OXIDATION OF ACETATE BY ASHBYA GOSSYPII

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Abstract
Washed mycelial suspensions obtained by culturing in the presence of added ethanol, oxidize acetate about 4 times as rapidly as suspensions prepd. from media to which no ethanol is added. Such suspensions oxidize alpha ketoglutaric, succinic, fumaric, malic, oxalacetic and citric acids. Addition of (0.002[image]) alpha ketoglutaric, succinic, fumaric and malic acids to suspensions oxidizing acetate (0.02[image]) results in a stimulation of O2 uptake greater than the addivitive values from the substrate and added acid alone. The stimulation is 61% with alpha-ketoglutaric acid, 49% with succinic, 35% with fumaric, and 13% with malic acid. More acetate also disappears from flasks to which the dicarboxylic acids are added. Oxalacetic, pyruvic or citric acids do not show this effect. Citric acid is synthesized during the oxidation of acetate and the amt. synthesized is increased when oxalacetic acid is added, and still further increases result with the addition of oxalacetic and malonic acids. High concns. of malonate (0.04[image]) block acetate oxidation and citrate synthesis. With lower concns. (0.04[image]) there is a stimulation of O2 uptake and no inhibition of citrate synthesis. In the presence of acetate and oxalacetate neither of the concns. of malonate has any influence on citrate synthesis. No evidence for C2 to C4 condensation was obtained. Dried mycelial suspensions oxidize citrate, succinate and several of the other dicarboxylic acids but have no activity on acetate or ethanol. The results are discussed in relation to the mechanism of acetate oxidation.
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