Structure and function of the human skin microbiome

• A new understanding has emerged of links between human physiology and skin microbiota.
• Microbial diversity is governed by genetics and diverse skin environments.
• Host and microbe interactions shape and influence skin health.
• Commensal microorganisms exhibit unique behaviors that permit tolerance.

An abundant and diverse collection of bacteria, fungi, and viruses inhabits the human skin. These microorganisms vary between individuals and between different sites on the skin. The factors responsible for the unique variability of the skin microbiome are only partly understood, but results suggest that host genetic and environmental influences play a major role. Today, the steady accumulation of data describing the skin microbiome, combined with experiments designed to test the biological functions of surface microbes, has provided new insights into links between human physiology and skin microbiota. This review describes some of the current information regarding the skin microbiome and its impact on human health. Specifically, we summarize the present understanding of the function of microbe–host interactions on the skin and highlight some unique features that distinguish skin commensal organisms from pathogenic microbes.