Manganese tolerance in yeasts involves polyphosphate, magnesium, and vacuolar alterations

Basidiomycetous and ascomycetous yeast species were tested for manganese tolerance. Basidiomycetous Cryptococcus humicola, Cryptococcus terricola, Cryptococcus curvatus and ascomycetous Candida maltosa, Kluyveromyces marxianus, Kuraishia capsulata, Lindnera fabianii and Sacharomyces cerevisiae were able to grow at manganese excess (2.5 mmol/L), while the growth of basidiomycetous Rhodotorula bogoriensis was completely suppressed. The lag phase duration increased and the exponential growth rate decreased at manganese excess. The increase of cell size and enlargement of vacuoles were characteristics for the cells grown at manganese excess. The alterations in inorganic polyphosphate content and cellular localization were studied. L. fabianii, K. capsulata, C. maltosa, and Cr. humicola accumulated the higher amounts of inorganic polyphosphates, while Cr. terricola and Cr. curvatus demonstrated no such accumulation. The polyphosphate content in the cell wall tested by DAPI staining increased in all species under the study; however, this effect was more pronounced in Cr. terricola and Cr. curvatus. The accumulation of Mg(2+) in the cell wall under Mn(2+) excess was observed in Cr. humicola, Cr. curvatus and Cr. terricola. The accumulation of polyphosphate and magnesium in the cell wall was supposed to be a factor of manganese tolerance in yeasts.