THE INHIBITION OF BACTERIOCHLOROPHYLL BIOSYNTHESIS IN RHODOPSEUDOMONAS SPHEROIDES BY 8-HYDROXYQUINOLINE

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Abstract
The addition of 8-hydroxyqulnollne to the medium of Rhodopseudomonas spheroides caused a decrease in the in-tracellular concentration of bacterlochlorophyll but not of heme pigments or carotenoids. This inhibition was accompanied by the secretion of tetrapyrrolic pigments into the medium. 8-Hydroxy-qulnoline was effective when Cu2+ but not other metal ions were omit-ted from the medium. When the extracellular pigments were purified by chromatography, magnesium-protoporphyrin-monomethyl-ester and protoporphyrin-monomethyl-ester occurred in the medium of inhibitor-free cultures. The other compounds resembled phaeophorbide-a, Chloroblum phaeophorbide-660, Chlorobium phaeophorbide-650, mag-nesium-vinyl-phaeoporphyrin-a5, vinyl-phaeoporphyrin-a5 and a copper-phaeophorblde in their spectroscopic properties. The cells, when grown in the presence of the chelator, contain the same pigments. As the concentration of 8-hydroxyquinbline in the medium was in-creased, the intracellular bacteriochlorophyll concentrations de-creased; but the excretion of phaeophorbide-a-like and magnesium-vinyl-phaeoporphyrin-[alpha]5-like material increased.