Studies on the enzymatic formation of citrovorum factor by Streptococcus faecalis.

There is evidence that before pteroylglutamic acid (PGA) can carry out certain catalytic functions in animal tissues it must first be converted to citrovorum factor (CF). This conversion has been studied in rat liver slices by Nichol and Welch (l), who found that the conversion was enhanced by ascorbic acid. Since Streptococcus faecalis utilizes either PGA or CF to meet its growth requirement for folic acid (2), this organism presumably carries out this conversion efficiently. This organism might therefore be conveniently employed to study the enzymatic transformation of PGA to CF by the resting cell technique. The biochemical conditions favoring this transformation by S. faecalis and by a strain of X. faecalis resistant to 4-amino-lo-methylpteroylglutamic acid (Amethopterin) are the subject of this report.