title: Temporal Stability of the Salivary Microbiota in Oral Health.
abstract: OBJECTIVE
  Saliva is a biological fluid suitable for biomarker analysis, and differences in the salivary microbiota in oral health and disease have been reported. For such comparative analyses, time of sampling is critical since the bacterial composition may vary throughout the day, i.e., diurnal variation. The purpose of this study is to compare the salivary microbiome over time to determine the optimal time for sampling.
  
  
  METHODS
  Stimulated saliva samples were collected from 5 orally healthy individuals in 4 h intervals for 24 h, and collection was repeated 7 days later (number of samples per person, n = 12, total number of samples, n = 60). Salivary microbiota was analyzed using the Human Oral Microbe Identification using Next Generation Sequencing (HOMINGS), and statistical analysis was performed using the Kruskal-Wallis test with Benjamini-Hochberg's correction for multiple comparisons, cluster analysis, principal component analysis and correspondence analysis.
  
  
  RESULTS
  From a total of 60 saliva samples, 477 probe targets were collectively identified with a mean number of probes per sample of 207 (range: 153-307). Little or no variation in microbial profiles within subjects was observed over time.
  
  
  CONCLUSIONS
  Although there was considerable variation between subjects, microbial profiles within subjects were stable throughout a 24 hour period and after 1 week. Since there is little or no evidence of diurnal variation of the salivary microbiome, time of sampling of saliva is not critical for perturbation or other microbial studies.
authors.affiliation: Section for Periodontology, Microbiology, and Community Dentistry, School of Dentistry, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Daniel
authors.initials: D
authors.lastname: Belstrøm
authors.affiliation: Section for Periodontology, Microbiology, and Community Dentistry, School of Dentistry, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Palle
authors.initials: P
authors.lastname: Holmstrup
authors.affiliation: Department of Oral Medicine, School of Dentistry, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Bardow
authors.affiliation: The Forsyth Institute, Department of Microbiology, Cambridge, Massachusetts, United States of America.
authors.forename: Alexis
authors.initials: A
authors.lastname: Kokaras
authors.affiliation: Department of Immunology & Microbiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nils-Erik
authors.initials: NE
authors.lastname: Fiehn
authors.affiliation: The Forsyth Institute, Department of Microbiology, Cambridge, Massachusetts, United States of America.|Department of Oral Medicine, Infection & Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Paster
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D064307:Microbiota / Q000502:physiology; D009909:Oral Health; D012463:Saliva / Q000382:microbiology* / Q000502:physiology; D013997:Time Factors; D055815:Young Adult