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Microbiota influences odor detection in mice

The impact of the microbiota on the gut epithelium is clearly now well described but very few studies have been made on the other epithelia. While both epithelia share similar structures, the olfactory epithelium where the first step of odorant detection occurs has been ignored in terms of potential influence of the microbiota. Researchers have found that when the microbiota is absent, both olfactory epithelium development and its capacity to detect odors are affected.

Microbiota, the intestinal revolution. © INRA, Shutterstock
Updated on 05/10/2017
Published on 05/10/2017

Context and challenge:

A better understanding of the sensory modalities is required in order to improve palatability of food and animal welfare in livestock feeding. The olfactory system is essential in both feeding behavior and social interactions. Microbiota could affect most of the first steps of odorant detection.

● By altering the olfactory epithelium turnover

● By producing metabolites recognized as odorant

● By metabolizing environmental odorants

These changes could in turn modulate animal feeding behaviour as well as its social interactions for both livestock and experimental models.


By studying variations of the olfactory system in germfree mice, we have shown that the absence of microbiota did not impact the olfactory epithelium as much as in the gut. However, while the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. We also recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice. These changes were associated with a decreased transcription level of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium.


This work opens a new perspective of microbiota influence on animal physiology. As olfaction is very important for most animal behaviour, the influence of the microbiota on various animal parameters could be linked to changes in olfaction. Further research is needed to clarify whether the nature of the microbiota could differentially impact olfactory preferences.

Scientific contact(s):

Associated Division(s):
Animal Physiology and Livestock Systems
Associated Centre(s):


Francois, A. et al. Olfactory epithelium changes in germfree mice. Scientific reports 6, 24687, doi:10.1038/srep24687 (2016).