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An improved chemically defined culture medium for strain L mouse cells based on growth responses to graded levels of nutrients including iron and zinc ions

Nutritional factors were evaluated for effects on growth of mouse fibroblast cells in suspension in a chemically defined medium. Quantitative requirements for each of the essential amino acids, choline, inorganic phosphate, iron, and zinc were established. An improved chemically defined medium was formulated on the basis of the findings yielding populations of L cells in excess of 5 × 106 per ml without nutrient replenishment. When spent medium was replaced periodically, yields approaching 30 × 106 cells per ml were attained. The efficiency of utilization of most amino acids in the new medium appears to be 2‐ to 3‐fold better than results reported by others.