicity, uptake, accumulation

Summary:
The chromium uptake and bioaccumulation were studied for selected yeast Saccharomyces cerevisiae ZIM-198 after standardised cultivation in designed substrate with adequate amount of Cr(HI) in the media. The impact of Cr(HI) on biomass accumulation, RNA, metal accumulation, and organically bound chromium was studied in vivo. Efficiency of Cr(III) in yeast biomass was primarily studied in vitro to define the impact of pH and energy source. A strong correlation between energy supplementation and chromium uptake was found. The optimal pH value was found to be approximately 4. Selected pH minimised also the possibility of Cr(IIl) precipitation in the media. High Cr(IlI) concentrations (> 1.9 mmol L^-1) intensify the pH decrease in the media. Further studies in vivo in standardised media confirmed the impact of Cr(III) on yeast cell metabolism. It was proved that Cr(HI) has an important effect on cell components. Total chromium concentration in the yeast cell increased in Sacch. cerevisiae when continuous growth in a concentration of 96 µmol L^-1 of Cr(UI) in the medium was applied. The same tendency was detected for organically bound intracellular chromium where 43% higher concentration of chromium was determined under the same conditions of cultivation. The yeast detoxification capability for high intracellular chromium was reduced owing to the toxic action of environmental chromium loading pressure on yeast cell growth and viability. The cell detoxification system enables the yeast Sacch. cerevisiae to survive and grow at a moderate and higher concentration of inorganic chromium. In these processes, the distribution of excess inorganic chromium in the cell plays an important role.

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