title: Characterization of saliva microbiota's functional feature based on metagenomic sequencing.
abstract: OBJECTIVE
  Saliva, a mixture of exocrinally secretive fluids, amounts to ~1.5 L daily and harbors numerous microbial inhabitants. However, except the organismal structure of saliva microbiota, the functional profile of saliva microbiota remain elusive.
  
  
  METHODS
  Here we used metagenomic sequencing to experimentally reconstruct the global genomic profile of saliva by sequencing total saliva DNA from two healthy and two caries-active (DMFT ≧ 6) adults.
  
  
  RESULTS
  We found that saliva microbiota, representing 30-60% of total saliva DNA in our samples, might carry functional signatures that were site-specific and caries-state-specific. Among microbiota from different hosts, a prominent functional core, but not an organismal core, was identified. Each microbiota exhibited functional redundancy where dominant genomes tend to encode more functional diversity yet without necessarily contributing to dominant functions. Furthermore, genetic polymorphisms of hosts were also unraveled from salivary DNA without apparent physical or sequence bias in human chromosomes.
  
  
  CONCLUSIONS
  The microbial functional sensitivity to disease, links to specific functions, and permission of simultaneous genotyping of hosts and microbiota suggested sequencing salivary DNA might be an advantageous venue in uncovering both human and microbial basis of oral infections.
authors.affiliation: Department of Stomatology, Qingdao Municipal Hospital, Qingdao, 266011 Shandong China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Shandong Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels and BioEnergy Genome Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 Shandong China.
authors.forename: Kang
authors.initials: K
authors.lastname: Ning
authors.affiliation: Shandong Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels and BioEnergy Genome Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 Shandong China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Shandong Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels and BioEnergy Genome Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 Shandong China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Shandong Key Laboratory of Energy Genetics, CAS Key Laboratory of Biofuels and BioEnergy Genome Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101 Shandong China.
authors.forename: Xiaoquan
authors.initials: X
authors.lastname: Su
authors.affiliation: Department of Stomatology, Qingdao Municipal Hospital, Qingdao, 266011 Shandong China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yuan
keywords: Caries; Function; Metagenome; Microbiota; Saliva; Whole-ecosystem sequencing