Ethanol concentration was determined by high performance liquid chromatography using a Shim-pack SPR-Pb column. The operating conditions were 80 ◦C with a water mobile phase and flow rate of 0.6 mL/min. The ethanol concentration was determined using a refractive index detector. Culture supernatant was separated from the fermentation broth by centrifugation at 14,000 × g for 10 min and then analyzed by HPLC. The activities of the glucoamylase and -amylase in the fermentation
broth were assayed as described previously using kits , respectively.