Optimization of culture conditions in CO2 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(3) (2-), 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.

The effect of carbon dioxide availability on succinic acid production with biofilms of Actinobacillus succinogenes

“…) in the liquid medium. Carbonate salts that are insoluble in water, such as MgCO 3 and CaCO 3 , are often used as a source of CO 2 in fermentation media [8,10,11]. For these cases, the dissolution rate of the solid will be the rate determining step since the carbonate-bicarbonate-CO 2 equilibrium is rapidly established.…”

“…Under typical fermentation conditions (pH = 6.8, T = 37 °C and CO 2 atmosphere at 1 bar) the dissolved carbonate concentration is low, while bicarbonate and dissolved CO 2 are present at approximately equal concentrations. The highest possible value is determined by the CO 2 partial pressure in the gas phase and is in the vicinity of 20 mM for pure CO 2 at atmospheric pressure [10][11][12].…”

“…It has been shown that the supply of CO 2 influences SA productivity and catabolite distribution in A. succinogenes fermentations [8,10,11]. All these studies were performed in batch fermentations where the initial carbonate/bicarbonate concentrations and CO 2 partial pressures were varied.…”

“…is en y's const nt (kPa.L.mol -1 ) for CO 2 in a pure solvent. However, since the fermentation medium contains various salts and organic substances, the solubility of CO 2 will be ffected nd the efo e en y's const nt needs to be adjusted accordingly [10][11][12].…”

Fermentative Succinate Production: An Emerging Technology to Replace the Traditional Petrochemical Processes

“…As one mole of CO 2 is theoretically required for the synthesis of one mole of succinate, optimization of CO 2 partial pressures would contribute to succinate production. Under the optimized conditions, a succinate concentration of 51.6 g/L with a yield of 75.8% was reached for the producer A. succinogenes [60]. The culture temperature should be optimized according to the strain employed.…”