Urea production and putrescine biosynthesis by Escherichia coli.

Cultures of Escherichia coli B and K-12 produce urea during growth in minimal medium. Results of isotopic labeling experiments were consistent with the sole source of urea being from the conversion of arginine to putrescine. Since E. coli itself has no demonstrable urease activity, the rate of urea production is a measure of the flux through the arginine to putrescine pathway.