According to the theory of metabolic control fermentation, the dissertation focuses on the breeding, fermentation condition and fermentation kinetics of L-tryptophan producing strain. The main research contents and results are as follows:[1] One L-tryptophan high-producing strain TQ2223 was derived from Corynebacterium glutamicum Tx5-32 by stepwise mutagenic treatments with DES and UV, which could produce L-tryptophan 6.76 g/L under the fermentation condition without being optimized.[2] The batch fermentation condition of strain TQ2223 in shake flask was studied in this dissertation. The seed medium was optimized by orthogonal design experiment and the seed culture conditions were also studied. The fermentation medium was optimized by response surface analysis and the fermentation condition was also studied. Under the optimum condition, strain TQ2223 could produce L-tryptophan 8.56g/L after fermentation for 72 hours by flask-shaking batch fermentation.[3] Based on the above optimum condition, the batch fermentation was performed with strain TQ2223 in 30-liter fermentor. The result showed that the strain could produced L-tryptophan 7.28g/L after fermentation for 64 hours. The L-tryptophan batch fermentation kinetics was studied based on the experimental data from the batch fermentation in 30-liter fermentor. Three kinetic models were constructed which could reflect the regularity of growth, product formation and substrate consumption in the process of batch fermentation. Then, through fitting analysis by software MATALAB the better fitting models were obtained.[4] Fed batch fermentation was studied with strain TQ2223 according to the optimum condition of batch fermentation. The optimum initial glucose concentration was 80g/l in shake flask fed batch fermentation. Through feeding amonia the value of pH was controlled for 7.0-7.2. The intermittent glucose feeding was performed at the 24th, 36th, 48th, 60th hour respectively. The production of L-tryptophan could reach 10.47g/L after fermentation for 72 hours. Based on the above experiment, fed batch fermentation in 30-liter fermentor was performed. The fermentation kinetics was researched, which could reflect the fermentation process very better. It could produce L-tryptophan 8.6g/L after fermentation for 72 hours.The strain TQ2223 obtained has been potential to apply to industrialproducing, whose genetic character was very stable. Based on the data in the 30L fermentor, the proper models were obtained through software MATLAB analyzing, which would benefit the optimizing control of L-tryptophan fermentation in industrial producing. |