Kinetic modelling and metabolic shifts in Clostridium carboxidivorans during CO-driven continuous fermentation

This study investigated the effects of pH and liquid dilution rate (D_L) on the growth and metabolite production of Clostridium carboxidivorans during CO fermentation in a continuous stirred-tank reactor (CSTR). Experiments were conducted at pH values between 5.0 and 6.0 and D_L ranging from 0.034 to 0.25 h⁻¹ under differential CO conditions. Additional tests were conducted to evaluate the impact of acetic acid and ethanol supplementation on the fermentation performance. Steady-state data were analyzed using a Ierusalimsky-based model, which incorporates metabolite inhibition effects. The model accurately captured the specific growth kinetics of C. carboxidivorans, with an average deviation below 20 %. The results showed that pH and D_L significantly influenced the fermentation performance, with pH affecting the balance between acidogenesis and solventogenesis. This study highlights the potential of optimized pH and D_L control to improve industrial-scale fermentation processes, offering a predictive tool for optimizing industrial-scale fermentation processes.