title: Molecular analysis of human oral microbiota.
abstract: OBJECTIVE
  The application of molecular, mainly 16S ribosomal RNA (rRNA)-based approaches enables researchers to bypass the cultivation step and has proven its usefulness in studying the microbial composition in a variety of ecosystems, including the human oral cavity. In this mini-review, we describe the impact of these culture-independent approaches on our knowledge of the ecology of the human oral cavity and provide directions for future studies that should emphasize the role of specific strains, species and groups of microbes in periodontal disease.
  
  
  METHODS
  Recent findings are summarized to elucidate the relationship between periodontal disease and human oral microbiota, including as-yet-to-be-cultured organisms.
  
  
  RESULTS
  The real-time polymerase chain reaction (PCR) method was developed to detect and quantify periodontopathic bacteria, such as Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis (formerly Bacteroides forsythus) and Treponema denticola. The checkerboard DNA-DNA hybridization technique allowed enumeration of large numbers of species in very large numbers of samples. 16S rRNA gene clone library analysis revealed the diversity of human oral microbiota and the existence of as-yet-to-be-cultured organisms that are presumed periodontal pathogens. In addition, terminal restriction fragment length polymorphism (T-RFLP) analysis was applied for assessment of diversity of human oral microbiota.
  
  
  CONCLUSIONS
  Culture-independent approaches are useful for studying the microbial ecology in the human oral cavity and should be useful in the future to elucidate the etiology of periodontal disease.
authors.affiliation: Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Center, Wako, Saitama, Japan. sakamoto@jcm.riken.jp
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Umeda
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Benno
mesh_terms: D015342:DNA Probes; D006801:Humans; D025202:Molecular Diagnostic Techniques; D009055:Mouth / Q000382:microbiology*; D010510:Periodontal Diseases / Q000235:genetics / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000032:analysis*
chemical_list: D015342:DNA Probes; D012336:RNA, Ribosomal, 16S