Two-stage in situ gas stripping for enhanced butanol fermentation and energy-saving product recovery

► High-titer n-butanol was produced by C. acetobutylicum in a fibrous bed bioreactor. ► In situ gas stripping for butanol separation alleviated butanol toxicity in the fermentation. ► Two-stage gas stripping produced butanol at a high titer of >400 g/L (500 g/L ABE). ► This process can produce n-butanol with greatly reduced energy consumption.