Glucose tolerance of Clostridium acetobutylicum fermentation in the anaerobic system

Abstract

Solvent-producing Clostridium acetobutylicum was purified and used in an acetone-butanol-ethanol (ABE) fermentation process. The objective of this study is to design a fermentation medium for the synthesis of butanol and determine the ideal glucose concentration for appropriate microbe ingestion. The fermentation medium was incubated at 37 °C for up to 90 h before inoculation while being sparged with nitrogen gas under anaerobic conditions. Based on the optical density of fermentation media, the growth rate was also monitored. At 60 g/L of glucose, which was the optimum condition for fermentation, the process followed a log phase pattern until the death phase, with the largest growth taking place between 10 h and 50 h after incubation. The C. acetobutylicum steadily consumed the glucose content, reaching its maximal consumption with only around 12 g/L remaining. In contrast to acetone and ethanol, which produced the highest concentrations at 6.4 g/L and 5.2 g/L, respectively, butanol productions were seen appropriately, with the greatest concentration yielding 11.2 g/L of butanol. This shows that C. acetobutylicum expressed its active metabolism for up to 60 g/L and further increase of glucose content will deteriorate the performance of butanol production.