Effects on the Fermentation Property of the Strain in Ethanol Fermentation of Xylose

The fermentation property of the wild yeast 1125-3,which can quickly and effectively ferment xylose to ethanol,was studied.After domestication and cultivation,the utilization ratio of xylose is 92.92%,the ethanol yield rate is 12.88%,the residual sugar concentration dropped from 18.74g/l to 2.80g/l.Effects of culture condition,including temperature,pH value and nitrogen source on fermentation were investigated.The optimum temperature and pH value of the growth were 30℃ and 4.6～5.0,respectively.The optimum temperature and pH value of the xylose fermentation were 37℃ and 4.6～5.0,respectively.The growth and fermentation were good with urea as the nitrogen source.When a mixed sugar with 2.5% glucose and 2.5% xylose was present in the fermentation culture medium,the ethanol yield rate of strain 1125-3 can attain the pure glucose fermentation level.