Relationship between the bacterial community structures on human hair and scalp

In this study, we investigated and compared characteristics of the bacterial community structures on hair (scalp hair) and scalp in 18 individuals. Significant differences were found between the sites, in terms of cell density, alpha and beta diversity, and relative abundance of the phyla, Firmicutes and Proteobacteria, whereas no difference was found in relative abundance of the phylum Actinobacteria. Bacteria of the genus <i>Cutibacterium</i> showed similar relative abundance at both sites, whereas those of genus <i>Pseudomonas</i> were highly abundant on hair, and those of genus <i>Staphylococcus</i> were significantly lesser in abundance on hair than on scalp. Statistical correlations between the sites were high for the individual relative abundance of five major operational taxonomic units (OTUs). This suggests that the bacterial community structure on hair is composed of hair-specific genus, <i>Pseudomonas</i>, and skin-derived genera, <i>Cutibacterium</i> and <i>Staphylococcus</i>, and is distinguishable from other human skin microbiomes. The bacterial community structure on hair was specific and distinguishable from that on scalp, although major bacterial species were commonly present at body sites.