Fermentation profile of the control strain USM21 (top) and the xylose-fermenting strain TMB3400 (down) in batch fermentation of dilute-acid spruce hydrolysate. Strains were grown in defined mineral medium until biomass concentration reached approximately 2.5 g/L. Then hydrolysate was added at approximately time 18 hours (dashed line). CER is represented by the continuous line. Furfural (▲), HMF (●), Glucose (○), Ethanol (△). Data for USM21 is taken from .