Role of extracytoplasmic function sigma factors in biofilm formation of Porphyromonas gingivalis

Satosu Onozawa, Yuichiro Kikuchi, Kazuko Shibayama, Eitoyo Kokubu, Masaaki Nakayama, Tetsuyoshi Inoue, Keisuke Nakano, Yukinaga Shibata, Naoya Ohara, Koji Nakayama, Kazuyuki Ishihara, Toshiyuki Kawakami, Hiromasa Hasegawa

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Background: Porphyromonas gingivalis has been implicated as a major pathogen in the development and progression of chronic periodontitis. P. gingivalis biofilm formation in the subgingival crevice plays an important role in the ability of the bacteria to tolerate stress signals outside the cytoplasmic membrane. Some bacteria use a distinct subfamily of sigma factors to regulate their extracytoplasmic functions (the ECF subfamily). The objective of this study was to determine if P. gingivalis ECF sigma factors affect P. gingivalis biofilm formation. Methods: To elucidate the role of ECF sigma factors in P. gingivalis, chromosomal mutants carrying a disruption of each ECF sigma factor-encoding gene were constructed. Bacterial growth curves were measured by determining the turbidity of bacterial cultures. The quantity of biofilm growing on plates was evaluated by crystal violet staining. Results: Comparison of the growth curves of wild-type P. gingivalis strain 33277 and the ECF mutants indicated that the growth rate of the mutants was slightly lower than that of the wild-type strain. The PGN_0274- and PGN_1740-defective mutants had increased biofilm formation compared with the wild-type (p < 0.001); however, the other ECF sigma factor mutants or the complemented strains did not enhance biofilm formation. Conclusion: These results suggest that PGN_0274 and PGN_1740 play a key role in biofilm formation by P. gingivalis.

Original languageEnglish
Article number4
JournalBMC Oral Health
Issue number1
Publication statusPublished - Dec 12 2015


  • Biofilm
  • Extracytoplasmic function sigma factor
  • Periodontal disease
  • Porphyromonas gingivalis

ASJC Scopus subject areas

  • Dentistry(all)


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