The Study On The Glutamate Fermentation Process Based On RQ On-line Measurement

Glutamate fermentation was regarded as research object in the paper, the control and optimization of its fermentation process were studied via mathematical modeling and computer simulation on the basis of experimental research. During glutamate fermentation using Corynebacterium glutamicum S9114, it was found that respiratory quotient (RQ) control was closely related to the distribution of metabolic flux among glutamic acid, lactate and tricarboxylic acid cycle through metabolic reaction network model. To improve the concentration of glutamate and inhibit the metabolic byproduts, the"balanced metabolic control"(BMC) strategy based on the RQ on-line measurement for regulating metabolic flux of tricarboxylic acid cycle was established. According to the study of the time respondence of RQ to large step changes in agitation rate, we found that the RQ control could be achieved by regulating the agitation rate of fermenter. Thus, a PI feedback controller was used to control RQ, so that the metabolic flux of TCA cycle maintained at a suitable level to achieve glutamic acid fermentation process optimization. Because the delay between the RQ with the agitation rate of fermentor, how to improve the control performance must be study. Dynamic model between the agitation rate of fermentor and RQ was constructed applying differential equations on the premise of obtaining basic data and the equation parameter was determinated based on the MATLAB software,using the simplex search method. It was found that the control performance was unsatisfactory by ordinary PI feedback control. So an on-line self-adaptive PI controller based on the auto-regression and moving average model was established, which could real-time adjust PI parameters of the fermentation process. Self-adaptive PI control could improve the performance of RQ control compare to ordinary PI control through computer simulation.