The Metabolic Significance of the Citric Acid Cycle in the Growth of the Fungus Zygorrhynchus moelleri

Abstract

The fungus was grown in media containing either radioactive CO2 or methyl or carboxyl-labelled acetate. Following growth, a number of amino acids were isolated and their specific radioactivities determined by chromato-graphy and radioautography. The intramolecular distributions of labelled C in aspartic and glutamic acids were measured, and the quantities of certain amino acids synthesized during growth were determined. Seventeen free amino acids in the cells were identified chromatographically. The existence of the citric acid cycle was supported by agreement between theoretical predictions concerning the distribution of radio-C in certain amino acids, and the observed findings. The experiments indicate that the tricarboxylic cycle plays a large part in the mechanism of terminal oxidations.