The utilisation of assimilable nitrogen and the main by-product or glycerol production from the three VHG media (with and with- out the nutrient supplements) were compared (Table 3). According to nitrogen content, the total nitrogen content of 9 g l−1 of YE and 13.5 g l−1 of DSY was equal. However, the assimilable nitrogen in DSY was only ∼57% of that in YE (Table 3), implying that DSY contained more nonassimilable nitrogen than YE. The nitrogen utilisation in the medium supplemented with YE coupled with the metals was significantly higher than that of other conditions. However, the P and Yp/s values of the two VHG media were not different (Table 2). This again implied that some essential elements containing in YE might promote the rate of ethanol production. In addition, glycerol formation (11.3–12.4 g l−1 ) during fermentation in the three media was similar (Table 3), indicating that the metabolic pathway during the ethanol fermentation under no aeration was unchanged. Many researchers have studied the effects of aeration during ethanol production under VHG conditions. It was found that S. cerevisiae required a certain supply of elemental oxygen to synthesise ergosterol and the unsaturated fatty acids, which are essential for plasma membrane integrity. Lin et al. (2011) reported that a small amount of aeration during the initial stage of yeast growth resulted in increased ethanol production efficiency. Therefore, in this study, the combination effect of nutrient supplementation and aeration on the VHG fermentation was investigated under different aeration rates (0.05, 0.2 and 0.35 vvm) during log phase (12 h)