Induced cross-protection responses against Cr(III) and Fe(III) ions in Saccharomyces cerevisiae.

Stress tolerance of yeast Saccharomyces cerevisiae was examined after exposure to iron and chromium, which are essential minerals in low concentrations but can be toxic if present in high concentrations. Induction of possible cross-protection responses was performed with the yeast pre-treatment at the start of cultivation with low concentrations of Fe(III) or Cr(III) ions, which slightly inhibit the growth and the subsequent exposure to sub-lethal concentrations of Fe(III) or Cr(III) ions in the mid-exponential phase. No cross-protection was found if yeasts were pre-treated with 0.1 mM Cr(III) and subsequent exposure to 2.5 mM Fe(III) ions took place. If pre-treated with 0.1 mM Fe(III) Saccharomyces cerevisiae conferred protection to subsequent challenges with a sub-lethal concentration of 2.5 mM Cr(III) ions resulting in higher biomass formation and higher relative cell viability in comparison to cells without pre-treatment. It is shown for the first time that iron pre-treatment enhanced yeast condition against chromium related stress via cross-protection mechanism.