Folate Coenzymes of Lactobadhs casei and Streptococcus faecalis*

During growth in the presence of 10 ng of [3H]pteroylglutamic acid (PteGlu) per ml of medium, Zactobacillus casei (ATCC ‘7469) incorporated 80 to 90 % and Strepfococcus faecolis (ATCC 8043) 40 to 60% of the added radioactivity. Folate compounds in Z. cusei were identified as reduced derivatives of PteGlus (w-19%), of PteGlus (-42 %), of PteGlu, (~14%)~ and PteGluc (-8%); in S. faecalis as reduced derivatives of PteGluc (w-24%), of PteGlup (w-61%), and PteGlu3 (~4%). After treatment of cell extracts with hog kidney conjugase -39% of folate compounds in Z. casei were converted to tetrahydrofolic acid (H$teGlu), -26% to 5-methyl-HPteGlu and ~10% to 5and loformyl-HgteGlu; in the case of S. faecalis -25% were converted to H$teGlu and -45% to 5and lo-formylH$teGlu. No 5-methyl-HgteGlu derivatives could be found in S. faecalis. Simple methods for the preparation and separation of the biologically active forms of S-methyl[3H]HJ%eGlu and 5-formyl-[3H]HJJteGlu, (n = 1 to 9 glutamic acid residues) with a high specific radioactivity are described. Growth of Z. casei in the presence of 100 ng of PteGlu[U-W]Glu-Glu or 100 ng of PteGlu3-[UJ4C]Glu-Glu per ml of medium was the same as in the presence of 100 ng of PteGlu per ml. PteGlus (100 ng per ml of medium) did not inhibit the uptake of [3H]PteGlu (0.3 ng per ml of medium), in contrast to PteGlu3 (100 ng per ml) and PteGlu (100 ng per ml). Z. casei converted PteGlu-[UJC]Glu and PteGlus[U-14C]Glu-Glu to the same metabolites as [3H]PteGlu without loss of the 14C label.