Biosynthesis of δ-Aminolevulinic Acid from Glutamate in Agmenellum quadruplicatum

delta-Aminolevulinic acid accumulated in the culture medium when Agmenellum quadruplicatum strain PR-6 was incubated in the presence of levulinic acid, a competitive inhibitor of delta-aminolevulinic acid dehydratase, and specifically labeled glutamate and glycine. The delta-aminolevulinic acid was purified using Dowex 50W-X8 and cleaved by periodate to yield succinic acid and formaldehyde. The distribution of radioactivity in the two fragments suggested that in blue-green algae the carbon skeleton of delta-aminolevulinic acid is derived directly from glutamate. However the possibility of the pathway of delta-aminolevulinic acid synthesis, from glycine and succinyl-coenzyme A also functioning in blue-green algae was not eliminated as uptake of glycine was minimal.