Strain Improvement of Pachysolen tannophilus by Co60 Mutagenesis for Xylose Alcoholic Fermentation

Xylose-fermenting yeast Pachysolen tannophilus was mutated by Co60 rays. The mutant 800-3,which shows superior xylose utilizing and ethanol producing efficiency was isolated after selection. The effects of fermentation conditions on ethanol production were investigated. It is shown that the dissolved oxygen level and culture medium components exhibit significant effects on the ethanol yield. Under the conditions of shaking rate 100 r/min, medium volume 20/100 mL and YE concentration 1 g/L, the concentration of ethanol is 5.86 g/L, while that of xylitol is 12.95 g/L. Comparing with the former studies, the ethanol yield is much lower.