The porphyrin pigmentation of subspecies of Bacteroides melaninogenicus

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Abstract
Various subspecies of B. melaninogenicus differ in their pigmentation. B. melaninogenicus ssp. asaccharolyticus produces protoheme almost exclusively, ssp. intermedius both protoheme and a smaller proportion of protoporphyrin, and ssp. melaninogenicus mainly protoporphyrin with a trace of protoheme. As a consequence young colonies can be differentiated by their red fluorescence in UV light (365 nm): ssp. asaccharolyticus does not fluoresce, ssp. intermedius shows a limited fluorescence, and ssp. melaninogenicus shows a bright fluorescence. The pigments were isolated as the dimethyl esters of protohemin and of protoporphyrin and identified by electronic spectroscopy, mass spectrometry and comparisons of TLC. Incorporation of .delta.-aminolevulinate into these pigments was not detected, nor was porphobilinogen formation observed. B. melaninogenicus ssp. melaninogenicus grown in the presence of [14C]protohemin formed [14C]protoporphyrin. This appears to represent a novel biological demetallation.