Two-stage continuous CO fermentation process strategy for high-titer bioethanol production using Clostridium...

As global trends favor sustainable and cleaner energy options, the demand for bioethanol, a renewable energy source with lower carbon emissions than fossil fuels, is rising. This study introduces a novel two-stage process for producing high-concentration bioethanol from carbon monoxide using Clostridium autoethanogenum. The two-stage process consisted of 1) Stage I, the growth stage, and 2) Stage II, the production stage. Stage I was designed to cultivate high-density cells through a co-feeding strategy using fructose and carbon monoxide as carbon sources, supplemented by a cell recycling strategy. These cells are transferred to Stage II, optimized for continuous bioethanol production under favorable conditions. This process was successfully operated for over 104.0 days, achieving a peak cell density with an optical density at 600 nm of 49.489 and producing up to 41.176 g/L of bioethanol continuously.