Effect of carbon and nitrogen growth limitation upon nutrient uptake and metabolism in batch cultures of Catharanthus roseus (L) G. Don

Cell suspension cultures of the Madagascan Periwinkle, Catharanthus roseus (L). G. Don were grown as batch cultures in two different types of media; in one medium the limiting nutrient was inorganic nitrogen, and in the other it was carbon. The response of the cells to these growth-limiting conditions was monitored by measuring cellular fresh weight, dry weight and protein accumulation, cell viability, medium sugar and nitrate levels, and the activities of certain intracellular enzymes throughout growth in batch culture. The enzymes investigated were glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), hexokinase (EC 2.7.1.40), phosphofructokinase (EC 2.7.1.11), nitrate reductase (EC 1.6.6.1), glutamate dehydrogenase (EC 1.4.1.2) and glutamine synthetase (EC 6.3.1.2). The effect of culturing the cells under different nutritional regimes was apparent in all aspects of growth; only some enzyme activities were unaffected. Cell viability remained at a high level for several days after growth limitation in both types of culture. The possibility that protein degradation in nitrogen-limited batch cultures is under very stringent control is discussed.