4.1 Firstly , Saccharomyces cerevisiae yeast and 40 mL of 2% glucose solution were added to a 100-mL glass flask and placed in a 38 C water bath for 15– 20 min, and then moved to a 33 C water bath for 1.5 h to preculture preparation of the yeast.
4.2 Secondly,the ethanol fermentation solutions were prepared from enzymatic hydrolyzates solutions supplementing with the nutrients peptone (5.0 g/L), KH2PO4 (2.0 g/L), MgSO4 (1.0 g/L), and CaCl2 (0.25 g/L). After the pH of the fermentation solutions weresterilized in an autoclave at 121 C for 20 min.