title: Reduction of vitamin K concentration by salivary Bifidobacterium strains and their possible nutritional competition with Porphyromonas gingivalis.
abstract: OBJECTIVE
  To assess the possibility that bifidobacteria compete with Porphyromonas gingivalis for their mutual growth factor vitamin K. This study also examined whether salivary Bifidobacterium species decrease vitamin K concentration in the growth medium.
  
  
  RESULTS
  Sixty-five strains of Bifidobacterium were obtained from 20 of 24 periodontally healthy subjects. Bifidobacterium dentium was most frequently detected in the saliva of subjects, followed by Bifidobacterium adolescentis, Bifidobacterium longum, and Bifidobacterium urinalis. The growth of most Bifidobacterium isolates, except that of B. urinalis, was stimulated by vitamin K. Moreover, the isolates were capable of decreasing vitamin K after incubation, which suggests that bifidobacteria compete with P. gingivalis for vitamin K. In a co-culture, a representative strain -B. adolescentis S2-1 - inhibited the growth of P. gingivalis if it was inoculated in the medium before P. gingivalis.
  
  
  CONCLUSIONS
  B. adolescentis S2-1 decreased vitamin K concentration and inhibited the growth of P. gingivalis by possibly competing for the growth factor.
  
  
  CONCLUSIONS
  Salivary bifidobacteria may possess the potential to suppress the growth of P. gingivalis by reducing the growth factor(s) in the environment.
authors.affiliation: Food Science Institute, Meiji Dairies Co., Odawara, Kanagawa, Japan. kenichi_houjou@meiji-milk.com
authors.forename: K
authors.initials: K
authors.lastname: Hojo
authors.forename: S
authors.initials: S
authors.lastname: Nagaoka
authors.forename: S
authors.initials: S
authors.lastname: Murata
authors.forename: N
authors.initials: N
authors.lastname: Taketomo
authors.forename: T
authors.initials: T
authors.lastname: Ohshima
authors.forename: N
authors.initials: N
authors.lastname: Maeda
mesh_terms: D000328:Adult; D001431:Bacteriological Techniques; D001644:Bifidobacterium / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D005260:Female; D006801:Humans; D008297:Male; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D019936:Probiotics / Q000378:metabolism*; D012463:Saliva / Q000737:chemistry* / Q000382:microbiology*; D014678:Veillonella / Q000378:metabolism; D014812:Vitamin K / Q000032:analysis* / Q000494:pharmacology; D024483:Vitamin K 3 / Q000494:pharmacology; D014815:Vitamins / Q000032:analysis / Q000494:pharmacology
chemical_list: D003470:Culture Media; D014815:Vitamins; D014812:Vitamin K; D024483:Vitamin K 3