Fixing carbon dioxide in situ during ethanol production by formate dehydrogenase

Abstract

Concerns regarding the increasing carbon dioxide (CO₂) concentration has aroused global interest in renewable fuels and conversion of CO₂ into chemicals. This study provides a sustainable strategy for fixing CO₂in situ during the production of ethanol in a single cell expressing formate dehydrogenase (FDH) without the addition of a cofactor. Glucose was converted to ethanol, with the main by-product CO₂ fixed to formate, increasing the yield of ethanol and glucose fermentation efficiency in the recombinant Saccharomyces cerevisiae-fdh. Higher concentrations of glucose and amount of ScFDH1 yielded more formate, confirming the feasibility of CO₂ fixation. Significantly, the glucose consumption rate and ethanol yield increased by 30% and 13% after the overexpression of ScFDH1, respectively. Finally, the increase in CO₂ concentration with the addition of zeolite imidazole framework-8 (ZIF-8) further demonstrated the CO₂ fixation in situ, increasing the production of formate 2.1 times. Due to ZIF-8, up to 60.67 mg L⁻¹ formate was produced. Our findings establish a green, economical, and sustainable alternative for CO₂ conversion in situ, contributing to the ethanol yield by ScFDH1 without extra energy input and cofactor supply. This synergistic strategy has significance for both the energy and environmental crises.