The enhancement of butanol production by in situ butanol removal using biodiesel extraction in the fermentation of ABE (acetone–butanol–ethanol)

High butanol accumulation is due to feedback inhibition which leads to the low butanol productivity observed in acetone–butanol–ethanol (ABE) fermentation. The aim of this study is to use biodiesel as an extractant for the in situ removal of butanol from the broth. The results indicate that adding biodiesel as an extractant at the beginning of fermentation significantly enhances butanol production. No significant toxicity of biodiesel on the growth of Clostridium acetobutylicum is observed. In the fed-batch operation with glucose feeding, the maximum total butanol obtained is 31.44 g/L, as compared to the control batch (without the addition of biodiesel) at 9.85 g/L. Moreover, the productivity obtained is 0.295 g/L h in the fed-batch, which is higher than that of 0.185 g/L h for the control batch. The in situ butanol removal by the addition of biodiesel has great potential for commercial ABE production.

► Adding biodiesel as an extractant for butanol removal is an attractive idea to relieve butanol toxicity. ► Butanol dissolved in biodiesel could act as an additive to enhance energy content. ► No significant toxicity of biodiesel on cell growth was observed. ► Adding biodiesel could greatly enhance butanol productivity.