Taxonomic profiling and functional characterization of the healthy human oral bacterial microbiome from the north Indian urban sub-population.

Poor oral health has broad consequences that can be seen at personal as well as societal levels, especially in developing countries like India. We have limited information on the healthy oral cavity's inhabitant microorganisms that play a crucial role in overall oral health. In a comprehensive culture-independent approach, the bacterial composition of healthy human oral cavities was determined from a sub-population of northern India. During this study, 20 mouthwash-derived metagenomes were explored for identifying bacterial diversity using the 16S rRNA hypervariable V3 region with the MiSeq Illumina platform. On the taxonomy assignment of operational taxonomic units (OTUs), 20 assigned phyla and 162 genera were recovered among the participants. The mean relative abundance revealed that Streptococcus was the dominant genera among the participants. However, at inter-individual analysis, Neisseria and Haemophilus exhibited first-order dominance among five and three healthy individuals, respectively. Correlation studies indicate that Streptococcus shares a strong relationship with Rothia, Corynebacterium, Prevotella, and Veillonella, whereas it was negatively correlated with Neisseria, Aggregatibacter, Porphyromonas, and Fusobacteria like Gram-negative bacteria. Bacterial diversity showed insignificant differences at the level of age and gender within and between the participants. The results support several of the major findings of previous reports on the healthy oral microbiome of the Indian population, however, the present investigation further illustrates that demographic region leaves an impact on overall bacterial composition. The study will assist in a better understanding of the oral microbiome from region-specific Indian population that was otherwise highly under-represented.