Regulation of the potassium to sodium ratio and of the osmotic potential in relation to salt tolerance in yeasts.
Birgitta Norkrans,A. Kylin +1 more
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The findings fit the working hypothesis tested, which regards salt tolerance as partly dependent on the ability to mobilize energy to extrude Na from the cells and to take up K, and the total salt level of the cells is not sufficient to counteract the osmotic potential of the medium.Abstract:
By using the isotope pairs 22Na-24Na and 42K-86Rb, the uptake and retention of Na and K was studied in the salt-tolerant Debaryomyces hansenii and in the less tolerant Saccharomyces cerevisiae at NaCl levels of 4 mm and 0.68, 1.35, and 2.7 m in the medium. The ratio of K to Na is much higher in the cells than in the media, and higher in D. hansenii than in S. cerevisiae under comparable conditions. The difference between the two species is due to a better Na extrusion and a better uptake of K in D. hansenii. The kinetics of ion transport show that at about the time when extrusion of Na could be demonstrated in D. hansenii, K-Rb previously lost to an easily washable compartment of the cells was reabsorbed in both organisms. More H+ was given off from S. cerevisiae than from D. hansenii in the course of these events. The findings fit the working hypothesis tested, which regards salt tolerance as partly dependent on the ability to mobilize energy to extrude Na from the cells and to take up K. The volume changes in S. cerevisiae are greater and are more slowly overcome than those in D. hansenii. The total salt level of the cells is not sufficient to counteract the osmotic potential of the medium, so that additional osmoregulatory mechanisms must be involved in determining halotolerance.read more
Citations
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Water stress, growth, and osmotic adjustment
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Physiology of osmotolerance in fungi
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TL;DR: Combined genetic and physiological analysis is required for a deeper understanding of fungus-water relations and has revealed sequential induction of osmotically controlled genes in enteric bacteria and given exciting insights in signal transduction and regulation of the process.
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Compatible Solutes and Extreme Water Stress in Eukaryotic Micro-Organisms
TL;DR: The physiological basis of the environmental tolerances of the microorganisms in groups of the xerotolerant yeasts, moulds, and the halophilic algae, which represents some species of the genus Dunaliella is discussed.
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Halotolerant and halophilic fungi.
TL;DR: It is believed that Debaryomyces hansenii, Hortaea werneckii, and Wallemia ichthyophaga have been isolated globally from natural hypersaline environments and are more suitable model organisms to study halotolerance in eukaryotes than S. cerevisiae.
References
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Journal ArticleDOI
Solute concentrations within cells of halophilic and non-halophilic bacteria.
Book ChapterDOI
Biochemical Aspects of Extreme Halophilism
TL;DR: This chapter describes red-colored bacteria living in very salty environment, their growth relations, metabolic apparatus of the extreme halophiles, and cell envelope of the halobacteria.
Journal ArticleDOI
Enzymatic aspects of active linked transport of Na+ and K+ through the cell membrane
Journal ArticleDOI
Studies on marine occurring yeasts: Growth related to pH, NaCl concentration and temperature
TL;DR: The aim of the present work was to ascertain if these yeasts reproduce in alkaline milieu, at high salt concentrations, and at low temperature, three physico-ehemical characteristics of sea water in this northern temperate zone.
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