Effect of Cu~(2+) on Fermentation Characteristics of Saccharomyces cerevisiae

The aim of this study was to understand the effect of Cu2+ on the growth and fermentation characteristics of Saccharomyces cerevisiae. An industrial S. cerevisiae strain Freddo(F) and a new S. cerevisiae strain BH8(B) isolated in our lab were used, and a simulated grape juice fermentation system was conducted. The results showed that Cu2+ inhibited the early growth of S. cerevisiae, and the extent and time of alcoholic fermentation positively correlated with Cu2+ concentration. When fermentation with 0.2 m M Cu2+, the process terminated earlier. The Residual glucose and fructose concentrations in the control(with no Cu2+)for strain B were 2.51 g/L and 10.80 g/L, respectively. On the other hand, at 0.1 m M Cu2+, these values were 0.43 g/L and 3.43 g/L, respectively, for Cu2+-treated strain B. This indicated that 0.1 m M Cu2+promoted sugar utilization in late fermentation by strain B. There was no significant difference in residual sugar concentration between control and Cu2+-treated groups for strain F. The ethanol yield of 0.1 m M Cu2+-treated strain B was 10.80%, which was significantly higher than that of the control(10.27%) and 0.05 m M Cu2+-treated(10.37%) strain B groups. The glycerol yield of 0.05 m M Cu2+-treated strain B was 6.66 g/L, which was significantly higher than that of the control(6.37 g/L) and 0.1 m M Cu2+-treated(6.29 g/L) strain B groups. In comparison, Cu2+-treated strain F and control groups showed no significant difference in ethanol and glycerol yield. Therefore, the adaptability of different yeast strains to Cu2+ stress was different.