Porphyrin Production and Regulation in Cutaneous Propionibacteria.

Porphyrins are intermediate metabolites in the biosynthesis of vital molecules, including heme, cobalamin, and chlorophyll. Bacterial porphyrins are known to be proinflammatory, with high levels linked to inflammatory skin diseases. species are dominant skin commensals and play essential roles in defending against pathogens and in triggering an inflammatory response. To better understand how the inflammatory potential of the skin microbiome may vary depending on its propionibacterial composition, we compared the production levels of porphyrins among , , , and strains. We found that porphyrin production varied among these species, with type I strains producing significantly larger amounts of porphyrins than type II and III strains and other species. strains that are highly associated with the common skin condition acne vulgaris responded to vitamin B supplementation with significantly higher porphyrin production. In contrast, vitamin B supplementation had no effect on the porphyrin production of health-associated strains and other propionibacteria. We observed low-level porphyrin production in most strains harboring the repressor gene, with the exception of strains belonging to type I clades IB-3 and IC. Our findings shed light on the proinflammatory potential of distinct phylogenetic lineages of as well as other resident skin propionibacteria. We demonstrate that the overall species and strain composition is important in determining the metabolic output of the skin microbiome in health and disease. Porphyrins are a group of metabolites essential to the biosynthesis of heme, cobalamin, and chlorophyll in living organisms. Bacterial porphyrins can be proinflammatory, with high levels linked to human inflammatory diseases, including the common skin condition acne vulgaris. Propionibacteria are among the most abundant skin bacteria. Variations in propionibacteria composition on the skin may lead to different porphyrin levels and inflammatory potentials. This study characterized porphyrin production in all lineages of , the most dominant skin , and other resident skin propionibacteria, including , , and We revealed that type I strains produced significantly more porphyrins than did type II and III strains and other species. The findings from this study shed light on the proinflammatory potential of the skin microbiome and can be used to guide the development of effective acne treatments by modulating the skin microbiome and its metabolic activities.