Effects of deuterium oxide on folate metabolism in Lactobacillus casei

Various folate coenzymes and their polyglutamyl derivatives involved in 1-carbon metabolism are modulated as a result of altered physiological states and also vary with respect to growth conditions. We studied the metabolic changes in folic acid and their conjugated polyglutamyl derivatives in Lactobacillus casei cells grown in the presence of D20. A 40% decrease in methyltetrahydrofolyl polyglutamate derivatives was observed in the cells grown in media prepared with D20-depleted water (D20 content, 8-10 ppm). Chromatographic analysis of folates showed significant alterations in the formyl- and methyltetrahydrofolate derivatives and their polyglutamylation profiles. Higher amounts of oxidized folates were also present in the cells grown in D20-depleted conditions. No significant changes were observed in folates and their polyglutamate derivatives when the cells were grown in the presence of 300, 450 and 600 ppm D20. The altered folate homoestasis is attributed to changes in the metabolic adaptation of cells to D20-depleted environment.