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  • The halophilic fungus Hortaea werneckii and the halotolerant fungus Aureobasidium pullulans maintain low intracellular cation concentrations in hypersaline environments
    Kogej, Tina ...
    Hortaea werneckii and Aureobasidium pullulans, black yeast-like fungi isolatedfrom hypersaline waters of salterns as their natural ecological niche,have been previously defined as halophilic and ... halotolerant microorganisms, respectively. In the present study we assessed their growth and determined the intracellular cation concentrations of salt-adapted and non-salt-adapted cells of both species at a wide range of salinities (0 to 25%NaCI and 0 to 20% NaCI, respectively). Although 5% NaCI improved the growthof H. werneckii, even the minimal addition of NaCI to the growth medium slowed down the growth rate of A. pullulans, confirming their halophilic and halotolerant nature. Salt-adapted cells of H. werneckii and A. pullulans kept very low amounts of internal Na+ even when grown at high NaCI concentrations and can be thus considered Na+ excluders, suggesting the existence of efficient mechanisms for the regulation of ion fluxes. Based on our results, we can conclude that these organisms do not use K+ or Na+ for osmoregulation. Comparison of cation fluctuations after a hyperosmotic shock, to which nonadapted cells of both species were exposed, demonstrated better ionic homeostasis regulation of H. werneckii compared to A. pullulans. We observed small fluctuations of cation concentrations after a hyperosmotic shock in nonadapted A. pullulans similar tu those in salt-adapted H. werneckii, which additionsilly confirmed better regulation of ionic homeostasis in the latter. These features can be expected from organisms adapted to survival within a wide range of salinities and to occasional exposure to extremely high NaCI concentrations, both characteristic for their natural environment.
    Vir: Applied and environmental microbiology. - ISSN 0099-2240 (Letn. 71, št. 11, 2005, str. 6600-6605)
    Vrsta gradiva - članek, sestavni del
    Leto - 2005
    Jezik - angleški
    COBISS.SI-ID - 20005849

vir: Applied and environmental microbiology. - ISSN 0099-2240 (Letn. 71, št. 11, 2005, str. 6600-6605)

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