Hedgehog Spine and Porcupine Quill 16S Amplicons

A 1925 report suggested that the red fluorescence detected in the spines of the European hedgehog (Erinaceus europaeus) is due to free base porphyrins. In light of the growing number of reports of free base porphyrins - of mostly unknown biological function - occurring in keratinaceous materials, such as feathers and fur, we endeavored to detail the molecular structure of any porphyrin present in European hedgehog spines. Spines irradiated with UV (365-395 nm) light displayed red fluorescence localized in the light-colored sections of their proximal ends. Reflectance fluorescence spectra of the light sections of the hedgehog spines recorded in the UV-vis region were found to be consistent with the presence of at least one free base porphyrin. The porphyrins were extracted by base-induced degradation of the spine matrix, and the extract was analyzed by reverse-phase HPLC employing UV-vis detection, ESI+ mass spectrometry, and by comparison with genuine porphyrin standards, identifying the presence of a mixture of coproporphyrin III, uroporphyrin III, and protoporphyrin IX. The porphyrins are proposed to originate from commensal bacteria, as supported by microbiome sequencing data that indicate the abundant presence of bacteria known to secrete and/or interconvert porphyrins. We suggest the porphyrins have no biological function for the hedgehog. The extraction protocol described will assist in the characterization of porphyrins in other keratinaceous materials.