Suprathreshold non-volatile flavour perception is associated with multiple species rather than any single species via bacterial metabolism.

Background: The microbiome is the characteristic microbial community inhabiting a well-defined habitat with distinct physicochemical properties. During eating, food is masticated and mixed with saliva to form a bolus; non-volatile flavour molecules are released into the saliva and delivered to receptors on the tongue. Throughout this process, the oral microbiome is in direct contact with non-volatile flavour molecules. In this cross-sectional study, we hypothesised that the oral microbiome interacts with non-volatile flavour molecules to modulate suprathreshold taste perception. Materials and methods: Fifty-three participants were included, with suprathreshold sensory data, salivary microbiome data (including both taxonomic and functional profiles), and salivary metabolome data. Associations were explored using fixed-effects linear-regression models and unsupervised clustering. Results: Suprathreshold non-volatile flavour perception was associated with the salivary microbiome via multispecies interactions rather than single-species effects. Taurine (an amino acid and confirmed bacterial metabolite) and ethanolamine (a phospholipid-related metabolite and confirmed bacterial metabolite) showed the greatest number of associations with suprathreshold taste perception in this study (6 of 8 sensory solution each). Conclusion: This study suggested that suprathreshold taste perception was associated with inferred microbial metabolic pathways via multispecies interactions. Because inferred microbial metabolic pathways are encoded by multiple bacteria, they may better capture multispecies contributions than species-level taxonomic profiles.