Physiological basis for the high salt tolerance of Debaryomyces hansenii

• Published in: Applied and Environmental Microbiology Vol. 63; no. 10; pp. 4005 - 4009
• Main Authors: Prista, C, Almagro, A, Loureiro-Dias, M.C, Ramos, J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01-10-1997
• Subjects: Biological and medical sciences; Cations, Monovalent - pharmacology; Chemical reactions; DEBARYOMYCES; Debaryomyces hansenii; Fundamental and applied biological sciences. Psychology; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; ION; ION TRANSPORT; Ion Transport - drug effects; IONES; IONS; Kinetics; LITHIUM; Lithium Chloride - pharmacology; LITIO; Microbiology; Mycology; Osmotic Pressure; Physical growth; POTASIO; POTASSIUM; Potassium Chloride - pharmacology; Rubidium - pharmacokinetics; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - physiology; Saccharomycetales - drug effects; Saccharomycetales - growth & development; Saccharomycetales - physiology; Salt; SALT TOLERANCE; Salts - pharmacology; SODIO; SODIUM; Sodium Chloride - pharmacology; Species Specificity; TOLERANCE AU SEL; TOLERANCIA A LA SAL; Yeast; Culture medium; Microorganism growth; Yeast; Tolerance; Ion transport; Biomass; Fungi; Debaryomyces hansenii; Biological fixation; Salt effect; Medium effect; Microorganism culture; Ascomycetes; Cations; Saccharomyces cerevisiae; Comparative study; Thallophyta
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.63.10.4005-4009.1997

The effects of KCl, NaCl, and LiCl on the growth of Debaryomyces hansenii, usually considered a halotolerant yeast, and Saccharomyces cerevisiae were compared. KCl and NaCl had similar effects on D. hansenii, indicating that NaCl created only osmotic stress, while LiCl had a specific inhibitory effect, although relatively weaker than in S. cerevisiae. In media with low K+, Na+ was able to substitute for K+, restoring the specific growth rate and the final biomass of the culture. The intracellular concentration of Na+ reached values up to 800 mM, suggesting that metabolism is not affected by rather high concentrations of salt. The ability of D. hansenii to extrude Na+ and Li+ was similar to that described for S. cerevisiae, suggesting that this mechanism is not responsible for the increased halotolerance. Also, the kinetic parameters of Rb+ uptake in D. hansenii (Vmax, 4.2 nmol mg [dry weight]-1 min-1; Km, 7.4 mM) indicate that the transport system was not more efficient than in S. cerevisiae. Sodium (50 mM) activated the transport of Rb+ by increasing the affinity for the substrate in D. hansenii, while the effect was opposite in S. cerevisiae. Lithium inhibited Rb+ uptake in D. hansenii. We propose that the metabolism of D. hansenii is less sensitive to intracellular Na+ than is that of S. cerevisiae, that Na+ substitutes for K+ when K+ is scarce, and that the transport of K+ is favored by the presence of Na+. In low K+ environments, D. hansenii behaved as a halophilic yeast