Actinobacillus succinogenes in Bioelectrochemical Systems: Influence of Electric Potentials and Carbon Fabric...

The fermentation of Actinobacillus succinogenes in bioelectrochemical systems offers a promising approach to enhance biotechnological succinate production by shifting the redox balance towards succinate and simultaneously enabling CO₂ utilization. Key process parameters include the applied electric potential, electrode material, and reactor design. This study investigates the influence of various carbon fabric electrodes and applied potentials on product distribution during fermentation of A. succinogenes. Building on prior findings that potentials between -600 mV and -800 mV increase succinate production, recent data reveal that more negative potentials, beyond the water electrolysis threshold, trigger electrochemical side reactions, altering product yields. Specifically, succinate decreased from 19.76 ± 0.41 g∙L^-1 to 14.1 ± 1.6 g∙L^-1, while lactate rose from 0.59 ± 0.12 g∙L^-1 to 3.12 ± 0.21 g∙L^-1. Contrary to common assumptions, the shift is not primarily driven by oxygen formation. Instead, the results indicate that the intracellular redox potential is affected by both the applied potential and hydrogen evolution, which alters metabolic pathways to maintain redox balance. These findings demonstrate that more negative applied potentials in electro-fermentation processes can impair succinate yields, emphasizing the importance of fine-tuning electrochemical conditions in the system for optimized biotechnological succinate production.