Effect of slow feeding of xylose on ethanol yield byPachysolen tannophilus

Summary

With slow feeding of xylose to a batch fermentation byPachysolen tannophilus, the yield of ethanol from xylose was improved to 0.41 g/g (80% of theoretical) with a maximum ethanol concentration of 26.5 g/L at 120 h. This is a 41% improvement on the ethanol yield observed for batch fermentations without slow feeding. The optimum level of xylose in the medium was determined to be between 5 and 8g/L; xylose at greater than 10 g/L leads to xylitol accumulation, whereas xylose below 3 g/L permits ethanol to be oxidized to acetate. This latter effect is exacerbated by increased aeration.