The environments we share with others can shape the types of microbes living on our skin, with potential effects on health. New research reveals that regular contact in shared spaces increases the similarity of skin microbes, while oral microbes are more stable and largely influenced by factors such as lifestyle, diet, and age.

The findings, published in Scientific Reports, reveal how environments and social factors shape human microbiotas.

Scientists have known that shared indoor environments could influence microbial communities on the skin. However, it remained unclear how regularly sharing spaces changes microbial diversity and similarity, whether these effects differ between body sites, and how specific environments affect microbiotas. 

To examine how shared environments influence microbes on the skin and mouth, researchers led by Han Lee at Eulji University in Uijeongbu, Korea, collected microbial samples from the fingers and oral cavities of 96 people who shared different environments, including daycare centers, offices, mosques, and universities. The spaces were distinguished between regularly shared spaces and irregularly shared spaces.

Shared microbes

Skin microbes were influenced by how often and regularly spaces were shared, the researchers found. People regularly sharing spaces such as daycare centers and offices had more similar skin microbiotas, suggesting that frequent contact promotes microbial exchange. In contrast, irregularly shared spaces, such as leisure areas, resulted in less microbial similarity.

Unlike skin microbiotas, oral microbiotas were influenced less by shared spaces. Instead, they reflected a person’s lifestyle, diet, and other factors such as age and cultural practices. For example, participants in mosques had distinct oral microbial communities influenced by religious dietary rules, including halal food, while university students had a great abundance of bacteria linked to alcohol consumption.

These findings suggest that while environmental exposure shapes skin microbiotas, oral microbiotas are more stable and shaped by longer-term influences, the researchers say.

Health implications

Skin microbes can carry both beneficial organisms and harmful pathogens, so understanding how regular interactions alter microbial diversity could inform hygiene practices and public health strategies. 

“These insights underscore the dual importance of maintaining hygiene to prevent pathogen transmission while preserving microbial diversity through controlled environmental exposure,” the researchers say. The findings also suggest that oral microbiotas could serve as markers for group-specific habits and cultural practices.

Although more work is needed to explore how shared spaces influence microbial exchange, the authors say, “this study provides crucial foundational data for protecting public health and personal well-being by providing insights into the transmission of diseases in shared environments.”