In yeast strains, the synthesis of trehalose needs a two-step process. Firstly, trehalose-6-phosphate is formed from uridine-diphosphate glucose (UDP-glucose) and glucose-6-phosphate by trehalose-6-phosphate synthase (TPS1). Secondly, this compound is dephosphorylated into trehalose by trehalose-6-phosphate phosphatase (TPS2)[17]. Actually, the accumulation of trehalose in yeasts began at the logarithmic phase, and reached the peck in the stabilization period.