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

CO 2 -to-Acetate is one of the innovative approaches for converting CO 2 into organic carbon molecules by use of renewable electricity, either directly or via electrolytically produced H 2 . Identifying efficient microbial biocatalysts is therefore essential for maximizing conversion rates and ensuring the practical feasibility of such a process. This study evaluated seven acetogenic species using lab-scale batch stirred reactors fed with H 2 :CO 2 . The performance of mesophilic and thermophilic acetogens was compared by monitoring pressure, gas composition, fermentation products, and growth throughout sequential batches. Among the strains tested, Acetobacterium wieringae and A. woodii achieved the highest final acetate product concentrations (14 ± 1.5 g L −1 , 12.5 ± 1.7 g L −1 , respectively), while Thermoanaerobacter kivui presented the highest rates of H 2 consumption (17.4 ± 1 mM h −1 ) and acetate production (3.8 ± 0.2 mM h −1 ) without pH control. These findings also provide insights into different species-specific factors that can influence the performance of future industrial applications. • Acetogenic H 2 /CO 2 conversion into acetate was evaluated in 7 different strains. • Acetobacterium showed the highest potential for CO 2 -to-Acetate among mesophiles. • T. kivui showed the highest potential for CO 2 -to-Acetate among thermophiles.