[Effects of ammonia on cell metabolism in the culture of recombinant CHO cells].

The effects of ammonia on metabolism of glucose, glutamine and other amino acids in the batch culture of recombinant CHO cells were investigated. It was showed that the yields of cells to glucose, glutamine and other consumed amino acids decreased with the increase of initial ammonia concentrations. In the batch culture with initial ammonia concentration 5.66 mmol/L, the yields of cell to glucose and glutamine reduced 78% and 74%, respectively, compared to that with ammonia initial concentration 0.21 mmol/L, and the yields of cells to other consumed amino acids also reduced 50%-70%. The metabolic pathways were altered in the cultures with the higher ammonia concentrations. The glucose consumption was more prone to form lactate by anaerobic metabolism. In the glutamine metabolic process, the reaction of glutamate to alpha-ketoglutarate by the glutamate dehydrogenase was inhibited by ammonia, and that by the glutamate amino transferase was facilitated. However, the yields of glutamate to glutamine decreased with the increase of ammonia concentrations, showing that the reaction of glutamate to alpha-ketoglutarate was inhibited by ammonia as a whole.