Studies on the Biosynthesis of Pyocyanine

The biosynthesis of pyocyanine, the blue phenazine pigment produced by Pseudomonas aeruginosa, was studied by the addition of radioactive substrates to a culture growing on a complete medium. The distribution of labelled carbon from radioactive substrates in the pyocyanine was examined by degrading the pigment to 1-hydroxyphenazine, quinoxaline dicarboxylic acid, quinoxaline, and pyrazine tetracarboxylic acid dipotassium salt, and thus 7 of the 13 carbons were assayed separately or in pairs.Glycerol-1,3-C 14 is the principal donor of radioactivity to the pyocyanine carbon, but not all the carbon atoms tested were labeled. Alanine-U-C 14 contributed carbon to pyocyanine also, but not to all carbons, and at a much lower level of efficiency than glycerol. However, with leucine-U-C 14 , all carbon atoms tested were labeled to a slight extent. These amino acids, when labeled specifically, and glutamate-U-C 14 , oxalic acid-C 14 , and sodium formate-C 14 did not contribute significantly to pyocyanine carbon.The distribution of radioactivity from glycerol in the pyocyanine molecule suggests the pigment is formed from glycerol or a product closely related to it by the condensation of two carbon units or the condensation of four and two carbon units.