Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Sucrose from sugar beets is used for commercial ethanol production in Europe and is being considered in the United States. Sugar beet biomass also contains cellulose, hemicellulose and pectin which can be hydrolyzed into monosaccharides and fermented to produce ethanol. Three different enzymes (pectinase, cellulase and cellobiase) were used for hydrolysis and hydrolyzates were fermented with Saccharomyces cerevisiae or Escherichia coli KO11 in a simultaneous saccharification and fermentations (SSF) for ethanol production. This study compared the effectiveness of Saccharomyces cerevisiae and Escherichia coli KO11 using whole sugar beet as a substrate. Variations in buffer concentration, solid loading and inoculum loading were also tested to determine their effects on ethanol yield from whole sugar beets. Maximum ethanol concentrations obtained were 45 g/L and 41 g/L at 12% solids and 5% inoculum loading for E. coli KO11 and S. cerevisiae, respectively. However, the volumetric productivity of fermentation yield was higher when sugar beet was fermented with S. cerevisiae (0.86 g/L/h) than the E. coli (0.21 g/L/h). While solids loading were increased from 12 to 18% and inoculum loading was adjusted to 3%, ethanol concentrations of 74 g/L were achieved by S. cerevisiae which corresponds to 92% of theoretical ethanol yield. S. cerevisiae had higher fermentation yields and rates than E. coli thus making S. cerevisiae the preferred strain in fermentation of whole sugar beet hydrolyzates.