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Repeated fed-batch lactic acid production in a packed bed-stirred fermentor system using a pH feedback feeding method
Yong Zhang1, Wei Cong, Shao Yuan Shi
1National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, PO Box 353, Beijing 100190, People's Republic of China.
Bioprocess and Biosystems Engineering
|July 8, 2010
Summary
This study optimized lactic acid production using immobilized Lactobacillus lactis-11 cells in a packed bed-stirred fermentor. Ceramic beads as support material enhanced lactic acid yield and stable production over repeated fed-batch runs.
Area of Science:
- Biotechnology
- Microbial Fermentation
- Biochemical Engineering
Background:
- Lactic acid is a valuable organic acid with diverse industrial applications.
- Optimizing microbial fermentation processes is crucial for efficient lactic acid production.
- Immobilized cell systems offer potential advantages over free cell cultures.
Purpose of the Study:
- To investigate lactic acid production by Lactobacillus lactis-11 using free and immobilized cells in a packed bed-stirred fermentor (PBSF).
- To evaluate the effect of different support materials on fermentation performance.
- To determine optimal operating conditions for enhanced lactic acid yield and productivity.
Main Methods:
- Utilized Lactobacillus lactis-11 in a packed bed-stirred fermentor (PBSF) system.
- Compared free cells with immobilized cells on ceramic beads, macro-activated carbon cylinders, and glass fiber balls.
- Investigated the impact of recirculation rate on fermentation parameters.
Main Results:
- Optimal support material identified as ceramic beads (1-2 mm diameter).
- PBSF system with immobilized cells increased lactic acid production by 16.6% and volumetric productivity by 12.5% compared to free cells.
- Stable lactic acid production was maintained over five consecutive fed-batch runs despite a decrease in free cell concentration.
- Maximum lactic acid production, productivity, and yield were achieved at a recirculation rate of 50 mL/min.
Conclusions:
- Immobilization of Lactobacillus lactis-11 on ceramic beads in a PBSF system significantly enhances lactic acid production and productivity.
- The PBSF system demonstrates stability and robustness for repeated fed-batch fermentation.
- Recirculation rate is a critical parameter influencing fermentation performance in immobilized cell systems.
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