The performance of four different strains of Pichia stipitis, CBS 6054, FPL-061, FPL-DX26 and FPL-SHI21, engineered for improved ethanol fermentation from C6 and C5 carbon sugars, were evaluated for production of ethanol from a biomass derived glucose/xylose mixture.  Distilled dried grains and solubles (DDGS) were used as a feedstock and pretreated using Ammonia fiber expansion (AFEX).  The monomeric sugars were generated in two ways:  i) use of an enzyme cocktail containing cellulase and hemicellulase, and ii) hydrolysis with cellulase enzyme followed by mild acid treatment.   Both processes generated streams that contained 5-carbon and 6-carbon sugars.  Ethanol production by the described Pichia stipitis strains was monitored and compared to fermentations using clean, synthetic sugars.  The productivity and ethanol yields seen in these fermentations will be discussed in view of using Pichia for the industrial production of ethanol.