SIMULTANEOUS SACCHARIFICATION AND EXTRACTIVE FERMENTATION OF CELLULOSIC SUBSTRATES

Alcohol fermentation has traditionally been carried out in aqueous env ironments because of the ready solubility of reactant (sugar) and prod uct (ethanol). However, extraction of the product ethanol into a nonmi scible phase can result in kinetic benefits due to reduced inhibition of the fermentation reactions. In this study, we report the developmen t of a novel simultaneous saccharification and extractive fermentation (SSEF) process. Ethanol productivity was increased by up to 65% over conventional (nonextractive) fed-batch simultaneous saccharification s ystems when calculated on the basis of aqueous phase volume. The amoun t of water required for SSEF reactions was dramatically reduced from t hat required for conventional SSF. In batch SSEF reactors with 2.5% aq ueous phase, 50% conversion of 25% (aqueous phase concentration) Solka Flee could be achieved in 48 h using 2 FPU/g cellulase. (C) 1996 John Wiley & Sons, Inc.