Influence of Age of Culture and Light Intensity on Solute Concentrations in TwoDunaliella Strains

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Abstract
Two strains of Dunaliella, one halotolerant and one halophilic, were grown in batch culture at NaCl concentrations varying from 500 mol m−3 to 3000 mol m−3. Measurements were made of the following solutes: glycerol, Na+, K+, Mg2+, Cl−, phosphate in the cells of logarithmic and of stationary-phase cultures. The method used was to separate the cells from the bulk of the medium by differential density centrifugation. Solute concentrations were calculated using Blue Dextran as a marker for extracellular space. It was found that in log-phase cells, glycerol accounted for one-half to two-thirds of the total cell solute concentration, the remainder being largely accounted for by Na+ and Cl−. In the stationary phase glycerol fell and Na+, plus Cl−, rose. Light intensity was found to affect cell volume and solute content. The means whereby solute concentrations are controlled is discussed.