Abstract

BackgroundBacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth. The highly stimulatory effect of porphyrins on Bacteroides growth lead us to propose their use as a potential determinant of bacterial colonization. However, showing a role for porphryins would require sensitive detection methods that work in complex samples such as feces.ResultsWe devised a highly sensitive semi-quantitative porphyrin detection method (detection limit 1-4 ng heme or PPIX) that can be used to assay pure or complex biological samples, based on Bacteroides growth stimulation. The test revealed that healthy colonized or non-colonized murine and human hosts provide porphyrins in feces, which stimulate Bacteroides growth. In addition, a common microbiota constituent, Escherichia coli, is shown to be a porphyrin donor, suggesting a novel basis for intestinal bacterial interactions.ConclusionsA highly sensitive method to detect porphyrins based on bacterial growth is devised and is functional in complex biological samples. Host feces, independently of their microbiota, and E. coli, which are present in the intestine, are shown to be porphryin donors. The role of porphyrins as key bioactive molecules can now be assessed for their impact on Bacteroides and other bacterial populations in the gut.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0616-0) contains supplementary material, which is available to authorized users.

Highlights

  • IntroductionBacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth

  • Bacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins for normal growth

  • Heme-PPIX-screen setup to detect heme via Bacteroides thetaiotaomicron (Bt) growth stimulation A vertical gel setup was designed such that Bt was suspended in porphyrin-free medium in the gel

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Summary

Introduction

Bacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth. Are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth. The highly stimulatory effect of porphyrins on Bacteroides growth lead us to propose their use as a potential determinant of bacterial colonization. Bacteroides are dominant anaerobes of the human intestinal flora [1]. These bacteria are auxotrophic for protoporphyrin IX (PPIX, which is metal-free) or heme (Fe-charged-PPIX) (collectively called porphyrins; for review; [2, 3]). Bacteroides are capable of charging PPIX with Fe, and can fulfill their heme requirement when supplied with PPIX [9]

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