The skin microbiome provides important functions to support human health, yet the modes of acquisition of these microbes to the skin remains vague. Although the skin microbiome is shaped strongly by biogeography, it also reflects a strong degree of individuality that could be explained by differential exposures to microbial communities in the environment. Furthermore, the built environment has been suggested as an important reservoir that contains microbial communities likely sourced from humans, plants, and soil (Dunn et al., 2013). We know that humans can colonize the built environment (Lax et al., 2014), but it is less well understood if the built environment could colonize human beings. The objective of the present study was to assess the ability of microbial communities commonly found in the built environment (those from humans, houseplant leaves, and soil) to persist on the skin of human subject volunteers after a controlled dispersal event. Dispersal was manipulated in three distinct ways: direct transfer of microbial communities to the skin using a sterile swab, transfer via an inoculated built environment surface, and indirect transfer from naturally inoculated air. After the dispersal event, non-destructive swab samples were taken at the recipient site 2-, 4-, and 8- hours post-transplant.
Across subjects, one skin-to-skin direct transplant type (sebaceous to moist) resulted in a post-transplant profile significantly similar to that of the donor community and persisted for 8 hours. The direct transfer of plant leaf and soil communities to the skin also resulted in a post-transplant profile similar to that of the donor community that persisted for 8 hours. The indirect (inoculated tile surface) transfer of plant leaf and soil communities to the skin resulted in a less significant community shift over time, while the indirect transfer from naturally inoculated air resulted in no noticeable community shift on the skin of participants. In order to successfully manipulate the human skin microbiome to improve health, it is essential to understand the dynamics of microbial acquisition on the skin. Here, we show that microbial communities are able to persist on the skin of human subjects over 8 hours, under specific conditions. As recipient habitats, moist and dry skin sites are more amenable to transplant than sebaceous skin habitats, while the sebaceous community is a more successful donor community than the moist and dry communities. Finally, direct swab inoculation (rather than indirect surface or air) produces the most significant recipient community shift over time.