Gas vector and surface tension reducer to enhance biofuel production through syngas fermentation with <i>Clostridium carboxidivorans</i>

Abstract Background Syngas fermentation using acetogenic bacteria as biocatalysts has emerged as an alternative for a carbon‐neutral economy. One of the major challenges in syngas fermentation is gas–liquid mass transfer. In this work, the surfactant Tween®80 (0.15%) and perfluorodecalin (PFC, 20% v/v) – a gas vector—were added to the fermentation medium with Clostridium carboxidivorans to increase acetic acid, ethanol, and butanol production through gas–liquid mass transfer improvement. The production of biofuels and biochemicals was evaluated in heterotrophic (non‐syngas) and mixotrophic (with syngas) fermentations. Results Although higher biomass was achieved in heterotrophy, mixotrophic fermentation resulted in 27% higher ethanol production, and in presence of butanol, which was not detected in the first condition. Acetic acid concentration was not affected. Gaseous fermentation in serum flasks with Tween®80 and PFC increased the production of butanol and acetic acid by 1.3‐fold compared with syngas fermentation without these compounds. Ethanol production was similar in both conditions. In the bioreactor, the productivity of the total metabolites was 3.3‐fold higher with Tween®80 and PFC. Conclusions The combination of Tween® 80 and PFC enhances metabolite production even without syngas and improves gas–liquid mass transfer during syngas fermentation, offering a promising solution to overcome mass transfer challenges in this process. © 2025 Society of Chemical Industry (SCI).