Journal of Biotechnology, 19 (1991) 211-220 0 1991 Elsevier Science Publishers B.V. 0168-1656/91/$03.50 ADONIS 016816569100106R 211 BIOTEC 00622 Osmotic accumulation of y-decalactone by the yeast Sporidiobolussalmonicolor Patrick Gervais and Isabelle PCcot ENSBANA, Luboraloire de Biologic Physico-Chimique, Campus Universiiaire Montmuzard, Dijon, France (Received 31 October 1990; revision accepted 20 December 1990) Summary The accumulation of y-decalactone by the yeast Sporidiobolus salmonicolor was studied when the yeast cells were grown at low water activity. Two methods to estimate the intracellular content were compared: an osmotic shock obtained by dilution and a mechanical grinding of the cells. The grinding method allowed recovery of the effective intracellular metabolites and avoided the dilution of the medium as a result of the osmotic shock. Glycerol, lev-ulose and sorbitol were compared as depressor agents of water activity. The experimental results showed that cells grown at low water activity (0.97) in presence of high concentrations of glycerol (but not levulose and sorbitol) accumulated high amounts of y-decalactone. In presence of levulose and sorbitol, glycerol was found to be synthesized and accumulated by the cells. Water potential; Osmoregulation; Glycerol; y-Decalactone; Sporidiobolus salmoni- color; Yeast Introduction Numerous authors have shown that the osmotic pressure or water activity (a,) of the medium has a great influence on the physiology and metabolism of micro- organisms (Scott, 1953; Zimmermann, 1978; Griffin, 1981; Gould, 1985; Gervais et al., 1988a). In a previous work, Gervais and Battut (1989) reported that variations of Correspondence 10: P. Gervais, ENSBANA, Laboratoire de Biologie Physico-Chimique, Campus Uni- versitaire Montmuzard, 21000 Dijon, France.