The oral-gut microbiota relationship in healthy humans: identifying shared bacteria between environments and age groups

Although the oral and gut microbiota are vastly different, a subset of 61 ASVs were present in both the oral cavity and gut of the same individual, and represented 1.6% of all ASVs detected. From these, 26 ASVs (classified into 18 genera: <i>Actinomyces</i>, <i>Rothia</i>, <i>Bacteroides</i>, <i>Porphyromonas</i>, <i>Prevotella</i>, <i>Alistipes</i>, <i>Fusobacterium</i>, <i>Neisseria</i>, <i>Haemophilus</i>, <i>Akkermansia</i>, <i>Solobacterium</i>, <i>Granulicatella</i>, <i>Streptococcus</i>, <i>Gemella</i>, <i>Mogibacterium</i>, <i>Dialister</i>, <i>Veillonella</i>, <i>Christensenellaceae R-7 group</i>) were present in both children and adults, suggesting the possibility of persistent colonization of both habitats by these microorganisms, initiating in childhood. Additionally, 62% of shared ASVs were more abundant in the oral cavity, indicating that oral-to-gut translocation may be the main route of translocation between environments, and highlighting that this phenomenon might be more common than previously thought in healthy individuals of all ages.