The effects of uniform and gradient fed nitrogen on glutamine synthetase(GS),glutamate dehydrogenase(GDH)and glutamate synthase(GOGAT)were investigated in glutamine production by fermentation of Corynebacterium glutamicum NS611 after 3h of in-situ nitrogen starvation. It was shown that the strain in the later growth phase entered naturally into in-situ nitrogen starvation by controlling the initial concentration of urea and the biomass was slightly decreased. The pH value reached 6.5 again in the culture system, which confirmed the beginning of nitrogen starvation in the culture system. After 3h nitrogen starvation the activity of GS was increased over two folds and the time of high activity of GS persisted three folds longer in the gradient fed nitrogen system than that in the normal fed batch. The higher activity of GDH was also maintained. The glutamine production increased by 72% than the original technology of nitrogen starvation and the time of fermentation was shortened by above 12h.
The chemical decomposition of glutamine is a first-order reaction. Its reaction constants under storage and culture conditions were determined as 0 0009 h\+\{-1\} and 0 0032 h\+\{-1\} respectively. Batch culture of hybridoma cell C50 with different initial contents of glutamine helped to understand its real metabolic characteristic. The results show that when the initial concentration of glutamine is lower than 5 mmol/L, more than 80% is used by cells. And the lower the initial content, the more being used. As the initial glutamine concentration increases, the ratio of its utilization decreases. When it reaches 10 mmol/L, the ratio decreases dramatically.
