Optimization of culture conditions in CO 2 fixation for succinic acid production using Actinobacillus succinogenes

Abstract

The culture conditions in CO 2 fixation by Actinobacillus succinogenes for succinic acid production were investigated by a model of available CO 2 in a 3-l fermentor. The results from the model analysis showed that the available CO 2 for succinic acid production in the fermentation broth is the sum of HCO 3-, CO 32-, and CO 2 influenced by external culture conditions such as medium components, CO 2 partial pressures, and temperature. The optimized conditions for CO 2 supply in a 3-l fermentor were determined as follows: CO 2 partial pressure and stirring speed were maintained at 0.1 MPa and 200 r min -1, respectively, with a pH of 6.8 and a temperature of 37°C; 0.15 mol l -1 NaHCO 3 was added. Under the optimized conditions, a CO 2 fixation rate of 0.57 g l -1 h -1 was obtained, and a succinic acid concentration of 51.6 g l -1 with a yield of 75.8% was reached. These results suggest that optimized conditions of CO 2 supply are effective in high succinic acid production and thus have potential applications in succinic acid production and CO 2 fixation. © 2011 Society for Industrial Microbiology.