SimBiology of Metabolic Pathway of Biobutanol Production by Clostridium acetobutylicum

Butanol is a fuel blended more readily with gasoline and hydrocarbon products and contains higher heat value in comparison with ethanol. Clostridium acetobutylicum is able to produce considerable amount of butanol. Acetone and ethanol are other products of this strain. Simple models describing the production of these metabolites like Monod model are restricted to prognosticate intracellular processes. The mathematical expression of intracellular metabolites production is applied to optimize the production of the desired compound, especially, in metabolic engineering. In this study, the structured model of the metabolic pathway of Clostridium acetobutylicum was utilized to describe and to predict the dynamical variations of intracellular and extracellular metabolites. Mathematical equations were solved by SimBiology and results were compared with experimental data published in literature, which revealed an appropriate conformity. The effect of butyrate and acetate on the butanol production was investigated and results demonstrated the butanol production enhancement in the presence of these substances in the culture media. The butyrate presence in the media led to both increase of butanol concentration and decrease of time required to attain the maximum butanol production. The butanol concentration were 120.48 and 138.35 mM when the initial concentrations of acetate and butyrate were 100 and 0 mM, and 0 and 100 mM respectively .Due to the irreversible production reaction of acetone in the metabolic pathway, butanol production was not influenced by the acetone concentration, but its elimination from the cell pathway increased the butanol production.