BIOSYNTHESIS OF CITRIC ACID

Abstract
Labeled citric acid was synthesized by Aspergillus niger from sucrose in the presence of Na ace-tate-2-C14 and C13O2. The labeled citric acid was degraded by a new method which allowed a separate isotope detn. of each of the 6 C atoms. The finding of wide divergence in labeling between the primary carboxyls confirmed the Ogston concept in the case of a microbial system. The exptl. evidence indicated extensive C4- or C6-acid cycling in an organism which has a C metabolism predominantly shifted toward the bulk production and excretion of citric acid.