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Biosynthesis of pyocyanine Ingledew, Michael William

Abstract

A new medium for the production of the phenazine pigment pyocyanine by Pseudomonas aeruginosa has been developed. This medium contains 2-ketogluconate as the sole carbon source and allows rapid synthesis of pyocyanine in yields which are proportional to the carbon added. The availability of this new resuspension medium and the isolation of a mutant of P. aeruginosa unable to oxidize shikimic acid, quinic acid, and some other compounds related to the aromatic pathway, has facilitated the evaluation of components of this pathway as precursors to pigment. Using the competition technique and direct incorporation of ¹⁴C, shikimic acid has been shown to account for virtually 100% of the carbon atoms required for the phenazine nucleus of pyocyanine, implicating the branch point of synthesis of the pigment as occurring at this level of the aromatic pathway. Quinic acid competed only by virtue of its conversion by quinic dehydrogenase and biosynthetic enzymes, to shikimate. These observations were confirmed utilizing polyauxotrophic mutants which were unable to synthesize pyocyanine until quinate or shikimate were supplied. The involvement of a permease for the concentration of hydroaromatics intracellularly has been demonstrated. Attempts at the isolation of postulated N-containing derivatives involved in "dimerization" to form pyocyanine have only met with limited success.

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