Research Of Off-gas On-line Analysis Application In Fermentation Process Control And Optimization

Microbial fermentation process is the process of cell metabolism. Optimization of the fermentation process has been confined to microbial reaction kinetics (focuses on operating parameters, like temperature, pH, dissolved oxygen and culture medium formula) optimization), stoichiometry (uses the chemical elements balance to represent the activities of microbial cells) and thermodynamics (emphasizes the starting and ending states of systems and is able to obtain the greatest extent of the reaction) studies for a long time. There are great defects in all of the above studies as they have not consider the on-line detect of cell physiological metabolism to be the starting point. In this paper, on-line measurement of several off-gas during the aerobic fermentation process was obtained, which was associated with the metabolic properties of cells and was able to realize the fermentation process control and optimization.The off-gas detection in fermentation process was studied for research and mainly had the following aspects:1. The principle of gas detection equipment and important physiological parameters were described, and the different methods were compared. It was found that for most of the fermentation process, the proposed steady-state method to calculate OUR, CER, RQ and kLa was more convenient and reliable. However, dynamic method had limitations and could interfere the fermentation process, which made the final measured data could hardly reflect the actual fermentation process.2. Various types of fermentation process were studied utilizing process mass spectrometer, which could obtain the important on-line physiological parameters. OUR and RQ in different types of microbial fermentation processes were summarized, which could provide a reference for the reactor design and bioprocess control. Furthermore, the obtained data was deeper analyzed with the principles of microbial metabolism and multi-scale analysis.3. This research was focused on the studies of rifamycin, erythromycin, and methanol-inducible Pichia fermentation process. Process mass spectrometer, two electronic nose and parameter acquisition system were used. During the rifamycin fermentation, the data of the exhaust gas was used to process optimization and amplification. For the methanol- inducible Pichia fermentation, the data of the exhaust gas was used to monitor the cell physiological metabolism and optimize the concentration of methanol. For erythromycin fermentation, the data was used to measure the exhaust gas in the n-propanol concentration in the fermentation broth which could direct the feed rate of n-propanol.