1887

Abstract

SUMMARY: Cell extracts of the fermentative Mollicutes B-PG9, S2, 14, S6, FH, J and G-37, and the non-fermentative PG-21, 1620 and PG-11 were examined for 39 cytoplasmic enzyme activities associated with the tricarboxylic acid (TCA) cycle, transamination, anaplerotic reactions and other enzyme activities at the pyruvate locus. Malate dehydrogenase (EC 4.2.1.2) was the only TCA-cycle-associated enzyme activity detected and it was found only in the eight species. Aspartate aminotransferase (EC 2.6.1.1) activity was detected in all Mollicutes tested except S6. Malate synthetase (EC 4.1.3.2) activity, in the direction of malate formation, was found in the eight species, but not in any of the species. Phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) was detected in the direction of oxaloacetate (OAA) formation in both species, but not in any of the species. Pyruvate carboxylase (EC 6.4.1.1), pyruvate kinase (EC 2.7.1.40), pyruvate dehydrogenase (EC 1.2.4.1) and lactate dehydrogenase (EC 1.1.1.27) activities were found in all ten Mollicutes tested. No activities were detected in any of the ten Mollicutes for aspartase (EC 4.3.1.1), malic enzyme (EC 1.1.1.40), PEP carboxytransphosphorylase (EC 4.1.1.38), PEP carboxykinase (EC 4.1.1.32) or pyruvate orthophosphate dikinase (EC 2.7.9.1). In these TCA-cycle-deficient Mollicutes the pyruvate-OAA locus may be a point of linkage for the carbons of glycolysis, lipid synthesis, nucleic acid synthesis and certain amino acids. CO fixation appears obligatory in the species and either CO fixation or malate synthesis appears obligatory in the species.

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/content/journal/micro/10.1099/00221287-134-3-791
1988-03-01
2020-01-24
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