Study On The L-glutamate Fermentation By The Corynebacteria Glutamicum F343 Of Temperature Tolerance

L-glutamate is one of bulk fermentation products. Temperature is one of the most important factors of glutamate fermentation directly related to the production efficiency. High-temperature fermentation, can improve the economic benefit by reducing the cooling water, which is attractive for industrial applications. This paper studied on the fermentation of the genome shuffled strain F343 in 5L fermentation jar, including medium components, fermentation parameters, ferment flux during the glutamate producting period and different in genetic level between the F343 and S9114.Firstly the fermentative condition of the shuffled strain F343 was investigated. F343 got a higher production of 6% in the medium containing 10 g/L corn pulp and thiamin of 75μg/L. Fermented in 5L jar with strain F343, the optimal initial glucose concentration and glucose concentration during L-glutamate fermentation were 140 g/L,and between 20 g/L to 40 g/L respectively. Fermentation parameters such as temperature, pH, DO were observed. Controlling fermentation temperature at 36℃-39℃, DO above 20%, as well as pH benween 7.2-7.5 in the different fermentation periods,119 g/L of L-glutamate acid was produced with a inver ratio of 56% after 30 h fermentation, which the best yield obtained to 126 g/L in 34 h.The fermentation characteristics of the strain S9114 and the F343 were compared. During the whole fermentation, the strain F343 has a high level of the special glutamate production rate, which was between 0.3 to 0.55 g/g/h compared the highest 0.45 g/g/h in the S9114. Analysis the metabolic flux of the product-period, the PEP node and the KG node were found different between the strain F343 and the stain S9114, the metabolic flux at the branch path, catalyzed by the phosphoenolpyruvate carboxylase (PEPc) and the glutamate dehydrogenase (GDH), were higher in fermentation of F343 than that of S9114. In addition, the by-products of L-glutamate fermentation at the high temperature were lower correspondingly.Comparing the requirement of biotin between F343 and the original strain S9114, we found that the optimum biotin concentration of F343 and S9114 were 0.3μg/L and 10μg/L correspondingly in CGXⅡmedium. It was also found that keeping tittle biotin in the cell of F343 was useful for glutamate production with F343.Amplified Fragment Length Polymorphism (AFLP) was applied to analysis the DNA polymorphism of S9114, the first round shuffled F19 and F343. The cluster result showed that genetic similarity coefficient of F343 and S9114 is 0.9655, which means differences occurred in the strain F343.