Is the oral microbiota implicated in taste perception? Investigation of saliva and tongue dorsum using shotgun metagenomics

Background: Taste is a crucial sensation for driving food choices and impairments can lead to eating disorders and malnutrition. Taste perception is triggered by the stimulation of receptors located mainly on the tongue surface by sapid compounds present in foods. However, the tongue surface is covered by a biological film containing saliva and also microorganisms which are suspected to modulate the environment at the vicinity of the taste receptors and then influence their sensitivity to stimulation. Therefore, the aim of the present study is to elucidate the links between the taste sensitivity to the five basic tastes; sweetness, saltiness, sourness, bitterness, umami; and the salivary and tongue microbiota on a panel of 100 subjects. Results: Using the shotgun metagenomics approach, the analysis of the salivary and lingual microbiota allows the identification of 666 bacterial species, saliva being richer than lingual film. Stronger homologies were identified between the two ecosystems for a same subject, compared to those between the different subjects for the same ecosystem. A total of 109 bacterial species were correlated to at least one taste modality. Interestingly, when a species was correlated to at least two taste modalities, the correlations were systematically in the same direction meaning a putative global implication of the various species in taste perception independently of the nature of the taste. Especially, some Streptococcus, Prevotella, SR1 and Rickenellaceae species are correlated to four or five tastes. When comparing both ecosystems, saliva appears to be a better predictor of taste sensitivity compared to lingual film. Conclusions: This research shows the implication of the oral microbiota in taste perception in human at the species level and exhibits specificities in function of the ecosystem considered. Considering the number of species implicated, it appears that the implication of oral microbiota in taste perception is complex and involves different bacterial consortia.