Cell Mass. A spectrophotometer (Coleman model 55, Perkin-Elmer, Maywood, IL) was used to measure the absorbance of the samples at a wavelength of 600 nm that is in the visible region. Samples were diluted as required to assure absorbences of less than 0.5. In this region the calibration curve was linear with a slope of 0.65 g dry weight per unit absorbance.

HPLC. Hitachi HPLC (Hitachi Ltd., Tokyo, Japan) with RI detector was used to analyze the concentrations of glucose, xylose, xylitol, ethanol and glycerol. A BioRad HPX-87H Ion-Exclusion column was used. The mobile phase was 0.005M H2S04 at a flow rate of 0.4 mL/min.

Glucose Analyzer. YSI 2700 Select Biochemistry Analyzer (YSI Inc., Yellow Springs, OH) equipped with glucose membrane was used for rapid analysis of glucose concentration in the fermentation media.