Development of redox potential-driven fermentation process for recombinant protein expression

Area of Science:

• Biotechnology
• Microbial Fermentation
• Protein Expression

Background:

• Optimizing recombinant protein expression in microbial systems is crucial for industrial applications.
• Traditional methods for guiding fermentation processes, such as optical density measurements, can be imprecise.
• Redox potential offers a dynamic indicator of cellular metabolic state during fermentation.

Purpose of the Study:

• To develop and evaluate a novel redox potential-driven fermentation strategy for guiding recombinant protein expression.
• To establish clear indicators within the redox potential profile for critical process steps like induction and harvesting.
• To compare the efficiency of the redox potential-guided process with traditional optical density-based methods.

Main Methods:

• A redox potential-driven fermentation strategy was developed, maintaining dissolved oxygen at a specific level.
• Recombinant E. coli strains expressing prolinase were cultivated using the developed process.
• Oxidation-reduction potential (ORP) profiles were continuously monitored to identify key inflection points.
• The timing of inducer addition and cell harvesting was guided by distinct ORP valleys.

Main Results:

• Two distinct oxidation-reduction potential (ORP) valleys were identified during the fermentation of prolinase-expressing E. coli.
• The first ORP valley accurately indicated the optimal time for adding the inducing agent.
• The second ORP valley effectively guided the optimal timing for cell harvesting, leading to higher enzyme activity.
• The developed process resulted in a prolinase activity of 0.172 μmol/mg/min, surpassing the 0.154 μmol/mg/min achieved with optical density-guided methods.

Conclusions:

• The developed redox potential-driven fermentation process provides a more precise method for guiding recombinant protein expression.
• The identified ORP valleys serve as reliable indicators for critical process control points.
• The process demonstrates potential for further development into an automated fermentation system, enhancing efficiency and reproducibility.