Publication: Increasing the succinate yield in A. succinogenes by fumigation of H2 in Bioreactor

BioVT is co-author of the publication "Increasing the succinate yield in A. succinogenes by fumigation of H₂ in Bioreactor" in the journal Biofuels, Bioproducts & Biorefining.

The microbial conversion of CO₂ into value-added chemicals offers a promising and scalable route for sustainable bioproduction, particularly when conducted under mild reaction conditions and with technically straightforward reactor setups. Actinobacillus succinogenes, a natural succinate producer, is capable of fixing CO₂ via anaplerotic carboxylation, yet its product yield remains limited by the metabolic availability of reducing equivalents. In this study, we demonstrate that the simultaneous fumigation of molecular hydrogen (H₂) and carbon dioxide (CO₂) enhances succinate production in A. succinogenes. The supplementation of H₂ via the fermentation led to a succinate yield of 0.79 ± 0.07 g·g^-1 glucose, representing a substantial increase compared to control fermentations and ranking among one of the highest yields reported in the literature for A. succinogenes 130Z under non-genetically modified conditions. After 48 h, the succinate titer showed an increase of 29%, which directly correlates with the net CO₂ fixation rate. Furthermore, the gas supplementation influenced the product selectivity, with the succinate share in total fermentation products reaching 72% under H₂ and CO₂ fumigation, in contrast to only 62% when CO₂ was supplied alone. These findings indicate that H₂ serves as an effective external source of reducing power, shifting the redox balance and promoting enhanced C4-dicarboxylate synthesis. This study represents a substantial advancement in the integration of CO₂ utilization and biological hydrogen valorization, providing a novel strategy for coupling microbial fermentation with carbon capture.

J. Tix, G. Zimpel, R. Ulber, N. Tippkötter; Increasing the succinate yield in A. succinogenes by fumigation of H₂ in Bioreactor; Biofuels, Bioproducts & Biorefining (2025) in press