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Simulation of citric acid production by rotating disk contactor
A Sakurai1, H Imai, Y Takenaka
1Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Fukui University, Fukui 910, Japan; fax: +81-776-27-8747.
Biotechnology and Bioengineering
|July 22, 2008
Summary
A mathematical model accurately simulates citric acid production by Aspergillus niger in a rotating disc contactor (RDC). This model, incorporating cell growth and oxygen diffusion, aids in optimizing bioprocesses.
Area of Science:
- Biotechnology
- Biochemical Engineering
- Microbial Fermentation
Background:
- Citric acid is a key industrial chemical produced via microbial fermentation.
- Rotating disc contactors (RDCs) are used for continuous bioprocesses, but modeling their dynamics is complex.
- Understanding factors influencing citric acid production in biofilms is crucial for process optimization.
Purpose of the Study:
- To develop and validate a simple mathematical model for citric acid production by Aspergillus niger in an RDC.
- To describe the time courses of citric acid production, considering cell growth, product formation, and oxygen diffusion.
- To investigate the relationship between biofilm characteristics and citric acid production rates.
Main Methods:
- A mathematical model integrating Monod-type cell growth, Luedeking-Piret production rates, and oxygen diffusion in biofilm was formulated.
- The model's five parameters were determined using nonlinear least squares fitting to experimental data.
- Cell density within the biofilm was estimated using an empirical equation relating cellular mass to biofilm area.
Main Results:
- The model successfully simulated the experimental time courses of citric acid production.
- The model accurately predicted citric acid production dynamics under RDC conditions.
- Simulations revealed a relationship between specific biofilm surface area and citric acid production rate.
Conclusions:
- The developed model provides a robust framework for understanding and simulating citric acid production in RDCs.
- The model can be used to optimize bioprocess parameters for enhanced citric acid yield.
- This study contributes to the improved design and operation of bioreactors for microbial fermentation.
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