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KMID : 0355420110350010001
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Journal of Korean Academy of Oral Health
2011 Volume.35 No. 1 p.1 ~ p.9
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Comparison of virulence in xylitol-resistant mutans streptococci exposed to various carbohydrates
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Chung Sun-Young
Kim Ji-Hye
Choi Youn-Hee
Song Keun-Bae
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Abstract
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Objective. This study aimed to compare the cariogenic traits in xylitol-resistant (XR) mutans streptococci (MS) exposed to various carbohydrates.
Methods. To select the XR MS, S. mutans KCTC 3065 and S. sobrinus KCTC 3308 were cultured in TYE medium containing 0.5% glucose and 1% (66 mM) xylitol at 37oC, 10% CO2 conditions for 30 days. Both the strains were divided into the following 4 groups in terms of the culture medium that was used: (1) 0.5% glucose containing basal culture medium (BCM), (2) BCM plus 0.5% sucrose (BCM-S), (3) BCM plus 0.5% fructose (BCM-F), and (4) BCM plus 0.5% maltose (BCM-M). To examine the cariogenic traits, cell growth, acid production, mRNA expressions related to glucan synthesis, and the formation of extracellular polysaccharides (ECPs) in each culture media, they were measured by ELISA, pH meter, real-time RT-PCR, and TEM, respectively in the 4 culture media.
Results. The characteristics of xylitol-resistant MS were identified by confirming that the growth curve on glucose in the presence of xylitol was identical to that in its absence. Both the S. mutans and S. sobrinus expressed the final pH without any significant differences depending on carbohydrate sources. Cell growth, gene expression levels and the formation of ECPs were apparently distinct in S. mutans depending on sugar sources whereas these were not different in S. sobrinus except for BCM-S.
Conclusions. The virulence of XR S. mutans responded differently when grown in various carbohydrates, yet the virulence of XR S. sobrinus, in general, showed no difference depending on sugar sources except for BCM-S. Further study is needed to explain the metabolite mechanism related to carbohydrate sources inside the XR MS cells.
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KEYWORD
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carbohydrates, resistance, S. mutans, S. sobrinus, xylitol
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