Enhanced n-butanol production by Clostridium beijerinckii MCMB 581 in presence of selected surfactant.

Extractive butanol fermentation with non-ionic surfactant, a recently explored area, has shown promising results with several advantages but is relatively less investigated. This work reports the extractive fermentation with selected non-ionic surfactants (L62 and L62D) to enhance butanol production using a high-butanol producing strain (Clostridium beijerinckii MCMB 581). Biocompatibility studies with both the surfactants showed growth. Higher concentrations of surfactant (>5%) affected the cell count. 15.3 g L ^-1 of butanol and 21 g L ^-1 of total solvents were obtained with 3% (v/v) L62 which was respectively, 43% (w/w) and 55% (w/w), higher than control. It was found that surfactant addition at 9th h doubled the productivity (from 0.13 to 0.31 g L ^-1  h ^-1 and 0.17 to 0.39 g L ^-1  h ^-1 , respectively for butanol and total solvent). Butanol productivity obtained was 2-3 times higher than similar studies on extractive fermentation with non-ionic surfactants. Interestingly, mixing did not improve butanol production.