Folic acid involvement in cyclopropane fatty acid synthesis in lactobacilli.

Henderson, Thomas O. (North Carolina State University, Raleigh), John J. McNeill, and S. B. Tove. Folic acid involvement in cyclopropane fatty acid synthesis in lactobacilli. J. Bacteriol. 90:1283-1287. 1965.-Evidence for the involvement of folic acid in the synthesis of lactobacillic acid (11,12-methyleneoctadecanoic acid) was obtained with Lactobacillus plantarum and L. casei. L. plantarum, in the presence of aminopterin, incorporated 25% less radioactivity from methionine-methyl-C(14) into long-chain fatty acids than did control cultures, whereas the incorporation of acetate-1-C(14), representing overall fatty acid synthesis, was the same in both conditions. Control cultures of L. plantarum contained 3 to 4.5 times more lactobacillic acid than did aminopterin-grown cultures. Similarly, L. casei, in the presence of folic acid, synthesized six times more lactobacillic acid than did folic-deficient cultures. The results of this study indicate that coenzymes of the folic acid group are involved in the synthesis of lactobacillic acid in these organisms.