Kinetic Modeling of ABE Fermentation in Mono- and Co-Cultures of Clostridium Saccharobutylicum DSM 13864 and Clostridium Pasteurianum DSM 525

Abstract

Acetone–butanol–ethanol (ABE) fermentation is the primary method for producing butanol from renewable feedstocks. Butanol is used in several applications, notably as a precursor for acrylates and as an automotive fuel. Clostridium species perform ABE fermentation using a variety of carbon sources. A kinetic model that predicts butanol production dynamics is valuable for assessing industrial feasibility and for gaining insights that can guide future process improvements. This study adjusts kinetic models of butanol production using two carbon sources (glucose or xylose) and two Clostridium species (C. saccharobutylicum DSM 13864 and C. pasteurianum DSM 525). Six fermentations were performed (in triplicate) in synthetic P2 medium at 35°C with an initial sugar concentration of 60 g/L. For each sugar, three conditions were tested: monocultures of each Clostridium strain and a coculture. The predictive models (mass balances and reaction rates) were taken from the literature. Parameter fitting was performed using the library SciPy (function scipy.optimize.least_squares). The coculture results were not statistically different from the C. saccharobutylicum monoculture (Tukey test, p = 0.05), suggesting that C. saccharobutylicum dominates the fermentation and does not show a significant improvement with the coculture under the tested conditions. The adjusted kinetic models presented the best results in modeling the sugar consumption values (R² > 80 %); however, further modification of the equation will be investigated to improve the fit on the butanol concentration.