Fermented foods (FF) are produced by the transformation of the raw material by microorganisms, giving organoleptic and/or conservation properties to the food. Consequently, they are sources of living microorganisms and there is a body of clue that their regular consumption, in particular the ones containing Lactic Acid Bacteria (LAB), is a promoting factor of human health. Moreover, considering the regularity of the consumption, LAB could modulate the oral microbiota (OM) and the oral functions of the host. The composition of the OM has been shown to be related to taste sensitivity (TS) in human. Therefore, a modulation of the OM could modify TS. Despite a certain disparity between studies, some LAB can persist in the oral cavity from several hours to several days with an important inter-individual variability. The factors at the origin of this variability are not fully known but they could include the oral environment properties such as the oral biology and the interactions with the host OM. Our group has recently shown that oral LAB persistence was lower in rats presenting markers of response to oxidative stress in their saliva. This last finding leads to the hypothesis that a pro-oxidative diet could be an antagonistic factor to the persistence of LAB in the oral cavity. The vegetarian diet has been reported to be less oxidative than the omnivorous diet in many studies. Therefore, subjects who adopted a vegetarian diet appear to be appropriate candidates to study LAB oral persistence and activity. The overall objective of the present project is to elucidate the contribution of oral factors and FF consumption habits on oral LAB persistence and activity and on TS in vegetarian versus omnivorous subjects. The PERSIST project involves 3 research units with expertise in sensory sciences, salivary biochemistry, microbiology and metagenomics.