Streptococcus faecalis, folic acid studies

Nearly all microbiologic assays for folic acid activity have used Streptococcus faecalis and Lactobacillus casei. Earlier it appeared that these organisms could not detect folic acid deficiency in man (C2, L8) for example, in one study using S. faecalis there was no detectable activity in the fasting serum of humans (C3). Administration of a loading dose of folic acid with subsequent assay by S. faecalis (G9) has served as a workable means of determining folic acid deficiency (C6), a technique having definite drawbacks (G10). 

Studies on growth factors required by certain microorganisms, for example Streptococcus faecalis and Lactobacillus casei, and of their relevance in animal nutrition, led to the isolation and characterization of folic acid, pteroylglutamic acid (104), the structure of which was determined in 1946. It is an essential vitamin for man and together with vitamin B12 it is involved in the development of blood cells. Deficiency causes macrocytic anaemia. Many microorganisms do not use exogenous folic acid, but synthesize their own, and some... 

It is the purpose of this paper to record the results of clinical and hematologic studies on 5 children with acute leukaemia treated by the intramuscular injection of a synthetic compound, 4-aminopteroylglu-tamic acid (aminopterin). This substance is an antagonist of folic acid regarding growth of Streptococcus faecalis R. ... 

Nutritional studies with Lactobacillus casei and Streptococcus faecalis R resulted in the discovery of new growth factors given the names norite eluate factor and folic acid, respectively. Assay methods using these two organisms were employed in the isolation of folic acid and related compounds from natural extracts. However, a number of previously reported biological responses to natural extracts may now be attributed to the folic acid group. 

The close biogenetic relationship that appears to exist between folic acid and riboflavin is further borne out by a recent study of Clapper and Meade ( 8b) who found that when the amount of folic acid required for growth of a strain of Streptococcus faecalis was limiting, the amount of riboflavin synthesized by the organism was depressed. This relationship also held in nonproliferating cells. The authors speculate that folic acid may be degraded to a pteridine that can be utilized for riboflavin synthesis. 

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