Studies on the Accumulation of Orotic Acid by Escherichia coli K12

More than 300 mg/liter of orotic acid was found to accumulate in the supernatants of the cultures of wild type strains of E. coli K12. The pyrimidine precursor was accumulated in a synthetic medium such as glucose-ammonium sulfate medium. The substance was isolated from the culture, crystallized, and identified as orotic acid. Orotic acid was excreted mainly during logarithmic phase of the bacterial growth. Yeast extract or nutrient broth stimulated bacterial growth, but suppressed orotic acid accumulation. E. coli strains other than K12 failed to accumulate orotic acid.

The results suggest that the accumulation of orotic acid is specific to E. coli K12.