[Characteristics of the tricarboxylic acid cycle in Nocardia erythropolis].

The activity of enzymes involved in the tricarboxylic acid cycle was studied in Nocardia erythropolis IBFM B-293. It was found to be low and hardly change, with some exceptions, in the course of growth in the presence of various carbon sources. Acetate induced enzymes of the glyoxylate cycle which was here an important mechanism of oxalacetate synthesis. The absence of alpha-ketoglutarate dehydrogenase in the case of all studied substrates and the absence of 4-aminobutyrate aminotransferase, the key enzyme of the compensating 4-aminobutyrate shunt, suggest that the tricarboxylic acid cycle is decoupled. Therefore, this cycle does not operate as a mechanism generating energy in N. erythropolis, but fulfills mainly biosynthetic functions.