Abstract
The nitrogen source of the medium for Escherichia coli was substituted by ^<15>NH_4Cl and (^<15>NH_4)_2SO_4. The ^<15>N atom was incorporated directly into pyridoxine. The competitive ^<14>N-compounds, amino acids, glucosamine, N-acetylglucosamine, carbamoylaspartate, bases of nucleic acids, and vitamins did not inhibit the incorporation of ^<15>N into pyridoxine. The labeled compounds, L-[^<15>N]glutamic acid, L-[<15>N]aspartic acid, L-[amide-^<15>N]glutamine, L-[amide-^<15>N]asparagine and [^<15>N]glycine were not incorporated into pyridoxine. These results suggest that ammonium ion is the origin of the nitrogen atom of pyridoxine in E. coli.
