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The depletion of petroleum-based fuels and environmental problems has stimulated a development of inexpensive biofuels production. The lignocellulosic materials have been focused as the economically attractive substrate for the production of biofuels. Lignocellulose is abundant and renewable resources with great potential as substrates for biofuel fermentation. Hardwood hemicelluloses contain mostly xylan that 60-70% of its residues are acetylated, which leads to the formation of acetic acid by peeling off during the hydrolysis process. The acetic acid in lignocellulose hydrolysate inhibits seriously the cell growth and ethanol production by microorganisms. In this study, alkaline-pretreatment method was introduced for the extraction of acetic acid from xylan of hemicellulose, prior to concentrated acid hydrolysis of yellow poplar wood meal. Ethanol fermentability in deacetylated yellow poplar hydrolysate (DYPH) by Pichia stipitis was also investigated. The alkali-pretreatment conditions were elucidated in terms of temperature, reaction time, and alkalinity. The 94% of acetyl group in xylan of yellow poplar hemicellulose fraction was extracted by 0.5% sodium hydroxide solution at 60 ℃ during 60 min. P. stipitis was affected seriously on cell growth and ethanol production in the synthetic medium added 7.1 g/l of acetic acid or yellow poplar hydrolysate (YPH) containing 7.1 g/l of acetic acid. On the other hand, ethanol production in DYPH was slightly higher than that of the control although cell growth decreased by 34%. The alkaline-pretreatment method greatly enhanced the
ethanol fermentability of yellow poplar hydrolysate.