Study On Breeding Of L-Arginine Producer And Fermentation Metabolic Regulation

L-arginine (L-Arg) is a semi-essential amino acid. It is also an important metabolite of the body, with a wide range of application in food, medicine, feed and other industries. In this paper, methods of physical and chemical mutagenesis combined with structural analogues D-Arg by giving resistance to the original strain and used the method of aminoacid auxotrophy, breeding a strain with significantly improved production, and fermentation conditions and metabolic regulation of the strain are preliminary explorated. 1. Medium OptimizationThe best concentration of glucose, (NH4)2SO4, CaCO3, MgSO4,and KH2PO4 inside the culture media are respectively 80 g/L,25 g/L,15 g/L,0.5 g/L and 1 g/L. Investigate adding of biotin and VB1, discover that join 80 ug/L biotin, the production is promoted 18%, and join 160 g/L VB1, the production is promoted 9%. The new culture media turn to ferment after 96h under the same condition, the L-Arg yield is 0.71 g/L, compared original germ stub to raise 31.5%.2. UV single factor mutation Ultraviolet radiation is used alone when the death rate is 75%-85%, to determine the optimal conditions for mutation 40s. After batches mutagenesis, structural analogues of D-Arg plate resistance screening and determination of stability of continuous passage, a High-yield strain BC307 is gained with the D-Arg resistant concentration 4g/L, L-Arg production was 2.94g/L3. Mutagenesis DES single factorThe death rate when used DES alone is 70%-80%, the optimum mutation concentration is 1%. After several batches mutagenesis, structural analogues of D-Arg screened on resistance, it is found the output from strain not only did not markedly improved, but the majority has shown down. SoDES used alone, mutation is very poor.4. Proline auxotrophic strainWe chose BC307130315 as the starting strain, processed it by compound mutation. We study on the starvation time, double nitrogen incubation time, concentration of penicillin and processing time. After several batches of breeding, by proline plate screening and stability of passage, breeding a strain BC30713031584, its structural analogues resistant to 6g/L, L-Arg yield of 5.76g/L.5. Fermentation metabolism in the preliminary studyTo used strain BC30713031584 as the target, precursor fermentation to add, additional carbon and nitrogen made a preliminary exploration, discovery that add the L-glutamate (the first 18 hours of fermentation to add) 3g/L, malonic acid (from Before adding) 3g/L, can make the final yield to be significantly improved. The additional glucose andammonium sulfates, only to a certain extent, promotes the fermentation, or join if you add too much time is not correct, will have a stronger acid inhibition.