The effect of osmotic stress on the biosyntheses of trehalose and glycerol by Candida krusei was quantitatively studied. With the increase of initial osmotic pressure (IOP) between 959 and 2108 mOsm kg(-1). the cell growth and trehalose accumulation were decreased: the extracellular and intracellular glycerol syntheses were enhanced with an increase of IOP from 1320 to 1678 mOsm kg(-1), and leveled off at an even higher IOP (i.e. 2108 mOsm kg(-1)). The cellular response to medium osmotic pressure was also dependent on the physiological state of cells (growth phase). The cells in exponential growth phase survived better than those in stationary and lag phases. For the exponential phase cells, the glycerol concentration doubled and the trehalose content increased 19% compared to the control. In contrast. for the lag phase cells, the trehalose content decreased while the glycerol synthesis was enhanced. The results are considered helpful to the further understanding of the metabolism of the osmophilic yeast under osmotic environments and the work may be useful for quantitative manipulation of the metabolites' production on a large scale. (c) 2005 Elsevier Ltd. All rights reserved.