ORIGINAL PAPER J. C. Gonza´lez-Herna´ ndez Æ M. Jime´ nez-Estrada A. Pen˜a Comparative analysis of trehalose production by Debaryomyces hansenii and Saccharomyces cerevisiae under saline stress Received: 20 February 2004 / Accepted: 6 July 2004 / Published online: 25 August 2004 Ó Springer-Verlag 2004 Abstract The comparative analysis of growth, intracel- lular content of Na + and K + , and the production of trehalose in the halophilic Debaryomyces hansenii and Saccharomyces cerevisiae were determined under saline stress. The yeast species were studied based on their ability to grow in the absence or presence of 0.6 or 1.0 M NaCl and KCl. D. hansenii strains grew better and accumulated more Na + than S. cerevisiae under saline stress (0.6 and 1.0 M of NaCl), compared to S. cerevisiae strains under similar conditions. By two methods, we found that D. hansenii showed a higher production of trehalose, compared to S. cerevisiae; S. cerevisiae active dry yeast contained more trehalose than a regular com- mercial strain (S. cerevisiae La Azteca) under all condi- tions, except when the cells were grown in the presence of 1.0 M NaCl. In our experiments, it was found that D. hansenii accumulates more glycerol than trehalose under saline stress (2.0 and 3.0 M salts). However, under moderate NaCl stress, the cells accumulated more tre- halose than glycerol. We suggest that the elevated pro- duction of trehalose in D. hansenii plays a role as reserve carbohydrate, as reported for other microorganisms. Keywords Debaryomyces hansenii Æ Glycerol Æ Halophile Æ Saccharomyces cerevisiae Æ Saline stress Æ Trehalose Introduction It has been previously shown that the halophile yeast Debaryomyces hansenii accumulates high levels of intracellular Na + and K + when grown at high salinity (Norkrans and Kylin 1969), and that glycerol accumu- lates intracellularly proportionally to increasing extra- cellular NaCl concentrations (Gustafsson and Norkrans 1976). It was also reported that in D. hansenii, the intracellular levels of polyols are markedly enhanced by high salinity, the dominant solutes being glycerol in log phase cells and arabinitol in stationary phase cells (Adler and Gustafsson 1980). Two different fundamental adaptation strategies exist, allowing certain microorganisms to bear osmotic stress due to the presence of a high concentration of salt, as described by Gonza´lez-Herna´ndez and Pen˜a (2002): (1) the cells maintain high intracellular concentrations of salt, osmotic or at least equivalent to the external con- centration of salt (salt-in strategy), and intracellular systems must adapt to the presence of high concentra- tions of salt; and (2) the cells maintain lower concen- trations of salts in their cytoplasm (compatible-solute strategy). The osmotic pressure of the medium is bal- anced by compatible solutes, and no special adaptation of the intracellular systems is required (Bayley and Morton 1978). Under osmotic stress, microorganisms must be able to restore their volume and turgor pressure by increasing the internal osmolarity, and many microorganisms re- spond to such environmental change by accumulating low-molecular-weight organic solutes (LeRudulier et al. 1984; Higgins et al. 1987). The transfer of growing cells of the salt-tolerant yeast D. hansenii to media of higher salinity resulted in an increased production and intra- cellular accumulation of glycerol, proportional to the magnitude of the salinity shift (Andre´ et al. 1988). Jovall et al. (1990) reported the accumulation of or- ganic solutes in D. hansenii after transfer to media of increased salinity. Cells were incubated with labeled Communicated by W.D. Grant J. C. Gonza´lez-Herna´ndez (&) Æ A. Pen˜a Departamento de Gene´tica y Biologı´a Molecular, Instituto de Fisiologı´a celular, Universidad Nacional Auto´noma de Me´xico, Apartado 70-242, 04510 Me´xico D. F., Me´xico E-mail: jcgonza@ifc.unam.mx Tel.: +52-55-56225633 Fax: +52-55-56225630 M. Jime´ nez-Estrada Departamento de Productos Naturales, Instituto de Quı´mica, Universidad Nacional Auto´noma de Me´xico, Me´xico D. F., Me´xico Extremophiles (2005) 9:7–16 DOI 10.1007/s00792-004-0415-2