title: Porphyromonas endodontalis binds, reduces and grows on human hemoglobin.
abstract: Porphyromonas endodontalis is a black-pigmented, obligate anaerobic rod-shaped bacterium implicated as playing a major role in endodontic infections. We have previously shown that P. endodontalis requires the porphyrin nucleus, preferably supplied as hemoglobin, as a growth supplement. The bacteria also actively transport free iron, although this activity does not support growth in the absence of a porphyrin source. The purpose of this study was to further investigate the binding and subsequent utilization of human hemoglobin by P. endodontalis. P. endodontalis binds hemoglobin and reduces the Fe(III) porphyrin, resulting in a steady accumulation of ferrous hemoglobin. Reduction of methemoglobin was similar to the extracellular reduction of nitrobluetetrazolium in the presence of oxidizable substrate. Turbidimetric and viable cell determinations showed that P. endodontalis grew when supplied only hemoglobin. Therefore, we conclude that hemoglobin appears to serve as a sole carbon and nitrogen source, and that these bacteria reduce extracellular compounds at the expense of oxidized substrates.
authors.affiliation: Dows Institute for Dental Research, College of Dentistry, University of Iowa, Iowa City 52242, USA.
authors.forename: M
authors.initials: M
authors.lastname: Zerr
authors.forename: D
authors.initials: D
authors.lastname: Drake
authors.forename: W
authors.initials: W
authors.lastname: Johnson
authors.forename: C D
authors.initials: CD
authors.lastname: Cox
mesh_terms: D000693:Anaerobiosis; D015169:Colony Count, Microbial; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007202:Indicators and Reagents; D007501:Iron / Q000378:metabolism; D008706:Methemoglobin / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D009580:Nitroblue Tetrazolium; D010084:Oxidation-Reduction; D010858:Pigmentation; D011166:Porphyrins / Q000378:metabolism; D017861:Porphyromonas / Q000254:growth & development / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D006454:Hemoglobins; D007202:Indicators and Reagents; D011166:Porphyrins; D009580:Nitroblue Tetrazolium; D008706:Methemoglobin; D007501:Iron