Metabolic rates for major nutrients in suspension cultures of plant cells

Abstract

Well-habituated cells, which had been initiated from root tissue of Ipomoea sp. and kept in suspension culture for more than 2 years, were grown in 14-liter stirred-jar fermenters in complex media containing casein hydrolysate. Samples were taken at 12-h intervals, and both cells and media analyzed for major constituents. Polynomial functions of time were fitted, by least squares, to these data, and the rate of disappearance or accumulation (medium and cells, respectively) of the major components was calculated by dividing the first derivative of these functions by the corresponding dry cell weight. The results indicate that growth of these cultures involved a sequence of activities such that the culture as a whole, during the period of rapid increase in cell yield, progressed from one containing predominantly dividing cells with a high rate of nitrogen anabolism to one containing predominantly "maturing" cells with a proportionately higher rate of carbohydrate anabolism. Increasing the nitrogen content of the medium affected the metabolic rates and the apparent net growth rate to only a minor extent, but did alter cell composition.