With growing concern over global warming, interest in renewable alternatives to fossil fuels has surged. Among these, syngas derived from municipal solid waste (MSW) offers a promising solution that addresses both waste management and sustainable energy production. This study explores a gas fermentation process using Eubacterium callanderi KIST612, an anaerobic acetogen, to convert MSW-derived syngas (30% CO, 30% H₂, 30% CO₂, 10% N₂) into value-added organic acids. To enhance gas utilization, a closed-loop gas recirculation system was designed. Gas-specific fermentations revealed that H₂/CO₂ conditions favored organic acid production, while CO promoted higher cell growth. Four cultivation modes were tested, with the best performance observed in a batch culture incorporating 24-hour continuous gas supply followed by recirculation. This mode achieved the highest organic acid yield (0.20 mM-AA+BA/mM-carbon source), with improved CO and H₂ utilization efficiencies of up to 89.6% and 48.8%, respectively. These findings highlight the potential of E. callanderi KIST612 in syngas fermentation and demonstrate a feasible approach for efficient resource recovery from waste. This process contributes to the development of integrated biotechnologies aligned with circular economy and carbon-neutral goals.
