Oral Microbiota In Early Childhood Caries:Studies On Community Structure And Novel Cariogenic Pathogen

Oral microbiota plays a critical role in the pathogenesis of dental caries.However,current studies on the oral microbiome in dental caries via sequencing are usually limited to the level of genus.In present study,oral microbiome in early childhood caries were revealed by Pacbio single-molecule sequencing technology.Bacteria which may be associated with the occurrence of dental caries were screened out.Abilities of Prevotella histicola to adhere and produce acid were investigated in vitro.By whole genome sequencing,the whole gene map of the bacterium was revealed,the cariogenic mechanisms and associated genes were predicted.Method:Saliva of children with or without caries was collected.Genome DNA of bacteria was extracted and single-molecule sequencing was performed.The structure of microbiome was revealed at the level of species.New suspects respobsible for the occurance of dental caries were screened out by the analysis including caries susceptible population.Specific bacterium selected was studied in vitro to reveal the abilities of adherence and acid-production.The whole genome of the new cariogenic pathogen was mapped by illumine Hi-seq sequencing.Results:1 Oral microbiome in dental cariesThe oral microbiome among children with dental caries have greater variability than those of children without caries.The dominant bacteria in dental caries were classified to Firmicutes at phylum level,Lactobacillus,Mogibacterium,Dialister,ect.at genus level,and Streptococcus mutans,Veillonella atypical,Veillonella denticariosi,Streptococcus sobrinus,Prevotella histicola,etc.at species level.2 Verification of cariogenic abilities of suspected cariogenic bacterium in vitroPrevotella histicola showed strong abilities of adhesion and acid-production in vitro.After 1,3,5,7 days,surfaces of the enamel in bacterial cultivations were demineralized,with decreased hardness and changed morphology.3 Whole genome sequencing of Prevotella histicola2334 coding genes of Prevotella histicola have been detected by whole genome sequencing.Prevotella histicola was predicted to produce acetic acid and lactic acid by fermentation of glucose.The ability of adhesion was speculated dependenting on the structure of lipopolysaccharide and capsule on the cell surface,as well as the active quorum sensing system.Conclusion:1 Oral microbiomes of children with or without caries differ from each other.Specific bacteria have been detected suggesting important roles in the occurrence and process of dental caries.2 The bacterium Prevotella histicola has strong cariogenic potentials.3 The whole genome of Prevotella histicola was mapped and the cariogenic genes were screened out.