Three strains of red yeast Rhodosporidium kratochvilovae, Rhodotorula glutinis and Sporidiobolus salmonicolor were studied for their responses to the presence metal stress, oxidative stress and a combination of these stress factors. For all yeast strains, the production of β-carotene increased in stress conditions. The combination of H2 O2 and Zn2+ significantly activated the pathways for the production of torularhodin in the strain R. glutinis (from 250 to 470 μg g-1 DCW) as well as β-carotene (from 360 to 1100 μg g-1 DCW) and torulene (from 100 to 360 μg g-1 DCW) in Sp. salmonicolor. Strains of R. glutinis and Rh. kratochvilovae bound the majority of Zn(II) ions to the fibrillar part of the cell walls, whereas the strain Sp. salmonicolor bound them to both extracellular polymers and the fibrillar part of the cell walls. A decrease in the ability of yeasts to tolerate higher concentrations of Zn(II) in the presence of free radicals (hydrogen peroxide) was also found.

Culture Collection of Yeasts Institute of Chemistry Slovak Academy of Sciences Dúbravská cesta 9 845 38 Bratislava Slovakia

Institute of Biotechnology Faculty of Chemical and Food Technology Slovak University of Technology Radlinského 9 812 37 Bratislava Slovakia

Institute of Food Chemistry and Biotechnology Faculty of Chemistry University of Technology Purkyňova 118 612 00 Brno Czech Republic

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