An adaptive, continuous substrate feeding strategy based on evolved gas to improve fed-batch ethanol fermentation

Area of Science:

• Biotechnology
• Biochemical Engineering
• Fermentation Science

Background:

• Optimizing ethanol fermentation is key to enhancing bioethanol production efficiency.
• Fed-batch fermentation strategies are crucial for increasing final ethanol concentration.
• Developing effective substrate feeding strategies remains a challenge in fed-batch processes.

Purpose of the Study:

• To investigate and compare fixed vs. adapted feeding strategies in Saccharomyces cerevisiae fed-batch fermentation.
• To evaluate the impact of an adapted feeding strategy on ethanol productivity, titer, and cell growth.
• To assess the performance of the adapted feeding strategy under varying nitrogen availability.

Main Methods:

• Fed-batch fermentation of Saccharomyces cerevisiae was conducted in a 5-L bioreactor.
• An adapted feeding strategy utilized evolved gas production to control sugar feed rate.
• Fixed feeding strategy maintained a constant sugar feed rate for comparison.

Main Results:

• The adapted feeding strategy increased ethanol productivity by 21% over the fixed feeding strategy.
• A final ethanol titer of 91 g/L (11.5% v/v) was achieved with no residual sugar.
• Significant improvements in cell biomass accumulation and growth rate were observed with adapted feeding.

Conclusions:

• The adapted feeding strategy offers a superior method for optimizing substrate delivery in fed-batch ethanol fermentation.
• This strategy enhances ethanol productivity and concentration, benefiting downstream processing in the bioethanol industry.
• Adapted feeding with low-nitrogen content medium reduces costs while maintaining high productivity.