Continuous butanol and iso-propanol fermentation using immobilized Clostridium beijerinckii optonii

Clostridium beijerinckii optonii predominately produces butanol and iso-propanol from sugars. In this study, two consecutive 300 mL packed columns were constructed filled with porous ceramic Raschig rings immobilized with Clostridium beijerinckii optonii. Continuous fermentation was performed at a dilution rate of 0.09 h^-1 at 36 ˚C using a fermentation media containing 30 g L^-1 or 50 g L^-1 glucose. Fermentation broths were collected for sugar and solvent analyses at three different points: effluent from the 1^st column, effluent from the 2^nd column, and final collection. With a feed of 30 g L^-1 glucose, butanol fermentation predominately took place in the 1^st column with more than 85% glucose consumption. Effluent from the 1^st column contained 7.65 g L^-1 butanol and 4.49 g L^-1 iso-propanol. Butanol concentration was lower at the other two collection points. However, when feed contained 50 g L^-1 glucose, a butanol concentration of 2.60 g L^-1 was observed at the output of the second column with 60% glucose still remaining. Moreover, there was also a significant amount of butyric acid accumulating, 6.0 – 8.3 g L^-1, which competes with butanol as the end product in Clostridium fermentation. Work will continue to determine the carbon consumption and butanol production patterns of immobilized Clostridium beijerinckii optonii in a continuous fermentation system.