| According to the theory of metabolic control fermentation, the dissertation focuses on the breeding and fermentation conditions of L-leucine producing strain. The main research contents and results are as follows:(1) Original strain, Brevibacterium flavum TQ9806 (Met-+2-TA+ a -ABr+ -HLr+SGr+30011 g/mL Rifr) , was mutated by DES and LiCl, UV and LiCl successively. Then an L-leucine producing strain TK0303 with all original marks which was resistant to rifampin 800 g/mL was obtained, which could produce higher L-leucine production of 25.2g/L than 18.5g/L of TQ9806 under the fermentation condition without being optimized.(2) The batch fermentation conditions of strain TK0303 in shake-flask were studied in this dissertation. The proportions of seed medium and fermentation medium components were optimized by uniform design experiment and software MATLAB. The seed culture conditions and fermentation conditions were also studied. Under the optimum conditions, the strain TK0303 could produce L-leucine 28. 3g/L after fermentation for 64 hours by flask-shaking fed-batch fermentation.(3) Based on the above optimum condition, the batch fermentation was performed with strain TK0303 in 5-liter fermentor. The result showed that the strain could produced L-leucine 26.44g/L after fermentation for 68 hours. The L-leucine batch fermentation kinetics was studied based on the experimental data from the batch fermentation in 5-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, the better fitting models were obtained through fitting analysis by software MATALAB.The aim mutant TK0303 obtained has been potential to be applied to industrial producing, which could produce L-leucine 28.3g/L in the conditions of shake-flask fed-batch fermentation, 26.44g/L in the conditions of 5-liter fermentor batch fermentation and whose genetic character was stable.
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