Glutamine-free media : use of pyruvate to avoid accumulation of ammonia in mammalian cell culture

Glutamine is known to be one of the mayor energy sources in mammalian cell culture technology together with glucose. Different pathways for glutamine metabolism are possible, resulting in different energy and ammonia output. Ammonia can limit cell growth and product formation. Ideas to reduce ammonia formation are numerous. Here we present new aspects on the role of glutamine in mammalian cell culture media. We will show that the replacement of glutamine by pyruvate is supporting growth of different commercial cell lines (MDCK, BHK21, CHO) in serum containing and serum free media without ammonia production. No further additives, like peptides or hydrolysates are required. In addition, less lactate, another cell growth inhibitor is produced as less glucose is used. 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 large-scale microcarrier cultures as an example. The metabolite profiles for glucose, lactate, glutamine, ammonium, glutamate, pyruvate and extracellular amino acids will be analyzed. Metabolic pathways, which allow the cells to grow without glutamine, will be discussed. Further insights on the glutaminolysis are given by comparing metabolite profiles from variations of this new medium formulation. Additionally the impact on virus yield will be reported