The supernatants were stored at -20 C for reducing sugars and fermentation metabolites analysis, and the biomass was washed twice to measure the biomass concentration by dry weight. Reducing
sugars were assayed by the 3,5-dinitrosalicylic acid (DNS)method (Bernfeld, 1951) with glucose as standard, and ethanol and glycerol were measured by a high-performance liquid chromatograph
equipped with a RI-150 Spectra System refractive index detector (Thermo Separation Products) and a column model ION-300 (Transgenomic, San Jose, CA) eluted with 0.0085 M H2SO4 at 35 C and a flow rate of 0.4 mL/min during 40 min. On the other hand, a 30 mL