Performance of mesophilic and thermophilic acetogenic strains for CO2 -to-acetate production

CO2-to-Acetate is one of the innovative approaches for converting CO2 into organic carbon molecules by use ofrenewable electricity, either directly or via electrolytically produced H2. Identifying efficient microbial bio-catalysts is therefore essential for maximizing conversion rates and ensuring the practical feasibility of such aprocess. This study evaluated seven acetogenic species using lab-scale batch stirred reactors fed with H2:CO2. Theperformance of mesophilic and thermophilic acetogens was compared by monitoring pressure, gas composition,fermentation products, and growth throughout sequential batches. Among the strains tested, Acetobacteriumwieringae and A. woodii achieved the highest final acetate product concentrations (14 ± 1.5 g L 1, 12.5 ± 1.7 gL 1, respectively), while Thermoanaerobacter kivui presented the highest rates of H2 consumption (17.4 ± 1 mMh 1) and acetate production (3.8 ± 0.2 mM h 1) without pH control. These findings also provide insights intodifferent species-specific factors that can influence the performance of future industrial applications.