Efficient carbon dioxide utilization and simultaneous hydrogen enrichment from off-gas of acetone–butanol–ethanol fermentation by succinic acid producing Escherichia coli

The off-gas from acetone–butanol–ethanol (ABE) fermentation was firstly used to be CO₂ source (co-substrate) for succinic acid production. The optimum ratio of H₂/CO₂ indicated higher CO₂ partial pressures with presence of H₂ could enhance C₄ pathway flux and reductive product productivity. Moreover, when an inner recycling bioreactor was used for CO₂ recycling at a high total pressure (0.2 Mpa), a maximum succinic acid concentration of 65.7 g·L⁻¹ was obtained, and a productivity of 0.76 g·L⁻¹·h⁻¹ and a high yield of 0.86 g·g⁻¹ glucose were achieved. Furthermore, the hydrogen content was simultaneously enriched to 92.7%. These results showed one successful attempt to reuse the off-gas of ABE fermentation which can be an attractive CO₂ source for succinic acid production.