Coupled CO₂ fixation from ethylene oxide off-gas with bio-based succinic acid production by engineered recombinant Escherichia coli

Industrial exhaust gases contributed heavily to anthropogenic CO₂ emissions. In this study, a novel approach of capturing CO₂ from ethylene oxide off-gas and converting it into a platform C4 chemical was established by using succinate-producing E. coli. Fermentation results showed that the acetaldehyde in the off-gas was the main factor inhibiting cell metabolic capability, thus IrrE which is a global regulator from Deinococcus radiodurans was used to improve cell resistance to acetaldehyde. A final succinic acid titer of 68.12 g L⁻¹ with a CO₂ fixation rate of 4.7 mmol L⁻¹ h⁻¹ was achieved. Notably, this coupled process not only realized the CO₂ fixation from ethylene oxide off-gas but also provided a potential cost-effective gas source which holds potential application for bio-based succinate production.