The effect of Tween-20 on simultaneous saccharification and fermentation of softwood to ethanol

Simultaneous saccharification and fermentation (SSF) of steam-pretreated wood constitutes an attractive process configuration for ethanol production from biomass. However, the high enzyme addition in SSF contributes to a high process cost. In this study we explore the effect of the non-ionic surfactant Tween-20 as an additive in SSF. Tween-20 addition at 2.5 g/l had several positive effects on SSF: (i) the ethanol yield was increased by 8%; (ii) the amount of enzyme loading could be reduced by 50%, while maintaining a constant yield; (iii) the enzyme activity increased in the liquid fraction at the end of SSF, probably by preventing unproductive binding of the cellulases to lignin, which could facilitate enzyme recovery; (iv) the time required to attain maximum ethanol concentration was reduced. Surfactants as an additive in SSF can significantly lower the operational cost of the process. However, less expensive surfactants must be investigated.