Effect of Alanine and Threonine on the Synthesis of Serine by Leuconostoc Mesenteroides.

O'Barr, Thomas P. (Agricultural Research Service, Washington, D.C.). Effect of alanine and threonine on the synthesis of serine by Leuconostoc mesenteroides. J. Bacteriol. 86:1321-1325. 1963.-Growth of Leuconostoc mesenteroides in the absence of serine was inhibited by l-alanine and l-threonine. Varying the glycine concentration when l-alanine was present suggested a direct relationship between the molar ratio of these two amino acids and the amount of growth achieved by the test organism. Supplements of leucovorin did not reverse the effect of l-alanine upon growth. In experiments with washed cells of L. mesenteroides, both l-alanine and l-threonine reduced the amount of C(14)-labeled formate fixed into serine and the amount of glycine-1-C(14) found in boiling-water extracts of the cells. Neither l-alanine nor l-threonine had any inhibitory effect upon the glycine-dependent disappearance of formaldehyde by acetone powders prepared from L. mesenteroides.