ROLE OF CITRITASE IN ACETOIN FORMATION BY STREPTOCOCCUS DIACETILACTIS AND LEUCONOSTOC CITROVORUM

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Abstract
Harvey , R. J. (University of California, Davis) and E. B. Collins . Role of citritase in acetoin formation by Streptococcus diacetilactis and Leuconostoc citrovorum . J. Bacteriol. 82: 954–959. 1961.—Cell-free extracts of Streptococcus diacetilactis and Leuconostoc citrovorum converted citrate to acetate, oxalacetate, pyruvate, carbon dioxide, and acetoin. The products, stoichiometry, and cofactor requirements of the citrate-splitting reaction were identical to those reported for citritase. Coenzyme A was not required; the reaction was stimulated by magnesium or manganous ions, and inhibited by calcium ions. In S. diacetilactis the enzyme is constitutive; it has been found inducible in all other organisms that have been studied. Ten strains of S. diacetilactis , three strains of Leuconostoc , and one strain of S. liquefaciens contained the enzyme; 21 strains of S. cremoris and 3 strains of S. lactis did not. Cell-free extracts of S. diacetilactis and L. citrovorum converted pyruvate to acetoin and carbon dioxide in the presence of manganous ions and thiamine pyrophosphate.