Evolutionary progress in chemostat culture supplemented with spruce hydrolysate. (a) Yields of biomass (Y X/S) and ethanol (Y E/S) on consumed sugars (left ordinate) and xylose concentration in the chemostat (right ordinate). Biomass (crosses), ethanol (circles), xylose (triangles). (b) Specific consumption rate of xylose (r xyl) (left ordinate) and xylitol yield (Y XOH/xyl) from consumed xylose (right ordinate). Xylose (closed triangles), xylitol (plus). (c) Specific conversion rates of HMF (r HMF) and furfural (r fur) (left ordinate), line with step wise increase shows the generation points at which the spruce hydrolysate concentration was increased (right ordinate). HMF (squares), furfural (diamonds).