Stimulation of Fusobacterium nucleatum biofilm formation by Porphyromonas gingivalis.
OBJECTIVE
Bacterial infection is a major cause of periapical periodontitis. Eradication of these microorganisms from apical lesions is essential to the success of endodontic treatment. The aim of this study was to clarify the molecular interaction between Fusobacterium nucleatum, Porphyromonas gingivalis and other microorganisms associated with periapical periodontitis.


METHODS
Microorganisms isolated from periapical lesions were inoculated into type-I collagen-coated polystyrene microtiter plates and maintained at 37 degrees C under anaerobic conditions for 2 days, after which, the quantity of organized biofilm on the plates was evaluated by crystal violet staining. Growth enhancement via soluble factor was evaluated by separated coculture using a 0.4-mum membrane filter.


RESULTS
F. nucleatum exhibited strong adherence to type-I collagen-coated polystyrene microplates. Biofilm formation by F. nucleatum was significantly enhanced by P. gingivalis. It was complemented by compartmentalized coculture with P. gingivalis. Enhancement of biofilm formation by P. gingivalis was only slightly reduced by inactivation of its autoinducer-2-producing gene luxS.


CONCLUSIONS
The results suggest that P. gingivalis enhances biofilm formation by F. nucleatum by releasing diffusible signaling molecules other than autoinducer-2.
Saito
Y
Y
Department of Endodontics, Pulp and Periapical Biology, Tokyo Dental College, Chiba, Japan.
Fujii
R
R
Nakagawa
K-I
KI
Kuramitsu
H K
HK
Okuda
K
K
Ishihara
K
K
D000693:Anaerobiosis; D001422:Bacterial Adhesion / Q000502:physiology; D016866:Bacteroidaceae Infections / Q000382:microbiology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018920:Coculture Techniques; D024042:Collagen Type I; D004396:Coloring Agents; D003470:Culture Media; D017077:Culture Media, Conditioned; D005674:Fusobacterium Infections / Q000382:microbiology; D016967:Fusobacterium nucleatum / Q000254:growth & development / Q000502:physiology*; D005840:Gentian Violet; D006714:Homoserine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D007783:Lactones / Q000494:pharmacology; D050296:Microbial Viability; D010485:Periapical Periodontitis / Q000382:microbiology; D016966:Porphyromonas gingivalis / Q000254:growth & development / Q000502:physiology*; D013212:Staphylococcus epidermidis / Q000502:physiology; D013298:Streptococcus sanguis / Q000502:physiology; D013696:Temperature
D024042:Collagen Type I; D004396:Coloring Agents; D003470:Culture Media; D017077:Culture Media, Conditioned; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D005840:Gentian Violet