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STARR, MORTIMER P. (University ofCalifornia, Davis), GLADYS COsENS, AND HANS-JOACHIM KNACKMUSS. Formation of the blue pigment indigoidine by phytopathogenic Erwinia. Appl. Microbiol. 14:870-872. 1966.-Most cultures belonging to the "Erwinia chrysanthemi group" of soft-rot bacteria form traces of a blue, extracellular, water-insoluble pigment. This pigment is generally not found in cultures of the other members of the genus Erwinia. The blue substance has been isolated and purified from three members of the E. chrysanthemi group; it has been identified as indigoidine, 5, 5'-diamino4,4'-dihydroxy-3, 3'-diazadiphenoquinone-(2,2').

The production and purification of indochrome, the soluble pigment from Arthrobacter polychromogenes, is described. Four isomeric 3-hydroxy-6-d-ribosyl-2-aza-benzoquinone-(1,4)-4-[2,6-dihydroxy-5-d-ribosyl-pyridyl-(3)-imides] have been isolated from the natural product as the main components. In indochrome A two β-d-ribopyranosyl residues, in indochrome B II two β-d-ribofuranosyl residues, are bound to the aglycone. The pigment fractions B I and B III contain differently configurated d-ribosyl residues, which for B I were found to be the α- and β-configurations of the pyranose form. Nitric acid degradation of the pigment and condensation with phenylhydrazine yields mainly 3-β-d-ribopyranosyl-5-benzeneazo-2,6-dihydroxy-pyridine. All d-ribopyranosyl residues were found to be in the C1(D) conformation. d-Ribose was liberated from the aglycones by ozonolysis

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The interaction of magnesium with two other mineral elements, calcium and zinc, was studied in maternal tissues and fetuses of pregnant rats fed a magnesium deficient diet throughout gestation. Reduction in maternal femur magnesium and a trend for increased kidney calcium reflected the dietary magnesium deficiency. In fetuses, however, total magnesium content was reduced and , in addition, fetal zinc content was also lower than normal in the group most severly deficient in magnesium. The possible interpretation of this magnesium-zinc interaction is discussed.