JKAOH Journal of Korean Academy of Oral Health

ISSN(Print) 1225-388X ISSN(Online) 2093-7784


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Original Article

Journal of Korean Academy of Oral Health 2017; 41(1): 22-27

Published online March 30, 2017 https://doi.org/10.11149/jkaoh.2017.41.1.22

Copyright © Journal of Korean Academy of Oral Health.

Red fluorescence of oral bacteria interacting with Porphyromonas gingivalis

Se-Yeon Kim1,2, Dong-Hyeob Woo1, Min-Ah Lee1, Ji-Soo Kim1,2, Jung-Ha Lee1,2, Seung-Hwa Jeong1,2

1Department of Preventive and Community Dentistry, School of Dentistry, Pusan National University, 2BK21 PLUS Project, School of Dentistry, Pusan National University, Yangsan, Korea

Received: December 16, 2016; Revised: January 16, 2017; Accepted: January 26, 2017


Objectives: Dental plaque is composed of 700 bacterial species. It is known that some oral microorganisms produce porphyrin, and thus, they emit red fluorescence when illuminated with blue light at a specific wavelength of <410 nm. Porphyromonas gingivalis belongs to the genus Porphyromonas, which is characterized by the production of porphyrin. The aim of this study was to evaluate red fluorescence emission of some oral microorganisms interacting with P. gingivalis.Methods: Five bacterial strains (P. gingivalis, Streptococcus mutans, Lactobacillus casei, Actinomyces naeslundii, and Fusobacterium nucleatum) were used for this study. Tryptic soy agar medium supplemented with hemin, vitamin K3, and sheep blood was used as a growth medium. The fluorescence emission of bacterial colonies was evaluated under 405 nm-wavelength blue light using a Quantitative Light-induced Fluorescence Digital (QLF-D) camera system. Each bacterium was cultured alone and co-cultured in close proximity with P. gingivalis. The red/green (R/G) ratio of fluorescence image was cal-culated and the differences of R/G ratio according to each growth condition were compared using the Mann-Whitney test (P<0.05).Results: Single cultured S. mutans, L. casei and A. naeslundii colonies emitted red fluorescence (R/G ratio=2.15±0.06, 4.31±0.17, 5.52±1.29, respectively). Fusobacterium nucleatum colonies emitted green fluorescence (R/G ratio=1.36±0.06). The R/G ratios of A. naeslundii and F. nucleatum were increased when P. gingivalis was co-cultured with each bacterium (P<0.05). In contrast, the R/G ratios of S. mutans and L. casei were decreased when P. gingivalis was co-cultured with each bacterium (P=0.002, 0.003).Conclusions: This study confirmed that P. gingivalis could affect the red fluorescence of other oral bacteria under 405 nm-wavelength blue light. Our findings concluded that P. gingivalis has an important role for red fluorescence emission of dental biofilm.

Keywords: Actinomyces naeslundii, Fluorescence, Fusobacterium nucleatum, Lactobacillus casei, Porphyromonas gingivalis, Red fluorescence, Streptococcus mutans