Abstract
The amount of bound water in yeast cells is estimated by TG (thermogravimetry) -DTA (differential thermal analysis) measurements. It is shown that when the trehalose content is beyond 2-3% (w/w), the amount of bound water is drastically decreased and simultaneously the viability of dried cells is increased. This suggests that the major part of bound water is replaced by trehalose. In addition, by the measurement of NMR spin-lattice relaxation time (T_1) for the intracellular water protons, it is shown that extra trehalose (> 3-4%) acts as a water structuring agent in yeast cells. In conclusion, such a dual role is essential in endowing yeast cells with high water-stress resistance.
