Media formulation — what is the typical optimum range of L-glutamine concentration used in mammalian cell culture media for growth and productivity?

Introduction / Context:
L-glutamine is a pivotal amino acid in mammalian culture, serving as both a nitrogen donor and an anaplerotic carbon source. Its concentration strongly influences growth rate, lactate/ammonia by-products, and recombinant protein yield.

Given Data / Assumptions:

• Question asks for an optimum range, not a single exact value.
• Common basal media provide 2–4 mmol/L glutamine; higher levels may be used with stabilized dipeptides.
• Glutamine is unstable in solution, degrading to ammonia over time.

Concept / Approach:

Practical “sweet spots” for many CHO and hybridoma processes sit around 2–6 mmol/L, balancing sufficient anaplerosis with manageable ammonia load. Thus, 2–7 mmol/L best reflects the broadly accepted, workable window across diverse cell types and processes.

Step-by-Step Solution:

Verification / Alternative check:

Process development routinely titrates glutamine within 2–6 mmol/L, or uses stable dipeptides (e.g., 2–8 mmol/L equivalent) to reduce ammonia formation while maintaining flux.

Why Other Options Are Wrong:

1–2 mmol/L can be limiting; 7–15 or 15–20 mmol/L risks excessive ammonia and acid load; 0.1–0.5 mmol/L is insufficient for most proliferative cultures.

Common Pitfalls:

Ignoring glutamine decay; not adjusting feed strategies in high-density cultures; conflating glutamine with glutamate (transport/usage differ).

Final Answer:

2–7 mmol/L