Fixation of CO2 from ethanol fermentation for succinic acid production in a dual-chamber bioreactor system

Abstract

Harnessing the ability of microorganisms to fix, convert and utilize CO2 for chemical production has important implications for global carbon reduction. In this study, carbonic anhydrase (CA) and/or phosphoenolpyruvate carboxykinase (PEPCK) were overexpressed in Corynebacterium acetoacidophilum. A process was established to capture CO2 and convert it into succinic acid (SA) from the off-gas produced by Saccharomyces cerevisiae fermenting ethanol (EtOH), using the engineered strain of C. acetoacidophilum. By constructing a coupling device and optimizing the ratio of working medium volumes in the two-chamber bioreactor, the maximum yields of EtOH and SA from glucose were 0.51 g/g and 0.70 g/g, respectively. A scale-up trial was performed in a 3-L fermenter and calculation of the environmental factors demonstrated that the linked-fermentation strategy was more environmentally-friendly than conventional SA fermentation, indicating potential for industrial application.