Effect of Phosphorus Deficiency on Two Algae Growing in Chemostats1

SUMMARY phosphorus‐limited chemostats were used to study the effect of degree of phosphorus deficiency on several aspects of the composition and metabolism of Anabaena variabilis Kütz. and Scenedesmus quadricauda (Turp.) Bréb. The changes as a function of the dilution rate could be placed into 3 patterns. Most aspects of the composition showed it progressive change with dilution rate. The carbohydrate content generally increased while cellular P and nitrogen, protein, nucleic acid and chlorophyll contents generally decreased over the entire range of increasing deficiency studied. The changes in metabolism fell into a second pattern, showing great sensitivity to the onset of P deficiency. The ability to take up phosphate and the alkaline phosphatase activity increased most markedly with increasing deficiency at the higher dilution rates. The third pattern was confined to the, lipid content of S. quadricauda, which increased with deficiency only at the lowest dilution rates.