Lipid Synthesis in the Presence of Nitrogenous Compounds in Chlorella pyrenoidosa

Acetate was incorporated by Chlorella pyrenoidosa into nonvolatile water-soluble compounds (amino acids, organic acids and carbohydrates) with pH optimum between 4 and 5. Incorporation into lipid was maximal at pH 7.5. The proportion of incorporated acetate in lipid was not significantly affected by acetate concentration and chlorophyll concentration in the ranges tested. Illumination of Chlorella during acetate metabolism increased the synthesis of lipid with concomitant decrease in the synthesis of water-soluble compounds. Nitrate and ammonium ions had essentially no effect on acetate metabolism. Inhibition by nitrite was greater on the synthesis of lipid. Illumination reversed the gross inhibition by nitrite, but altered the distribution of incorporated label in favor of the water-soluble compounds.