Long-term robustness of the skin microbiome as a stable personal identity

Background: Inter-individual variability of the human skin microbiome is known to be greater than the temporal variability for an individual. However, the identification of individuals using the human skin microbiome has shown low accuracy in recent studies. Here, we demonstrate an accurate personal identification method using the human skin microbiome that can distinguish individuals even beyond a one-year sampling interval. Results: We found that the personal skin microbiome was relatively stable over one year. Therefore, we could identify individuals with >90% accuracy using the taxonomic composition of their skin microbiome. In addition, some contributors to the personal identification were bacterial species observed not only in humans but also in the environment. Conclusions: We demonstrate that the human skin microbiome represents a type of personal identity in addition to the human genome. Long-term stability of the skin microbiome thus expands the definition of the known human genetic universe. Hence, the skin microbiome is strongly controlled by its host. These results will help us understand the relationship between the human skin microbiome and health.