Spatio-Temporal Change of Skin and Oral Microbiota: A Longitudinal Study of Microbial Diversity and Stability

The human skin and oral cavity harbor complex microbial communities, which exist in dynamic equilibrium with the host's physiological state and the external environment. This study investigates the microbial atlas of human skin and oral cavities using samples collected over a 10-month period, aiming to assess how both internal and external factors influence the human microbiome. We examined bacterial community diversity and stability across various body sites, including palm and nasal skin, saliva, and oral epithelial cells, during environmental changes and a COVID-19 pandemic. The skin microbiome was confirmed to display spatial and temporal stability compared to the oral microbiome, particularly the oral epithelium, which was susceptible to changes in the host's physiological state and immune response. Moreover, significant differences in the microbial community structure among the 4 sample types were observed, and 87 distinct bacteria biomarkers were identified. The random forest prediction model achieved an overall prediction accuracy of 95.24% across the four types of samples studied. Additionally, nasal skin samples showed significant promise for individual identification through profiling the skin microbiota. These findings highlight the potential of skin and oral microbiota as forensic markers for inferring body sites and identifying individuals. In summary, despite facing limitations such as a small cohort size and the need for broader validation, this research provides an overall perspective and initial insights for refining experimental designs and conducting in-depth research in various microbial research fields.