ABSTRACT
The skin microbiota is an inseparable component of the skin barrier structure, which participates in the stabilization or impairment of the barrier function as well as the development of many skin diseases. To characterize the normal skin microbiota and its association with skin sites, age and sex, we recruited 50 volunteers divided into children, adolescents, young adults, middle-aged adults and the elderly. The skin sites consisted of cheeks, volar forearms (representing dry environments) and upper back (representing sebaceous environments). A total of 9 574 365 high-quality sequences of the V3 to V4 region of the 16S rRNA gene were annotated with taxonomic information related to two archaeal phyla (Thaumarchaeota and Euryarchaeota) and five dominant bacterial phyla (Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes and Cyanobacteria). The skin bacteria community structure was influenced by skin sites, and was closely related to age and sex. The upper back was dominated by Propionibacterium and Staphylococcus, and the cheeks facilitated the survival of Betaproteobacteria, while Alphaproteobacteria were prevalent on the volar forearms. Regarding the effects of age, after sexual maturity, the cheek microbiota became more similar to sebaceous sites (i.e. the upper back). The volar forearms appeared to experience the aging process earlier than the other two sites. The elderly had greater species richness and diversity and their community composition no longer had skin-site selectivity. Males had a greater species richness than females, but the sex differences in the community structure only present at certain age groups and skin sites.
