Photoassimilation of organic compounds by autotrophic blue-green algae.

Four obligately photoautotrophic blue-green algae were shown to assimilate acetate. This reaction was light dependent and was greatly decreased in the absence of carbon dioxide. Acetate was incorporated mainly into the ethanol extractable (lipid) fraction of the organisms and into the protein fraction. Only four amino acids (glutamate, proline, arginine, leucine) were significantly radioactive as a result of the incorporation of (I-) or (2-)14Cacetate. Partial degradations of amino acids derived from specifically labelled acetate and enzyme assays on crude cell-free extracts of Anacystis nidulans support the operation of established pathways for the biosynthesis of these amino acids. Growth of blue-green algae was not significantly affected by the presence of moderate concentrations of the sodium salts of the lower fatty acids, with the exception of propionate, low concentrations of which inhibited growth.