Controlling fermentation of lignocellulose hydrolysates in a continuous hollow-fiber reactor using biosensors

Fermentation of lignocellulose hydrolysates as spent sulfite liquor or as hydrolysate from sulfur-dioxide-treated wood to ethanol has been controlled by using biosensors for glucose and ethanol. Yield and productivity were studied with respect to concentration level of the metabolites in a continuous hollow-fiber reactor. High constant yield was achieved by controlling the glucose to low concentration levels. Reduced productivity were obtained when fermenting at high ethanol concentrations as an effect of inhibition of the yeast cells. The observations emphasize the advantage of controlling the process to favorable concentrations of monosaccharides and ethanol.