Butanol production from organosolv treated spent mushroom substrate integrated with in situ biodiesel extraction

The aim of this study is to convert spent mushroom substrate (SMS), a by-product from industrial mushroom production, to high production of biobutanol via integration with in situ butanol removal strategy. The modified organosolv pretreatment under mild conditions (35 °C, without acid catalyst) could efficiently improve the sugar yield (9.7% Vs 41.7%) of SMS by reducing lignin content (20.2% Vs 10.5%). The batch fermentation results using the organosolv treated SMS enzymatic broth indicate that adding extractant of biodiesel could enhance butanol production (14.65 g/L) compared to the control batch (12.03 g/L). Moreover, no significant toxicity of biodiesel is observed on the growth of solventogenic Clostridium acetobutylicum. In the fed-batch fermentation system with sugar feeding, the maximum amount of butanol is obtained at 30.21 g/L. This study suggests that in situ butanol removal using biodiesel from SMS enzymatic hydrolysate has great potential for commercial butanol production.