Studies On L-Valine Fermentation Conditions Of 5L Fermenter

According to the theory of metabolic control fermentation and metabolic flux analysis, the dissertation focuses on the fermentation conditions of L-valine high-yielding strain .The main research contents and results are as follows:(1) Based on the optimized conditions of flask, Fermentation in 5L fermenter of L-valine by TV2564 has proceeded. The effect of different C/N on fermentation was studied, and the results show high C/N or high concentration of initial glucose is adverse to fermentation of valine.(2) According to the change of DO in 5L fermenter, with dynamics analysis during fermentation process, two stages oxygen supply was provided .The L-valine batch fermentation kinetics was studied by MATLAB tool based on the experimental data from 5-liter fermenter's batch fermentation. Three kinetic models were constructed which could reflect the regularity of growth, product formation and substrate consumption in the process of batch fermentation.(3) The metabolic network was proposed for L-valine producing strain. The metabolic flux distributions of Brevibacterium flavum TV2564 during the different fermentation period were calculated by linear program of MATLAB software according to metabolic flux analysis theory. The metabolic flux distributions of EMP, HMP, TCA cycle and the key principle nodes of GLC6P, PEP and PYR were analyzed. At the same time it can be indicated to provide theory guide for the fermentation process.(4) Fed batch fermentation was studied with TV2564 according to the optimum condition of batch fermentation. According to the change of DO in fed-batch fermentation, the optimized oxygen supply was provided. The optimum conditions was obtained, which were the technology of low glucose and amino, feeding corn syrup liquid in the former and later phase of fermentation, controling pH by feeding amino liquid, feeding 80% glucose in later phase, production of L-valine reached 52.68g/L after fermentation for 72 hours under the optimized conditions.(5) By membrane filtration, the cells and protein were leached. The results are perfect, and the removal rate of protein is 79.89%.