The pretreated corn stover samples were
pre-hydrolyzed in the flasks including 50 mMsodium citrate buffer
(pH 4.8) and fermentation nutrients (5.0 g/L yeast extract, 5.0 g/L
peptone, 5.0 g/L KH2PO4, 0.4 g/L MgSO4 and trace element) with a
working volume of 50 mL at a solid loading of 10%. The experiments
were started by adding a commercial enzyme blend Cellic
C-Tec 1 (Novozymes, Denmark) with an activity loading of 30
FPU/g cellulose and pre-hydrolyzed for 24 h at 50 C. After prehydrolysis,
an inoculum of S. cerevisiae was added into the medium
(10%, v/v), and then SSF was run at reduced temperature to 38 C
for another 96 h. The samples were withdrawn periodically to
determine the glucose and ethanol concentration