Molecular analysis of the prevalent microbiota of human male and female forehead skin compared to forearm skin and the influence of make-up.

AIMS: To compare the bacterial diversity of two different ecological regions including human forehead, human forearm and to estimate the influence of make-up. METHODS AND
RESULTS: Twenty-two swab-scraped skin samples were analysed by profiling bacterial 16S rRNA genes using PCR-based sequencing of randomly selected clones. Of the 1056 clones analysed, 67 genera and 133 species-level operational taxonomic units (SLOTUs) belonging to eight phyla were identified. A core set of bacterial taxa was found in all samples, including Actinobacteria, Firmicutes, and Proteobacteria, but pronounced intra- and interpersonal variation in bacterial community composition was observed. Only 4·48% of the genera and 1·50% of the SLOTUs were found in all 11 subjects. In contrast to the highly diverse microbiota of the forearm skin, the forehead skin microbiota represented a small-scale ecosystem with a few genera found in all individuals. The use of make-up, including foundation and powder, significantly enlarged the community diversity on the forehead skin.
CONCLUSIONS: Our study confirmed the presence of a highly diverse microbiota of the human skin as described recently. In contrast to forearm skin, gender does not seem to have much influence on the microbial community of the forehead skin. However, the use of make-up was associated with a remarkable increase in the bacterial diversity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study enhances our knowledge about the highly complex microbiota of the human skin and demonstrates for the first time the significant effect of make-up on the bacterial diversity of the forehead skin.