THE ABSENCE OF A TRYPTOPHAN-NIACIN RELATIONSHIP IN ESCHERICHIA COLI AND BACILLUS SUBTILIS

Abstract

The existence of a tryptophan-niacin relationship was examined in bacteria Escherichia coli and Bacillus subtilis. A group of compounds, including known intermediates in niacin synthesis from tryptophan in other organisms, were found incapable of supporting growth of niacin auxotrophs of Escherichia coli and Bacillus subtilis. Kynureninase appeared to be absent from the strain examined. Tryptophan auxotrophs of both Escherichia coli and Bacillus subtilis were unable to use C14 - uniformly labeled indole or tryptophan uniformly labeled in the indole ring as a precursor of niacin. Uniformly labeled indole was converted to tryptophan, without dilution, by a tryptophan auxotroph of Escherichia coli. The results obtained indicate that tryptophan does not serve as a precursor of niacin in the strain examined.