Continuous propionic acid fermentation by immobilized Propionibacterium acidipropionici in a novel packed-bed...

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Propionic acid is a valuable chemical with diverse industrial applications.
• Conventional batch fermentations for propionic acid production often suffer from low cell densities and productivity.
• Immobilized cell systems offer potential advantages for continuous fermentation processes.

Purpose of the Study:

• To investigate the continuous fermentation of lactate to propionic acid using immobilized Propionibacterium acidipropionici.
• To evaluate the performance and scalability of a spiral wound fibrous bed bioreactor for this process.

Main Methods:

• Immobilization of Propionibacterium acidipropionici within a spiral wound fibrous bed bioreactor.
• Continuous fermentation of lactate over a 4-month period.
• Monitoring of cell density, reactor productivity, and operational stability.

Main Results:

• Achieved a high immobilized cell density of approximately 37 g/L.
• Demonstrated a reactor productivity approximately 4 times higher than conventional batch fermentation.
• Maintained continuous operation for 4 months without clogging, degeneration, or contamination.
• Successfully processed low-nutrient and low-pH feed streams with minimal impact on productivity.

Conclusions:

• Spiral wound fibrous bed bioreactors are effective for high-density, continuous propionic acid fermentation.
• The system is robust, scalable, and suitable for industrial propionate production.
• Immobilized cell technology offers significant improvements over traditional fermentation methods.