Host traits, lifestyle and environment are associated with the human skin bacteria

BackgroundThe human skin offers diverse ecosystems for microbial symbionts. However, the factors shaping skin-microbiome interactions are still insufficiently characterized. This contrasts to the broader knowledge about the factors influencing the gut microbiota.ObjectivesWe aimed to investigate major patterns of associations of host traits, lifestyle, and environmental factors with skin bacteria in two German populations.MethodsThis is a cross-sectional study with 647 participants from two population-based German cohorts, PopGen (n=294) and KORA FF4 (n=353), totaling 1794 skin samples. The V1-V2 regions of the 16S rRNA gene were sequenced. Associations were tested with two bacterial levels, community (beta-diversity) and 16S rRNA gene amplicon sequence variants (ASVs).ResultsWe validated known associations of the skin microbiota with skin microenvironment, age, body mass index (BMI) and sex. These factors were associated with beta diversity and abundance of ASVs in PopGen, which was largely replicated in KORA FF4. Most intriguingly, dietary macronutrients and total dietary energy were associated with several ASVs. ASVs were also associated with smoking, alcohol consumption, skin pH, skin type, transepidermal water loss, education, and several environmental exposures, including hours spent outdoors. Associated ASVs included members of the genera Propionibacterium, Corynebacterium, and Staphylococcus.DiscussionWe expand the current understanding of factors associated with the skin bacterial community. We show the association of diet with the skin bacteria. Finally, we hypothesize that the skin microenvironment and the host physiology would shape the skin bacterial community at greater extent in comparison to a single skin physiological feature, lifestyle and environmental exposition.