title: Serine-rich Repeat Adhesin Gordonii Surface Protein B is Important for Streptococcus gordonii Biofilm Formation.
abstract: BACKGROUND
  Streptococcus gordonii is a predominant member of the oral microflora and has been isolated from root canals of teeth with refractory apical periodontitis. Biofilm formation is important for various dental diseases, and S. gordonii is involved in dental biofilm formation as an early colonizer. Although serine-rich repeat (SRR) adhesins of S. gordonii such as gordonii surface protein B (GspB) are associated with bacterial colonization, the role of GspB in biofilm formation is not clearly understood. In the present study, we investigated the effect of S. gordonii GspB on biofilm formation using wild-type and GspB-deficient mutant S. gordonii strains.
  
  
  METHODS
  Confocal microscopy and crystal violet assay were used to determine biofilm formation. Bacterial growth was examined by measuring optical density with spectrometry. Bacterial adherence and biofilm on the culture plate and human dentin slices were visualized with a scanning electron microscope.
  
  
  RESULTS
  The GspB-deficient S. gordonii mutant strain was less potent than the wild-type strain in biofilm formation. Of note, there was no difference in the bacterial growth rate between the mutant and wild-type strains. Differences in biofilm-forming ability between the wild-type and mutant strains were more distinct in the sucrose-supplemented media. Furthermore, the GspB-deficient mutant exhibited attenuated formation of aggregates on the surface of the culture plate and human dentin slices.
  
  
  CONCLUSIONS
  These results suggest that GspB is important for S. gordonii biofilm formation, which may contribute to the development of dental biofilm-associated diseases.
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: A Reum
authors: AR
authors: Kim
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Ki Bum
authors: KB
authors: Ahn
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Hyun Young
authors: HY
authors: Kim
authors: Radiation Biotechnology Research Division, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea.
authors: Ho Seong
authors: HS
authors: Seo
authors: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
authors: Cheol-Heui
authors: CH
authors: Yun
authors: Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea. Electronic address: shhan-mi@snu.ac.kr.
authors: Seung Hyun
authors: SH
authors: Han
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D003804:Dentin / Q000382:microbiology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D012694:Serine / Q000378:metabolism*; D054773:Streptococcus gordonii / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D012694:Serine; D013395:Sucrose
keywords: Biofilm formation; Streptococcus gordonii; gordonii surface protein B; human dentin; serine-rich adhesin