More glycogen and trehalose is formed in aerobically incubated baker's yeast than under anaerobic conditions, glucose being a more favourable source of sugar than maltose. The regulation of the formation of glycogen in aerobic incubations of non-proliferating baker's yeast in the presence of glucose can be explained by the action of the activators and inactivators (Rothman & Cabib, 1967). The level of ATP in the cell does not affect the formation of trehalose in the same way as it influences the formation of glycogen.
The incubation temperature chosen can be used to manipulate the relative proportions of glycogen and trehalose in baker's yeast. 30°C is the optimum for the formation of glycogen, and at 45°C none at all is formed. The inhibition of the biosynthesis of glycogen is not, at least primarily, a consequence of the effect of the elevated temperature on the enzymes taking part in the formation of glycogen. The optimum temperature for the formation of trehalose is 45°C, and at this temperature baker's yeast containing as much as 20% trehalose can be obtained.