Production of butanol and isopropanol with an immobilized Clostridium.

Clostridium beijerinckii optinoii is a Clostridium species that produces butanol, isopropanol and small amounts of ethanol. This study compared the performances of batch and continuous immobilized cell fermentations, investigating how media flow rates and nutritional modification affected solvent yields and productivity. In 96-h batch cultures, with 80 % of the 30 g L(-1) glucose consumed in synthetic media, solvent concentration was 9.45 g L(-1) with 66.0 % as butanol. In a continuous fermentation using immobilized C. beijerinckii optinoii cells, also with 80 % of 30 g L(-1) glucose utilization, solvent productivity increased to 1.03 g L(-1) h(-1). Solvent concentration reached 12.14 g L(-1) with 63.0 % as butanol. Adjusting the dilution rate from 0.085 to 0.050 h(-1) to allow extended residence time in column was required when glucose concentration in fresh media was increased from 30 to 50 g L(-1). When acetate was used to improve the buffer capacity in media, the solvent concentration reached 12.70 on 50 g L(-1) glucose. This continuous fermentation using immobilized cells showed technical feasibility for solvent production.