Abstract: Xylose solution containing acetate, formate and other fermentation inhibitors was obtained from dilute-acid pretreated poplar sawdust steeped with 1.0% sulfuric acid for 20min at 150℃, from which 66.5% xylan and 7.1% glucosan in poplar were hydrolyzed into soluble xylose and glucose. Some detoxication treatment is necessary for Candida shehatae R to ferment this solution to produce ethanol, but even so it was still deadly for the growth of Pichia stipitis NL23. Over 70.0% acetate and 40.0% formate were removed, while the loss of xylose and glucose was only 5.0%-6.0% simultaneously, when the process of vacuum evaporation followed by lime powder neutralization was used for cleaning the solution as an optimal detoxication technique. After detoxication, C.shehatae R was able to utilize 93.2% sugar and the ethanol yield reached 83.6%. Low-cost inorganic salts could supply the nutriments for growth and fermenting of C.shehatae R in the detoxicated solution (DS). The optimal initial mass concentration of DS for C.shehatae R fermentation to produce ethanol is 30.0g/L sugar because of inhibitors besides acetate and formate. The strain could use 84.7% sugar to produce 8.54g/L ethanol at the yield of 75.3% together with 6.08g/L xylitol after 12h of culture. The glucose-inhibition effect on xylose fermentation was not detected for fermenting DS into ethanol by C.shehatae R.

Key words: fuel ethanol, xylose fermentation, poplar, dilute-acid pretreatment, Candida shehatae