Pyocyanine carbon sources

Shikimic acid, an intermediate in the biosynthesis of phenazine derivatives (e.g., iodinine, pyocyanin) can act as the sole carbon source in the formation of the phenazine skeleton. 

Some experiments were done to compare quinic and shikimic acid as carbon sources for pyocyanine biosynthesis in a medium also containing uniformly-labeled glyceroP C and L-alanine- C (MacDonald, 1963). The best incorporation (74%) of the carbon atoms of quinic acid into the carbon atoms of pyocyanine was obtained when quinic acid was added at a concentration of 1 % at the time of inoculation with a small inoculum. If quinic acid was added when pigment formation had just started, or if quinic acid was added at a concentration of 0.25 %, or if a large inoculum of washed cells was used, the incorporation of quinic acid into pyocyanine was less (21— 46 %). The best incorporation (29 or 31 %) of the... 

Frank and deMoss (1959) incubated a mixture of washed cells of P. aeruginosa, salts, and alanine- C for 24 hours, and then isolated and purified the pyocyanine produced. With uniformly-labeled L-alanine C as the substrate, the ratio of the specific activity of the pyocyanine synthesized to the specific activity of the alanine added was close to the value expected if the carbon atoms of the L-alanine were the sole source of carbon for the synthesis of pyocyanine. In another experiment, C-labeled cells were produced by growing P. aeruginosa on a medium containing uniformly-labeled L-alanine- C as the sole source of carbon. Such cells, when incubated with unlabeled alanine and salts, produced pyocyanine which contained little radioactivity. One can conclude from the above results that the pyocyanine synthesized was derived from alanine and not from preformed intermediates in the cells. The authors showed also that when DL-alanine-1- C and DL-alanine-2- C were tested as precursors in the system described, the former compound contributed relatively less radioactive carbon for the biosynthesis of pyocyanine than did the latter. Interpretation of these results is difficult because the distribution of radioactivity in the pyocyanine produced was not known, and because results obtained with DL-alanine may not be directly comparable with those obtained with L-alanine. 

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