CONTROLLED-PH BATCH BUTANOL-ACETONE FERMENTATION BY LOW ACID PRODUCING CLOSTRIDIUM-ACETOBUTYLICUM B18

C. acetobutylicum B18 produced a large amount of butanol over a wide range of pH (4.5-6.0). At pH 6.0 fermentation and cell growth were most active at pH 6.0, and the highest values of glucose consumption rate (4.37 g/L-h), butanol productivity (1.0 g/L-h), butyric acid recycle rate (0.31 g/L-h), and cell growth rate (0.2 h-1) were obtained. There existed a critical pH between 6.0 and 6.5 above which cells switched to organic acid producing mode. Clostridial stage appeared essential for solvent production by strain B18 but sporulation was not necessary for solvent formation.