High-throughput sequencing identifies salivary microbiota in Chinese caries-free preschool children with primary dentition

Objectives:The study aimed at identifying salivary microbiota in caries-free Chinese preschool children using highthroughput sequencing.Methods:Saliva samples were obtained from 35 caries-free preschool children(18 boys and 17 girls)with primary dentition,and 16 S ribosomal DNA(r DNA)V3–V4 hypervariable regions of the microorganisms were analyzed using Illumina MiSeq.Results:At 97%similarity level,all of these reads were clustered into 334 operational taxonomic units(OTUs).Among these,five phyla(Firmicutes,Proteobacteria,Actinobacteria,Bacteroidetes,and Candidate division TM7)and13 genera(Streptococcus,Rothia,Granulicatella,Prevotella,Enterobacter,Veillonella,Neisseria,Staphylococcus,Janthinobacterium,Pseudomonas,Brevundimonas,Devosia,and Gemella)were the most dominant,constituting 99.4%and 89.9%of the salivary microbiota,respectively.The core salivary microbiome comprised nine genera(Actinomyces,Capnocytophaga,Gemella,Granulicatella,Lachnoanaerobaculum,Neisseria,Porphyromonas,Rothia,and Streptococcus).Analysis of microbial diversity and community structure revealed a similar pattern between male and female subjects.The difference in microbial community composition between them was mainly attributed to Neisseria(P=0.023).Furthermore,functional prediction revealed that the most abundant genes were related to amino acid transport and metabolism.Conclusions:Our results revealed the diversity and composition of salivary microbiota in caries-free preschool children,with little difference between male and female subjects.Identity of the core microbiome,coupled with prediction of gene function,deepens our understanding of oral microbiota in cariesfree populations and provides basic information for associating salivary microecology and oral health.