Anaerobic heme recycling by gut microbes: Important methods for monitoring porphyrin production

Heme is the most abundant species of iron inside the human body and an essential cofactor for numerous electron/chemical group transfer reactions and catalyses, especially those involving O₂. Whole anaerobic biomes exist that also depend on heme but lack widespread, O₂-dependent pathways for heme synthesis and breakdown. The gastrointestinal tract is an anaerobic ecosystem where many microbes are auxotrophic for heme, and where the abundant members of the Bacteroidetes phylum convert heme into iron and porphyrins. Working with mixtures of these hydrophobic compounds presents challenges for analyses, especially when their source is biological. In this brief chapter, we detail a handful of important methods and point out caveats necessary for their concurrent detection, separation, and quantification.