Relationship between purines and folic acid-vitamins in the micrococcus, Gaffkya homari.

Microorganisms that require p-aminobenzoic acid or compounds of the folic acid group may have either requirement replaced by a purine and thymine (or thymidine) and several amino acids or vitamin B12 (Lampen et al., 1949; Stokstad, 1941; Baker et al., 1955); the vitamins, p-aminobenzoic or folic acids, are believed necessary for the synthesis of those compounds which can bypass them (Shive, 1950). Further support for this concept comes from the observation that the same combination of amino acids, a purine, and thymine annul the inhibition by sulfanilamide of several microorganisms (Winkler and DeHaan, 1948; Shive, 1950). In the micrococcus, Gaffkya homari, a new relationship was found: any one of several purines (Aaronson and Rodriguez, 1957) or, alternatively, any of the following vitamins: p-aminobenzoic, pteroylglutamic, or folinic acids are required. This suggests that a purine may be necessary for the synthesis of the metabolically active form of folic acid and, conversely, purine synthesis depends on folic acid.