Aqueous two-phase extraction of 2

3-butanediol from fermented broths was investigated by using ethanol/potassium carbonate system. The bioconversion of saccharified hydrolyzate of Dioscorea zingiberensis into 2

3-butanediol was carried out by Klebsiella pneumoniae. The partitioning experiment indicated that the optimal conditions for aqueous two-phase extraction of 2

3-butanediol from the fermentation broth clarified by hollow fiber membrane were 22% (mass) of ethanol and 26% (mass) of potassium carbonate. Under this optimal condition

aqueous two-phase extraction of 2

3-butanediol was carried out directly from the fermentation broth without filtration. The recoveries of 2

3-butanediol and acetoin in the top phase as well as reducing sugar in the bottom phase were 97%

97% and 87%

respectively. The removal rates of cells and proteins were 99% and 94%

respectively. Pyruvic acid

citric acid

malic acid

fumaric acid and butane diacid were partitioned into the bottom phase. Aqueous two-phase system of ethanol/potassium carbonate exhibited a great potential in the industrial separation of 2

3-butanediol.