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

This study investigated the effects of pH and liquid dilution rate (DL) 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 DL 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 DL significantly influenced the fermentation performance, with pH affecting the balance between acidogenesis and solventogenesis. This study highlights the potential of optimized pH and DL control to improve industrial-scale fermentation processes, offering a predictive tool for optimizing industrial-scale fermentation processes.