title: Profiling of dental plaque microflora on root caries lesions and the protein-denaturing activity of these bacteria.
abstract: OBJECTIVE
  To profile plaque microflora on root-caries lesions, and to examine the protein-denaturing activity as a pilot study.
  
  
  METHODS
  Six subjects with root-caries were investigated. Plaque samples on root caries lesions (R), as well as from healthy supragingival sites (S) and periodontal pockets (> or = 5 mm) (P) were collected and cultured anaerobically on blood agar plates. The isolated bacteria were identified by 16S rRNA sequencing analysis, and examined for the protein-denaturing activity using the skim-milk plates and the SDS-PAGE, and for the acidogenicity using the FAB broth containing 1% glucose.
  
  
  RESULTS
  Propionibacterium, Actinomyces, Streptococcus, Lactobacillus and Bifidobacterium were predominant in R, while Actinomyces, Streptococcus, Veillonella and Capnocytophaga in S, and Actinomyces, Prevotella, Actinobaculum, Streptococcus, Olsenella and Eubacterium were predominant in P. Proteolytic bacteria comprised 40%, 26% and 57% of microflora in R, S and P, respectively. The skim-milk plates distinguished between protein-degrading and protein-coagulating bacteria, which comprised 7 and 33%, 0 and 26%, and 17 and 40% of microflora, in R, S and P, respectively. The SDS-PAGE analysis revealed that protein-degrading isolates were capable of degrading collagen molecules. Furthermore, the final culture pHs of protein-degrading and -coagulating bacteria were 5.0-5.4 and 3.8-3.9, respectively. The latter pH was low enough to denature proteins in skim milk. The microbial composition of R was distinct from those of S and P.
authors.affiliation: Division of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Takuichi
authors.initials: T
authors.lastname: Sato
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Shimauchi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Takahashi
mesh_terms: D000368:Aged; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism; D004269:DNA, Bacterial / Q000032:analysis; D003739:Dental Cementum / Q000378:metabolism; D003773:Dental Plaque / Q000382:microbiology*; D003804:Dentin / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D008894:Milk Proteins / Q000378:metabolism; D010514:Periodontal Pocket / Q000382:microbiology; D010865:Pilot Projects; D011489:Protein Denaturation; D059748:Proteolysis; D017213:Root Caries / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D008894:Milk Proteins; D003094:Collagen