(138g) Invited Talk: Chemicals Production from CO2 Via Acetate As an Intermediary Metabolite in an Integrated Fermentation Process

The increasing level of CO₂ in the atmosphere is causing global warming issues and extreme climate changes. But the fuel demand is still increasing, and most fermentation process still generates CO₂ as a major byproduct. Therefore, scientists are looking for ways to reduce the CO₂ emission. One way is storing CO₂ in some form (carbon sequestration), and the other way is converting CO₂ to some other useful chemicals. For example, extensive research has been done to convert CO₂ to formate either catalytically or electrochemically. But further converting formate to other chemicals is still challenging. Here, we used an integrated fermentation process to convert CO₂ to acetate, which is an intermediary metabolite that can be uptaken by a variety of microorganisms for different chemical production. C. formicoaceticum is an anaerobic bacterium that can efficiently convert formate into acetate. We used C. formicoaceticum coupling with a catalytic reaction to convert CO₂ to acetate. A high acetate yield (>0.9 g/g) can be obtained if co-feeding C. formicoaceticum with formate and lactate. A co-culture system of C. formicoaceticum and L. lactis was also developed to convert lignocellulosic biomass-derived sugars and CO₂-derived formate simultaneously to acetate with a high yield (>0.9 g/g). The obtained acetate was also demonstrated that can be used for further chemical production using two examples: n-butanol by C. tyrobutyricum and polyhydroxyalkanoates (PHA) by P. putida.