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NADH fluorscence in a carbon-limited fermentation
1Centre for Bioprocess Engineering, Department of Chemical Engineering, McGill University, 3480 University Street, Montreal, Canada H3A 2A7.
Biotechnology and Bioengineering
|June 20, 1991
Summary
Lowering sugar in continuous fermentation reduced solvent production by decreasing cell reduction energy. Increasing sugar restored acetone-butanol fermentation, highlighting NADH
Area of Science:
- Biotechnology
- Metabolic Engineering
- Fermentation Science
Background:
- Continuous fermentation processes are crucial for industrial biotechnology.
- Acetone-butanol fermentation (ABF) is vital for biofuel and chemical production.
- Optimizing substrate concentration is key to maximizing yield and productivity in ABF.
Purpose of the Study:
- To investigate the impact of low inlet feed sugar concentrations on continuous acetone-butanol fermentation.
- To determine the relationship between cell reduction energy and solvent production.
- To identify optimal conditions for resuming solvent production after inhibition.
Main Methods:
- Continuous flow fermentation at a constant dilution rate (D = 0.075 h⁻¹).
- Manipulation of inlet feed sugar concentrations (20 g/L and 40 g/L).
- Analysis of cell population reduction energy (F/X) and specific butanol production rate (qB).
Main Results:
- Lowered sugar concentrations (20 g/L) led to decreased cell reduction energy (F/X) and accumulation of intermediate acids.
- Increasing sugar concentration to 40 g/L at the same dilution rate restored solvent production.
- A linear correlation was observed between F/X and qB, indicating NADH availability is critical for butanol production.
Conclusions:
- Cellular redox balance, specifically NADH availability, is a critical factor limiting solvent production in continuous ABF.
- Optimizing substrate feeding strategies, particularly sugar concentration, is essential for efficient continuous acetone-butanol fermentation.
- The study provides insights into controlling fermentation by managing cellular energy and substrate levels.
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