EXPERIMENTAL APPROACHES TO A RAPID ETHANOL FERMENTATION OF GLUCOSE BY A ZYMOMONAS-MOBILIS STRAIN

Rapid ethanol fermentation is defined as a fermentation in which the ethanol content increases from 0 to 94.8 g 1-1 in 6 horless. To achieve this by the fermentation of glucose with Zymomonas mobilis, the initial biomass concentration must be at least 20 g dry wt 1-1 and that of the substrate must not exceed 150 to 200 g 1-1 during fermentation. The best results were obtained with a medium containing initielly 16% of the total sugar with the remaining glucose being added continuously, after 20 min of incubation, over 5 h at a rate of 0.21 g/min. After 6 h, ethanol reached 102 g 1-1, the volumetric productivity was 17g ethanol 1-1 h-1 and the yield 79.8 or 88% of the theoretical value, calculated according to the total fed or the consumed glucose, respectively. © 1990 Rapid Communications of Oxford Ltd.