A Reum Kim1, Ki Bum Ahn1, Hyun Young Kim1, Ho Seong Seo2, Cheol-Heui Yun3, Seung Hyun Han4. 1. Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea. 2. Radiation Biotechnology Research Division, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea. 3. Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea. 4. 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.
Abstract
INTRODUCTION: 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.
INTRODUCTION: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.
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