SOIL2GUT: From Soil to Gut: Tracing Nature’s Hidden Connections

Exposure to environmental microorganisms through contact with soil affects mammalian immune function and gut bacteria. It is unknown, however, whether these impacts are conditional on the specific origin of the soil and/or extend to the gut fungi. Using a wild animal model Clethrionomys glareolus we quantified whether soil from urban areas or national parks elicited comparable responses in the host’s gut microbiota and immune function. Overall, soil exposure altered gut microbiota composition and organization, but gut fungi responded more strongly than bacteria. Notably, exposure to urban soil stimulated innate immunity activation characterized by epithelial defenses. Our results demonstrate that the outcomes of biodiversity intervention extend beyond the gut bacteria to the gut fungi, and are conditional on the origin of the soil. These findings indicate how anthropogenic impacts on soil, such as those impacting microbial biodiversity in urban areas, can affect key components of health in humans and wildlife.