Cell physiology and metabolism : is glutamine really one of the main energy sources of mammalian cells?

In cell culture technology glutamine is known to be one of the mayor energy sources together with glucose. Different pathways for glutamine metabolism are possible, resulting in different energy and ammonium output. Ammonium can limit cell growth and product formation. Ideas to reduce ammonium formation are numerous. Here we present a new discussion on the glutaminolysis of mammalian cells. We will show that the replacement of glutamine by one single organic acid is supporting growth of different commercial cell lines (MDCK, BHK21, CHO) in serum containing and serum free media. No further additives, like peptides or hydrolysates are required. The use of this new medium formulation is presented in detail, considering the metabolism of MDCK cells in an influenza vaccine production process in roller bottles and microcarrier cultures as an example. The metabolite profiles for glucose, lactate, glutamine, ammonium, glutamate and extracellular amino acids will be analyzed. Additionally the impact on virus yield will be reported. How these cells can still grow and produce without glutamine will be discussed. Further insights on the glutaminolysis are given by comparing metabolite profiles from variations of this new medium formulation