THE UTILIZATION OF ACETATE BY NEOCOSMOSPORA VASINFECTA

Abstract

Summary Mycelium of Neocosmospora vasinfecta, harvested during active growth, was incubated for up to 10 minutes in dilute solutions of [1‐14C]acetate or [2‐14C]acetate. Radioactivity in the respiratory CO2 and in identifiable compounds extracted from the mycelium was measured. Closely similar results were obtained with both [1‐14C]acetate and [2‐14C]acetate except for the loss of radioactivity to CO2, which took place much more rapidly from the [1‐14C]acetate. Water‐soluble compounds accounted for over 80% of the radioactivity of the mycelium. With incubation periods of up to 2.5 minutes, most of the radioactivity in the water‐soluble material was associated with organic acids, whereas with longer incubation, the label in basic compounds predominated, Glutamate was consistently the most heavily labelled basic compound, with small amounts of radioactivity in glutamine and aspartic acid. Radioactivity in the organic acid fraction was practically confined to citric acid after 2.5 minutes incubation; succinic, malic and other acids were significantly labelled after 10 minutes. The specific activities of these acids after 10 minutes decreased in the order citrate, succinate, malate, suggesting their involvement in the tricarboxylic acid cycle. The results are discussed in relation to the importance of the tricarboxylic acid cycle in acetate utilization, nitrogen assimilation and respiration.