The intracellular blue pigment of Pseudomonas lemonnieri

Summary

The large-scale production, isolation, and purification are described of the blue insoluble intracellular pigment of the bacterium Pseudomonas lemonieri. The pigment, C₂₆H₃₇N₅O₆, occurs in the cells as a salt (cation unknown) of 6-octanoylamino-3-hydroxy-2-aza-benzoquinone-(1,4)-4-[5-octanoylamino-2,6-dihydroxy-pyridyl-(3)-imide] (I). Nitric acid oxidation of pigment I yields IV, 6-octanoylamino-3-hydroxy-2-aza-benzoquinone-(1,4). Further hydrolysis of IV splits off n-octanoic acid, which is free of homologues. The structures given for the pigment and its degradation products have been proven by identification with authentic preparations.

Although they have different chromophores, the pigment (I) of Pseudomonas lemonnieri and N,N′-dioctanoyl-indigoidine (VI) nevertheless resemble one another in IR-absorbances, NMR-spectra, and chromatographic behavior, because of homogeneous functional groups and ring structures. I and VI are indeed chemically related, as can be seen from the facts that aminocitrazinic acid is a common starting material for the in vitro syntheses of both compounds, and that the diazaindophenol (I) can be converted to the diaza-diphenoquinone (VI) by hydrogenation and subsequent autoxidation.