Protogen and its Relation to Ketoacids in Metabolism of Tetrahymena. ∗

Abstract

Summary

Tetrahymena geleii strain W was grown in media in which the concentrations of protogen and of acetate were varied. The effect of additions of Krebs cycle intermediates and of fatty acids to such media was studied. In deficient media the organisms grow to a limited extent and then die. Death is due to the acidity of the medium. The acids accumulated have been tentatively identified as consisting mainly of pyruvic and α-ketoglutaric acids using paper chromatography and differential solubility of the 2,4-dinitrophenyl hydrazones. α-ketoglutaric acid accumulates at the expense of pyruvic acid in the absence of added acetate. In the presence of acetate or of higher fatty acids pyruvic acid and α-ketoglutaric acid accumulate in about equal amounts. A mixture of succinate and acetate does not replace protogen. A function other than the oxidation of pyruvic and α-ketoglutaric acids in the metabolism of Tetrahymena is postulated.