Kinetic modeling of lactic acid and acetic acid effects on butanol fermentation by Clostridium saccharoperbutylacetonicum

Kinetic models of acetone-butanol-ethanol fermentation with lactic acid or acetic acid addition were developed and implemented in COPASI for metabolic analysis of acid effects on butanol synthesis. The simulation results were compared with experimental data in batch cultures of Clostridium saccharoperbutylacetonicum under various initial lactic acid or acetic acid concentrations. High average correlation coefficients (r(2)) of over 0.92 between simulation and experimental results were obtained in both models. According to parameter scan in both models, reducing glucose uptake rate, increasing the conversion rate from glyceraldehyde 3-phosphate (G3P) to pyruvate or from butyryl-CoA (BCoA) to butanol would enhance butanol production. On the other hand, increasing consumption rate of supplemented lactic acid or acetic acid could also contribute to improved butanol synthesis. Overall, the developed kinetic models can accurately predict the dynamic behavior of metabolites in ABE fermentation with lactic acid or acetic acid addition and consequently identify genetic manipulation strategies for higher bio-butanol production in the future.