Calcium binding to S. mutans grown in the presence or absence of sucrose

Tarcísio Jorge Leitão,Guilherme Ishi,Jaime Aparecido Cury,Livia Maria Andaló Tenuta

doi:10.1590/s1806-83242012000200003

Tarcísio Jorge Leitão, Guilherme Ishi + Show 2 more

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https://doi.org/10.1590/s1806-83242012000200003

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Journal: Brazilian Oral Research	Publication Date: Apr 1, 2012
Citations: 7	License type: cc-by

Affiliation: Universidade Estadual de Campinas

Abstract

Sucrose is the most cariogenic dietary carbohydrate because it is a substrate for insoluble extracellular polysaccharide (IEPS) production in dental biofilms, which can proportionally decrease bacterial density and, consequently, the number of biofilm calcium (Ca) binding sites. Ca bound to bacterial cell walls can be released into the biofilm fluid during a cariogenic challenge, reducing the driving force for mineral dissolution provoked by the pH drop. Thus, we investigated the effect of an IEPS-rich extracellular matrix on bacterial Ca binding after treatment with Ca solutions. Streptococcus mutans Ingbritt 1600 was cultivated in culture broths supplemented with 1.0% sucrose or 0.5% glucose + 0.5% fructose. The IEPS concentration in bacterial pellets was determined after alkaline extraction. Bacterial pellets were treated with 1 mM or 10 mM Ca++ solutions at 37ºC for 10 to 60 min. Ca binding to bacterial pellets, determined after acid extraction using the Arsenazo III reagent, was fast and concentration dependent. Although the IEPS concentration was approximately ten times higher in bacterial pellets cultivated in sucrose as compared to its monossaccharides, bound Ca concentration after Ca treatment was similar in both conditions. These results suggest that IEPS may not influence the amount of Ca bound to reservoirs of dental biofilms.

Highlights

There is considerable evidence demonstrating that sucrose is the most cariogenic carbohydrate from the human diet,[1] with enhanced cariogenicity as compared to its component monosaccharides, glucose and fructose.[2]
Since insoluble extracellular polysaccharide (IEPS) decrease the bacterial density of biofilms,[7,8] they may reduce the amount of biofilm calcium (Ca) binding sites[9], which could influence biofilm cariogenicity
Bacterial preparation S. mutans Ingbritt 1600 was cultivated in Todd-Hewitt broth (THB) (Difco Labs., Detroit, USA) supplemented with 1% sucrose or 0.5% glucose + 0.5% fructose for 18 h at 10% pCO2 and 37°C

Summary

Introduction

There is considerable evidence demonstrating that sucrose is the most cariogenic carbohydrate from the human diet,[1] with enhanced cariogenicity as compared to its component monosaccharides, glucose and fructose.[2] The reason for this relies on the fact that sucrose, besides being fermented to acids, is used by oral bacteria to synthesize extracellular polysaccharides (EPS).[3] These EPS, mainly the insoluble ones (IEPS), play a significant role on the adhesion and accumulation of cariogenic streptococci on the tooth surface, especially S. mutans.[4] In addition, they change the biofilm structure, resulting in increased porosity,[5] which allows fermentable substrates to diffuse and be metabolized in the deepest parts of the biofilm.[6]. Since IEPS decrease the bacterial density of biofilms,[7,8] they may reduce the amount of biofilm calcium (Ca) binding sites[9], which could influence biofilm cariogenicity.

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