In the early 1900s, the house mouse (Mus musculus) was introduced to the laboratory as one of the pioneer (genetic) model organisms. Accordingly, it is extensively used as a model in dermatological and host-microbe research. However, the typical environment in which lab mice are bread differs from their original environment. Consistent with the notion that human hygiene and living conditions may influence immune disorders (e.g. the “hygiene hypothesis”), it is now clear that mice display different immune responses depending on the presence of a lab- versus wild-derived (gut) microbiota, but no information on the skin microbiota of free-living house mice was available. Given the potential insight on the outcome of mouse models of skin disease, we asked the question to what degree the microbial communities inhabiting lab mouse skin resemble those of their wild relatives.
To obtain a first insight into the wild mouse skin microbiota, we analyzed >200 wild–caught mice from field sites in South France and compared them to three laboratory mouse colonies housed in different facilities, including the strain most widely used in biomedical research, C57BL/6. This on the one hand revealed that despite radically different living conditions, the overall bacterial composition of wild and laboratory mice is quite similar, indicating strong control of microbial colonization by the host. On the other hand, we identified distinct and possibly functionally important differences among wild mice, including evidence of a rare biosphere and the diversity and dominance of members of the Staphylococcus genus. In particular, taxa belonging to Staphylococcus in the wild most closely match known novobiocin-resistant species, which interestingly also coincides with the unique presence of taxa belonging to the genus Streptomyces (phylum Actinobacteria).
Conclusion and outlook
We provide the first thorough description of the skin microbiota of wild house mice. The differences observed in our study could represent candidates for differential outcome in skin disease models, including Staphylococcus traits. Thus, future experimental evaluation of these taxa in the mouse skin, as well as the use of wild mice, would be warranted.