Outlines for the definition of halotolerance/halophily in yeasts: Candida versatilis (halophila) CBS4019 as the archetype?
Candida versatilis (halophila) CBS4019 was chosen to study the physiological reactions of long-term exposure to extremely high salt concentrations. In general, our results show a significant increase in enzyme expression during growth under stress conditions. Although glycerol and mannitol pathways are not under glucose repression, they were found to be metabolically regulated. Glycerol-3P-dehydrogenase used either of its cofactors NADPH or NADH, being in favor of NADPH during growth with high salt concentrations. This ability of interchanging cofactors, an increased fermentation rate, and the observed mannitol pathway activity are suggested to contribute to the yeasts' redox stability. Enzymes per se were not salt-tolerant in vitro. Consistently, intracellular sodium was low and intracellular potassium, a requirement for growth, was high. The concept of halophily and its applicability to yeasts is discussed.
Silva-Graça
Magda
M
Department of Biology/Environmental Sciences Research Centre (CCA/B), University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
Neves
Luisa
L
Lucas
Cândida
C
D000426:Alcohol Dehydrogenase / Q000378:metabolism; D015139:Blotting, Southern; D002175:Candida / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005285:Fermentation / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology*
D004271:DNA, Fungal; D009243:NAD; D008353:Mannitol; D012965:Sodium Chloride; D009249:NADP; D005993:Glycerolphosphate Dehydrogenase; D000426:Alcohol Dehydrogenase; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D006593:Hexokinase; D005947:Glucose; D005990:Glycerol; D011188:Potassium