Metabolic Versatility of acetogens in syngas Fermentation: Responding to varying CO availability
João Paulo Carvalho Moreira, Lucı́lia Domingues, J. I. Alves
Abstract
• Varying CO levels in syngas affect H 2 consumption, growth, and acetate production. • Acetobacterium wieringae JM exhibits the highest growth rate, 0.104 h −1 . • Clostridium autoethanogenum co-utilizes CO, H 2 , and CO 2 in all syngas compositions. • Syngas composition influences acetate production stoichiometry. Syngas fermentation using acetogenic bacteria offers a promising route for sustainable chemical production. However, gas–liquid mass transfer limitations and efficient co-utilization of CO and H 2 pose significant challenges. This study investigated the kinetics of syngas conversion to acetate by Acetobacterium wieringae and Clostridium species in batch conditions under varying initial CO partial pressures (19 – 110 kPa). A. wieringae strains, exhibited superior growth in all gas compositions, with a maximum growth rate of 0.104 h −1 . The distinct CO, H 2 , and CO 2 consumption patterns revealed metabolic flexibility and adaptation to varying syngas compositions. Notably, A. wieringae strains and C. autoethanogenum achieved complete CO and H 2 conversion, with C. autoethanogenum also exhibiting net CO 2 uptake. These findings provide valuable insights into the distinct metabolic capabilities of these acetogens and contribute to the development of efficient and sustainable syngas fermentation processes.