Pyridine nucleotide metabolism in Escherichia coli. II. Niacin starvation

The effect of niacin starvation has been studied in a niacin-requiring auxotroph of Escherichia coli. If a culture is totally deprived of niacin, cells continue to divide until the total pyridine nucleotide content has fallen from 1.9 X 10^6 to 1.2 X 10^5 molecules per cell. During starvation, the relative proportion of the pyridine nucleotides changes greatly: the TPN: DPN ratio increases from 0.30 to over 2.0 and nicotinic acid mononucleotide accumulates until it is present at concentrations comparable to DPN.