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Applied and Environmental Microbiology, November 2005, p. 6600-6605, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.6600-6605.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

The Halophilic Fungus Hortaea werneckii and the Halotolerant Fungus Aureobasidium pullulans Maintain Low Intracellular Cation Concentrations in Hypersaline Environments

Tina Kogej,1 José Ramos,2* Ana Plemenitas,3 and Nina Gunde-Cimerman1

University of Ljubljana, Biotech Faculty, Department of Biology, Vecna pot 111, SI-1000 Ljubljana, Slovenia,1 Universidad de Córdoba, Laboratorio de Microbiología Agrícola, Departamento de Microbiología, Edificio Severo Ochoa, Campus de Rabanales, E-14071 Córdoba, Spain;,2 University of Ljubljana, Medical Faculty, Institute of Biochemistry, Vrazov trg 2, SI-1000 Ljubljana, Slovenia3

Received 13 May 2005/ Accepted 13 June 2005

Hortaea werneckii and Aureobasidium pullulans, black yeast-like fungi isolated from 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% NaCl and 0 to 20% NaCl, respectively). Although 5% NaCl improved the growth of H. werneckii, even the minimal addition of NaCl 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 NaCl 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 to those in salt-adapted H.werneckii, which additionally 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 NaCl concentrations, both characteristic for their natural environment.

* Corresponding author. Mailing address: Universidad de Córdoba, Departamento de Microbiología, Campus de Rabanales, E-14071 Córdoba, Spain. Phone: 34 957 218521. Fax: 34 957 218563. E-mail: mi1raruj{at}uco.es.

Applied and Environmental Microbiology, November 2005, p. 6600-6605, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.6600-6605.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Benito, B., Garciadeblas, B., Perez-Martin, J., Rodriguez-Navarro, A. (2009). Growth at High pH and Sodium and Potassium Tolerance in Media above the Cytoplasmic pH Depend on ENA ATPases in Ustilago maydis. Eukaryot Cell 8: 821-829 [Abstract] [Full Text]  
  • Plemenitas, A., Vaupotic, T., Lenassi, M., Kogej, T., Gunde-Cimerman, N. (2008). Adaptation of extremely halotolerant black yeast Hortaea werneckii to increased osmolarity: a molecular perspective at a glance.. SIM 61: 67-75 [Abstract] [Full Text]  
  • Kogej, T., Stein, M., Volkmann, M., Gorbushina, A. A., Galinski, E. A., Gunde-Cimerman, N. (2007). Osmotic adaptation of the halophilic fungus Hortaea werneckii: role of osmolytes and melanization. Microbiology 153: 4261-4273 [Abstract] [Full Text]  


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